Yochum and Rowe’s
ESSENTIALS
OF
SKELETAL
RADIOLOGY
Third Edition
Volume One
Volume One
Yochum and Rowe’s
ESSENTIALS OF
SKELETAL RADIOLOGY
Third Edition
Terry R. Yochum
Lindsay J. Rowe
B.S., D.C., D.A.C.B.R., F.C.C.R. (C), F.I.C.C.,
Fellow, A.C.C.R
Director
Rocky Mountain Chiropractic Radiological Center
Denver, Colorado
Adjunct Professor of Radiology
Southern California University of Health Sciences
Los Angeles, California
Instructor of Skeletal Radiology
Department of Radiology
University of Colorado School of Medicine
Denver, Colorado
Formerly:
Professor of Radiology
Colorado College of Chiropractic
Marycrest International University
Denver, Colorado
Senior Lecturer
Department of Diagnostic Sciences
Division Head
Department of Radiology
Phillip Institute of Technology—School of Chiropractic
Melbourne, Australia
Professor and Chairman
Department of Radiology
Logan College of Chiropractic
St. Louis, Missouri
Assistant Professor of Radiology
National College of Chiropractic
Lombard, Illinois
M.App.Sc (Chiropractic), M.D., D.A.C.B.R.,
F.C.C.R. (C), F.A.C.C.R., F.I.C.C., F.R.A.N.Z.C.R.
Associate Professor, Diagnostic Radiology
Faculty of Medicine
University of Newcastle
Newcastle, Australia
Senior Staff Specialist Radiologist
Department of Medical Imaging
John Hunter Hospital
Newcastle, Australia
Consultant Radiologist
Pittwater Imaging
Gosford, Australia
Formerly:
Research Fellow in Musculoskeletal Radiology
Veterans Administration Hospital
University of California
San Diego, California
Associate Professor and Chairman
Department of Radiology
Northwestern College of Chiropractic
Minneapolis, Minnesota
Associate Professor and Chairman
Department of Radiology
Canadian Memorial Chiropractic College
Toronto, Canada
Executive Editor: Pete Darcy
Managing Editor: Karen Gulliver
Senior Project Editor: Karen Ruppert
Marketing Manager: Christen DeMarco
Designer: Doug Smock
Compositor: Circle Graphics
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Second Edition, 1996
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04 05 06 07 08
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DEDICATIONS
In a profession now 100 years old, a few giants rise above the
crowd. While each giant stands with unique distinction, a common
underlying principle unites them. Longfellow captured the essence:
The heights of great men reached and kept
Were not attained by sudden flight,
But they, while their companions slept,
Were toiling upward through the night.
Henry Wadsworth Longfellow,
“The Ladder of St. Augustine”
Joseph (Jozias) Janse, D.C.
(1909–1985)
T
hrough the hectic hallowed halls of college, first as a student, then as a resident, and finally as a faculty member,
Dr. Joseph Janse was before us as the example of dedication and commitment to a cause. He was more than a college president (National College of Chiropractic 1945–1983). He was more
than a person of international renown in politics, education, research, and chiropractic. Foremost, he was a teacher! Always concerned, “Did you get that?” he would ask, arms raised, elbows
bent, and a stiffened right forefinger pointing toward heaven. You
would think he was asking a higher power if it understood what he
was explaining until he brought his eyes back to focus on his students. He studied their faces waiting for the lights to go on inside.
The English language never received such an exercise as when he
spoke. Uncommon words pierced reality and definitions always
followed with clear examples that even his grandchildren could
understand. An artisan of the highest order, no one could experience his tutelage without being edified while being educated.
From his humble beginnings in Holland, Joe Janse experienced poverty and hard times. Supported by the toils of a dedicated father and mother, two older sisters, and an older brother
hampered with a severe kyphoscoliosis of the spine, “Jozias”
never complained because they were no worse off than anyone
else. The family migrated to Huntsville, Utah, after converting to
Mormonism in Holland. Father Pieter left in advance of the family by nearly a year to work and earn their passage to the New
World. Their newfound religion instilled lasting values of selfworth and compassion without prejudice and added an eternal
perspective to life. Coupled with forced frugality associated
with near frontier farm life, hard work, and a keen desire for excellence, Joe excelled in school. He returned to Europe for 3
years as a self-supported missionary for the Mormon church.
Upon his return, he sought direction for his secular life.
Janse’s mother had experienced severe migraine headaches
and relief came only from the hands of a chiropractor. Intrigued,
young Joe investigated. Soon convinced that chiropractic had
a place, he enrolled at the National School of Chiropractic
(Chicago). The Utah townsfolk, including prominent church leaders whom he respected, discouraged the decision. Undaunted,
J.J. (as so many affectionately called him) excelled as a student
and was invited to join the faculty after his graduation and marriage in 1938. For the next 7 years he would excite and guide
his students in the field of chiropractic. He served as Dean of
Students, and stories abound regarding his willingness to help individuals with their studies, their dissections, and their manipulative techniques.
By 1945, the business manager of the school (the president
had passed away) asked Janse to assume the role of president and
was charged to lead the college out of proprietorship into a nonprofit status, a bold move at the time. In the 1950s, Dr. Janse was
brought up short by a talented lawyer challenging the validity of
chiropractic education because of the absence of an educational
standard developed and maintained by a nationally recognized
accrediting body. As a result, Janse pioneered the creation of the
Council on Chiropractic Education (CCE) and led the charge to
gain accreditation from the North Central Accrediting Association
in 1974. He also pioneered, with his close friend Dr. Fred W. Ilii,
from Geneva, Switzerland, the early research on the movement
of the sacroiliac joints. This work served as a foundation for additional study to document true movement of these joints and
describe their relationship to gait and posture. He generated the
motivation for the development of specialty councils and specialty certification boards on a national level and was one of the
first three board-certified chiropractic radiologists. He placed the
school in deep debt to finance a new campus in Lombard,
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Yochum & Rowe’s Essentials of Skeletal Radiology
Illinois, in the 1960s and then proceeded to become the most
prolific fund-raiser in the history of the National College to meet
the financial challenge. A beautiful campus, debt free, now
stands as a monument to his dedicated stewardship, leadership,
and untiring efforts.
Some memorable quotes come to mind when we think back
to the times of his motivational lectures on life’s principles and
chiropractic philosophy. When asked, “What is it that you do?”
Janse would respond, “I am a chiropractor, nothing more, but incidentally, my friend, nothing less.” Perhaps his most memorable quote came from Rudyard Kipling, which speaks of the
great spirit of understanding and fellowship that Joseph Janse
held for his chiropractic colleagues.
Here’s to the men and women of my own breed,
Good or bitter bad, as though they may be,
At least they hear the things I hear,
And see the things I see.
Few children have the privilege of entering the same profession as
their father. I consider it a real honor to be a second-generation
chiropractor following in my father’s footsteps. Kenneth Emil
Yochum, D.C., my father and best friend, provided the impetus to
enter this great profession of chiropractic.
Kenneth E. Yochum, D.C.
(1914–1989)
K
enneth E. Yochum was a resident of South St. Louis,
Missouri. He graduated from Cleveland High School in
1933 and the Missouri Chiropractic College in 1936. He
was married to Cecelia G. Yochum for 48 years, father of Kay and
Terry, and grandfather to five children. He practiced in South St.
Louis at the Wilmington Chiropractic Clinic for 45 years. Dr.
Yochum presented many lectures at the National College of
The accolades could continue, but the legacy is clear. His inspiring example allowed no room for mediocrity or compromise. His
commitment to excellence remains unparalleled. How well he is
represented by one of his favorite poems:
Oh for the silent doer of the deed,
One who is happy with the deed’s own reward,
One who in people’s plight of night
has solitary certitude of that which is right.
Similarly, the creators of this book and its revisions have been
driven to bring to pass a text worthy of his emulation. We dedicate the product of our labors to the life of Dr. Joseph Janse in
the hope that its readers may come to understand the value of
“toiling upward through the night.”
TERRY R. YOCHUM
LINDSAY J. ROWE
Chiropractic and Logan College of Chiropractic in the area of clinical practice, nutrition, and the Nimmo technique. He had a keen
interest in orthopedics and nutrition, with a special love for radiology. In 1980, Dr. Yochum was honored to be invited to present
a lecture for the International College of Chiropractic in
Melbourne and Sydney, Australia. He was one of the first five certified instructors in the receptor tonus (RT) technique (Nimmo
technique), a topic on which he frequently lectured.
Dr. Yochum’s untimely death in 1989 deprived his family of
his love and guidance and many students of his great clinical expertise. Kenneth E. Yochum was a man of great character and
integrity who always put the best interest of his patients before
any personal need or gain. What a privilege it was to have been
raised in a chiropractic family with such a great role model as a
father and leader in the chiropractic profession. He lived his life
by a number of spirited commitments. I can remember him saying many times, “Son, right is right and wrong is nobody.” He
spent his life attempting to always do the right thing for his patients and family. A leader in his community in every way, he
stood as the pillar of his practice and family. So many times he
told me that “chiropractic was worth making a difference for—
extend yourself to make it better.” His most memorable quotation involves living one’s life as a reflective leader. He said that
I, as his son, should “make dust—not eat dust.” How thankful I
am to have had a father who cared so much about the chiropractic profession and his family to have extended himself so sincerely, seemingly at every turn within his personal life.
A motivated student of radiology and an excellent radiographic
technician, he produced radiographs of the finest quality in his
clinical practice in St. Louis. In fact, his name follows many films
in all three editions of this book, cases that came directly from his
practice.
Kenneth E. Yochum was a very proud man and this was reflected in all aspects of his professional and personal life. His
commitment to excellence was untiring and that driving spirit
was given to me by this great man. His influence upon my life
still continues. He is greatly missed by the entire Yochum family and it is befitting that the third edition of the Yochum and
Rowe textbook be dedicated to his memory.
TERRY R. YOCHUM
Dedications
Within a lifetime, a few select individuals will significantly affect
the life of another. For both of us, Bryan Hartley, M.D., was one
of those individuals. He was a person who seemed to achieve
whatever he wanted in life: an extraordinary professional career,
diversified personal interests, and close ties with family and
friends. Bryan was born in Aldershot, England, in 1926 and
studied medicine at Guy’s Hospital Medical School in London.
He was appointed house surgeon at the Royal Infirmary, Edinburgh, in 1950, following which he emigrated to Australia. He
became a flight lieutenant in the R.A.A.F. medical branch and
was a Fulbright traveling scholar. He was appointed medical
officer in the Northern Territory Medical Services in Western
Australia and was a resident medical officer at General Hospital
in Tasmania.
Bryan Hartley, M.D.
(1926–1984)
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B
ryan Hartley’s early postgraduate training appointments
alternated between the fields of surgery and radiology.
He held appointments in surgery at the Union Memorial
Hospital in Baltimore, Maryland; Launceston General Hospital in
Tasmania; the Royal Children’s Hospital in Melbourne, Victoria;
and as Surgeon Superintendent at the Lyell District Hospital,
Tasmania. His appointments in radiology were at the Launceston
General Hospital, St. Vincent’s Hospital, Melbourne, and the
Royal Hobart Hospital in Tasmania. After a short appointment in
Rome as a radiologist for the Department of Immigration, Bryan
returned to Melbourne to become the director of the Department
of Radiology at the Repatriation General Hospital and held this
position until 1981. At that time, he accepted a position as staff
radiologist in the Department of Radiology at the Austin Hospital
also in Melbourne, the post he occupied until his death.
In his chosen career of medicine, Bryan Hartley excelled in
both surgery and radiology, holding specialist qualifications in
both fields. This interest in surgery was of considerable advantage to him in radiology, as it enabled him to see a diagnostic
problem in its proper clinical perspective. A unique combination
of clinical understanding, experience, and aptitude for clear expression made Bryan an outstanding teacher for his many students, residents, and colleagues. His boundless enthusiasm and
wry humor provided for stimulating and informative discussions
on almost any topic. His opinions were highly valued, particularly in patient evaluation and treatment.
For both of us, it was Bryan who, by example, provided the
stimulus for developing our knowledge and abilities and advancing the standards of our profession. His influence on our careers
is reflected not only in the use of his personal case material in
this text but, more important, in the knowledge, expertise, and
teaching methods he so freely shared with us. His untimely death
in 1984 now deprives us and others of the opportunity of sharing
his special gifts. He is survived by his wife, Beverley, and their
children, Lynne and John.
In gratitude we have dedicated the first edition of this book to
Bryan Hartley, M.D.
TERRY R. YOCHUM
LINDSAY J. ROWE
FOREWORD to the Third Edition
I
t is my privilege to once again provide a foreword for this
remarkable new edition of the text Essentials of Skeletal
Radiology, by Terry R. Yochum and Lindsay J. Rowe. As
with the previous editions, this work is characterized by impeccable organization, a text that is extremely user friendly, supplemented by vivid illustrations and tabular material that provides
summaries of the important points discussed in the adjacent
paragraphs. What sets this book apart from others is the completeness of the coverage of the various disease processes that
affect the musculoskeletal system. Tumors, infections, metabolic
and articular disorders, traumatic conditions, and developmental
abnormalities among other things—it is all here in the pages of
this work. The manifestations of these processes are illustrated
through the use of all imaging methods, ranging from conventional radiography to MRI. The legends that accompany this
illustrative material are clear and to the point.
The quality of this text comes as no surprise to me. Both of
the authors are experienced and knowledgeable in the ways of
musculoskeletal diseases, both are gifted writers, and both share
a bond of enthusiasm and energy that is required to complete
the task. I have known both Terry and Lindsay for many, many
years, and they are formidable clinicians and educators. They
have a message and a desire to have others hear that message
and, through careful and thoughtful planning, they present that
message throughout the pages of this text. I know full well what
is required to maintain one’s focus during the months and years
of the publication process, to stay focused and on time, and I am
aware that both of these authors had the drive to see the process
through. The result is a text that will bring ample reward to the
reader, providing him or her with information that will ensure a
more complete understanding of the disease process and the ability to provide correct diagnoses in a more timely fashion. The
result will be improved patient care, something we all desire.
Terry and Lindsay, congratulations again on a job well done.
To the potential readers, here is critical information, now at your
fingertips, presented in a painless fashion. Enjoy!
DONALD RESNICK, M.D.
Professor of Radiology
University of California, San Diego
Chief of Osteoradiology Section
Veterans Affairs Medical Center
San Diego, California
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FOREWORD to the Third Edition
W
e are all so busy in our lives that I often ponder how we
accomplish the everyday things we must do, let alone
also find time for new or additional endeavors. Well,
Terry R. Yochum and Lindsay J. Rowe have an extraordinarily
busy daily schedule and, again, they have found the time and
energy to produce a third edition to their highly successful
Essentials of Skeletal Radiology.
This new edition represents the pinnacle of Terry’s and
Lindsay’s knowledge and compilation of work in this field.
Today, they have added four more contributing authors for a
total of 11. Incredibly, they have added 500 new illustrations and
more than 1000 new references.
The reader will greatly appreciate the use of a new bolder
color and shadings to highlight and enhance those important
points that are seen in the headings, tables, diagrams, and figure
captions. The quality of the reproductions is excellent, and there
is no question of what the authors wish to demonstrate with wellplaced arrows at the areas of interest. Of course, this text follows
the wonderful fluid writing style previously seen in their earlier
editions. I particularly enjoy the capsule summaries, which are a
welcome highlight of the text.
I believe you will like their new chapter, “Masqueraders of
Musculoskeletal Disease.” Here, they have utilized plain films,
CT, and MRI in areas of the head, neck, chest, and abdomen to
provide an insight to other abnormalities that could mimic musculoskeletal complaints.
I am very impressed with this new and wonderful text, just as
I was when I reviewed the earlier editions. Essentials of Skeletal
Radiology is for every student in the field. I believe the blending
of the new material and additions into the solid foundation of the
second edition has produced a masterful harmony of needed core
skeletal information with the newer imaging of the twenty-first
century.
Thank you, Terry and Lindsay, for a wonderful work and a
job well done.
M. BRUCE FARKAS, D.O., J.D.
Professor of Radiology (Retired)
Midwest University College of
Osteopathic Medicine
Chief, Radiology, Military Entrance
and Processing Station (Retired)
Chicago, Illinois
xi
FOREWORD to the Third Edition
A
s the saying goes, “The third time is the charm.” In skeletal radiology, the third edition of Yochum and Rowe’s
Essentials of Skeletal Radiology will become the gold
standard.
It is no easy task to improve upon a work that has received
acclaim worldwide but this third edition does more than improve upon the second edition. With its expanded material and
featured new chapter, “Masqueraders of Musculoskeletal
Disease,” this third edition brings together inside a single cover
all one needs to know to be an effective skeletal radiologist and
clinician. If by some circumstance all skeletal radiology texts
were burned to ashes, this edition would be a stand-alone, worthy of the risk and sacrifice required to preserve it from the fires
of ignorance.
Chiropractic representatives invited to write a foreword are
proud that such a well-used text has arisen from within our own
ranks. The authors have distinguished themselves as radiologists
in both the chiropractic profession and the medical profession.
They have worked with, walked with, and talked on the same
programs with the world’s greatest. We hope the chiropractic
profession recognizes the great contribution they have made,
not only to the practice of skeletal radiology but to enhance the
image of chiropractic.
We have been close enough to the action to know that creating
this third edition has been a monumental task. The same commitment of sweat and tears that went into the first and second editions are evident between the lines and around every picture on
every page. If any errors are present, it can only be blamed on
computers.
The golden thread that weaves this third edition together,
strengthening the authors’ skill in conveyance of subject matter,
is their love of teaching. They are master teachers, and their skill
in holding an audience on the front of the seat in a darkened conference room has been incorporated into this lively text. Whether
or not skeletal radiology is your love, Essentials will become
your nightly reading companion.
We salute the work of these great teachers with Lee Iacocca’s
sentiment:
In a completely rational society, the best of us would aspire to be teachers and the rest of us would have to settle for something less, because passing civilization along
from one generation to the next ought to be the highest
honor and the highest responsibility anyone could have.
REED B. PHILLIPS, D.C., D.A.C.B.R., PH.D.
President
Southern California University of Health Sciences
Whittier, California
JOSEPH W. HOWE, D.C., D.A.C.B.R.,
F.I.C.C., FELLOW, A.C.C.R.
Emeritus Professor of Radiology
Southern California University of Health Sciences
Whittier, California
Faculty
Department of Radiology
Logan College of Chiropractic
St. Louis, Missouri
xiii
PREFACE to the Third Edition
T
he overwhelming success of the first and second editions
of Essentials of Skeletal Radiology has now given us the
opportunity to publish the third edition. We believed in
our work and were convinced of its merits from the beginning.
What we did not fully perceive was the magnitude of the need
for this text. We have been startled by the widespread acceptance
of this publication. Although initially targeted to fill a need in the
chiropractic educational system, it has also been adopted into
the curricula of various medical and osteopathic teaching institutions worldwide. We have often seen the worn and torn covers
on our books as a testimony to its use. The number of citations
of the book in many scientific publications has been quite rewarding to see, and although morally and financially distressing,
a form of compliment was offered by the numerous illegal and
counterfeit copies that have surfaced here and abroad.
The most common question asked of any author in preparing
a new edition is, “Are there any differences from the previous edition?” This text has undergone significant structural and content
changes. Each chapter has been revised, some more extensively
than others, and a new chapter (Chapter 18, “Masqueraders of
Musculoskeletal Disease”) has been added to this edition. We feel
these modifications and additions will provide the reader with
a more “clinical” based text with respect to understanding the
approach to radiology as it relates to practice. In addition, a sample CD of cervical spine anatomy, range of motion testing, and
demonstration of orthopedic and neurological tests has been
included with this text. This CD was created in association with
Primal Pictures, Ltd., of London, England.
Our approach to a more clinical text will be evident early,
as the reader notices the modifications made to Chapter 1. In this
chapter, carefully selected radiographs displaying commonly
found pathologies have been added for comparison with the normal
radiographs. These images have been labeled “clinicoradiologic
correlations,” and we feel they will emphasize the importance
of being able to identify normal in order to better identify abnormal. These insertions will allow the reader to understand that
many radiologic findings may be subtle and that careful attention
to detail must be applied when reviewing radiographs. This comparison approach has been made easy by images displayed in close
approximation. Also, a new “common pitfalls” section has been
added to provide helpful information in hopes of preventing the
clinician from making the most frequently seen exposure, positioning, and technological errors.
Chapter 3 has grown significantly with the addition of many
new figures, references, and considerable expansion of the text.
The addition of a “synonym section” should be very helpful. The
normal variant segment has had many new images added to both
the spine and extremities section.
A quick glance at Chapter 6 again demonstrates our efforts in
not only compiling an informative text but also providing a clinical reference book. Remarkable new technologies continue to
emerge, sometimes complementing and occasionally supplanting the existing modalities. The sheer volume of knowledge and
the rate at which the knowledge base expands are both increasing
rapidly. This has resulted in numerous areas of imaging specialties and subspecialties based on anatomy, imaging technology, or
both. However, the edges of these specialty areas are not always
black and white. While the focus of an individual practitioner
may be specialized, it cannot be so narrow as to eliminate the
need for an “overview” perspective capable of recognizing findings that may indicate an abnormality in a different anatomical system, or necessitate the application of a different imaging
technology. In this chapter we have incorporated sections on the
technological advances made in the areas of magnetic resonance
angiography, DEXA osteoporosis scanning, musculoskeletal diagnostic ultrasound, and upright (stand-up) MRI of the spine.
Further progression through the text will make evident the
changes to Chapter 15, which will enable the clinician to create a
competent report and to better understand the importance of report
writing. A report commentary section has been added to each
case study in this chapter to critique the reports provided. This approach emphasizes the common errors people make while creating
a report and reiterates the proper format of report writing.
The new chapter, “Masqueraders of Musculoskeletal
Disease,” has been added to present an overview of the clinical
findings and imaging applications for areas other than the musculoskeletal system. This new chapter emphasizes plain films as well
as CT and MRI of the more common disorders involving the head,
soft tissues of the neck, chest, and abdomen that can mimic
musculoskeletal complaints. It follows the usual format of our
textbook with the clinical and radiological features emphasized.
Despite the numerous additions and modifications, there has
been a vigilant effort to maintain the hallmark features and core
material of the first and second editions, so familiarity in this
third edition may be evident. As we outlined in the preface of the
first and second editions, the emphasis has been placed on constructing a clear and concise presentation. Significant effort has
been directed at containing the size of this text to maintain its
usefulness in the classroom, while attempting to provide a comprehensive review that incorporates the phenomenal technological advances in diagnostic imaging that have occurred in the
interim.
Subsequent editions are like retouching original works of art.
Though there is always the risk of spoiling it, the challenge of constructing a revision that is better than our previous works provided
inspiration for this third edition.
The existing format has been enhanced by numerous design
and color changes. We believe these changes will improve readability and accentuate important points. Most of the diagrams
have been highlighted to emphasize key radiologic features.
Headings and figure captions have been selectively colored.
Some aspects of the book have remained the same owing to an
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Yochum & Rowe’s Essentials of Skeletal Radiology
overwhelming positive response to their appearance in the previous edition. For example, the structure of Chapters 5, 8, 10, 11,
12, 13, and 14 using progressive headings of “general considerations,” “clinical features,” “pathologic features,” “radiologic features,” and “treatment and prognosis” has been
maintained. The “capsule summary” remains an integral component to assist the reader in quick review for examination or to
expedite differential considerations. A key addition to the second
edition that has been repeated in this third edition is the “medicolegal implications” section that follows many of the conditions
discussed. This reflects the increasing emphasis that diagnostic
imaging has assumed in clinical practice and is designed to complement the case management decision-making process in a way
that will reduce liability. The use of imaging and treatment algorithms in Chapter 5 will significantly impact the treatment
of many patients with spondylolisthesis. In addition, the special
section on mnemonics continues to appear as an appendix at the
end of each volume.
Numerous favorable comments have been relayed to us regarding how the references in the first and second editions have
been used as the basis for various research and other scientific articles and case reports. Although a vast amount of relevant literature was again systematically reviewed for this third edition, we
have attempted to limit additional citations to those of significant
merit. All owners of this third edition, whether student, teacher,
researcher, or practitioner, should find these additions useful to
their clinical and scientific endeavors.
The photographic reproductions and diagrams have always
been listed as one of the most attractive and valuable characteristics of the book. New diagrams have been added and improvements on existing ones have been made, such as the skeletal
distribution diagrams that incorporate new localizing symbols to
identify most common and less common sites of involvement.
We have selectively removed some images and replaced them
with new ones when better examples could be found. We have
also continued with the teaching principle of placing arrows on
images that correlate with the descriptive caption and direct the
readers to important facets of the case. When possible, the case
material has been augmented with bone scans, CT, and MRI to
reflect the technological revolution in musculoskeletal diagnosis.
As with the first and second editions, this text is meant to be
used for at least three purposes: as a teaching text aimed at all
those who seek knowledge and expertise in musculoskeletal disorders, as a reference text when information is sought, and as a
clinical aid to assist you with those patients who seek your care.
In this regard, we encourage you to read this text carefully and
use it for its intended purposes.
We also hope the book will help the reader avoid the many
pitfalls of clinical decision making—one of the most obvious
being addressed in a quote from an unknown author, “You see
what you look for and recognize what you know.”
TERRY R. YOCHUM
LINDSAY J. ROWE
ACKNOWLEDGMENTS to the Third Edition
T
he release of Essentials of Skeletal Radiology in 1987 was
a dream fulfilled for both of us. We had hardly blinked an
eye before the publishers were requesting us to consider a
second edition, and now we have completed the third. This edition has been a monumental task, which has taken approximately
3 years to research, write, and publish. A task of this magnitude
is never accomplished without significant support from numerous people assisting in many different ways.
Our contributing authors have provided a distinct and unique
contribution to this third edition and we wish to recognize their
efforts:
Michael S. Barry, D.C., D.A.C.B.R., Denver, Colorado
Gary M. Guebert, B.S., D.C., D.A.C.B.R., St. Louis, Missouri
Bryan Hartley, M.D., Melbourne, Australia
Claude Pierre-Jerome, M.D., PhD., Oslo, Norway
Norman W. Kettner, D.C., D.A.C.B.R., F.I.C.C.,
St. Louis, Missouri
Robert J. Longenecker, D.C., D.A.C.B.R., Dallas, Texas
Chad J. Maola, B.S., D.C., Denver, Colorado
Melanie D. Osterhouse, D.C., D.A.C.B.R., St. Louis, Missouri
Margaret A. Seron, D.C., D.A.B.C.O., D.A.C.B.R.,
Denver, Colorado
David P. Thomas, M.D., Melbourne, Australia
Jeffrey R. Thompson, D.C., D.A.C.B.R., Houston, Texas
Their assistance in numerous chapters in this edition is greatly
appreciated.
We would also like to thank Leon L. Wiltse, M.D., Long
Beach Memorial Hospital, Long Beach, California, and Lyle J.
Micheli, M.D., Children’s Hospital, Harvard Medical School,
Department of Orthopedics, Boston, Massachusetts, for their expert review and editing of Chapter 5 (“The Natural History of
Spondylolysis and Spondylolisthesis.”)
There have been several new topics added to Chapter 6
(“Diagnostic Imaging of the Musculoskeletal System”), the nucleus of which has been provided by Norman W. Kettner, D.C.,
D.A.C.B.R., Robert J. Longenecker, D.C., D.A.C.B.R., and
Melanie D. Osterhouse, D.C., D.A.C.B.R. We wish to thank
them for their outstanding contribution. Thanks also to Steven
Gould, D.C., D.A.C.B.R., who provided us a number of musculoskeletal diagnostic ultrasound images used in this chapter.
Dr. Thomas H. Berquist, of the Mayo Clinic, provided excellent review and editorial comments for the new “Masqueraders”
chapter and we thank him. Gratitude is expressed to two radiology residents, Dr. Gregory Bathurst and Dr. Thanh Vu, from the
University of Colorado Health Sciences Center for their extraordinary efforts in proofreading this new chapter.
A special thank you to those physicians who have graciously
provided the forewords for the third edition:
Joseph W. Howe, D.C., D.A.C.B.R, Fellow, A.C.C.R.
M. Bruce Farkas, D.O., J.D.
Reed B. Phillips, D.C., D.A.C.B.R., Ph.D.
Donald Resnick, M.D.
Several people were involved at varying levels in the editorial
process of the production of the third edition of this textbook.
Special thanks are offered to Drs. Michael S. Barry, Gary M.
Guebert, John K. Hyland, Norman W. Kettner, Chad J. Maola,
Melanie D. Osterhouse, Jeffrey R. Thompson, and William M.
Ursprung. They were of great assistance to this project, conducting endless literature searches, proofreading, and offering editorial comments. The extensive updating of the references was
facilitated by Mr. Bob Snyder, Public Services/Reference
Librarian of the Logan College of Chiropractic. We thank him for
his endless efforts on our behalf. A special thank you is due to
Ms. Erica L. Collier, able assistant and secretary to Dr. Kettner at
the Logan College of Chiropractic. Erica received endless
phone calls and helped in locating the Logan radiology staff, always on short notice. Her pleasant attitude and quick response to
our needs with faxing and e-mailing numerous documents has
been most appreciated.
Special thanks to Michael L. Manco-Johnson, M.D., F.A.C.R.,
Professor of Radiology and Medicine, Chairman of the Department of Radiology, University of Colorado Health Science Center,
Denver, Colorado, and Ray F. Kilcoyne, M.D., Professor of
Radiology, Department of Radiology, University of Colorado
Health Science Center, Denver, Colorado, for allowing their valuable case material from various departments at the university to be
photographed and utilized in this third edition. Thanks also to the
many radiology residents at this university who have secured
unique skeletal radiology cases for our teaching file and, in particular, this third edition. Many of those residents’ names appear scattered throughout various chapters following their case material.
Chapter 8 (“Skeletal Dysplasias”) of this book provided a particular challenge in upgrading the case material. The staff of
Children’s Hospital, Department of Radiology, Denver, Colorado,
was most cooperative in allowing us to photograph their skeletal
teaching file. These cases are dispersed throughout the textbook,
particularly in the area of dysplasias. Our gratitude goes specifically to John D. Strain, M.D., Chairman of the Department of
Radiology, Children’s Hospital, Denver, Colorado, for his assistance in obtaining this case material.
The majority of the new photographs for this third edition
were skillfully processed and perfected by the able staff at the
Pro Lab, Inc., Denver, Colorado. The quality of their work is
evident by the end product.
Thanks to those who assisted us at Lippincott Williams &
Wilkins in the production of this book, including all who worked
behind the scenes and whom we never met or interacted with.
Special thanks to Karen K. Gulliver, freelance managing editor, for her diligent, thorough review and processing of this huge
manuscript. She did a great job in the second edition and equally
outstanding work in the third edition.
Finally, our gratitude is expressed to Joseph Janse, D.C., and
Kenneth E. Yochum, D.C., in our dedications.
TERRY R. YOCHUM
LINDSAY J. ROWE
xvii
xviii I
Yochum & Rowe’s Essentials of Skeletal Radiology
W
ith a deep sense of gratitude, I wish to thank my devoted wife, companion, and best friend, Inge. Her
understanding, support, and unconditional love fashioned the vehicle that carried me as I traveled the difficult road of
this third edition. Special thanks to my children, Kimberley
Ann, Philip Andrew, and Alicia Marie. They have readily forgiven their father’s frequent absences during this project. I want
to especially acknowledge my most devoted follower, Cecelia G.
Yochum, my mother, who gave me life and nurtured and encouraged me throughout my entire career. She knew of this third edition and inspired me to work hard to finish it. Unfortunately, she
passed away on August 22, 2001. I hope she would have been
proud of my efforts and the finished product.
I wish to acknowledge and thank the following special individuals who have shaped my professional career and touched my
personal life:
• Dr. M. Bruce Farkas, an exceptional osteopathic radiologist, who helped me greatly in the beginning of my career.
• Dr. Joseph W. Howe, my professor, after whom a progeny
of radiology diplomates emerged.
• Dr. Joseph Janse, modern-day father of chiropractic.
• Dr. William E. Litterer, who spared no detail and forgot
no face.
• Dr. Reed B. Phillips, a critical thinker, man of great
integrity and leadership, and one of my very best friends.
• Dr. Donald B. Tomkins, who is remembered for knowledge tempered by wisdom, and one of my teachers at
National College who inspired me early in my career to
enter into radiology.
• Dr. James F. Winterstein, one of my original teachers
and an outstanding radiologist who provided inspiration
for me to enter the radiology residency program at
National College.
For the development and production of this book I express sincere
gratitude to:
• my associate, Chad J. Maola, B.S., D.C., who has coauthored five chapters in this edition. There are no adequate words to express my sincere thanks for his exceptional devotion to this entire project. When this revision
was at risk of not being finished, he stepped in and
assisted me day and night to bring this project to fruition.
Chad is an outstanding individual who has gone above
and beyond the call of duty for me.
• my adopted resident and loyal friend, Norman W. Kettner,
D.C., D.A.C.B.R., F.I.C.C., who has co-authored three
chapters in this edition. His untiring efforts for this project
and support of me personally will forever by appreciated.
W
ith a few words much needs to be acknowledged. This
book was born in the early 1980s out of an idea to do
things better, to consolidate, to explain, to bring logic to
just one area of human disease. Along the way many contributed—
patients, students, colleagues, publishers, and all of our ancillary
staff. Many went to extraordinary lengths to make these volumes
better, for which we all benefit. All manner of obstacles have been
• my resident and good friend, Jeffrey R. Thompson, D.C.,
D.A.C.B.R., who has co-authored one chapter in this
edition and who once again responded graciously to my
request for help. His literary expertise and superior effort
on behalf of this entire project has been most appreciated.
• my associate, Michael S. Barry, D.C., D.A.C.B.R., who has
co-authored three chapters in this edition. His support was
exceptional. He proofread and edited many of these chapters
and our friendship is forever strengthened as a result.
• my staff, Connie L. Jones, R.T.(R), Lanna L. Gosage,
R.T.(R), and Wanda I. Hidy. My gratitude is extended to
these three wonderful women who have worked closely
with me for many years. They supported me through the
arduous task of the daily workloads of my radiology practice and the revision of this textbook. I could not have
gotten through this without their unflagging support.
• my able typist, Debbie K. Schlosser, for the time she freely
gave when her energy was needed to type and repeatedly
review chapters and manuscript submissions. Debbie typed
the second edition and had a significant impact on the third
edition. Her efforts are most appreciated.
• a family friend, Joshua Rohleder, who provided assistance in
the organization of many new photos throughout this text.
I express particular thanks to five very distinguished individuals:
• Mr. Kent S. Greenawalt, President, Foot Levelers, Inc,
Roanoke, Virginia
• Mr. Rodney Moulder, President, HCMI, Springfield,
Missouri
• Dr. Reed B. Phillips, President, Southern California
University of Health Sciences, Whittier, California
• Dr. Mark Sanna, President, Breakthrough Coaching,
Miami, Florida
• Mr. George Stamathis, experienced medical publisher and
publishing consultant, Bel Air, Maryland
These dear friends were never too busy to receive a late-night
phone call or to be a sounding board for my concerns and woes.
They carried me over hard, rocky places as I proceeded down the
long road of this project.
The inspiration to undertake the third edition of this text came
from the many doctors and students who have attended my lectures from coast to coast, and I wish to thank them for providing
this motivation.
And finally, thanks to my co-author, Dr. Lindsay J. Rowe, for
his efforts on behalf of this third edition, particularly his work on
our new chapter, “Masqueraders of Musculoskeletal Disease.”
TERRY R. YOCHUM
overcome. With this third edition all of these ideals continue with
but a few exceptions.
My thanks go to Stephen Heaney of the Medical Communication Unit at John Hunter Hospital, Newcastle, for their fine
photographic reproductions. To the radiographic technologists at
our Newcastle Hospitals for their fine work in obtaining examinations of the highest quality and bringing cases of interest to my
Acknowledgments I
attention is greatly appreciated. Similarly, the many radiology,
medical, and surgical residents who ensured all manner of cases
come to me for review I am indebted.
For the students of Medicine in Newcastle and Chiropractic
throughout the world who I teach, they provide the perpetual fertile environs and impetus to write, research, and understand this
subject area. Similarly, at the medical and chiropractic meetings
that I address domestically and throughout the world, I glean a
great deal that is directly reapplied back to teaching. A large proportion of the case material contained in this third edition has
been derived from these interactions.
Thanks to Professor Joe Ghabriel, M.D., orthopedist and
spine surgeon; Eric Ho, M.D., pediatric orthopedist; and Martin
Epstein, M.D., endocrinologist and bone mineral specialist, for
securing additional case material and allowing me to review their
patients’ studies on a regular basis and for providing me with
great stimulus to increase my expertise and knowledge.
To James Brandt, M.S., D.C., F.A.C.O., in Minneapolis,
Minnesota, for his perceptive insight, encouragement, guidance,
and friendship over many years I am very grateful to have him and
xix
his family as part of my life. Special recognition goes to Brian
Nook, D.C., C.C.S.P., of Perth, Australia, Associate Professor,
School of Chiropractic Murdoch University. As we shared an office in 1985–86 during the genesis of this text he provided a sense
of direction, purpose, and vision, which has been rekindled for this
third edition. My long-term friends and colleagues from different
parts of the globe Michael Buna, B.S., D.C., from Victoria,
Canada; Shane Carter, B.S., D.C., of Inverarie, Scotland; and
Wayne Minter, B.S., D.C., in Sydney, Australia, have given that
much needed sense of perspective, balance, and humor continuing
through all previous and present editions.
Finally, to my extraordinary wife, Anne Baxter, B.S., M.D.,
and my son, Ryan, the time given to this project is time lost for
us but much gained for others. You are indelibly entwined throughout these pages more than anyone could know. You are my life.
I hope in some way these books will assist all of those who use
them and will make a difference to those patients that seek their
care. I dedicate my last contribution to this book to these patients.
LINDSAY J. ROWE
CONTRIBUTING AUTHORS
Michael S. Barry, D.C., D.A.C.B.R.
Private Radiology Practice
Private Chiropractic Practice
Denver, Colorado
Post Graduate Faculty Member
Parker College of Chiropractic
Dallas, Texas
Postgraduate Faculty Member
Logan College of Chiropractic
Chesterfield, Missouri
Chad J. Maola, B.S., D.C.
Gary M. Guebert, B.S., D.C., D.A.C.B.R.
Formerly:
Instructor in Orthopedics and Radiology
Colorado College of Chiropractic
Marycrest International University
Denver, Colorado
Private Radiology Practice
St. Louis, Missouri
Assistant Professor of Radiology
Logan College of Chiropractic
Chesterfield, Missouri
Formerly:
Assistant Professor and Chairman, Radiology Department
Texas Chiropractic College
Pasadena, Texas
Orthopedic and Radiology Consultant
Denver, Colorado
Melanie D. Osterhouse, D.C., D.A.C.B.R.
Instructor, Clinical Science Division
Logan College of Chiropractic
Chesterfield, Missouri
Bryan Hartley, M.D. (deceased)
Margaret A. Seron, D.C., D.A.B.C.O., D.A.C.B.R.
Staff Radiologist
Austin Hospital
Melbourne, Australia
Private Radiology Practice
Denver, Colorado
Head, Department of Radiology
Heidelberg Repatriation Hospital
Melbourne, Australia
Claude Pierre-Jerome, M.D., Ph.D.
Associate Professor of Radiology—MRI section
Ulleval University Hospital
Oslo, Norway
Norman W. Kettner, D.C., D.A.C.B.R., F.I.C.C.
Chairman, Department of Radiology
Logan College of Chiropractic
Chesterfield, Missouri
Professor, Clinical Science Division
Logan College of Chiropractic
Chesterfield, Missouri
Robert J. Longenecker, D.C., D.A.C.B.R.
Private Radiology Practice
Dallas, Texas
Postgraduate Faculty Member
Southern California University of Health Sciences
Whittier, California
Formerly:
Assistant Professor of Radiology
Los Angeles College of Chiropractic
Whittier, California
David P. Thomas, M.D. (retired)
Formerly:
Head, Department of Radiology
Austin Hospital
Melbourne, Australia
Jeffrey R. Thompson, D.C., D.A.C.B.R.
Private Radiology Practice
Houston, Texas
Associate Professor, Diagnostic Imaging
Texas Chiropractic College
Pasadena, Texas
xxi
CONTENTS
VOLUME ONE
VOLUME TWO
10 Arthritic Disorders
1 Normal Skeletal Anatomy and
Radiographic Positioning
1
Lindsay J. Rowe and Terry R. Yochum
2 Measurements in Skeletal Radiology
11 Tumors and Tumor-Like Processes
197
Lindsay J. Rowe and Terry R. Yochum
3 Congenital Anomalies and
Normal Skeletal Variants
257
405
433
Lindsay J. Rowe, Terry R. Yochum,
and Chad J. Maola
15 Report Writing and Risk Management
Strategies in Skeletal Radiology
16 Radiographic Artifacts
485
1497
1547
1581
Terry R. Yochum and Lindsay J. Rowe
17 A Radiographic Anthology of
Vertebral Names
1701
Terry R. Yochum, Bryan Hartley, David P. Thomas,
and Gary M. Guebert
679
721
Margaret A. Seron, Terry R. Yochum,
Michael S. Barry, and Lindsay J. Rowe
9 Trauma
14 Nutritional, Metabolic, and
Endocrine Disorders
Lindsay J. Rowe, Terry R. Yochum,
and Chad J. Maola
Lindsay J. Rowe and Terry R. Yochum
8 Skeletal Dysplasias
1427
Lindsay J. Rowe and Terry R. Yochum
Terry R. Yochum, Norman W. Kettner,
Michael S. Barry, Melanie D. Osterhouse,
Robert J. Longenecker, Claude Pierre-Jerome, and
Lindsay J. Rowe
7 Principles of Radiologic Interpretation
13 Hematologic and Vascular Disorders
Lindsay J. Rowe and Terry R. Yochum
Terry R. Yochum, Lindsay J. Rowe, Michael S. Barry,
Chad J. Maola, and Norman W. Kettner
6 Diagnostic Imaging of the
Musculoskeletal System
1373
Lindsay J. Rowe and Terry R. Yochum
Lindsay J. Rowe, Terry R. Yochum, Chad J. Maola,
and Norman W. Kettner
5 Natural History of Spondylolysis
and Spondylolisthesis
1137
Terry R. Yochum and Lindsay J. Rowe
12 Infection
Gary M. Guebert, Lindsay J. Rowe, Terry R. Yochum,
Jeffrey R. Thompson, and Chad J. Maola
4 Scoliosis
951
Lindsay J. Rowe and Terry R. Yochum
18 Masqueraders of
Musculoskeletal Disease
Appendix
793
1715
Lindsay J. Rowe and Terry R. Yochum
Index
A-1
I-1
xxiii
ABBREVIATIONS OF ATTAINED DEGREES
B. App. Sc. (Chiro)
Bachelor of Applied Science (Chiropractic)
This is the chiropractic qualification issued by the Royal
Melbourne Institute of Technology, School of Chiropractic,
Melbourne, Australia
B.S.
Bachelor of Science
C.C.S.P.
Certified Chiropractic Sports Physician
D.A.B.C.O.
Diplomate of the American Board of Chiropractic Orthopedists
D.A.C.B.N.
Diplomate of the American Chiropractic Board of Nutrition
D.A.C.B.S.P.
Diplomate of the American Chiropractic Board of
Sports Physicians
*D.A.C.B.R.
Diplomate of the American Chiropractic Board of Radiology
Ed.D.
Doctor of Education
F.A.C.C.R. (Aus)
Fellow of the Australian Chiropractic College of Radiology
(Australia)
F.A.C.O.
Fellow of the Academy of Chiropractic Orthopedists
*F.C.C.R. (C)
Fellow Chiropractic College of Radiologists (Canada)
*Fellow, A.C.C.R.
Fellow American Chiropractic College of Radiology
F.I.C.C.
Fellow of the International College of Chiropractors
J.D.
Juris Doctor
*M.D.
Doctor of Medicine
D.A.C.B.R. (Hon.)
Honorary Diplomate of the American Chiropractic Board
of Radiology
M.I.R.
Member of the Institute of Radiography
D.C.
Doctor of Chiropractic
M.Sc. or M.S.
Master of Science
D.O.
Doctor of Osteopathy
Ph.D.
Doctor of Philosophy
D.P.M.
Doctor of Podiatric Medicine
R.T. (R.)
Radiological Technologist (Radiology)
*Physicians referred to in this text holding these degrees are radiologists.
xxv
Skeletal Radiology:
An Historical Perspective
Lindsay J. Rowe and Terry R. Yochum
A
ll disciplines within the health sciences have undergone
enormous change and technological development throughout the last century, with radiology being at the forefront
of innovation and discovery. The subspecialty of musculoskeletal
imaging has been an integral part of these advances, experiencing
a long and intricate history, with great changes witnessed over the
last 20 years. (1) For those involved in musculoskeletal imaging,
it is a demanding challenge to keep abreast of the ever-changing
technology and knowledge base and to develop the new skills necessary to serve the demands of those who seek their services.
Clinicians of musculoskeletal medicine face similar demands of
selecting appropriate imaging modalities for the clinical situation,
interpreting the clinically important findings, and integrating them
into the delivery of patient care. Given this crescendo of increasing demands on musculoskeletal radiologists and clinicians, the
need to interact, consult, and discuss patients on a regular basis is
paramount to optimizing patient care. The purpose of this prelude is to reflect on key achievements of the past and provide
a descriptive overview of where we are in the new millennium.
In 1995, the 100-year anniversary of the discovery of x-rays
was celebrated. As the first x-ray was that of a hand, so too was
it the centenary of the subspecialty of musculoskeletal radiology.
Such anniversaries present the opportunity to reflect on the past:
beginnings, leaders, martyrs, innovators, and advancements in
technology. So rapid and spectacular has been the acceleration of
knowledge and technology within radiology, it is arguably one
of the most dynamic and challenging specialties within the health
disciplines. Testament to this are the evolving terms describing
the specialty, from the early beginnings as roentgenology, honoring the original discoverer Roentgen; to radiology, encompassing
both the diagnostic and therapeutic applications; and to the more
recent imaging, including the non-x-ray producing modalities of
ultrasound and magnetic resonance. (1–4)
today’s x-ray apparatus. While conducting a stream of electrons
from the cathode through the evacuated tube, he noticed that a
plate covered with barium platinocyanoide located at some distance away began to fluoresce. Not knowing what to call these
invisible rays from the Crookes’ tube that induced fluorescence,
he named them “x-rays,” x standing for the unknown quantity.
Roentgen then feverishly began experimenting and defining their
characteristics, and in little more than a month he had described
all the major properties of the x-ray as they are recognized today.
THE EVOLUTION OF IMAGING
The history of the development of radiology is long and intricate. As with so many other significant advancements in science,
x-rays were discovered accidentally. In 1895, Wilhelm Conrad
Roentgen, a professor at the University of Würzburg in Germany,
was working on experiments in his laboratory. (Fig. A) He was
investigating the properties of an early cathode-ray tube, called a
Crookes’ tube, which accelerated electrons in a manner similar to
Figure A WILHELM CONRAD ROENTGEN. Professor at the
University of Würzburg in Germany, winner of the first
Nobel Prize for Physics in 1901 for his discovery of the x-ray.
xxvii
xxviii
I
Yochum & Rowe’s Essentials of Skeletal Radiology
Professor Roentgen produced the first clinical radiograph, an
image of his wife’s hand, on November 8, 1895, and first reported
his findings on December 8, 1895, to the Würzburg PhysicoMedical Society. (2–4) (Fig. B) In recognition of his discovery,
he received the first Nobel Prize for Physics in 1901. Others soon
recognized the potential role of the x-ray in industry and the
healthcare professions. Examples of the earliest diagnostic x-rays
are those made in 1896 by Pupin of a hand imbedded with multiple shotgun pellets, those made by Frost of a fractured wrist,
and a case of osteosarcoma imaged by Manell. (2)
Thereafter, a global technological revolution began. Pupin developed the first intensifying screen, and Edison, the first fluoroscope, to mention only two developments. In 1921, Potter and
Bucky introduced a moving grid mechanism. Sausser, a chiropractor, in 1934 was the first to produce a single-exposure, anteroposterior, full-spine radiograph. The cumulative result of all of
these refinements was the production of diagnostic images of
improved quality, which depicted abnormalities directing more
effective treatment. (2) (Figs. C–E)
These early advancements were tempered with the recognition of the harmful nature of radiation. Many severe and often
fatal injuries occurred to those who pioneered the research in
radiology. As a result, the use of the x-ray came under close
bureaucratic scrutiny and control. Despite these complications,
and in the face of increasingly poor publicity, the usefulness of
this new diagnostic tool could not be ignored, and innovations in
imaging technology continued, aimed at dose reduction, personnel
and patient protection, and improving image quality. Previously,
the use of rare earth screens, compensating filtration, and highfrequency generators were some of the significant advancements.
Figure C PLAIN FILM. Lateral Lumbar. Observe the excellent
bony detail along with the depth of the lumbar lordosis and
lumbosacral disc angle. The intervertebral disc spaces are
outlined; however, no details concerning the internal
substance of the disc or adjacent neural structures can be
assessed.
Figure B ROENTGEN’S FIRST RADIOGRAPH. Professor
Roentgen’s historic first radiograph of his wife’s hand taken
November 8, 1895, in Würzburg, Germany. (Courtesy of
Deutsches Roentgen-Museum, Remscheid-Lennep, West
Germany.)
Figure D PLAIN FILM. Dorsoplantar Foot. Bony alignment,
as well as joint spaces, are adequately assessed through the
foot and tarsal bones. Observe the filtration of the forefoot
and toes used to obtain a uniform exposure. This is done
with a compensating filter of copper and aluminum.
Skeletal Radiology: An Historical Perspective I
Figure E PLAIN FILM. Posteroanterior, Caldwell’s Projection,
Skull. The complexity of the anatomy requires careful attention to detail and anatomic landmarks. Supplemental imaging, such as CT or MRI, not only clarifies these structures but
also provides depiction of clinically important intracranial
structures.
(Fig. F) Today, updated technology leading to digital imaging has
virtually eliminated the need for darkroom procedures and x-ray
cassettes in hospital and smaller private practice environments.
The dynamics of joint motion have been extensively investigated with various imaging methods. Spinal mechanics have been
depicted with single views performed at the extremes of motion
(dynamic or stress radiography) and with compression–distraction
forces. Obtaining simultaneous views at 90° to each other (biplanar radiography) has been employed for complex computer
analysis of motion patterns. Continuous spinal and peripheral joint
motion can be observed with fluoroscopy and videotaped for retrospective analysis (videofluoroscopy). (3,4)
The use of radiopaque contrast media within hollow organs and
body spaces improved the diagnostic evaluations. Introduction of
radiopaque substances into the subarachnoid space of the spine
(myelography) provided information not previously available,
especially in regard to intraspinal and intervertebral disc lesions.
(Figs. G and H) Injection of the nucleus pulposus of the intervertebral disc, which can be performed in conjunction with CT
(discography, CT discography), has provided both a morphological evaluation of disc integrity and become a clinical
provocational tool for isolating a discogenic cause for spinal pain
syndromes. In the skeletal system, an opaque medium placed into
the joint space of a peripheral or spinal facet articulation (arthrography) has allowed demonstration of cartilage, synovium, and
ligamentous structures. (Fig. I) Introduction of contrast into a
peripheral lymphatic vessel will opacify both lymphatic channels
and lymph nodes (lymphangiogram). Injection of contrast can also
be made into sinus infection or pilonidal tracts to trace their
xxix
Figure F COMPENSATING FILTRATION. Lateral Lumbar. A
single-exposure standing lateral radiograph from the lower
sacrum to the T11 level has been achieved by the placement
of a number of aluminum filters in the primary beam at the
collimator. These have included 2 mm to the level of the iliac
crest, a curved tapered filter into the lumbar lordosis to
enhance detail of the spinous processes and neural arch, and
a curved filter conforming to the diaphragmatic contour to
eliminate overexposure of the lower thoracic segments.
(Courtesy of Lloyd Wingate, DC, Dapto, New South Wales,
Australia.)
course (sinogram). (Fig. J) In some bone lesions, such as simple
bone cysts, details of internal structure can be identified.
The inherent lack of sensitivity of conventional radiography was
countered by the administration of selective radioisotopes (nuclear
medicine) that seek out specific tissues and areas of cellular activity. In skeletal disorders the administration of isotopes such as
technetium-99m and gallium provided information on bone activity (bone scan) not recognizable with conventional procedures.
These are usually performed as a triphasic study consisting of an
initial “flow” study, a “blood pool,” and a “delayed” study. (Fig. K)
This has been particularly important in the early detection of many
skeletal disorders. The combination of computed tomograms with
nuclear medicine has added a third dimension to musculoskeletal
imaging (single-photon emission computed tomography; SPECT).
In the early 1970s, computed tomograms (CT scans, CAT
scans) were first produced, combining the technology of the computer with the advances in x-ray technology. With refinements in
machine and computer technology, exquisite sectional images are
now produced in almost every anatomic plane. CT studies have had
a particular impact on the evaluation of spinal and neurological
diseases (Figs. L –O) Three-dimensional images depict anatomy
Figure G METRIZAMIDE LUMBAR MYELOGRAM. Placement
of water-soluble contrast media into the subarachnoid space
allows demonstration of the normal cauda equina, dural
sleeves, and caudal sac. This contrast media is eliminated
through the filtration of the kidneys and excreted in the urine.
Figure I FACET ARTHROGRAM. Lumbar Oblique L4–L5.
Under fluoroscopic guidance a needle has been placed into
the facet joint space, which has been injected with a contrast agent. This reveals the integrity of the joint capsule
and identifies correct needle placement before injection of a
local anesthetic, irritant, or anti-inflammatory agent for diagnostic or therapeutic purposes.
Figure H DISCOGRAM. L3–L5. Contrast media has been
injected into the nucleus pulposus at three levels. Only the
L3 disc is normal in morphology, with both L4 and L5 demonstrating migration of contrast posteriorly and anteriorly
through discal tears. (Courtesy of Inger F. Villadsen, DC,
Newcastle, New South Wales, Australia.)
Figure J HIP SINOGRAM: PSOAS ABSCESS. A draining inguinal sinus was cannulated and opaque contrast media was
introduced. Observe the tracking of the contrast cephalad
outlining the course of the sinus, which proved later to be
continuous with a tuberculous infective focus in the spine at
the L2–L3 level.
Skeletal Radiology: An Historical Perspective I
xxxi
Figure M CONTRAST-ENHANCED (MYELOGRAM) CT STUDY.
S1 Level. The dural sac (DS) and the S1 spinal nerve roots
(arrows) are accurately depicted. In addition, the lumbosacral (arrowheads) and sacroiliac (crossed arrows) articulations are demonstrated.
Figure K FULL-BODY DELAYED NUCLEAR BONE SCAN. This
study is designated as “delayed” because the image is obtained some hours after intravenous injection of the isotope.
This is usually preceded by an immediate postinjection study
and within minutes another set of images obtained to evaluate capillary “pooling.” The delayed study demonstrates the
normal uptake of radioactive isotope in metabolically active
areas of the skeleton, demonstrated as dark regions (hot
spots) that require only a 3–5% change in activity to be
detectable. (Courtesy of Nuclear Medicine Department, M.D.
Anderson Hospital, Houston, Texas.)
Figure L CT STUDY. Axial L4 Level. Observe the exquisite details of the dural sac (DS), nerve roots (arrow), perineural fat
(arrowhead), paravertebral musculature, and bony confines.
Figure N THREE-DIMENSIONAL CT: A 1985 STUDY. Sagittal
Lumbar Spine. Observe the lumbar anatomy on this surfacerendered CT image. The more recent CT scans with helical
imaging render images of greater detail. This is a normal
study.
xxxii
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Yochum & Rowe’s Essentials of Skeletal Radiology
A
Figure O CT MYELOGRAM. A. Coronal Lumbar Spine.
B. Sagittal Lumbar Spine. This patient had a dorsal column
stimulator that prevented him from having an MRI scan.
and abnormalities in exquisite detail. (Fig. P) The use of strong
magnetic fields (MRI) has revolutionized body-imaging capabilities and the identification of abnormalities previously unrecognizable. (Figs. Q–V) The use of gadolinium-enhanced MRI delivers
information on vascularity and the inflammatory nature of a lesion. Ultrasound has expanded its applications in musculoskeletal
disorders. Evaluation of soft tissue lesions provides some limited information on its characteristics that can assist in management. Ultrasound screening for pediatric hip dysplasia has been
a particularly notable contribution to a common problem that has
considerable delayed morbidity if undetected.
Further progression of CT and MRI has allowed detailed analysis of the entire human body, including the vascular system. (Figs.
W and X) However, in spite of all these technological advances,
many fundamental principles of imaging remain unchanged. The
plain film radiograph still forms the foundation for a large portion
of the diagnostic investigations in clinical practice, especially in the
evaluation of skeletal disorders. This is demonstrated with an
example from the past. The radiograph shown in Figure Y was
taken in 1897 at the John Sealy Hospital in Galveston, Texas, just
2 years after Roentgen’s discovery of x-rays. In 1976, the patient,
Mrs. Minne Powell Bowers, consulted a chiropractor in Conroe,
Texas, for evaluation of a low back complaint. When questioned
about prior x-rays, she stated that she had fallen at the age of 14 and
her father, a medical doctor, had decided to transport her from
B
Observe the exquisite detail of the spinal cord and vertebral
segments on these multislice CT myelograms.
Figure P THREE-DIMENSIONAL CT STUDY. Thoracic Outlet.
The image was reconstructed from thin axial images and
then tilted to allow greater visualization of the bony thorax.
Soft tissues could similarly be detected by selecting a different “window” setting. (Courtesy of Kenneth B. Heithoff,
MD, Minneapolis, Minnesota.)
Skeletal Radiology: An Historical Perspective I
Figure Q OLDER-GENERATION MRI. Coronal and Sagittal Lumbar Spine.
Details of the posterior abdomen can be defined, including the liver (L), kidneys (K), and psoas muscles (P). The dural sac (DS) and the abdominal aorta
(AA) are also visible. Note the bright signal intensity of the nucleus of the
discs indicating adequate hydration and lack of degeneration. However, the
L2 and L5 discs are low in signal (arrows), representing underlying degenerative disc desiccation (dehydration).
xxxiii
Figure R NEWER-GENERATION MRI. T1-Weighted MRI, Sagittal
Lumbar. Exquisite anatomic detail is depicted, including the cauda
equina, vertebral bodies, and intervertebral discs. (Courtesy of
Kenneth B. Heithoff, MD, Minneapolis, Minnesota.)
A
B
Figure S MRI STUDIES. A. T1-Weighted MRI, Sagittal
Cervical. B. T2-Weighted MRI, Sagittal Cervical. These images
represent a normal cervical spine. Observe the difference in
appearance of the vertebral bodies and spinal cord on the
T1- and T2-weighted imaging sequences.
Skeletal Radiology: An Historical Perspective I
Figure T MRI. T1-Weighted, Midsagittal Brain. This view
clearly shows the normal pons (P), medulla oblongata (MO),
cerebellum (C), and corpus callosum (CC). Observe the cerebellar tonsils below the foramen magnum (arrow)—ArnoldChiari malformation type II.
Figure U MRI. A. T2-Weighted MRI, Coronal Cervical. B. T1Weighted MRI, Sagittal Cervical. Observe the low signal intensity of the C4 vertebral body. This has occurred as a result
of significant marrow replacement—cause unknown. The
most likely diagnosis with this appearance on MRI is
metastatic bone disease. Observe the vertebral arteries
(arrows). (Courtesy of Todd M. Aordkian, DC, Astoria,
New York.)
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Yochum & Rowe’s Essentials of Skeletal Radiology
A
K
K
Figure V T2-WEIGHTED MRI, CORONAL KNEE. Observe the
disruption of the medial collateral ligament (black arrow) as
a result of a recent severe knee injury. There is significant
joint effusion (white arrowhead) associated with a medial
collateral ligament tear. In the subarticular surface of the
lateral femoral condyle, there is bright signal intensity indicating bone marrow edema (white arrow). The small black
triangular densities seen on the medial and lateral joint
spaces represent the respective menisci.
B
Figure X MAGNETIC RESONANCE ANGIOGRAPHY. Coronal
Abdomen. There has been an acute and complete occlusion
of the aorta, which extends from the aortic bifurcation to
almost the renal arteries (arrow). This atherosclerotic occlusion of the aorta at its bifurcation has been referred to as
Leriche’s syndrome. This image was obtained with gadolinium
injection. Observe the aorta (A), kidneys (K), and bladder (B),
along with other vessels within the abdomen. Magnetic resonance angiography provides a non-invasive imaging modality
as an alternative to traditional angiography, with its use of
catheters and inherent risks.
Figure W SURFACE-RENDERED CT ANGIOGRAM: POSTINTRAVENOUS CONTRAST. Coronal Neck. This intravenous
contrast scan beautifully demonstrates the blood vessels of
the neck, particularly the vertebral arteries (arrows) and the
bony anatomy. This is a normal study.
Skeletal Radiology: An Historical Perspective I
Figure Y RADIOGRAPHIC ANTIQUE. Fractured Femur from
1897. Despite the crude radiographic image, observe the
ilium (I), femoral head (FH), and femoral shaft (FS). Careful
observation reveals an acute angular deformity of the
femoral neck caused by a fracture (arrow). (Courtesy of
Michael L. Davis, DC, Conroe, Texas.)
Willis, Texas, to Galveston in a horse-drawn wagon to have her hip
pain evaluated with this new x-ray procedure. Mrs. Bowers brought
on her next visit to the chiropractor the radiograph shown in
Figure Y. Although the radiograph has aged and lacks technical
clarity, careful observation of the image reveals an acute angular
deformity of the femoral neck owing to a displaced fracture. Even
today, some 100 years later, the initial diagnostic examination of
choice for a similar case is still the same: the plain film radiograph.
For examinations of the skeleton, there is no modality to match
the time and cost- effectiveness of the plain film radiograph. It
is from this “plain film” perspective that Essentials of Skeletal
Radiology has been written and integrated with examples of more
complex sophisticated imaging technologies.
THE FUTURE OF IMAGING
The immense advances made in musculoskeletal imaging technology have placed greater demands on professions that use these
xxxvii
Figure Z THREE-DIMENSIONAL SURFACE-RENDERED MRI.
Hand. What does the future hold in terms of further applications of MRI when an actual three-dimensional image of the
hand can be produced as demonstrated here?
procedures. The future applications of many of these imaging
modalities are yet to be defined, particularly MRI. (Fig. Z) For the
clinician and radiologist alike, there must be a commensurate
understanding of anatomy, physics, morbidity, economics, advantages, and disadvantages of each modality to correctly
choose those procedures that best suit the particular clinical
problem being investigated. It is the role of the musculoskeletal radiologist to complement these demands and assist colleagues
and patients in making such decisions. (1,2)
References
1. Feldman F: Musculoskeletal radiology: Then and now. Radiology
216:309, 2000.
2. Yochum TR: 1895–1995: Diagnostic imaging in its first century.
J Manipulative Physiol Ther 18(9):618, 1995.
3. Grigg ERN: The trail of the invisible light. Springfield, IL, Charles
C Thomas, 1965.
4. Eisenberg RL: Radiology: An illustrated history. St. Louis, MosbyYearbook, 1992.
Normal Skeletal
Anatomy and
Radiographic Positioning
1
Lindsay J. Rowe and Terry R. Yochum
INTRODUCTION
SKULL
PARANASAL SINUSES
CERVICAL SPINE
THORACIC SPINE
LUMBAR SPINE
SACRUM
COCCYX
PELVIS
FULL SPINE
HIP
KNEE
ANKLE
FOOT
TOES
CALCANEUS
SHOULDER
CLAVICLE
ACROMIOCLAVICULAR JOINT
INTRODUCTION
The imaging assessment of musculoskeletal disease usually
begins in the x-ray room. The performance of a high-quality,
properly positioned, and clinically appropriate examination
is pivotal to arriving at a correct diagnosis. These examinations provide an anatomic “blueprint” on which diagnostic
interpretations and therapeutic decisions can be made.
The purpose of this first chapter is to provide a foundation
for the chapters that follow. It is composed of three
parts—normal anatomy, radiographic positioning, and clinicoradiologic pathologies. These are synthesized to allow the
reader to be able to perform the examination and comprehend
the normal anatomy demonstrated on the obtained radiograph.
For each projection a concise description of the positioning parameters is given, supplemented with photographs demonstrating the actual position. The resulting radiograph is shown
and the visible anatomic structures are labeled. In many cases,
relevant spot radiographs of anatomic specimens are provided
and labeled to augment understanding. In addition to the normal radiograph, similar projections that show pathology have
been included to underscore the importance of proper positioning and the ability to recognize normal versus abnormal.
The emphasis is on the common, standard projections that
are obtained of each body area. More detailed and specialized texts should be consulted for views not included in this
chapter. (1– 4) A fundamental “law” in radiographic positioning is that a minimum of two views at 90° to each other
(orthogonal projections) must be obtained in every case. In
radiology, as in other clinical disciplines, to understand and
recognize the abnormal a thorough knowledge and familiarity with the normal is mandatory. Of equal importance is the
ELBOW
WRIST
HAND
FINGERS
THUMB
RIBS
CHEST
ABDOMEN
REFERENCES
technologic process involved in producing the radiograph,
since it is the quality of the image on which the accuracy of
the interpretation is largely based. (5) To produce radiographs
of inadequate technical quality is to handicap the interpretation, which ultimately compromises patient care. It is for
these reasons that the student of radiology and the healthcare
practitioner who uses skeletal radiographic procedures must
master these two aspects of the discipline.
Normal Skeletal Anatomy
There are 206 bones in the body. The appendicular skeleton
encompasses the 126 bones of the periphery, including the
limbs, shoulder girdles, and pelvis. The axial skeleton is composed of 80 centrally located bones, including the vertebral
column (with sacrum and coccyx), sternum, ribs, hyoid, auditory ossicles, and skull. (Table 1-1) Bone is a vital, connective
tissue that (a) supports mechanical loads, (b) protects vital organs, (c) contributes to mineral homeostasis, and (d) serves as
a site for hemopoiesis and immunogenesis. Knowledge of
bone and joint structure and their physiology is fundamental
for interpreting skeletal images, identifying both abnormal and
normal findings, and accurately describing and ascribing the
clinical significance to observed changes. A more in-depth discussion of the pathophysiology of disease processes and their
radiographic–anatomic correlations can be found in Chapter 7.
Skeletal Development
Bone is derived from mesodermal tissue. The first bone to
begin ossification in the human body is the clavicle. Two
processes of bone formation occur: intramembranous and endochondral ossification.
1
2
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Yochum & Rowe’s Essentials of Skeletal Radiology
Table 1-1
Total Number of Bones by Region
Axial Skeleton
SKULL
Cranium
Facial bones
HYOID
AUDITORY OSSICLES
VERTEBRAL COLUMN
Cervical
Thoracic
Lumbar
Sacrum
Coccyx
THORAX
Sternum
Ribs
Total
Appendicular Skeleton
8
14
1
6
7
12
5
1
1
1
24
80
SHOULDER GIRDLES
Clavicle
Scapula
UPPER EXTREMITIES
Humerus
Ulna
Radius
Carpals
Metacarpals
Phalanges
PELVIC GIRDLE
Innominate
LOWER EXTREMITIES
Femur
Tibia
Fibula
Patella
Tarsals
Metatarsals
Phalanges
Total
2
2
2
2
2
16
10
28
2
2
2
2
2
14
10
28
126
Intramembranous Ossification. Initially, a model is
formed from condensed mesenchymal cells. These cells then
differentiate into two forms: (a) fibroblasts, producing collagen fiber membranes, and (b) osteoblasts, producing osteoid.
Subsequently, bone is formed in this fibrous membrane. There
is no preformed stage of cartilage. Bones formed by this process include the parietal, squamous, and tympanic parts of
the temporal bone, upper occipital squamosa, vomer, medial
pterygoid, and upper face. The clavicles and mandible are
also membranous bones, but they later develop secondary
cartilaginous centers. The width of normal bone is largely
controlled by this method, as a result of the activity of the
periosteum (appositional bone growth).
Endochondral Ossification. Two forms of ossification
occur within cartilage: primary and secondary endochondral
ossification.
Primary Endochondral Ossification. During embryonic development from a condensed mesenchymal model, cartilage
cells (chondroblasts and chondrocytes) form and produce a
cartilage cast of the definitive bone. Subsequently, this cartilage template is transformed to bone as peripheral capillaries
penetrate and induce the formation of osteoblasts. This peripheral collar of new bone then extends bidirectionally along
the long axis of the bone. The outer perichondral envelope
becomes the periosteum, which retains the ability either to
resorb or to produce bone by intramembranous ossification
and is responsible for the maintenance of cortical thickness.
Secondary Endochondral Ossification. A similar but separate process occurs within epiphyses and apophyses. This
process is responsible for the formation of all ends of tubular
bones, vertebrae, ethmoids, and inferior conchae. This method
of ossification in epiphyses is primarily used to lengthen long
bones after birth and support the overlying articular cartilage.
At birth only the distal femoral epiphyses and occasionally
the proximal tibia are normally visible. In apophyses, ossification mechanically supports tendon and ligament insertions.
The appearance and subsequent fusion to the metaphysis
of these secondary centers occur in a generally predictable
and orderly sequence throughout the skeleton until skeletal
maturity, which for males is at approximately 20 years of age
and in females 17 years.
Structure of Bone
Bone is a specialized connective tissue consisting of mineral
(70%), collagen (20%), water (8%), and cells (2%). Approximately 95% of the mineral is hydroxyapatite stored as platelike crystals. The collagen component is secreted by osteoblasts and is referred to as osteoid, a type I collagen.
Osteoblasts. Osteoblasts are bone-forming cells that synthesize the protein osteoid and promote bone deposition. The
mechanism for bone formation by osteoblasts is a complex
interplay between chemical, electrical, and physical factors.
Osteoid is secreted locally by the osteoblast. Simultaneously
the osteoblast cell membrane forms many electronegative
vesicles to attract calcium cations and to exude phosphatase
and protease enzymes. These enzymes hydrolyze protein and
polysaccharide substrates as well as remove phosphate inhibitors. Together these factors promote deposition of calcium and phosphate into the osteoid matrix.
Osteoclasts. Osteoclasts are cells responsible for bone remodeling and resorption. They are multinucleated cells lying
within resorptive cavities called Howship’s lacunae. The cell
of origin is the hemopoietic mononuclear cell. These are metabolically very active cells with the ability to resorb the bone
produced by 100–1000 osteoblasts. Osteoclasts function by
secreting carbonic anhydrase, which degrades carbonic acid.
This produces protons that lower the pH of the local microenvironment to dissolve the mineral and activate hydrolytic
enzymes that degrade the protein osteoid matrix. (6)
Osteocytes. Derived from mesenchymal stem cells, osteocytes occupy spaces within lamellar bone (lacunae).
Though their function is incompletely understood, they
seem important for bone maintenance by receiving mechanical input signals. They then transmit those signals to
other cells via chemical messengers, thus altering regional
bone metabolism.
There are two distinct types of bone: compact and cancellous.
Compact Bone. Compact bone is dense, ivory-like bone
that literally forms the outer shell. It is composed of irregular
cylindrical units, termed osteons, that lie longitudinally and
are interconnected via Volkmann’s canals. This structural organization of bone is called the haversian system. Each osteon
contains a central haversian canal harboring a neurovascular
bundle (artery, vein, and nerve) surrounded by concentric
lamellae (lamellar bone). Between the lamellae are small
1
spaces (lacunae) in which the osteocytes reside. Lacunae
communicate with the central canal and other lacunae by
way of fine radiating channels (canaliculi). Cortical bone is
readily identified on radiographs as a thick, white, sharply
defined outer shell that is thickest in the diaphysis, gradually
tapering toward the metaphysis.
Cancellous Bone (Trabecular, Spongy, or Medullary
Bone, Spongiosa). The internal cavity of bone is traversed by thin interconnecting trabeculae forming a lattice of
criss-crossing bony spicules. The spaces between the trabeculae contain the bone marrow. Each trabecula is lined with a
metabolically active layer, called the endosteum, which in
normal bone is not histologically visible, being apparent only
in disease states. Endosteum extends into the cortex lining
the inner cortex and haversian canals. Normal trabeculae are
formed along lines of stress within bone and are radiographically visible. Wolff’s law encapsulates this phenomenon by
which bone mass is modified in size and orientation. (7) The
biological mechanisms for trabecular organization are multifaceted and involve gravity, muscle action, genetics, vascu-
Normal Skeletal Anatomy and Radiographic Positioning I
larity, and physical properties. Physical stress from gravity is
the major determinant to bone deposition by piezoelectric effect of crystal deformation. At sites where the compression
stress on bone is greater, local crystals will create a relative
electronegativity, which promotes calcium deposition and
bone formation. In areas of tension, a relative electropositive
charge is created that ultimately retards bone formation. (8)
Classification of Bones
Bones are often classified by their morphology as long, short,
flat, or irregular.
Long Bones
Long bones are located in the appendicular skeleton and include the femur, tibia, humerus, and radius. Each long bone
can be divided into components—the epiphysis, physis, metaphysis, diaphysis, apophysis, and periosteum. (Fig. 1-1)
e
p
z
a
m
d
m
z p
e
A
B
3
C
Figure 1-1 GROWING BONE, ANATOMIC DIVISIONS. A. Diagrammatic Representation.
B and C. Radiograph. Observe the epiphysis (e), physis (p), zone of provisional
calcification (z), metaphysis (m), diaphysis (d ), and apophysis (a).
4
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Yochum & Rowe’s Essentials of Skeletal Radiology
Epiphysis. The epiphysis is the expanded end of a long
bone; it is covered by articular cartilage, contributes to the
adjacent joint, and is separated from the metaphysis by the
growth plate. It often lies anatomically inside the joint capsule, where it is bathed in synovial fluid and derives its blood
supply from vessels that must penetrate the joint capsule. The
epiphysis is not covered with periosteum. The articular cortex
and the bone zone immediately beneath is often referred to
as the subchondral bone because there is overlying articular
cartilage.
Physis (Growth Plate). Between the epiphysis and metaphysis in a growing bone is a cartilage plate that is radiolucent
on radiography. Alternate terms for this structure include
epiphyseal plate, epiphyseal growth plate, and bone growth
center. Bone lengthening occurs from the physis by the proliferation of cartilage, its subsequent calcification, and reconversion to ossified tissue. A remnant thin sclerotic line at
the site of epiphyseal–apophyseal fusion is often visible radiographically as a normal variation in adults and is referred to
as an epiphyseal scar.
Metaphysis. The expanded, flared area beneath the growth
plate that tapers into the normal caliber of the shaft is called
the metaphysis. It is the greatest metabolic region of bone
and is responsible for formation of long bone shape during
growth. The cortex is characteristically tapered from thin to
thick toward the diaphysis. A variable portion lies in an intraarticular position and is not covered with periosteum. Trabeculae are visible and directed along lines of stress.
Diaphysis (Shaft ). The diaphysis is the narrowest and
longest portion of a long bone and mainly serves as the primary mechanical support mechanism. It houses the bone marrow and serves as an attachment site for muscle. The cortex
is thickest in the mid-diaphysis and, in general, in normally
mineralized bone the combined thickness of two opposing
cortices will be at least equal to the width of the contained
medullary cavity (corticomedullary ratio). The transition zone
between the cortex and medulla is sharp (corticomedullary
differentiation) and is referred to as the endosteal surface.
of the bone by appositional bone growth; provide a transition zone of attachment for muscles, ligaments, and tendons;
and serve as a source of vascular perfusion to the outer third
of the cortex. Unlike bone, the periosteum is abundantly
innervated. Radiographically, the periosteum is not visible
unless it is mechanically elevated or chemically irritated,
which results in external periosteal new bone formation as a
fundamental sign of disease.
Enthesis. The site of attachment of tendons and ligaments are termed entheses. These osteo-tendinous–osteoligamentous transition zones are highly vascularized and
represent sites of high metabolic activity, which in certain
disease states (such as seronegative arthropathy and hyperparathyroidism) produce diagnostic imaging signs that allow
for an accurate diagnosis.
Short Bones
Short bones are small, cube-shaped bones, such as the carpal
and tarsal bones. They form endochondrally in the same
manner as an epiphysis but do not have a physis and usually
have an individual blood supply. All articular surfaces exhibit slightly thicker cortex and support articular cartilage.
Flat Bones
Flat bones are rich in marrow and are characterized by their
broad surfaces; examples are the calvaria of the skull, sternum, scapula, and ilium. The cortical thickness is relatively
large and the medullary space is interposed. In the skull, the
cortices are called tables and the medullary space, the diploe.
Irregular Bones
Bones that do not conform to any particular shape are massed
together in the category of irregular bones. These include
bones of the cranial base and the vertebrae.
Vascular Supply of Bone
Apophysis. A protuberance beyond the external bone contour, usually at the metaphysis, functions as the site for the attachment of ligaments or tendons. The external cortex is thin
and the surface is often irregular. These structures are referred
to as trochanters, tuberosities, and tubercles. As secondary
growth centers in the developing skeleton they are separated
from the adjacent metaphysis by a physis, which when obliterated in adulthood is marked by an epiphyseal scar.
Periosteum. The periosteum is a soft tissue circumferential envelope, composed of an outer “fibrous” layer and an
inner cellular “cambium” layer that demarcate the contained
bone from surrounding soft tissue. (9) Periosteum covers the
diaphysis and a variable amount of the metaphysis but not
intra-articular bone, such as the epiphysis. It attaches to the
cortex by way of fibrous extensions called Sharpey’s fibers.
In children, periosteum is attached only at the metaphysis,
whereas in adults a firm attachment is made at the metaphysis and diaphysis. Its functions are to maintain the caliber
Arterial Supply
Blood provides nutrition to bone by three vascular systems:
nutrient artery, epiphyseal–metaphyseal arteries, and periosteal arteries. The skeletal system receives approximately
5% of the resting cardiac output.
Nutrient Artery. In a long bone the nutrient artery provides
up to 70% of total bone blood flow. (10) It supplies between
33% and 75% of the inner cortex and virtually 100% of the
medulla. Its entry point relative to a fracture site greatly influences the healing and complications that may occur, the best
example being with proximal scaphoid fractures. A single
vessel arises directly from the main adjacent artery, enters
obliquely through the cortex via a nutrient foramen, and
divides quickly into ascending and descending branches, with
sub-branches providing parallel supplies to the cortex and
medulla. Cortical branches form a circumferential network on
1
the endosteal surface, from which emanate radiating arterioles,
which occupy the haversian and Volkmann’s canals. Nutrition
to osteocytes from these intracanal vessels is by diffusion
along canaliculi. These same vessels eventually anastomose
with penetrating periosteal arterioles. Within the medulla, arterioles are continuous with dilated capillary sinusoids where
the exchange of marrow cells and nutrient exchange occur.
The foramen for entry into a bone can be detected on x-ray as
an oblique, linear radiolucency bordered by two thin parallel
sclerotic lines; they are often confused with fractures.
Epiphyseal–Metaphyseal
Arteries. Epiphyseal–
metaphyseal arteries arise from adjacent periarticular
branches, are multiple, and directly perforate the metaphyseal
cortex. They account for about 30% of total bone blood flow.
(10) Metaphyseal arteries anastomose with medullary arteries
from the nutrient artery. Epiphyseal arteries cross the physis
superficially before penetrating the cortex and supplying the
marrow of the epiphysis. In select locations, such as the proximal femoral neck, radial head, and odontoid process, these
arteries and accompanying veins are intracapsular and lie
on the external bone surface before penetrating the cortex,
rendering them prone to compression from joint effusion
or disruption from fracture. This is the common pathophysiological pathway for complications at these sites, including
avascular necrosis of the supplied epiphysis, fracture nonunion, and delayed union.
Periosteal Arteries. Multiple small arterioles derived from
adjacent soft tissues penetrate the outer fibrous periosteum,
often by way of entheses, to form a capillary network. Small
branches from this network pierce the cortex and become
continuous with the radiating vessels arising internally from
the nutrient artery. Periosteal arteries provide perfusion to the
outer third of the cortex and the cambium and fibrous layers
of the periosteum.
Venous Drainage
Three venous drainage systems are evident: emissary veins
and venae comitantes, cortical venous channels, and periosteal
capillaries. (11)
Emissary veins and venae comitantes are the major drainage vessels of bone, serving both the medulla and bone marrow. They begin in the venous sinuses, travel through the
haversian system, and exit either directly through the cortex
via the nutrient canal (venae comitantes) or other medullocortical penetrating veins (emissary veins). Small cortical
veins originating in the cortex flow into the medulla, periosteum, or emissary veins and are a minor source of venous return. The majority of the cortex drains by small capillaries into the periosteum. Bone is not considered to contain
significant lymphatic channels.
Anatomy of Joints
Joints are complex biological structures and present technical
challenges for obtaining diagnostic images. Specific intraarticular details such as menisci, articular cartilage, labrum,
and synovium require advanced imaging (e.g., computed tomography and magnetic resonance imaging), which is dis-
Normal Skeletal Anatomy and Radiographic Positioning I
5
cussed in Chapter 6. The relevant joint anatomy and pathophysiology of joint disease is discussed in Chapter 10. The
anatomy that is relevant to conventional radiography is covered here.
Joints can be categorized on two bases: joint motion and
articular histology. (12) Three types of joints are recognized
based on joint motion: synarthroses, amphiarthroses, and diarthroses. Synarthroses are fixed, immobile joints and include the skull sutures and growth plates. Amphiarthroses are
slightly movable joints, such as the intervertebral discs
and symphysis pubis. Diarthroses are freely movable joints
and the most common in the body, such as the hip and
shoulder joints.
The tissue type found in the joint space is especially useful in understanding joint disease. Three histologic types
of joints are identified: fibrous, cartilaginous, and synovial.
Essentially, these are equivalent to the joint motion classification, with fibrous tissue being present in synarthroses, cartilage within amphiarthroses, and synovial tissue and fluid
within diarthroses.
The anatomic components of a typical joint relevant to
radiographic depiction include the alignment of the joint
components, articular cortex, subchondral bone, joint space,
and recognizable bony landmarks.
Alignment. The position of the joint components relative to
each other should be assessed, because misalignments such as
subluxations and dislocations can be detected. Various lines,
measurements and bony landmarks are all useful in assessing
displacements.
Articular Cortex. The cortical bone outlining the surface
that participates in the joint is smooth, thin, uniform, and
congruous in configuration with the opposing surface. To
adequately demonstrate the surface of joints that are planar
in orientation, the x-ray beam must be parallel. Curved and
spheroidal surfaces require a minimum of two anatomic positions, and often more, to allow visualization of a large percentage of the articular cortex. Specific changes to the articular cortex such as angular deformation as a sign of collapse,
erosion, or destruction from infection are key signs of disease and are appreciated only if the articular cortex is adequately scrutinized.
Subchondral Bone. Subchondral bone is immediately
below the joint cartilage, including the articular cortex to
1–2 mm below. Bony trabeculae can be visible extending
into the subchondral bone.
Joint Space. The joint space is readily identified as a
smooth, regular, lucent space sandwiched between opposing
parallel bony surfaces. It is also referred to as the joint cavity, articular space, and interosseous space. It is important
to note that the radiographic joint space is a reflection of joint
cartilage, which occupies up to 99% of the space between
opposing bones on an x-ray. The true anatomic joint space,
where there is a gap between the two cartilages, is visible
only if contrast is injected into the joint (arthrogram) or with
traction, in which nitrogen gas may accumulate in the space
and be visible as a radiolucent line (vacuum phenomenon).
For a joint to be adequately demonstrated, the x-ray beam
must pass through the same plane as the joint surfaces.
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Yochum & Rowe’s Essentials of Skeletal Radiology
Radiographic Positioning
Format of Presentation
Each projection shown in this chapter is described in a standard format for simplicity and easy reference. The various
parameters for each projection are concisely provided under
the following headings.
Synonyms. For many views alternate names are applied.
Basic Projections. A list of routine views that are considered a standard series for that region is provided. The asterisk (*) denotes the projection being discussed.
Optional Projections. Specialized non-routine views that
may be employed in special circumstances for that region are
listed.
Demonstrates. The anatomic structures shown on the projection are listed.
Measure. The body area that is measured for calculating
the exposure factors is noted. This is usually the area through
which the central ray will pass.
kVp. The optimum kilovolts peak (kVp) and range are stated
for the body part being examined. (Table 1-2) Kilovolts peak
Table 1-2
Optimum Kilovolts Peak (kVp) a
Region
Skull
Sinuses
Cervical spine
Thoracic spine
Lumbar spine
Anteroposterior
Lateral
Pelvis
Sacrum
Coccyx
Full spine
Hip
Knee
Ankle
Foot
Toes
Shoulder
Clavicle
Acromioclavicular
Elbow
Wrist
Hand
Fingers
Thumb
Ribs
Chest
Abdomen
Soft tissue
Calcific densities
a
kVp
85
85
80
90
85
90
80
80
80
90
80
60
55
55
55
75
70
70
55
55
55
55
55
80
110
100
70
These kVp ranges can be lowered by 10 with 100 kHz high frequency.
values are recommended throughout this chapter for the purpose of creating a diagnostic radiograph of adequate contrast;
they should be applicable to most current film–screen combinations. Readers using detail (extremity) rare earth screens
may experience underexposed radiographs if values < 55 kVp
are routinely used, because of the diminished light output of
the crystals at this relatively low energy level. For these practitioners a kVp value of ≥ 55 should be used for the production
of such radiographs.
Film Size. As a guide, the film size is given; however, clinical discretion should be applied according to the size of the
body part under examination. The orientation of the long axis
of the film may also be changed to accommodate different
body types and clinical scenarios.
Grid. Extremities measuring < 10 cm; lateral, flexion–
extension, and oblique cervicals; and chest films may all be
done without a grid. All other projections should use a grid.
A minimum grid ratio of 10:1 is recommended.
Tube–Film Distance (TFD). TFD is often referred to as the
focal–film distance (FFD) and is the distance between the
tube and film. While a 40-inch (105-cm) TFD is traditionally
applied, faster film–screen combinations make it practical to
use 60–80 inches (160–200 cm) for some exposures.
Tube Tilt. The angulation of the tube in relation to the head
(cephalad) and feet (caudad) is noted. This allows for the central ray to pass parallel to a desired body part, demonstrating
it to better advantage such as the cervical intervertebral foramina (cervical oblique) or patella (“skyline” projection).
Patient Position. The recommended postural attitude of
the patient when the radiograph is obtained (e.g., upright, recumbent, seated) is given. Recumbent studies allow better
anatomic detail owing to tissue compression, smaller object
film distances, reduced scatter radiation, and less patient
motion. Upright studies allow the influence of gravity to affect
bony alignment (scoliosis, spondylolisthesis, osteoarthritis).
Part Position. The position of the body part that is being
radiographed (flexion, extension, supination, etc.) is given.
Central Ray (CR). The CR is the theoretical center of the
radiographic beam as defined by the position of the light
localizer cross-markings from the collimator.
Collimation. Limiting the irradiated film size is a practical decision based on the patient and film size. However, the
smallest size compatible with the body component should
be obtained, and collimation never should exceed the film
size. Collimation is instrumental in reducing radiation dose
to the patient and improving imaging quality.
Side Marker. Appropriate side markers should be placed,
preferably in the corner of the radiographic field, so as not
to obstruct any anatomic details.
1
Normal Skeletal Anatomy and Radiographic Positioning I
7
Breathing Instructions. The patient is told to either stop
breathing (arrested respiration), take a deep breath in and
hold it (suspended deep inspiration), or let the breath out and
hold it (suspended expiration). These respirations may be partial or complete. Occasionally, a breathing technique is used
to intentionally blur obscuring overlying anatomy, such as the
ribs when obtaining a lateral thoracic view.
vey is useful to direct the radiographic examination to include
the abnormal areas. A typical skeletal survey could include bilateral anteroposterior (AP)–posteroanterior (PA) views of
the hands, forearms, humerus, feet, legs, femurs, pelvis, lateral spine, and skull. A joint survey would include AP–PA
views of the hands and wrists, elbows, shoulders, feet and ankles, knees, hips, sacroiliac joints, and lateral spine.
Common Pitfalls. Common errors in positioning or technique calculation are highlighted to improve image quality,
reduce radiation dose, and reduce repeat examinations.
Film Identification. Each film must be identified with the
patient’s name, date of exposure, and clinic where taken.
These demographic details are usually a legal requirement
for proper identification.
Clinicoradiologic Correlations. Key clinically important
radiographic anatomic features are highlighted. This typically follows the ABC’s format: A = alignment, B = bone,
C = cartilage, and S = soft tissue. Selected pathologies shown
on these projections have also been included to highlight the
utility of the view.
Specialized Projections. There are numerous variations
in technique that are used to demonstrate particular aspects
of anatomy not seen to advantage on routine views. These
are listed and briefly described.
Positioning Terminology
The technical jargon in radiographic technology can be complex and only the most clinically relevant terms are presented
here to assist in understanding.
Radiographic Series. In any body location a minimum of
two views perpendicular to each other (orthogonal studies)
must be performed on initial evaluation. A radiographic series is the set of radiographs obtained on a particular body
area. A scout radiograph is a single view taken for the sole
purpose of obtaining a general, non-specific overview of the
body part, which is later followed by more specific projections. In general scout studies have significantly reduced
diagnostic value and are discouraged.
Spot Projections. Spot projections are isolated, closely collimated views of a particular region taken to more closely
evaluate an area that is not well seen on routine views or that
may be abnormal. By reducing scatter radiation and selecting
the optimum exposure significant improvement in detail is
achieved, allowing improved interpretation.
Skeletal Survey. In numerous skeletal disorders characterization of bone or joint lesions according to their location and
appearances can be used to confirm or exclude a diagnosis,
gauge its progress or response to therapy, and assess severity.
The exposures performed are tailored according to the condition. Common indications for skeletal survey include bone
dysplasia, disseminated infection, metastatic disease, multiple
myeloma, non-accidental injury, Paget’s disease, polyarthropathy (rheumatoid arthritis, ankylosing spondylitis),
and metabolic or endocrine-mediated bone disease (renal
bone disease, hyperparathyroidism, scurvy, rickets). Frequently a nuclear bone scan performed before the skeletal sur-
Bucky. The bucky is the mechanism for housing and moving the grid. Generally, the surface the patient contacts during the exposure is often referred to as the bucky. Motion
induced by the bucky on the grid eliminates the appearance
of grid lines on the film. An exposure time of < 0.2 s may
“freeze” the grid and create grid lines. The bucky is used on
thicker body parts to improve image quality. For examinations of the chest and thinner body parts (< 10 cm), a grid
need not be used, since the scatter radiation generated is relatively small. Lateral cervical spine views taken at 72 inches
(200 cm) can also be performed without a grid, because the
air gap between the neck and film allows for scattered rays
to not reach the film. Non-bucky techniques significantly reduce the radiation exposure required to produce a diagnostic image.
Grid. A grid consists of lead strips separated by a radiolucent material and serves to eliminate scattered radiation.
The scattered x-rays tend to be multidirectional and are absorbed by the lead strips, improving film contrast and image
quality. (5,13) Use of a grid increases the patient dose as
a result of this removal of scattered radiation after the beam
has exited the patient. Generally a grid is not necessary for
body parts < 10 cm in thickness and for air-gap techniques,
such as lateral cervical views.
Tube. The tube is the apparatus in which the x-rays are produced by bombarding the anode with high-velocity electrons
produced at the cathode. The x-rays are emitted toward the
patient through the window formed by the collimator.
Tube Tilt. The angle of the beam is occasionally altered to
better depict certain anatomic details. A general rule with tube
tilt is for every 5° of angulation the tube should be moved
1 inch (2 cm) closer to the patient; otherwise, the film may be
underexposed.
Tube–Film Distance (TFD). TFD is the measured distance
between the tube and film.
Collimator. The cube-shaped structure on the outside of
the x-ray tube is the collimator, which can be manipulated to
reduce the field size of the emitted radiation. Inside the collimator is a light source that produces a light beam that accurately simulates the exiting radiation. On this light beam
intersecting lines that represent the center of the emission can
be easily identified.
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Yochum & Rowe’s Essentials of Skeletal Radiology
Kilovolts Peak (kVp). Kilovolts peak is the potential difference created between the cathode (filament) and the anode
during the exposure. It represents the speed that electrons
will have when they interact at the anode. This determines
the “strength” of the emitted x-rays, which translates into the
ability to pass through the body (penetration). Therefore, kVp
is the main determinant of beam quality and alters the film’s
scale of contrast (gray scale). (13,14) As body thickness increases, generally, so does the kVp. In this chapter optimum
kVp is given for each body region.
Milliampere Seconds (mAs). Milliampere seconds refers
to the number of electrons generated per second and determines the density (film blackness) of the image. A linear
relationship exists between film density and mAs, which
allows simpler computation when it is necessary to perform
a retake of an overexposed or underexposed radiograph.
(13,14) Generally, doubling the mAs doubles the film density,
halving the mAs halves the film density.
Lead Blockers. Lead blockers are usually used to block part
of a cassette during an exposure to protect that portion of film
from scatter radiation so that it can be used for multiple projections on the same film. This is commonly used in examinations of the extremities on the same piece of film.
Markers (Figure 1-2). For oblique and lateral views the
general rule is to identify the side closest to the film, placing
the marker so that it does not obstruct important anatomy.
Many types of markers are available. At a minimum, on AP
A
B
views the right or left side should be identified, and on laterals and obliques the side closest to the film is marked. Specialized projections such as stress studies of the spine can be
identified with the addition of an arrow to show the direction
of patient motion. Upright and recumbent studies can be identified by the appropriate word, arrow, or a mercury ball inside
the marker.
Filtration (Figure 1-3). The placement of aluminum and/
or aluminum-copper filters (added filtration) at the collimator considerably reduces the amount of low-energy x-rays
reaching the patient. In addition to reducing patient radiation
dose, filters (sectional filtration) can be used to compensate
for varying body thickness. This is especially the case in the
thoracic and lumbar spine. The effect is to eliminate overexposure of thinner body parts, creating a more homogeneous
density radiograph. (13,15)
Relative Exposure. Radiographs are assessed according
to film density (film blackness). Assuming an optimal kVp,
an overexposed film will appear exceedingly dark because
of too much mAs, whereas an underexposed film will be too
light because of too little mAs.
Object Density. If an area on a radiograph appears black,
it is termed radiolucent; if it appears to be whiter, then it is
called radiopaque.
Patient Position (Figure 1- 4). Various terms are commonly used to describe the patient’s body position in relation
to the x-ray beam.
1. Posteroanterior (PA). The x-ray beam enters the
posterior surface and exits the anterior surface.
2. Anteroposterior (AP). The x-ray beam enters the
anterior surface and exits the posterior surface.
3. Lateral (L). Right lateral (RL) or left lateral (LL)
indicates that the right or left side of the patient is
in contact with the film.
4. Right anterior oblique (RAO). The right anterolateral surface of the body is closest to the film.
5. Left anterior oblique (LAO). The left anterolateral
surface of the body is closest to the film.
6. Right posterior oblique (RPO). The right posterolateral surface of the body is closest to the film.
7. Left posterior oblique (LPO). The left posterolateral
surface of the body is closest to the film.
8. Upright (erect, weight bearing). The patient stands
for the film.
9. Recumbent. The patient lies down for the film.
10. Lateral decubitus. The patient lies on one side, with
the beam passing through horizontally.
11. Seated. The patient sits on a chair or other surface.
C
Figure 1-2 EXAMPLES OF RADIOGRAPHIC MARKERS.
A. Mitchell Markers. Note the central position of the
mercury ball, indicating the horizontal position of the
cassette. B. Upright Markers. The mercury ball has now
gravitated inferiorly, indicating the vertical position of
the cassette. C. Oblique Markers. RPO, Right posterior
oblique; LPO, left posterior oblique; RAO, right anterior
oblique; LAO, left anterior oblique.
Patient Variability. Various differences in body type, position, and bone density alter certain aspects of the technology involved in producing optimum radiographs.
1. Obese patients. Although the overall dimensions of
the body part may be increased, fat is of relatively
low radiodensity and may cause inadvertent over-
1
Normal Skeletal Anatomy and Radiographic Positioning I
A
B
C
D
E
Figure 1-3 EFFECTS OF DENSITY EQUALIZING FILTRATION. A. Anteroposterior Thoracic Spine: Filtration. Observe the
filtered region (arrows). The filter is placed on the collimator. B. Anteroposterior Thoracic Spine: Without Filtration.
Note the overexposed upper thoracic spine (arrows) and the underexposed lower thoracic spine. C. Anteroposterior
Thoracic Spine: With Filtration. The entire thoracic spine is of a uniform density. D. Lateral Lumbar Spine: Without
Filtration. The lumbosacral junction is underexposed; the thoracolumbar region is overexposed (arrow). E. Lateral
Lumbar Spine: With Filtration. Observe that the density from the upper sacrum through to the lower thoracic vertebrae is uniformly exposed. Numerous filters have been used: for lower lung fields, iliac crests, and spinous processes.
(Courtesy of Felix G. Bauer, DC, DACBR (Hon), Sydney, Australia.)
9
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Yochum & Rowe’s Essentials of Skeletal Radiology
of approximately 25% may avoid overexposure.
Conversely, in disorders of increased bone density,
the mAs should be increased by approximately 25%.
6. Traumatized patient. Under no circumstances should
optimal patient positioning take priority over patient
safety. Attempts to position the truly injured patient
may exacerbate the injury.
Motion. Causes of motion include inadequate stabilization
of the respective body part, misinstruction of the patient, long
exposure time, and patient discomfort. All such factors should
be controlled as much as possible.
Patient Protection. In general only the area of interest
should be in the x-ray beam. All other body parts should
be positioned outside the primary beam or be protected. To
reduce patient exposure to primary radiation, collimation to
film size (or smaller) must be performed. A pregnant woman
should not be irradiated unless the clinical circumstances are
life threatening. The risk of irradiating an early-stage developing fetus can be reduced by appropriate patient questioning and application of the 10-day rule. (16)
Gonadal Shielding. In general every attempt to reduce
gonadal radiation must be made. All female patients should be
asked about possible pregnancy as a contraindication to radiographic examination. Various methods for gonadal shielding
have been devised, which require accurate placement. In
examinations of the hips or pelvis, especially in females,
shields should not be used if the suspected pathology would
be obscured. Patients who have had a complete hysterectomy
or who are postmenopausal do not require gonadal shielding.
The Bureau of Radiological Health recommends that gonadal
shielding be used in three particular instances: (a) when
gonads lie within the primary x-ray field or within close proximity (about 5 cm), (b) if the clinical objective of the examination will not be compromised, and (c) if the patient has a
reasonable reproductive potential. (17)
Figure 1-4 RADIOGRAPHIC POSITIONS.
2.
3.
4.
5.
exposure. For this reason, recumbent projections will
compress the body tissues and provide a better radiographic exposure. A reduction in kVp will help
improve film contrast.
Muscular patients. Increased muscle mass can be
compensated for by an increase in kVp of approximately 10 from the original optimum kVp settings.
Pediatric patients. To ensure a proper exposure,
younger patients must be appropriately immobilized.
For the extremities, routine bilateral views for comparison are discouraged. They should be performed
only when specifically indicated.
Upright and recumbent projections. The body thickness alters with changes in postural position. A measurement obtained in the upright position will not be
accurate for determining exposure factors in the
recumbent position because of tissue compression.
Bone density changes. Decreased bone density
(osteopenia) is frequently associated with various
disorders. Under these conditions, and with increasing age (senile osteoporosis), a reduction in the mAs
Measurement. Measuring calipers are used to determine
the thickness of the body part traversed by the central ray,
from which the exposure can be calculated.
Relationship Terms. The following are standard anatomic
terms.
Cephalad. Toward the head.
Caudad. Toward the feet.
Proximal. Toward the center of the body.
Distal. Toward the periphery of the body.
Lateral. Toward the right or left side of the body.
Medial. Toward the middle of the body.
Flexion. The angle between body parts is decreased.
Extension. The angle between body parts is increased.
Abduction. Movement of the body part away from the
midline.
Adduction. Movement of the body part toward the
midline.
Inversion. Outward movement of the ankle; plantar surface faces medially.
Eversion. Inward movement of the ankle; plantar surface
faces laterally.
1
Supination. Palm up.
Pronation. Palm down.
Normal Skeletal Anatomy and Radiographic Positioning I
Table 1-3
Patient Preparation. Before examination of a particular
body part, various steps should be performed.
Common Artifacts of Various
Body Regions
Skull
1. Removal of all objects that may cause a radiographic
artifact (Table 1-3), including metallic objects, dental
appliances, and clothing. If necessary, provide the
patient with a gown.
2. Evacuation of the bowel or bladder, if the abdomen,
sacrum, or coccyx is being examined.
Cervical spine
Thoracic spine
Lumbar spine
Breathing Instructions. In most projections respiration
is transiently halted to prevent motion of the body part (arrested respiration). On occasion breathing may assist in blurring out overlying structures, such as the ribs on a lateral thoracic spine study. Suspended deep inspiration is used for chest
and thoracic exposures to depress the diaphragm, while suspended expiration is used in abdominal films to elevate the
diaphragm.
11
Pelvis, hips, and
shoulders
Wrist and hand
Ankle and foot
Hairpins, wigs, false teeth,
eyeglasses, necklaces,
earrings, bizarre hair styles
Hairpins, wigs, false teeth,
eyeglasses, necklaces,
earrings, bizarre hair styles,
clothing
Necklaces, brassieres, clothing
Orthopedic supports,
brassieres, underwear, pants
with objects in the pockets
Orthopedic supports,
brassieres, underwear, pants
with objects in the pockets
Watches, rings, bracelets,
orthopedic supports
Shoes, socks, orthopedic
supports
Medicolegal Implications
RADIOGRAPHIC TECHNOLOGY
•
•
•
•
• A rationale for obtaining the study
should be established. (18–20) Obtaining
radiographs should not be a “screening”
procedure without the clinical expectation for finding an abnormality that will significantly alter patient
management. Obtaining a radiographic history of
previous studies performed and their location may
assist in deciding what and whether to x-ray.
Adequate views must be obtained. A minimum of
a frontal (AP or PA) and a lateral projection of the
region is required. (21) Supplemental views, such as
oblique and spot views, should be obtained when
clinically indicated or when abnormal findings are
found on an initial study. (21)
Re-examination by x-ray must be substantiated by
clear criteria. Practitioners run the same risks for taking too many films, taking too few films, taking films
too often, and taking films too infrequently. Other
than scoliosis, there are few postural alterations that
indicate a need to repeat a radiographic examination to evaluate therapeutic progress. Indicators for
re-examination include an intervening complication
(neoplasia, trauma, fever, rigors, weight loss, drug or
alcohol use, surgery), appearance of abnormal clinical re-examination findings, failure to respond to
therapy within 4 –6 weeks, and an unexplained deterioration in the condition.
Contraindications to a particular study should be
identified. Examples include pregnancy with lumbar–
pelvic studies, odontoid abnormalities, vertigo,
or vertebrobasilar ischemia with cervical flexion–
extension studies. Patient care extends to the radiography room.
Patient preparation should be rigorously conducted. (18) This includes removal of potential arti-
•
•
•
•
•
facts such as metallic objects (clasps, necklaces, earrings, etc.) and practicing procedures to reduce motion artifacts.
Optimum image quality is paramount. Films must exhibit collimation and must be properly exposed, free
of artifacts, processed accurately, and properly identified. (22) This is one of the most common sources for
antagonistic medicolegal action. (23) Measurement
of the patient and accurate calculation of exposure
factors are crucial to diminishing retakes. (18)
Adequate demonstration of desired anatomy is vitally
important. Poor positioning fails to demonstrate
structures accurately and hinders the diagnostic process. Inclusion of the clinically important area on
the radiograph should be made. (24)
Gonadal shielding should be used whenever possible,
unless it obscures a pelvic structure that is deemed
clinically important, such as the sacroiliac joint. Females in menopause or who have undergone a hysterectomy do not require gonadal shielding. (16) In
males gonadal shielding has few contraindications.
A log book should be kept documenting the patient’s
name, date of the study, views performed, measurement of the patient, TFD, kVp, mAs, and screen type;
there should be space for recording comments on
image quality.
The facility, the equipment, and the operator should
be appropriately licensed and certified. All equipment should be functional and present no hazard
to the safety of the operator or the patient. Equipment should be modern and preferably state-ofthe-art, such as high-frequency generators and rare
earth screens. (25) A quality assurance program
should be in place and routinely applied at regular
intervals.
SKULL: Lateral Projection
OPTIONAL: Vertex
Positioning (Figure 1-5, A and B)
A
B
Figure 1-5 LATERAL, SKULL A. Patient
Position. B. Collimation and Central Ray.
Demonstrates: Lateral cranial structures closest to the
bucky (temporal, parietal), sella turcica, sphenoid sinus,
occipitocervical junction, and calvarium. (1–4) (Fig. 1-C )
2. Artifacts: Removal of head/hair jewelry wherever possible. Tight hair braids and tie bands also can produce
confusing artifacts.
Measure: At the CR.
Clinicoradiologic Correlations: Both right and left laterals should be performed routinely. (4) The most common clinical indications for skull radiography are trauma,
bone malignancy, and metabolic bone disease.
kVp: 85 (80 to 90).
Film Size: 10 × 12 inches (24 × 30 cm), horizontal orientation.
Grid: Yes.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Semiprone. (Fig. 1-5A)
Part Position: Head is in true lateral position against the
bucky. The infraorbital meatal line is parallel with the
long edge of the cassette, and the interpupillary line is
perpendicular.
CR: Passes 3⁄4 inch superior and 3⁄4 inch anterior to the external auditory meatus. (Fig. 1-5B)
Collimation: To skull size.
Side Marker: Side closest to the film, in a corner.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Head rotation: Must be parallel to the film for proper
demonstration.
12
1. Alignment: A well-positioned lateral should show
superimposition of the mandibular rami, orbital roofs,
and sella turcica. The tip of the dens should lie not
more than 8 mm above the plane from the hard
palate to the occipital convexity (McGregor’s line).
(See Chapter 2.)
2. Bone: The vascular markings off the middle meningeal
artery should not be confused with a fracture line. (4)
(Fig. 1-5D) Fractures are better seen on plain film
rather than CT studies. The sclerotic density of the skull
base may mimic bone pathology. Normal bone thinning of the squamous portion of the temporal bone
and occipital bone create a normal decrease in radiographic density of these regions and should not be
confused with bone destruction. (Fig. 1-5E )
3. Cartilage: The lambdoidal and coronal sutures can
occasionally be recognized by their characteristic zigzag pattern. The atlantodental interspace should be
inspected.
4. Soft tissue: The palate and retropharyngeal tissues
should be perused for evidence of swelling or abnormal
density. A fluid level in the sphenoid sinus when performed upright is an indicator of a skull base fracture.
BASIC: *Lateral (right and left), PA Caldwell’s, AP Towne’s
Normal Anatomy (Figure 1-5C)
Figure 1-5 C. Lateral, Skull.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Frontal bone.
Parietal bone.
Occipital bone.
Squamous portion, temporal
bone.
Petrous portion, temporal bone.
Middle meningeal artery.
Frontal sinus.
Ethmoid sinus.
Maxillary sinus.
C
10.
11.
12.
13.
14.
15.
16.
17.
18.
Sphenoid sinus.
Mastoid air cells.
Transverse venous sinus.
Sella turcica.
Internal occipital protuberance.
External occipital protuberance.
Inner table.
Diploe.
Outer table.
19. Parietal star (diploic venous
confluence).
20. Pinna of the ear.
21. Internal auditory meatus.
22. Temporomandibular joint.
23. Nasopharynx.
24. Hard palate.
25. Orbit.
26. Odontoid process.
Clinicoradiologic Correlations (Figure 1-5, D and E )
D
E
Figure 1-5 D. Lateral, Skull, Parietal Fracture. A linear fracture extends though the parietal bone (arrows).
E. Lateral Skull, Multiple Myeloma. Multiple, well-defined radiolucent lesions are visible throughout the parietal and
frontal bones.
13
OPTIONAL: Vertex
SKULL: PA Caldwell’s Projection
Positioning (Figure 1-6, A and B)
Figure 1-6 PA CALDWELL’S, SKULL. A. Patient Position. B. Collimation and Central Ray.
Demonstrates: Frontal bone, frontal sinus, ethmoid sinus,
orbits, sphenoid wings, petrous ridges, and internal auditory canals. (1–4) (Fig. 1-6C)
Measure: Through the CR.
kVp: 85 (80 to 90).
Film Size: 10 × 12 inches (24 × 30 cm), vertical orientation.
Grid: Yes.
TFD: 40 inches (102 cm); must correct for tube tilt with
TFD to 37 inches (94 cm).
Tube Tilt: 15° caudad.
Patient Position: Prone or upright. (Fig. 1-6A)
Part Position: Frontal bone in contact with the bucky.
Remove all lateral head tilt and rotation. The orbitomeatal line should be perpendicular to the cassette.
CR: Exits through the nasion. (Fig. 1-6B)
Collimation: To skull size.
Side Marker: In an open space away from the cranium.
14
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Head position: Failure to tuck chin impairs depiction
of the orbits.
2. Artifacts: Removal of hair jewelry and eyeglasses is
essential.
Clinicoradiologic Correlations:
1. Alignment: The nasal septum and calcified pineal gland
should be midline. If the pineal is displaced, this may
indicate an intracranial mass or hemorrhage.
2. Bone: Done upright, this is a useful projection in the
evaluation of sinus disease, frontal bone, orbits, and
sphenoid. (Figs. 1-6, D and E ) Orbital detail is superior in this projection compared with the straight PA
view without tube tilt.
3. Cartilage: No joints are clearly depicted.
4. Soft tissue: Aeration of the sinuses, the thickness of
the mucosal lining, and evidence of air–fluid levels
should be noted.
BASIC: Lateral (right and left), *PA Caldwell’s, AP Towne’s
Normal Anatomy (Figure 1-6C )
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Frontal bone.
Frontal sinus.
Ethmoid sinus.
Maxillary sinus.
Nasal septum.
Petrous ridge.
Greater wing of sphenoid.
Infraorbital rim.
Supraorbital rim.
Nasal turbinates.
Mandible.
Figure 1-6 C. PA Caldwell’s, Skull.
Clinicoradiologic Correlations (Figure 1-6, D and E)
Figure 1-6 D. PA Caldwell’s, Skull, Frontal Bone Fracture. The fracture is visible as multiple radiolucent lines. The
sinus is filled with hematoma (arrows). E. PA Caldwell’s, Skull, Frontal Sinus Osteoma. Dense, ivory-like new bone fills
a frontal sinus.
15
SKULL: AP Towne’s Projection
OPTIONAL: Vertex
Positioning (Figure 1-7, A and B)
Figure 1-7 AP TOWNE’S, SKULL. A. Patient Position. B. Collimation
and Central Ray.
Demonstrates: Occipital bone, petrous pyramids, posterior foramen magnum, dorsum sellae, posterior clinoids,
zygomatic arches, and mandibular condyle. (1–4) (Fig.
1-7C)
Measure: Through the CR.
kVp: 85 (80 to 90).
Film Size: 10 × 12 inches (24 × 30 cm), vertical orientation.
Grid: Yes.
TFD: 40 inches (102 cm); must correct TFD to 35 inches
(89 cm) for tube tilt.
Tube Tilt: 35° caudad.
Patient Position: Supine or upright. (Fig. 1-7A)
Part Position: Centered, with removal of lateral head tilt
and rotation. Infraorbital meatal line is perpendicular to
the cassette.
CR: Passes through the midline at the external auditory
meatus. (Fig. 1-7B)
Common Pitfalls:
1. Collimation: Care must be taken not to crop off the
vertex.
2. Underexposure: The film is commonly too light, as this
view requires the greatest exposure of any skull view.
3. Head rotation: Will displace the pineal gland and unequally project the petrous pyramids.
Clinicoradiologic Correlations:
1. Alignment: The dorsum sellae and posterior clinoid
processes should project into the anterior portions
of the foramen magnum.
2. Bone: The occipital bone is best demonstrated as are
the petrous ridges, auditory meatus, zygoma, and
mandibular condyle. Fractures through the occipital
bone, zygomatic arches, and the foramen magnum
as well as bone disease of these structures are shown
to advantage in this view. (Figs. 1-7, D and E)
Collimation: To skull size.
3. Cartilage: The temporomandibular joint is poorly
demonstrated. The lambdoidal suture can usually be
seen at the periphery of the occipital convexity.
Side Marker: In an open space at a corner of the film.
4. Soft tissue: The pineal gland should lie in the midline.
Breathing Instructions: Suspended expiration.
16
BASIC: Lateral (right and left), PA Caldwell’s, *AP Towne’s
Normal Anatomy (Figure 1-7C)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
Occipital bone.
Parietal bone.
Lambdoidal suture.
Sagittal suture.
Internal occipital protuberance.
Transverse venous sinus.
Petrous pyramids.
Mastoid air cells.
Foramen magnum.
Dorsum sellae.
Mandibular condyle.
Zygomatic arch.
Cervical pillar.
Figure 1-7 C. AP Towne’s, Skull.
Clinicoradiologic Correlations (Figure 1-7, D and E)
Figure 1-7 D. AP Towne’s, Skull, Occipital Bone Fracture. A linear fracture extends through the
occipital bone (arrows). E. AP Towne’s, Skull, Occipital Bone Paget’s Disease. A sharply defined region of decreased bone density is visible in the occipital bone (arrows), an indication of the osteolytic phase Paget’s disease (osteoporosis circumscripta).
17
PARANASAL SINUSES: Lateral Sinus and
Facial Bones Projection
OPTIONAL: Submentovertical
Positioning (Figure 1-8A)
Figure 1-8 LATERAL, PARANASAL SINUSES.
A. Patient Position.
Demonstrates: Maxilla, hard palate, maxillary sinus, ethmoid sinus, sphenoid sinus, frontal sinus, and orbits. (1–4)
(Fig. 1-8B)
Measure: Between left and right lateral canthus.
kVp: 85 (80 to 90).
Film Size: 8 × 10 inches (18 × 24 cm), vertical orientation.
Grid: Yes.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Head rotation: Does not deliver a true lateral projection.
2. Overexposure: Frequently the sinuses and nasal bone
are overexposed as a result of the contained air.
TFD: 40 inches (102 cm).
Clinicoradiologic Correlations: Upright films are preferred to demonstrate fluid levels within the sinuses.
Tube Tilt: None.
1. Alignment: The palate should lie parallel to the film.
Patient Position: Semiprone or upright, with head turned
to lateral position. (Fig. 1-8A)
2. Bone: Details of the maxillary, frontal, ethmoid, and
sphenoid sinuses are well shown. (5) The pituitary fossa
is shown in true profile and can be assessed for enlargement or erosion. (Fig. 1-8, C and D)
Part Position: Head is turned to a true lateral position.
The midsagittal plane is parallel to the cassette, and the
interpupillary line is perpendicular.
CR: At the lateral canthus of the eye. (Fig. 1-8B)
Collimation: To film size.
Side Marker: At the side closest to the film, near a corner of the film.
18
3. Cartilage: The temporomandibular joint is occasionally demonstrated.
4. Soft tissue: The maxillary antra are radiolucent and
superimposed on the ethmoid air cells and nasal cavity. Air–fluid levels are indicators of sinus disease;
sinuses may contain fluid, pus, or blood.
BASIC: *Lateral, Water’s
Normal Anatomy (Figure 1-8B)
1. Vascular impression of middle
meningeal artery.
2. Orbital plate, frontal bone.
3. Frontal bone.
4. Tuberculum sellae and
anterior clinoids.
5. Posterior clinoids.
6. Sella turcica.
7. Clivus (dorsum sellae).
8. Sphenoid sinus.
9. Ethmoid sinus.
10. Maxillary sinus.
11. Frontal sinus.
12. Frontal process, zygoma.
13. Hard palate.
14. Soft palate.
15. Posterior wall, maxillary sinus.
16. Petrous portion, temporal
bone.
Figure 1-8 B. Lateral, Paranasal Sinuses.
Clinicoradiologic Correlations (Figure 1-8, C and D )
Figure 1-8 C. Lateral, Sinuses, Sella Enlargement. The pituitary fossa is enlarged as
a manifestation of pituitary adenoma in acromegaly. D. Lateral, Sinuses, Depressed
Frontal Bone Fracture. The anterior cortex is depressed into the frontal sinus because
of a fracture (arrow).
19
OPTIONAL: Submentovertical
PARANASAL SINUSES:
Water’s Projection
Positioning (Figure 1-9, A and B)
Figure 1-9 WATER’S, PARANASAL SINUSES. A. Patient Position.
B. Collimation and Central Ray.
Demonstrates: Maxillary sinuses, ethmoid sinuses, frontal
sinuses, orbits, and zygomatic arches. (1–4) (Fig. 1-9C)
Measure: Through the CR.
kVp: 85 (80 to 90).
2. Neck extension: If unable to extend the head, compensate by tube tilt, otherwise the sphenoid sinus will
not be seen.
Grid: Yes.
Clinicoradiologic Correlations: Upright positioning is
preferred to demonstrate fluid levels within the sinuses.
This view is the optimum view following trauma to exclude orbital fractures and for identifying sinusitis.
TFD: 40 inches (102 cm).
1. Alignment: The nasal septum should lie in the midline.
Tube Tilt: None.
2. Bone: The bony outlines of the orbits and maxillary sinuses are well shown. Three lines need to be assessed
(6): the inferior orbital margins (lazy W line), lateral zygoma and arch (elephant’s trunk), and lateral maxilla
(elephant’s neck and leg). This is a decisive view in
orbital trauma to detect blowout fractures, to show
polyps and fluid levels in sinus disease, and to demonstrate destruction in malignancy. (Fig. 1-9D)
Film Size: 8 × 10 inches (18 × 24 cm), vertical orientation.
Patient Position: Prone or upright (PA). (Fig. 1-9A)
Part Position: Midline, with no lateral head tilt or rotation. The head is extended such that the canthomeatal
line is elevated 37° relative to the CR.
CR: Should exit just below the nares. (Fig. 1-9B)
Collimation: To film size.
Side Marker: In an open space.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Mouth position: If the mouth is closed the sphenoid
sinus will be obscured.
20
3. Cartilage: The temporomandibular joint can be identified.
4. Soft tissue: Air–fluid levels within the maxillary sinus
may be fluid, pus, or blood.
BASIC: Lateral, *Water’s
Normal Anatomy (Figure 1-9C)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
Frontal sinus.
Ethmoid sinus.
Maxillary sinus (antrum).
Supraorbital fissure.
Frontal process, zygoma.
Inferior turbinate.
Greater wing of sphenoid.
Lesser wing of sphenoid.
Nasal septum.
Infraorbital foramen.
Coronoid process, mandible.
Top incisors.
Zygomatic arch.
Frontal bone.
Figure 1-9 C. Water’s, Sinus.
Clinicoradiologic Correlations (Figure 1-9D)
Figure 1-9 D. Water’s, Orbital Fracture.
Fracture through the inferior orbital margin
(blowout fracture) is visible (arrowhead).
Additional fractures are seen in the zygomatic
arch (arrow) and lateral wall of the maxilla
(crossed arrow).
21
OPTIONAL: Flexion, Extension, Pillar, Moving jaw
CERVICAL SPINE: AP Lower
Cervical Spine Projection
Positioning (Figure 1-10, A and B)
CR: Thyroid cartilage (C4). (Fig. 1-10B)
Collimation: To film size, with 8-inch wide collimation
to include the lung apices. Include the lower margin of
the mandible.
Side Marker: Indicate left or right at the midneck outside the skin line.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Artifacts: Necklaces and earrings should be removed.
2. Neck position: Overextension of the neck will obscure
the upper segments by the occiput; underextension
will overlap the mandible with these same segments.
Minimize head rotation to centralize tracheal position.
3. Collimation: Exclude the orbits but ensure the lung
apices are included.
4. Tube tilt: If the lordosis is reduced or the tube is underangulated the intervertebral disc spaces will not be visible. Also, failure to employ tube tilt greatly distorts
bony anatomy and diminishes the radiograph’s diagnostic value.
Figure 1-10 AP LOWER CERVICAL SPINE. A. Patient
Position. B. Collimation and Central Ray.
Demonstrates: Lower five cervical vertebrae—vertebral
bodies, vertebral endplates, von Luschka’s joints (neurocentral, uncovertebral joints), and spinous processes—
upper two or three thoracic vertebrae and ribs; medial
border of the clavicles; lung apices; trachea; and neck
muscles. (1–5) (Fig. 1-10, C–E )
Measure: At C4 level (apex of thyroid cartilage).
kVp: 80 (75 to 85).
Film Size: 8 × 10 inches (18 × 24 cm) or 10 × 12 inches
(24 × 30 cm), vertical orientation.
Grid: Yes.
TFD: 40 inches (102 cm); must correct for tube tilt to
37 inches (94 cm) TFD.
Tube Tilt: 15° cephalad, dependent on lordosis.
Patient Position: Upright or supine. (Fig. 1-10A)
Part Position: Center cervical spine to the midline of the
bucky. Extend head so that a line from the lower edge
of the chin to the base of the occiput is perpendicular to
the film. Minimize head rotation.
22
Clinicoradiologic Correlations: Many conditions, including traumatic, arthritic, neoplastic, and congenital anomalies, are well shown on this view. (Fig. 1-10F )
1. Alignment: Spinous processes. Normal coupled rotation with lateral flexion or scoliosis is marked by the
spinous processes deviating in a synchronous, progressive manner to the convexity. A sudden intersegmental
rotation between spinous processes or a widened interspinous space may be a marker of facet subluxation or
dislocation. (6) Similarly divergent opposing endplates
may indicate facet offset.
2. Bone: The vertebral bodies are U shaped in this projection owing to the upgoing uncinate processes.
The endplates are usually visible as thin cortices at the
upper and lower margins of the vertebral body. The
posterior elements of the spinous processes, laminae,
pedicles, transverse processes, and articular pillars
can be identified. Identify T1 by the transverse
processes that are oriented cephalad, which will assist in identifying the presence of cervical ribs. Trace
the upper ribs and clavicles.
3. Cartilage: Recognize each intervertebral disc space
between opposing endplates. The uncovertebral joints
occur laterally at the discovertebral margin as reciprocating convex (uncinate process) and concave (uncinate fossa) surfaces. The facet joints can be recognized
as lying at the apex of the convexity of the undulating
contour of the articular pillars. The upper costotransverse and costovertebral joints can be identified.
4. Soft tissue: The trachea should be midline and uniform
in caliber except for the laryngeal constriction (vocal
cords). The lung apices should be equally aerated and
the aortic arch is frequently visible to the left of the trachea, on which it creates a prominent impression.
BASIC: *AP lower cervical, AP open mouth, Lateral, Obliques
Normal Anatomy (Figure 1-10, C–E)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
C7 spinous process.
C7 lamina.
C7 pedicle.
C7 transverse process.
C6 articular pillar.
C5–C6 von Luschka joint
(uncinate process and fossa).
T1 spinous process.
T1 lamina.
T1 pedicle.
T1 transverse process.
First costotransverse joint.
First rib.
Second costotransverse joint.
Medial clavicle.
Trachea.
Mastoid process.
Angle of mandible.
C5 intervertebral foramen.
Lung apex.
Figure 1-10 C. AP Lower Cervical Spine. D. Specimen Radiograph
(C7–T1). E. Anatomic Specimen, Cervical Spine.
Clinicoradiologic Correlations (Figure 1-10F )
Figure 1-10 F. AP Lower Cervical Spine, von Lushka’s Joint Degeneration. With progressive loss of disc height, the uncinate processes
impact the reciprocating fossa, producing osteophytes, which cause the
uncinates and the fossa to enlarge, sclerose, and become deformed
(arrows). Such changes are best shown on this view.
23
OPTIONAL: Flexion, Extension, Pillar, Moving jaw
CERVICAL SPINE: AP Open
Mouth Projection
Positioning (Figure 1-11, A and B)
Figure 1-11 AP OPEN MOUTH, CERVICAL SPINE. A. Patient Position.
B. Collimation and Central Ray.
Synonyms: Transoral view, AP dens (peg) view.
Demonstrates: Atlas, dens, axis, and occipital condyles.
(7, 8) (Fig. 1-11, C and D)
Measure: At C4 level.
kVp: 80 (75 to 85).
Film Size: 8 × 10 inches (18 × 24 cm), horizontal orientation.
Grid: Yes.
TFD: 40 inches (102 cm).
3. Underexposure: With close collimation, increasing the
mAs by at least 50% from the lower cervical exposure
will avoid underexposure.
4. Malpositioning: The most common cause for retakes
is having the head extended, which places the occiput
over the atlantoaxial joint. Head flexion will descend
the incisors and maxilla, covering the joint. Set the
exposure before positioning to minimize drift and
patient fatigue. Practice the position with the patient
and, when ready, have the patient open the mouth
slowly while fixing the head and maintaining the
incisor–mastoid tip alignment; expose quickly.
Tube Tilt: None.
Patient Position: Upright or supine. (Fig. 1-11A)
Part Position: The neck is centered to the midline of the
bucky. The mouth is opened as wide as possible, with the
lower border of the upper incisors and the tips of the mastoid processes in the same plane perpendicular to the film.
CR: Directed to the midpoint of the open mouth, through
the uvula. (Fig. 1-11B)
Collimation: To the dimensions of the open mouth below
the eyes, include the mastoid processes laterally and exclude the symphysis menti.
Side Marker: Placed inferior to the mastoid process at
the film’s edge.
Breathing Instructions: Suspended expiration. By saying
“ah” during the exposure the tongue will be depressed,
minimizing overlap with C1–C2.
Common Pitfalls:
1. Dentures: If worn should be removed. When the
exposure is completed replace dentures for patient
comfort.
2. Collimation: Failure to adhere to strict four-sided collimation to unnecessarily include the orbits is common.
24
Clinicoradiologic Correlations: This is a vital view in
the assessment of the upper cervical complex and should
be a part of any radiographic study of the neck. It is especially important in trauma to exclude fractures, arthritis, and tumors and to identify congenital variations such
as agenesis. (Fig. 1-11, E and F )
1. Alignment: The atlas lateral mass should not overlap
the lateral margin of the axis by more than 2 mm. The
lateral atlantodental interspaces should be equidistant, and the width of the atlas lateral masses should
be the same. The dens should not be tilted more than
5° and can be a sign of fracture. (9)
2. Bone: All bony landmarks must be identified: atlas
(lateral mass, anterior and posterior arches, transverse
foramen process), axis (odontoid process, pedicle, lamina, spinous process, transverse foramen and process),
and skull base (mastoid process, occiput, mandible).
3. Cartilage: Though often obscured, the convex occipital condyle can be seen reciprocating the atlas lateral
mass surface as the atlanto-occipital joint. The downward sloping atlantoaxial joints are clearly visible, and
the joint space should be visible bilaterally, with the
atlas surface concave and the axis straight to slightly
convex. (10)
BASIC: AP lower cervical, *AP open mouth, Lateral, Obliques
4. Soft tissue: The tongue is frequently visible overlying
the atlas or axis and may produce a pseudofracture
radiolucent line (Mach band), often at the base of the
odontoid. (11)
3. Fuch’s method: Performed AP with the mouth closed,
the chin is elevated so the tips of the mastoid and chin
are aligned with the CR just beneath the chin. The
view should not be attempted in trauma. (14)
Specialized Projections: The complex anatomy and
common clinically significant abnormalities of the upper cervical spine have spawned numerous specialized
projections.
4. Judd’s method: Performed PA with the mouth closed,
the neck is hyperextended so the orbitomeatal line is
about 35° to the film. The CR passes through the midoccipital bone. The view should not be attempted in
trauma.
1. Open mouth variation: If the lower edge of the incisors are superimposed over the lower margin of the
occipital bone and the atlas–dens complex remains
obscured, a 3–5° cephalad tube tilt may help. In cases
of occipitalization this projection will not show the
bony details to any better advantage.
5. Kasabach’s method: The head is rotated 40–45° away
from the midline, the CR is directed to midway between the outer canthus of the eye and external auditory meatus, with 10–15° caudad tube tilt. The study
is performed bilaterally. (15)
2. Otonello projection (wagging, chewing, moving jaw
technique): A combination open mouth and lower
cervical projection can be obtained with an extended
exposure time, while moving the jaw more than once
and providing appropriate head stabilization. (12,13)
Increase exposure by 2– 4 kVp to compensate for
mandibular overlap.
6. Atlantoaxial rotational fixation views: With the patient
in the open mouth position, two views are obtained
bilaterally (four exposures) with the head in 10–15°
of lateral flexion and then rotation. Failure of atlas
rotation and lateral shift as well as non-rotation of
the axis spinous process may be signs of atlantoaxial
rotary fixation. (16)
25
OPTIONAL: Flexion, Extension, Pillar, Moving jaw
CERVICAL SPINE: AP Open
Mouth Projection
Normal Anatomy (Figure 1-11, C and D)
Figure 1-11 C. AP Open Mouth, Cervical. D. Specimen
Radiograph (C1–C2).
1.
2.
3.
4.
5.
6.
7.
8.
26
Atlas lateral mass.
Atlas anterior arch.
Atlas posterior arch.
Atlas transverse foramen.
Atlas transverse process.
Atlanto-occipital joint.
Mastoid process.
Odontoid process.
9.
10.
11.
12.
13.
14.
15.
16.
Axis pedicle.
Axis lamina.
Axis spinous process.
Axis transverse foramen.
Axis transverse process.
Mandible.
Tongue.
Styloid process.
BASIC: AP lower cervical, *AP open mouth, Lateral, Obliques
Clinicoradiologic Correlations (Figure 1-11, E and F )
Figure 1-11 E. AP Open Mouth, Agenesis of the Odontoid Process. Observe the congenital absence of the odontoid
process and lateral subluxation of the atlas on the axis. F. AP Open Mouth, Fracture of the Odontoid Process. An irregular fracture line can be seen traversing through the base of the dens (arrow). Note also the lateral tilt of the
dens as an additional sign of fracture with displacement.
27
OPTIONAL: Flexion, Extension
CERVICAL SPINE: Neutral Lateral
Projection
Positioning (Figure 1-12, A and B)
Figure 1-12 NEUTRAL LATERAL, CERVICAL SPINE. A. Patient Position.
B. Collimation and Central Ray.
Synonyms: Grandy projection. (17)
Demonstrates: Cervical spine, soft tissues of the neck,
and the base of the skull. (1–4,18,19) (Fig. 1-12, C–E )
Measure: At C6 level (base of neck).
Part Position: Shoulder in contact with cassette holder.
Head and neck in true lateral position. Relax and drop
shoulders as much as possible (patient may hold weights).
CR: C4. Center film to the CR. (Fig. 1-12B)
kVp: 80 (75 to 85).
Collimation: Superior to inferior collimation to the top
of the ear and tip of the shoulder.
Film Size: 8 × 10 inches (18 × 24 cm) or 10 × 12 inches
(24 × 30 cm), vertical orientation.
Side Marker: At the side closest to the bucky, just below
the mandible.
Grid: No. Use vertical cassette holder. Air-gap technique
reduces scatter reaching the film.
Breathing Instructions: Suspended full expiration.
TFD: 72 inches (183 cm).
1. “Must see all seven”: Failure to demonstrate to at least
C7, especially in trauma should be avoided. This can
be overcome by (a) increasing the exposure and doing
a spot projection, (b) having the patient hold weights
during the exposure, or (c) performing a swimmer’s
lateral projection of the cervicothoracic junction. Occa-
Tube Tilt: None.
Patient Position: Upright lateral, either standing or sitting. Place the convex side of a scoliosis next to the film.
(Fig. 1-12A)
28
Common Pitfalls:
BASIC: AP lower cervical, AP open mouth, *Lateral, Obliques
sionally CT may be the only means of demonstrating
the cervicothoracic junction.
2. Mandible overlap: Slight extension of the neck will elevate the mandibular angles away from the atlantoaxial vertebrae.
3. Artifacts: Remove earrings and necklaces.
Clinicoradiologic Correlations: Of all cervical projections this single view is the most important for showing
fractures, dislocations, anomalies, and disc space integrity.
(Fig. 1-12, F–H)
1. Alignment: Assess the configuration of the lordotic
curve for reversal, angulation, or straightening. Chinon-chest head position (West Point or military) at the
time of exposure reduces the lordosis. (20) Four visual
lines of alignment should be checked: anterior and
posterior vertebral bodies, spinolaminar lines (posterior cervical line), and tips of the spinous processes.
Measure the atlantodental interspace (ADI) at < 3 mm
in adults and < 5 mm in children.
4. Soft tissue: The prevertebral spaces have smooth anterior air-soft tissue borders (retropharyngeal interspace at C2: < 7 mm; retrotracheal interspace at C6:
< 22 mm). A guideline rule can be used to assist remembering these important measurements: “seven at
two (C2) and two at seven (C7).” The calcified thyroid
cartilage can be identified. The air spaces of the nasopharynx, pharynx, and trachea are usually identifiable.
Specialized Projections: Specific clinical situations may
merit variation in positioning or exposure.
1. Cross-table trauma lateral: In circumstances of acute
cervical trauma in which fracture and dislocation need
to be excluded. The patient is recumbent and the tube
orientated horizontally centered to C4. The shoulders
and neck should not be moved until the exposure is
interpreted and clinical examination is completed. A
complete series can then be performed.
2. Swimmer’s lateral: Rotating the closest shoulder posteriorly with the same arm elevated above the head
will allow better visualization of the cervicothoracic
junction. (21) (Fig. 1-18, A and B)
2. Bone: All bony landmarks should be ascertained: atlas
(posterior tubercle and arch, anterior arch and tubercle, lateral masses), axis (dens, axis body, lamina, spinous), and C3–C7 levels (body, articular pillar and facet,
lamina, transverse process, spinous process, spinolaminar junction).
3. Lateral airways: Assessment for lodging of opaque foreign bodies within the pharynx or upper esophagus
and edema of the epiglottis can be performed by lowering the CR to C6 and reducing the exposure by
approximately 50% mAs.
3. Cartilage: The intervertebral discs, facets, and
atlantodental joints should be identified and assessed for joint space and smooth articular contours.
The ADI should be < 3 mm in adults and < 5 mm in
children.
4. “Off” lateral: Asymmetric demonstration of the posterior elements may aid in the detection of fractures,
especially fractures of the posterior arch of the atlas.
This may be achieved by about 10° of lateral flexion
of the neck at the time of the exposure.
29
OPTIONAL: Flexion, Extension
CERVICAL SPINE: Neutral Lateral
Projection
Normal Anatomy (Figure 1-12, C–E)
Figure 1-12 C. Neutral Lateral, Cervical. D. Specimen Radiograph, Atlantoaxial Segments. E. Specimen Radiograph,
Lower Cervical Segment (C4–C5).
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
30
Atlas posterior tubercle.
Atlas posterior arch.
Atlas lateral masses.
Atlas anterior arch.
Odontoid process.
Axis body.
C4 body.
C4 intervertebral disc.
C5 articular pillar and facet.
C5 lamina.
C5 spinous process.
C5 spinolaminar junction.
C5 transverse process.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
Retropharyngeal interspace.
Retrolaryngeal interspace.
Retrotracheal interspace.
Trachea.
Thyroid cartilage and larynx.
Pharynx.
Hyoid bone.
Angle of mandible.
Sphenoid sinus.
Sella turcica.
Mastoid air cells.
Lambdoidal suture.
External occipital protuberance.
BASIC: AP lower cervical, AP open mouth, *Lateral, Obliques
Clinicoradiologic Correlations (Figure 1-12, F–H)
Figure 1-12 F. Neutral Lateral, Cervical Spine, Vertebral Fusion. Note the congenital block vertebra at C2–C3, where
the facet joints are fused (arrowhead) and the disc between C2 and C3 is almost fused (arrow). Calcification is seen
centrally in the nucleus pulposus. G. Neutral Lateral, Cervical Spine, Fracture–Dislocation (C6–C7). Fractures have occurred through the articular pillars (arrows) and pedicle (arrowhead). This has allowed anterior translation of the C6
vertebral body on C7. H. Neutral Lateral, Cervical Spine, Metastasis to C4 Vertebral Body. Observe the loss of bone
density in the C4 vertebral body, with anterior collapse and a retro-pharyngeal soft tissue mass (arrow). (Courtesy of
James F. Winterstein DC, DACBR, Chicago, Illinois.)
31
CERVICAL SPINE:
Oblique Projection
OPTIONAL: Flexion, Extension, Pillars, Moving jaw
Positioning (Figure 1-13, A–D)
Figure 1-13 OBLIQUES, CERVICAL SPINE. A. Patient Position, Anterior. B. Collimation and
Central Ray, Anterior. C. Patient Position, Posterior. D. Collimation and Central Ray,
Posterior.
Synonyms: Foraminal views.
Demonstrates: Intervertebral foramina, von Luschka
joints, apophyseal joints, and pedicles. (1–4,22,23) (Fig.
1-13E)
Collimation: Top and bottom of the film, with tight lateral collimation.
Measure: At C6 level (base of neck).
Side Marker: Under the mandible on posterior obliques;
behind the spine on anterior obliques when using right
or left markers. RPO and LPO or RAO and LAO markers
can be placed anywhere outside of the field of interest.
kVp: 80 (75 to 85).
Breathing Instructions: Suspended full expiration.
Film Size: 8 × 10 inches (18 × 24 cm), vertical orientation.
Common Pitfalls:
Grid: No. Use non-bucky cassette holder.
TFD: 69 inches (183 cm); must correct for tube tilt of 15°.
Tube Tilt: 15°. (a) Anterior obliques: caudad. (b) Posterior
obliques: cephalad.
Patient Position: Upright or recumbent. (Fig. 1-13, A
and C)
Part Position: (a) Anterior obliques: facing the bucky,
the body is rotated 45° away. The head is then rotated
to be parallel with the plane of the bucky, and the chin
is jutted out slightly. (Fig. 1-13, A and B) (b) Posterior
obliques: facing the tube, the body is rotated 45° away.
The head is then rotated to be parallel with the plane of
the bucky, and the chin is jutted out slightly. (Fig. 1-13,
C and D)
CR: C4 level. (Fig. 1-13, B and D)
32
1. Patient rotation: Inadequate rotation of the body of
< 45° will project the foramina over the vertebral
bodies. Overrotation will project the articular pillars
into the foramina.
2. Incorrect tube angulation: If the foramina appear reduced in vertical dimension then the tube tilt has been
inadequate.
3. Incorrect CR placement: Cervicothoracic abnormalities are often obscured on other views and frequently
will be visible only on oblique studies and so must be
included on the film.
4. Marker placement: Preferably use RAO/LAO or RPO/
LPO when possible—behind the spine for anterior
obliques; in front of the spine for posterior obliques.
If using only L or R markers, use to show which foramina are being displayed.
BASIC: AP lower cervical, AP open mouth, Lateral, *Obliques
Clinicoradiologic Correlations: In circumstances in
which these films cannot be performed at 72 inches
(183 cm), they can be done at 60 inches (152 cm) with the
bucky, which does compromise detail and increase patient
dose. Posterior obliques demonstrate the contralateral
foramina (e.g., RPO—left foramina), and anterior obliques
demonstrate the ipsilateral structures (e.g., RAO—right
foramina). When performing posterior obliques, rotating
the patient to 55° may enhance depiction of the lower
cervical intervertebral foramina. (24) (Fig. 1-13, F–H)
1. Alignment: The laminae in profile should be vertically
aligned. The alignment of the opposing facet surfaces
should be parallel and overlap completely (shingling).
2. Bone: This is a key demonstration of cervical pedicles
because on AP and lateral views they are obscured.
Also, the pillars and lamina are well seen. Often cervical ribs can be identified.
3. Cartilage: Facet and uncovertebral joints should be
assessed with smooth contours. The disc space is not
usually well determined.
4. Soft tissue: The key structures are the intervertebral
foramina, which are round to oval in configuration and
have smooth contours. Their borders should be traced
(pedicle, facet joints, vertebral body, and uncovertebral
joints). Degenerative spurs may narrow the foramen
from the facet or uncovertebral joints (hourglass foramen); a neurofibroma may expand the foramen.
Specialized Projections: So-called trauma obliques are
used when there is a high suspicion for the presence of
an unstable injury while in the emergency room.
1. Trauma obliques: In the supine position the head is in
the neutral position with the CR directed to 2 cm from
the midline at the level of the thyroid cartilage. The
tube is angled medially at 45° and toward the head
20°. The pedicles, pillars, facet, and vertebral body
alignment are readily assessed. (25,26)
2. Dynamic flexion obliques: In the oblique position the
neck is flexed and the alignment of the facet joints is
depicted. The study should be performed only after
fractures and dislocations have been excluded on
other views.
33
CERVICAL SPINE:
Oblique Projection
OPTIONAL: Flexion, Extension, Pillars, Moving jaw
Normal Anatomy (Figure 1-13E )
14
10
9
4
2
8
5
3
6
7
1
11
13
12
Figure 1-13 E. Oblique, Cervical.
1.
2.
3.
4.
5.
6.
7.
34
C6 vertebral body.
C5 transverse process.
C6 pedicle.
C5 lamina.
C6 articular pillar.
C6 spinous process.
C6–C7 intervertebral foramen.
8.
9.
10.
11.
12.
13.
14.
C5–C6 von Luschka joint.
C4 pedicle.
C3 pedicle.
C6 transverse process.
First rib.
Trachea.
Mandible.
BASIC: AP lower cervical, AP open mouth, Lateral, *Obliques
Clinicoradiologic Correlations (Figure 1-13, F–H)
Figure 1-13 F. Oblique, Cervical Spine, Neurofibroma (C3–C4). There is concentric enlargement of the C3–C4
intervertebral foramen with erosion of the posterior vertebral body (arrow) and lamina (arrowhead). The C3
pedicle remains as only thin bony spicule at the superior margin of the foramen. G. Oblique, Cervical Spine,
von Lushka’s Joint Arthrosis (C5–C6). Two protruding osteophytes are visible projecting into the C5–C6 intervertebral foramen originating off the posterolateral uncinate process and reciprocating fossa (arrow).
H. Oblique, Cervical Spine, Aneurysmal Bone Cyst (T1). Note the osteolytic bone destruction of the first
thoracic vertebral neural arch—specifically the pillar, lamina, and pedicle (white arrow)—with some loss of
the posterior vertebral margin (black arrow).
35
OPTIONAL: *Flexion, *Extension, Pillars, Moving jaw
Positioning (Figure 1-14, A and B)
CERVICAL SPINE:
Flexion–Extension Projections
Patient Position: True lateral position aligned to the
bucky midline. (Fig. 1-14, A and B)
Part Position: (a) Flexion: flex the head forward as far as
possible with the chin as close as possible to the sternal
notch. (b) Extension: elevate the chin, extending the head
backward as far as possible.
CR: At the C4 level.
Collimation: To film size.
Side Marker: Mark the side closest to the film, below
the chin in extension and behind the head in flexion.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Inadequate motion: Examination may be precluded
owing to failure to gain patient cooperation or if patient cannot perform an adequate range and induce
sufficient intersegmental motion because of pain.
2. Underexposure: Common on flexion, especially in
thick-necked individuals, and mandibular overlap with
the upper cervical spine may require a 25–50% increase in mAs.
3. Anatomic cutoff: In flexion, especially if the range of
motion allows the chin to approximate the sternum,
the cassette should be placed horizontally to allow inclusion of the upper cervical vertebrae.
4. Motion artifacts: Patient instability while holding
the extremes of neck motion is a common cause of
blurred images. Factor selection and fast exposures are
essential.
Figure 1-14 FLEXION–EXTENSION, CERVICAL SPINE.
A. Flexion, Patient Position, Collimation, and Central
Ray. B. Extension, Patient Position, Collimation, and
Central Ray.
Synonyms: Sagittal functional view, dynamic view, stress
view.
Demonstrates: As per neutral lateral, but additionally
evaluates patterns of global and intersegmental motion
and assesses ligamentous stability. (27) (Fig.1-14, C and D)
Measure: At the C4 level.
kVp: 80 (75 to 85).
Film Size: Depends on neck size. (a) Flexion: 10 ×
12 inches (24 × 30 cm), horizontal orientation. (b) Extension: 8 × 10 inches (18 × 24 cm), vertical orientation.
Grid: No. Use non-bucky cassette holder.
TFD: 72 inches (183 cm).
Tube Tilt: None.
36
Clinicoradiologic Correlations: Contraindications to
these studies include vertebrobasilar ischemia, postural
vertigo, fracture–dislocations, odontoid lesions, and significant neurological deficits. The neutral lateral projection
should be evaluated and the patient carefully examined before these exposures are taken. (20,28) Flexion–
extension films are often used in cases of trauma, congenital anomalies, and inflammatory arthropathy to assess for
ligamentous stability and may be part of a seven-view
examination (AP open mouth, AP lower cervical, neutral
lateral, right and left obliques, and flexion and extension
views) called a Davis series. (29) (Fig. 1-14, E and F)
1. Alignment: Four visual lines of alignment should be
checked: the anterior and posterior vertebral bodies,
spinolaminar lines, and tips of the spinous processes.
Measure the atlantodental interspace (ADI) at < 3 mm
in adults and < 5 mm in children. Normally there is a
uniform widening of the interspinous spaces (fanning)
in flexion and narrowing in extension. Retracting
the chin before full flexion increases the midcervical
kyphosis and reduces flexion at the lower cervical segments. (30) A greater range of motion is induced at the
atlanto-occipital and atlantoaxial joint by tucking the
chin in flexion and protruding it in extension. (31)
2. Bone: Motion can often separate fracture lines and render them more visible, especially those of the axis body
and odontoid process, though these views should not
be performed if such a fracture is already known.
BASIC: AP lower cervical, AP open mouth, Lateral, Obliques
3. Cartilage: Extension views often precipitate the formation of intradiscal nitrogen gas within intradiscal
clefts as a sign of degenerative disc disease (vacuum phenomenon). Degenerative disc disease often
causes alterations in motion patterns, reduction in
intersegmental motion, and retrolisthesis of the segment above the disc space narrowing. Facet arthrosis on flexion–extension may result in increased facet
translation and may be associated with anterior or
posterior intersegmental displacement (degenerative
spondylolisthesis).
4. Soft tissue: The prevertebral soft tissue measurements
should increase only by 1 mm in flexion or extension.
(32) Swallowing, endotracheal tube placement, rotation, lateral flexion, and screaming at the time of exposure can greatly increase the retropharyngeal space
(up to 19 mm). (32,33)
Normal Anatomy (Figure 1-14, C and D)
2
3
2
3
2
1
4
2
1
C
D
Figure 1-14 C. Flexion, Cervical. D. Extension, Cervical.
Review the structures seen in the neutral lateral position.
ALIGNMENT AND MOTION PATTERNS
1. Posterior vertebral bodies (George’s line).
2. Spinolaminar junction lines (posterior cervical line).
3. Atlantodental interspace.
4. Interspinous spaces.
Clinicoradiologic Correlations (Figure 1-14, E and F)
Figure 1-14 E. Extension, Lateral Cervical, Atlantoaxial
Joint. The space between the atlas anterior arch and
odontoid (ADI) is normal in extension. F. Flexion, Lateral
Cervical, Atlantoaxial Instability. On flexion the ADI has
increased to > 3 mm (arrow) as a sign of rheumatoid
arthritis inflammatory effects on the transverse ligament
of the atlas.
37
OPTIONAL: Flexion, Extension, *Pillars, Moving jaw
CERVICAL SPINE: Articular
Pillars Projection
Positioning (Figure 1-15, A and B)
Patient Position: PA. (Fig. 1-15A)
Part Position: Rotate head 45–50° away from side of
interest. Can use 10°. (35)
CR: Direct the CR through the C5 vertebra, to enter the
neck at superior margin of thyroid cartilage and 1 inch
lateral to the midline on the side of interest. Center film
to the CR. (Fig. 1-15B)
Collimation: Top and bottom of film, side 4 inches
wide.
Side Marker: Mark the side opposite the head rotation.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Underexposure: Commonly occurs if the AP factor
calculation is used, as a result of tube angulation and
increased tissue thickness. Increase the exposure by
at least 5–8 kVp.
Clinicoradiologic Correlations: This view can be taken
AP, with caudad tube tilt. The anatomic basis of the view
is to have the beam pass tangential through the facet
joint planes. The most common site for fracture in the
cervical spine is the neural arch, of which the articular
pillar is the most vulnerable to fracture. (28) (Fig. 1-15E)
Figure 1-15 PA ARTICULAR PILLARS, CERVICAL SPINE.
A. Patient Position. B. Collimation and Central Ray.
Synonyms: Pillar views; vertebral or neural arch projection.
Demonstrates: Articular pillars, apophyseal joints, laminae and spinous processes. Both sides must be done for
comparison. (1–4,34,35) (Fig. 1-15, C and D)
Measure: At C4 level.
kVp: 80 (75 to 85).
Film Size: 8 × 10 inches (18 × 24 cm), vertical orientation.
Grid: Yes.
TFD: 35 inches (90 cm); have corrected for tube tilt.
Tube Tilt: 35° cephalad.
38
1. Alignment: The facet joints alignment can be judged by
the congruity of the joint surfaces and their alignment
at the lateral margins.
2. Bone: The shape and height of each pillar can be
assessed. The position and integrity of the spinous
process and each lamina can be observed. The most
common indications for these views is fracture of the
articular pillar, lamina, spinous or transverse processes,
and upper ribs as well as facet dislocations, which are
often not visible on any other study (occult fractures).
(28,34,35) There is common asymmetric normal variation in pillar shape, size, and height.
3. Cartilage: The joint spaces should be symmetrical with
smooth articular surfaces.
4. Soft tissue: The trachea will be displaced toward the
side of mandible rotation.
BASIC: AP lower cervical, AP open mouth, Lateral, Obliques
Normal Anatomy (Figure 1-15, C and D)
Figure 1-15 C. PA Articular Pillars, Normal Cervical. D. Pillar, Fracture at C7. The pillar view shows
offset laterally (arrow) and at the articular surface of the superior articular facet (arrowhead). No
fracture was evident on any other views, highlighting the value of this special pillar projection.
(Courtesy of Thomas M. Goodrich, DC, DACBR, Indianapolis, Indiana.)
1. C5 articular pillar.
2. C4–C5 apophyseal joint.
3. C6 lamina.
4. C5 spinous process.
5. First rib.
Clinicoradiologic Correlations (Figure 1-15E)
Figure 1-15 E. Pillar, Cervical Spine, Pillar Fracture (C7). The C7 pillar is
diminished in vertical height owing to a compression fracture (arrow).
Note the excellent depiction of the adjacent laminae and spinous process.
39
OPTIONAL: Swimmer’s lateral, Obliques
THORACIC SPINE: AP Projection
Positioning (Figure 1-16, A and B)
Figure 1-16 AP THORACIC SPINE. A. Patient Position.
B. Collimation and Central Ray.
Demonstrates: Thoracic spine, posterior rib heads, lung
fields, and mediastinum. (1–3) (Fig. 1-16, C–E )
Measure: At T6 level.
kVp: 80 (75 to 85).
Film Size: 7 × 17 inches (18 × 43 cm) or 14 × 17 inches
(35 × 43 cm), if significant scoliosis is present. Vertical
orientation.
Grid: Yes.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Upright or supine with hips and knees
flexed. (Fig. 1-16A)
40
Part Position: Align midsagittal plane of the body to the
CR, with no rotation.
CR: Place the top of the cassette 2 inches above the
C7 spinous process. Center CR to film. CR will enter
approximately 3 inches inferior to sternal angle.
(Fig. 1-16B)
Collimation: 7 × 17 inch (18 × 43 cm) film: collimate to
film size; 14 × 17 inch (35 × 43 cm) film: collimate to area
of interest.
Side Marker: Place in one of the top corners, preferably
above the level of the clavicles.
BASIC: *AP, Lateral
Breathing Instructions: Suspended inspiration to depress the diaphragm.
Common Pitfalls:
1. Uneven exposure: Overexposure of the upper thoracic
spine is common owing to different body dimensions.
A compensating collimator-attached filter should be
used from the midthoracic to upper thoracic spine.
Use of the anode-heel effect can also be employed
with the anode toward the head.
2. Artifacts: Necklaces and underwear clasps need to be
removed.
3. Collimation: Lateral limitation of the x-ray beam is extremely important to reduce exposure to radiosensitive
breast tissue and superiorly to the thyroid.
Clinicoradiologic Correlations: As with all orthopedic
radiography, orthogonal views (AP and lateral) should
be obtained. If the thoracic spine is examined then it is
mandatory that a lateral also be obtained. Statistically,
the thoracic spine is one of the most common sites for
malignancy, fracture, and infection.
1. Alignment: Scoliosis is common in the thoracic spine
and should be identified as to its cause (idiopathic,
congenital, etc.), direction by convexity (left or right),
end and apex vertebrae, intersegmental rotation, and
rib and vertebral deformities. The normal interspinous
space, interpediculate distance, vertical interpediculate
distance, facet joint space, and vertebral wedging
should not vary more than 2 mm in adjacent segments
(Rule of Two’s). (4)
2. Bone: Each vertebra should have its individual components identified: transverse processes, pedicles, spinous
process, inferior and superior endplates, and intervertebral disc space. (5) The spinous processes are elongated caudally and overlap the segment below. The
pedicle is a key structure, seen as paired elongated
ovals in the upper third of the vertebral bodies. (5,6)
(Fig. 1-16F) The distance between the thoracic pedicles
gradually widens in the lower thoracic spine to accommodate the conus medullaris of the spinal cord, with
the lower thoracic pedicles often being very thin. (5,7)
The proximal ribs, sternum, and medial clavicles can
also be observed. The T1 transverse processes are oriented cephalad.
3. Cartilage: The intervertebral, costotransverse, and
costovertebral joints should be identified. (Fig. 1-16G)
Because of the kyphosis, the upper discs may not be
clearly visible. The facet joints are coronally orientated
from the cervicothoracic junction to at least T10 and
will not be visible at these levels. At the thoracolumbar junction— often at T11 or T12—the facet joints
undergo acute reorientation to a sagittal plane and
will be visible on the AP film as a space between two
smooth facets (referred to as the thoracolumbar
mortise). (8)
4. Soft tissue: The paravertebral soft tissue, heart–
mediastinum, diaphragm, and lung fields should all
be reviewed, often by using a “hot” (bright) light.
The lung–vertebral interface is marked by the sharp
transition from the lucent air-filled lung to the paraspinal soft tissues and are referred to as the paraspinal lines. (9) These occur bilaterally from approximately T8 to the diaphragm and should parallel the
spine, although the right line can be more difficult
to identify. Soft tissue pathology in this space—such
as blood (hematoma from fracture), pus (abscess
with spinal infection), and cells (tumor with vertebral
destruction)—can be recognized by localized bulging
of this line. (9,10) (Fig. 1-16H) Recognizing the aortic
arch to the left of the trachea, which causes a distinct
tracheal indentation, is important not to confuse with
a mediastinal abnormality. Calcification within the aortic arch can be seen as a curvilinear C-shaped density
(thumbnail sign). Tracheal position should be over the
thoracic spine, and its deviation can be a sign of disease
such as substernal thyroid, goiter, or lymphoma or
of lung volume changes, including upper lobe fibrosis
(healed tuberculosis), atelectasis, or carcinoma (Pancoast tumor). If such abnormalities are recognized, a
formal chest radiographic series should be performed.
The posterior costophrenic recesses lie at the level
of the 12th rib and may extend to as low as L1 and
should be distinct and subtend an acute angle with
the spine. (11)
Specialized Projections: Spot views with four-sided
collimation will greatly enhance the detail of the selected
area, because of the greater body thickness generating
degrading scatter radiation.
1. PA projection: In scoliosis assessment for which numerous films will be obtained over a period of often
years during skeletal development and high bone
marrow activity, significant radiation dose reductions
can be achieved in this position. (12)
2. Lateral bending: In scoliosis, flexibility assessment can
be achieved by placing the patient in the extremes of
right and left lateral bending. Curves that remain unchanged are “stable” and cannot be reduced even
with surgery and are less likely to advance.
41
OPTIONAL: Swimmer’s lateral, Obliques
THORACIC SPINE: AP Projection
Normal Anatomy (Figure 1-16, C–E )
Figure 1-16 C. AP, Thoracic Spine. D. Spot Radiograph, AP, Thoracic Spine. E. Specimen Radiograph,
Thoracic Segments.
1.
2.
3.
4.
5.
6.
7.
42
Rib.
Transverse process.
Costotransverse joint.
Costovertebral joint.
Pedicle.
Spinous process.
Inferior endplate.
8.
9.
10.
11.
12.
13.
Intervertebral disc space.
Clavicle.
Diaphragm.
Trachea.
Paraspinal line (arrowheads).
Aorta (arrows).
BASIC: *AP, Lateral
Clinicoradiologic Correlations (Figure 1-16, F–H )
Figure 1-16 F. AP, Thoracic Spine, Pedicle Osteolytic Metastases. Absence of the pedicle at T4 is obvious once comparison for the same structure is performed at all vertebral levels (arrow). Because this is a common presenting sign
for neoplasm in the spine, it underscores the importance of identifying all pedicles at all levels on spinal radiographs.
G. AP, Thoracic Spine, Degenerative Disc Disease. There are prominent bony spurs (osteophytes) visible on the right
side of the thoracic spine bridging over the intervertebral disc spaces (arrows). Note the absence on the left side
owing to the pulsatile inhibition influence of the left-sided descending thoracic aorta. H. AP, Thoracic Spine,
Infection with Paravertebral Abscess. A destructive infection of the disc is present with damage to the adjacent
endplates (arrowheads). Accumulation of pus (abscess) in the paravertebral space results in lateral displacement of
the paraspinal lines (arrows).
43
OPTIONAL: Swimmer’s lateral, Obliques
THORACIC SPINE: Lateral
Projection
Positioning (Figure 1-17, A and B)
Figure 1-17 LATERAL, THORACIC SPINE. A. Patient
Position. B. Collimation and Central Ray.
Demonstrates: Thoracic spine, ribs, lung fields, and heart.
(1,2,13) (Fig. 1-17, C–E)
TFD: 40 inches (102 cm).
Measure: At T6 level, under the axilla adjacent to the
scapula.
Patient Position: Lateral recumbent or upright lateral,
arms elevated anteriorly or above the head. (Fig. 1-17A)
kVp: 90 (85 to 95).
Part Position: Align midaxillary plane to CR.
Film Size: 7 × 17 inches (18 × 43 cm) or 14 × 17 inches
(35 × 43 cm), if kyphosis is increased. Vertical orientation.
CR: Place the top of the cassette 2 inches above the C7
spinous process. Center CR to film. CR will enter approximately 3 inches inferior to sternal angle at about
T6. (Fig. 1-17B)
Grid: Yes.
44
Tube Tilt: None.
BASIC: AP, *Lateral
Collimation: 7 × 17 inch (18 × 43 cm) film: collimate to
film size; 14 × 17 inch (35 × 43 cm) film: collimate to
area of interest.
Side Marker: Place in a corner behind the spine.
Breathing Instructions: Suspended inspiration to depress diaphragm.
Common Pitfalls:
1. Patient motion: With the arms flexed forward patient
motion is common and should be minimized by short
exposure times, compression, or stabilizing devices
such as a hand rail to grasp. Careful patient instruction
is imperative.
2. Uneven exposure: The upper thoracic spine is often
underexposed and may require a spot view. Insertion
of a collimator-mounted filter over the lower thoracic
segments may help overexposure.
3. Artifacts: Necklaces and underwear clasps, such as
from brassieres, need to be removed.
4. Lateral flexion: If the pelvis is pushed against the bucky,
the thorax will be laterally flexed and the image distorted. Placement of a pelvic pad will minimize the
lateral flexion, or tilting the tube 10° cephalad may
help compensate if the distortion cannot be avoided.
5. Scoliosis: Place the convexity of the curve toward the
bucky to use normal beam divergence to optimize the
demonstration of the intervertebral discs and vertebral
bodies.
Clinicoradiologic Correlations: The lateral film should
always be performed when a frontal film has been obtained, because it clearly shows to greater advantage the
discs and vertebral bodies that are common sites of disease. (Fig. 1-17, F–H)
by at least 5° and no more than 2 mm when compared with the adjacent segments. (4,14) Occasionally
the wedging is very prominent at T11, T12, or L1 as a
variant of normal. The vertebral endplates are smooth
and slightly concave to straight. The lower thoracic
bodies are tallest, the midthoracic segments the most
elongated, and the upper bodies the smallest. Rib elements can also be determined. Note that the axillary
border of the scapula is superimposed over the upper
thoracic vertebral bodies, which gives the appearance
that the vertebrae are fused.
3. Cartilage: Each intervertebral disc gradually diminishes
in height from caudad (T12) to cephalad (T1). Apophyseal joints can usually be identified in the middle to
lower thoracic spine.
4. Soft tissue: The diaphragm is readily discerned as an
arc of soft tissue density curving anteriorly. Typically
the right hemidiaphragm is higher than the left. The
posterior margin of the heart is formed by the left ventricle and left atrium. Linear branching opacities of the
pulmonary vasculature emanate from the hilar region
of the lung. The trachea can be traced from the thoracic inlet to the T4 level, where it bifurcates, and the
lung hila can be located by identifying the main stem
bronchi seen enface.
Specialized Projections: Spot views can be obtained at
any level.
1. Breathing technique: The overlying rib structures can
be obliterated from the film by allowing shallow respiration during an extended exposure time (approximately 1 sec).
2. Cross-table lateral: Performed supine with a horizontal
beam, arms elevated forward.
1. Alignment: The thoracic kyphosis is assessed as to degree and pattern of curvature. The posterior vertebral
bodies should be aligned.
3. Flexion–extension: Preferably the pelvis will be stabilized and exposures are performed in forward flexion
and extension.
2. Bone: All components of each vertebra should be
identified: vertebral body, endplates, pedicle, intervertebral foramen, and apophyseal joint. All thoracic vertebral bodies will be physiologically wedged anteriorly
4. Obliques: Rotating the body to 70° either anteriorly
or posteriorly so that the body forms an angle of 20°
to the film will allow demonstration of the thoracic
facet joints. (15,16)
45
OPTIONAL: Swimmer’s lateral, Obliques
THORACIC SPINE: Lateral
Projection
Normal Anatomy (Figure 1-17, C–E)
2
Figure 1-17 C. Lateral, Thoracic Spine. D. Specimen Radiograph, Thoracic Segments. E. Anatomic Specimen,
Thoracic Spine.
1.
2.
3.
4.
5.
6.
7.
8.
46
Vertebral body.
Endplate (arrowhead).
Intervertebral disc.
Pedicle.
Intervertebral foramen.
Apophyseal joint.
Spinous process.
Axillary margin, scapula (arrow).
9.
10.
11.
12.
13.
14.
15.
16.
Rib head.
Posterior rib.
Lateral rib.
Diaphragm.
Posterior costophrenic sulcus.
Heart.
Lung hilus.
Trachea.
BASIC: AP, *Lateral
Clinicoradiologic Correlations (Figure 1-17, F–H )
Figure 1-17 F. Lateral, Thoracic Spine, Compression Fractures. Two levels of compression fracture are evident in the
midthoracic spine (arrows). The vertical height of each vertebra is decreased. The superior vertebra shows fracture of
the superior and inferior endplates and loss of anterior and posterior vertebral body heights. The inferior vertebra
shows only depression of the inferior endplate, and the loss of height is limited to the anterior surface. G. Lateral,
Thoracic Spine, Scheuermann’s Disease. Contiguous midthoracic vertebrae show irregular endplates and vertebral
body wedging, with a generalized increase in the kyphosis. H. Lateral, Thoracic Spine, Osteopetrosis. All thoracic vertebral bodies show localized increased bone density confined to the sub-endplate regions. This represents a developmental failure to convert calcified cartilage into mature bone, which encroaches onto the marrow space of all bones
and produces brittle bones prone to fracture and anemia.
47
THORACIC SPINE: Lateral
Cervicothoracic Junction (Swimmer’s Projection)
OPTIONAL: *Swimmer’s lateral, Obliques
Positioning (Figure 1-18, A and B)
Figure 1-18 LATERAL CERVICOTHORACIC JUNCTION.
A. Patient Position. B. Collimation and Central Ray.
Synonyms: Twining view.
Demonstrates: Lower cervical and upper thoracic vertebrae, especially the vertebral bodies and intervertebral
discs. (17,18) (Fig. 1-18C )
Measure: As for lateral thoracic, at the T6 level, under
the axilla adjacent to the scapula.
CR: Passes just anterior to the tube-side shoulder through
the sternal notch. (Fig. 1-18B)
Collimation: To film size; include C5–T5.
Side Marker: Place in the top corner, posterior to the cervical spinous processes.
kVp: 90 (85 to 95).
Breathing Instructions: Suspended expiration to accentuate shoulder depression.
Film Size: 10 × 12 inches (24 × 30 cm). Vertical orientation.
Common Pitfalls:
Grid: Yes.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Upright. The arm closest to the bucky
is flexed, with the hand placed on the top or behind the
head. The arm closest to the tube is extended, the elbow
flexed with the hand placed over the anterior hip. If the
humeral heads can be separated, no rotation of the body
is preferable; if it is not possible to prevent humeral superimposition, minimal rotation of the posterior body 10–20°
toward the bucky may be used. (Fig. 1-18A)
48
1. Rotation artifact: Any rotation of the torso will not
show the vertebrae in true lateral projection.
2. Humeral superimposition: The shoulders have not been
separated adequately or the upper shoulder was depressed, which can be compensated with a 5° caudal
tube tilt.
3. Underexposure: Establishing correct exposure factors
for C7–T1 can be difficult and requires at least a doubling of the lateral cervical spine mAs.
Clinicoradiologic Correlations: The swimmer’s lateral is
useful following cervicothoracic trauma (C6–T3) and in
BASIC: AP, Lateral
broad-shouldered individuals where C7 and T1 cannot be
adequately demonstrated. (18) At least 25% of cervicothoracic fractures are not visible on routine views, which
underscores the importance for performing this projection.
Care must be taken in cases of trauma, because positioning for this view may accentuate any intersegmental instability at the cervicothoracic junction. (19)
3. Cartilage: Check the alignment of the facet joints and
congruity of opposing endplates and note any evidence
for dislocation.
4. Soft tissue: The retrotracheal space should be measured for any evidence of soft tissue swelling; the space
is normally < 22 mm.
1. Alignment: Alignment of the anterior and posterior
vertebral bodies must be evaluated. Identifying vertebral endplates is also important to ascertain compression fractures or dislocations.
Specialized Projections: Given the difficulty for imaging this region, CT is the preferred method for definitive
evaluation. (20)
2. Bone: Meticulous scrutiny of the lower cervical and
upper thoracic vertebrae is required to find evidence of
fracture, especially compression fractures of the vertebral bodies and fractures of the spinous processes.
1. Pawlow’s method: Lateral recumbent position, arm
closest to the bucky extended above the head with the
humeral head in front of the spine. The upper shoulder
is depressed with the hand on the posterior thigh.
Normal Anatomy (Figure 1-18C )
10
11
9
12
8
1
5
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
First rib.
Medial clavicle.
Manubrium.
Scapula.
Distal clavicle.
Posterior ribs.
Lateral ribs.
Trachea.
Retrotracheal space.
C6 vertebral body.
C6 intervertebral foramen.
Spinous process (C7, T5).
4
1
2
2
3
12
6
7
C
Figure 1-18 C. Lateral Cervicothoracic (Swimmer’s
Projection).
49
OPTIONAL: Lateral lumbosacral spot, Flexion,
Extension, Lateral bending
LUMBAR SPINE: AP
Lumbopelvic Projection
Positioning (Figure 1-19, A and B)
Figure 1-19 AP LUMBOPELVIC. A. Patient Position.
B. Collimation and Central Ray.
Synonyms: Weight-bearing orthoradiography. (1)
Demonstrates: Lumbar vertebrae, pelvis, hips, proximal
femora, and soft tissues of the abdomen. (2–5) (Fig. 1-19,
C and D)
Patient Position: Upright or supine. Use of a foot plate
to standardize feet position and equal weight distribution is a useful adjunct. (1,6) (Fig. 1-19A)
Measure: At L4–L5 level.
CR: 1.5 inches below the iliac crest level. Center film to
the CR. (Fig. 1-19B)
kVp: 85 (80 to 90).
Collimation: 14 × 17 inch (35 × 43 cm) field.
Film Size: 14 × 17 inches (35 × 43 cm), vertical orientation.
Side Marker: At one of the upper corners of the film.
Grid: Yes.
TFD: 40 inches (102 cm).
Tube Tilt: None.
50
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Reduced detail: A larger field of view, reduced tissue
compression, and patient motion all reduce anatomic
BASIC: *AP, Lateral, Obliques, AP spot
detail, which can be compensated for with rigorous
four-sided collimation, compression, and stabilizing
devices.
2. Incomplete inclusion of the pelvis: Whenever possible
include the iliac crests, ischia, and proximal femurs. (6)
3. Exclusion of the thoracolumbar junction: By including
the lower pelvis fewer vertebrae and lower ribs will be
included in the exposure field, which are often implicated in back pain syndromes (7).
4. Lordosis artifact: The intervertebral disc spaces and
endplates will be obscured away from L3 because of
the lordosis effect. The lumbosacral junction, sacrum,
and sacroiliac joints are significantly distorted and a
specific angulated lumbosacral view is a useful adjunct
in the pathologic assessment of low back pain.
5. Foot position: The feet should be equidistant from the
midline and separated to lie in line with the femoral
heads with equal weight distribution.
6. Large patients: Upright films are significantly reduced
in quality in large patients; supine views are preferred
to compress the abdomen and reduce the time of
exposure.
7. Gonad shielding: Use gonad shielding when possible,
since lumbar exposures deliver the largest single source
of gonadal radiation to the population.
Clinicoradiologic Correlations: Inclusion of the pelvis is
not a standard procedure, except when assessing for
weight-bearing-induced distortions and biomechanical
abnormalities. (Fig. 1-19, E–G) This should include the iliac
crests, ischia, and proximal femurs. In cases of leg pain,
assessment for lesions of the hip and lower pelvis may elucidate a cause. Techniques for low back complaints often
employ therapies or maneuvers using the pelvis and proximal femurs as levers or contact points; thus, structural integrity needs to be assessed before therapeutic delivery.
1. Alignment: Note the presence of any scoliosis and
the direction of intersegmental rotation to assess for
coupled motion patterns. If the pelvis is included evaluate for any pelvic obliquity, femoral alignment (Shenton’s, iliofemoral, Skinner’s, and Klein’s lines), acetabular depth, and angles (acetabular, femoral) to
determine normality.
2. Bone: All vertebral components should be located, including the neural arch (spinous process, lamina, pedicle, articular processes, transverse processes, pars interarticularis) and vertebral bodies (endplates, centrum).
(2) The distance between the inner margins of the
pedicles (interpediculate distance) increases progressively from L1 to L5. The sacrum, ilium, ischium, femur,
and lower ribs should also be observed.
3. Cartilage: The intervertebral disc spaces are most visible at L3 between the opposed superior and inferior
endplates. The upper and lower discs are obscured
because of the sagittal lumbar lordosis. The facet
joints lie between the superior and inferior articular
processes as a thin 1-mm gap; those visible are orientated predominantly in the sagittal plane. The sacroiliac joint lies at an oblique angle, with the anterior joint
space more elongated and lateral relative to the posterior joint, which is shorter and more medial. The
symphysis pubis surfaces are often curved. The hip
joint space has three compartments—medial, axial,
and superior—which are in the ratio of 2:1:1 in thickness. Observe that the superior acetabulum has a
dense superior border and a physiological axial defect
(acetabular notch).
4. Soft tissue: The psoas shadow is readily seen as a
pyramid-shape soft tissue density originating at T12–L1
and diverging laterally into the pelvis. Its absence can
be a sign of serious retroperitoneal pathology, psoas
abscess, and vertebral fracture. Less than 40% of normal patients will exhibit clear definition of both psoas
shadows; the left psoas is twice as commonly seen as
the right. (8) In scoliosis < 30% of patients will have
a visible psoas (being most common on the convex
side and rare on the concave side). (8) Outlines of the
liver, spleen, and kidneys may be visible as a result of
capsular fat.
Specialized Projections: Variations are numerous and
employed in specific clinical circumstances.
1. AP lumbar spine: The AP lumbosacral view without the
full pelvis is taken with a 14 × 17 inch (35 × 43 cm) or
7 × 17 inch (18 × 43 cm) film, collimated laterally to include the sacroiliac joints, with the CR at the level of
the iliac crests (L4).
2. PA lumbar spine: PA views can be used to take advantage of the diverging beam passing directly through
the vertebral endplates, discs, and sacroiliac joints, reducing the lordosis artifact; however, pathological
details of the pelvis will be compromised. (9)
3. Neural arch view: Angling the beam caudad, centering to the lower sternum, and tripling the mAs can be
used to demonstrate the neural arch to advantage
when obliques or tomography is not possible. (5)
4. Lateral bending: Performed sitting or standing, preferably with the pelvis stabilized. End motion films are
taken on left and right lateral flexion to stress the joints
and stabilizing soft tissues for evidence of abnormal
motion patterns, excessive motion, or reduced motion.
(1,10)
51
OPTIONAL: Lateral lumbosacral spot, Flexion,
Extension, Lateral bending
LUMBAR SPINE: AP
Lumbopelvic Projection
Normal Anatomy (Figure 1-19, C and D)
Figure 1-19 C. AP Lumbopelvic. D. Spot Radiograph, AP Lumbar Spine.
1.
2.
3.
4.
5.
6.
7.
52
Spinous process.
Pedicle.
Superior articular process.
Transverse process.
Inferior articular process.
Lamina.
Pars interarticularis (isthmus).
8.
9.
10.
11.
12.
13.
Twelfth rib.
Sacral ala.
First sacral tubercle.
Sacroiliac joint.
Descending colon.
Psoas muscle.
BASIC: *AP, Lateral, Obliques, AP spot
Clinicoradiologic Correlations (Figure 1-19, E–G )
53
OPTIONAL: Lateral lumbosacral spot,
Flexion, Extension, Lateral bending
LUMBAR SPINE: Lateral
Lumbosacral Projection
Positioning (Figure 1-20, A and B)
Figure 1-20 LATERAL LUMBOSACRAL, SPINE.
A. Patient Position. B. Collimation and Central Ray.
Demonstrates: Lower thoracic and lumbar vertebrae
(T12–L5); sacrum; coccyx; and soft tissues of the pelvis,
abdomen, and lower chest. (2,3,11,12) (Fig. 1-20, C
and D)
Measure: (a) Males: 1 inch below the iliac crests. (b)
Females: 1 inch below the iliac crests and 1 inch above the
iliac crests, then average the two.
kVp: 90 (85 to 95).
Film Size: 7 × 17 inches (18 × 43 cm) or 14 × 17 inches
(35 × 43 cm), if lordosis is increased, with obesity, or if
the abdominal organs are to be assessed, including the
aorta, for aneurysm; vertical film orientation.
Grid: Yes.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Upright lateral or lateral recumbent.
(Fig. 1-20A)
CR: 1 inch above the iliac crest level, with the vertical CR
passing halfway between the anterior superior iliac
spine (ASIS) and posterior superior iliac spine (PSIS).
Center film to the CR. (Fig. 1-20B)
54
Collimation: Top and bottom of film, side collimation to
accommodate the lordosis.
Side Marker: In a corner of the film or within the lordosis, away from the spine.
Breathing Instructions: Suspended expiration (elevates
diaphragm to show lower thoracic spine).
Common Pitfalls:
1. Uneven exposure: The lower thoracic vertebrae are
often overexposed because the lung base and the lumbosacral junction is underexposed because of the overlapping pelvis. Balancing filtration and suspended expiration can be used to minimize this effect. Patients
with a large difference in the pelvis and waist (> 5 cm)
may require a separate exposure for L5–S1 and T12–
L4. Spinous processes are usually overexposed and
may require specific underexposed study for adequate
demonstration.
2. Gonadal shielding: This is the single greatest dose delivered to the gonads, which should be shielded and
collimated from the field wherever possible.
3. Scoliosis, lateral bending artifact: An inherent scoliosis
should have the convexity placed toward the bucky
BASIC: AP, *Lateral, Obliques, AP spot
to show the discs to advantage. During positioning,
pushing the pelvis into the bucky—inducing lateral
flexion of the spine—will impair depiction of true
disc height and endplate definition, which can be
minimized with a sponge support between the waist
and bucky surface.
to a more sagittal plane at the thoracolumbar mortise
below T11–L1. The intervertebral disc heights are
smaller in the upper levels (L1–L2), maximal at L3 and
L4, and often slightly smaller again at L5. Note that
the vertebral endplates are slightly concave. The disc
spaces are wider anteriorly than posteriorly.
4. Motion artifact: Owing to tissue density and thickness,
exposures are often long and motion unsharpness is
common; use short exposure times and stabilizing
devices as much as practicable.
4. Soft tissue: The hemidiaphragms curve anteriorly over
the thoracolumbar junction. Colonic gas and, in erect
postures, the air–fluid level in the fundus of the stomach (magenblase) are often visible. Calcified aortic
atherosclerotic plaques are commonly observed anterior to the L3 and L4 vertebral body margins.
Clinicoradiologic Correlations: This is a crucial view for
demonstrating bone-disc detail and vertebral alignment
(Fig. 1-20, E–G).
1. Alignment: Observe the lordosis, sacral base angle,
intervertebral disc angles, and gravity weight-bearing
lines. Each posterior vertebral body margin (posterior
body line) should be in alignment.
2. Bone: All vertebrae should have their components
identified: vertebral body curved margins (endplates,
anterior and posterior borders), neural arch (pedicles,
articular processes, facets, spinous process, pars interarticularis), and intervertebral foramen. (2–5) Note that
the L5 foramen is projectionally small. Observe the
landmarks of the sacrum, including the sacral base and
promontory, ala, undulating anterior cortex, neural
canal, vestigial discs, and coccyx. Identify the lower ribs.
3. Cartilage: The facet joint spaces will be visible in the
lower thoracic segments, where they are coronally
orientated, but will not be visible after the transition
Specialized Projections: Variations are employed in specialized clinical situations.
1. Lateral lumbosacral spot: Supplemental view of L5–S1
when underexposed on the entire lateral study. (13,14)
2. Flexion–extension: Preferably performed with weight
bearing, exposures are obtained at the endpoints of
flexion and extension, respectively, ensuring that the
pelvis remains centered to the film. Stabilizing the pelvis during placement to reduce hip motion is preferred
to induce greater motion segment forces and demonstrate intersegmental instability. (10).
3. Traction–compression: Radiographs are taken while
suspended by grasping a bar (traction) and then while
wearing a weighted backpack (compression) to provoke latent intersegmental instability manifested by AP
displacement. (1,15)
55
LUMBAR SPINE: Lateral
Lumbosacral Projection
OPTIONAL: Lateral lumbosacral spot,
Flexion, Extension, Lateral bending
Normal Anatomy (Figure 1-20, C and D)
Figure 1-20 C. Lateral Lumbosacral, Spine. D. Spot Radiograph, Lateral Lumbar Spine.
1.
2.
3.
4.
5.
6.
7.
56
Vertebral body.
Pedicle.
Superior articular process.
Spinous process.
Inferior articular process.
Intervertebral foramen.
Pars interarticularis (isthmus).
8.
9.
10.
11.
12.
13.
14.
Intervertebral disc.
Vertebral endplate.
Sacral promontory.
Twelfth rib.
Iliac crest.
Apophyseal (facet) joint.
Superior articulating processes, sacrum.
BASIC: AP, *Lateral, Obliques, AP spot
Clinicoradiologic Correlations (Figure 1-20, E–G )
Figure 1-20 E. Lateral Lumbar, Spine, Multiple Fractures. A coronally orientated fracture is present at the L3 vertebral
body. More subtle compression fractures of the superior endplates of L2 and L4 are recognizable by the cortical offset
at the anterosuperior margins of these segments (arrows). F. Lateral Lumbar, Spine, Degenerative Disc Disease. All disc
spaces are decreased in height and contain a linear radiolucency (vacuum phenomenon) where nitrogen gas has accumulated within degenerative fissures in the disc (arrows). G. Lateral Lumbar, Spine, Metastatic Disease. All vertebrae
show diffuse areas of decreased density mixed with patchy areas of sclerosis. Observe the two vertebral bodies with
pathological compression fractures at T12 and L3 (arrows).
57
OPTIONAL: AP spot, Lateral lumbosacral spot,
Flexion, Extension, Lateral bending
LUMBAR SPINE: Oblique
Projection
Positioning (Figure 1-21, A and B)
Figure 1-21 OBLIQUE, LUMBAR SPINE. A. Patient Position, Collimation, and Central Ray, Anterior. B. Patient
Position, Collimation, and Central Ray, Posterior.
Demonstrates: Posterior neural arch elements—the socalled Scotty dog (2,16,17)—transverse process, pedicle,
articulating processes, facet joints, pars interarticularis,
and laminae. Also provides an additional view of the vertebral body and abdominal soft tissues. (2,3,16,17) (Fig.
1-21, C and D)
Measure: At the CR at L3.
kVp: 80 (75 to 85).
Film Size: 10 × 12 inches (24 × 30 cm), vertical orientation.
Grid: Yes.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Upright or recumbent.
Part Position: (a) Anterior oblique: semiprone, with the
body rotated 45°. On the side elevated, flex the knee and
elbow to support the position. Align the spine to the CR.
(Fig. 1-21A) (b) Posterior oblique: semisupine, with the
body rotated 45°. Arm along table rests at patient’s side.
The elevated arm crosses the body to grasp the edge of
the table. (Fig. 1-21B)
CR: (a) Anterior oblique: 1 inch lateral to L3 spinous
process. (b) Posterior oblique: 1 inch above the iliac crest
and 2 inches medial to the anterior superior iliac spine
(ASIS).
Collimation: Top to bottom, to film size, and 8 inches
from side to side.
58
Side Marker: (a) Anterior obliques: behind the spine, denoting which side is demonstrated. (b) Posterior obliques:
in front of the spine, denoting which side is demonstrated.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Rotation malposition: If the facet joint spaces are not
clearly seen in profile, body rotation is incorrect. If the
pedicle is well anterior on the vertebral body the patient is not oblique enough; if the pedicle is well posterior on the vertebral body, the patient is too
oblique. If only a few joint spaces are visible, the body
is not oblique as a unit, caused by axial torsion.
2. High CR: Visualizing the CR entry at L3 can be difficult,
and frequently the lumbosacral junction is clipped
from the exposure. Including the plane of the ASIS will
ensure its inclusion.
3. Lordosis artifact: Recumbent studies allow the knees
to be drawn up and the hips flexed, reducing the lordosis to give clearer definition of the facets and vertebral bodies.
Clinicoradiologic Correlations: Anterior obliques show
greater structural detail because the lumbar lordosis complements the diverging x-ray beam and the neural arch
side depicted is closest to the bucky. Both right and left
obliques must be performed. This view is especially useful
for depicting the pars, pedicle, facet joints, anterolateral
vertebral bodies, and aorta (Fig. 1-21, E–G).
BASIC: AP, Lateral, *Obliques
1. Alignment: The facet joints from L1 to L5 form virtually a straight line. The joint surfaces of each facet
should be parallel to each other and aligned at their
edges (Hadley’s “S” curve).
2. Bone: Components of the Scotty dog silhouette should
be identified: The “nose” is the transverse process, the
“ear” the superior articular process, the “front foot”
the inferior articular process, the “neck” the pars interarticularis, the “eye” the pedicle, and the “body”
the lamina. (17) Additional components represent the
contralateral neural arch: the “tail” is the superior
articular process and “hind foot” the inferior articular process. A separation at the pars interarticularis
(spondylolysis) can be seen as a linear radiolucency in
this view (collar sign) and may not be visible on other
projections. (18) The pedicle is a favored site for bone
malignancy (one-eyed pedicle sign) and is shown to
advantage in the oblique position. The anterolateral
vertebral body is also shown in profile, which may
demonstrate subtle compression fractures or bone
destruction. A tangential view of both iliac wings and
upper sacrum is also provided.
3. Cartilage: The key structure to analyze is the facet
joint space for narrowing (arthritis), misalignment
(subluxation–dislocation), and structural variations
(anomalies). (19) The contralateral sacroiliac joint space
is also frequently displayed; the articular cortices are
seen in profile, which should be smooth, be continuous, and have normal underlying bone density.
4. Soft tissue: The psoas muscle sheath edge may be visible diverging away from the thoracolumbar junction.
The kidney silhouette may also be visible and can show
renal calculi to advantage. When the aorta is calcified
its walls can be assessed for aneurysm formation.
59
OPTIONAL: AP spot, Lateral lumbosacral spot,
Flexion, Extension, Lateral bending
LUMBAR SPINE: Oblique
Projection
Normal Anatomy (Fig. 1-21, C and D)
Figure 1-21 C. Oblique, Lumbar Spine. D. Specimen Radiograph, Lumbar Segment.
1.
2.
3.
4.
5.
60
Pedicle.
Superior articular process.
Pars interarticularis (isthmus).
Lamina.
Inferior articular process.
6.
7.
8.
9.
Transverse process.
Spinous process.
Intervertebral disc.
Interlaminar space.
BASIC: AP, Lateral, *Obliques
Clinicoradiologic Correlations (Figure 1-21, E–G )
Figure 1-21 E. Oblique, Lumbar Spine, Spondylolysis (L5). In the pars interarticularis of the L5 vertebra there is a distinct radiolucency (arrow) (collar sign) representing an ununited stress fracture (spondylolysis). This is usually not
clearly visible on any other view. F. Oblique, Lumbar Spine, Facet Arthrosis. All facet joints show features of degeneration, including loss of joint space, sclerosis, and osteophytes at the tips of the superior and inferior articular processes.
G. Oblique, Lumbar Spine, Aortic Aneurysm. The curvilinear calcification outlining the dilated wall of an aortic
aneurysm can be seen projected anterior to the spine (arrows). This calcification often is not visible on standard frontal
and lateral films.
61
OPTIONAL: Lateral, Lumbosacral lateral
spot, Flexion, Extension, Lateral bending
LUMBAR SPINE: AP Lumbosacral
Spot Projection
Positioning (Figure 1-22, A and B)
Figure 1-22 AP LUMBOSACRAL SPOT. A. Patient
Position. B. Collimation and Central Ray.
Synonyms: Ferguson’s, Hibbs’, Chamberlain’s, or
Barsony’s projection; tilt-up view, lumbosacral tilt;
semi-axial AP projection. (20–22)
Part Position: Supine or erect. Center lumbosacral spine
to midline of film.
Measure: Through the CR.
CR: Enters at the midline at the level of the inferior aspect
of the anterior superior iliac spine (ASIS) (halfway between the umbilicus and the pubic articulation). Center
film to the CR. (Fig. 1-22B)
kVp: 85 (80 to 90).
Collimation: To film size.
Film Size: 8 × 10 inches (18 × 24 cm) AP or 10 × 12 inches
(24 × 30 cm) PA, vertical orientation.
Side Marker: In a corner of the film.
Demonstrates: L5 vertebra and disc, upper sacrum, and
sacroiliac joints. (2,3,20,23,24) (Fig. 1-22C)
Grid: Yes.
TFD: 40 inches (102 cm); must correct for tube tilt; for
20° tilt, reduce the TFD by 4 inches.
Tube Tilt: 20° cephalad or to coincide with the plane of
the sacral base.
Patient Position: Upright or supine. (Fig. 1-22A)
62
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Underexposure: At least a doubling of the mAs is necessary to obtain adequate exposure.
2. Undercollimation: Strict four-sided collimation must
be employed to reduce image-degrading scatter and
optimize sacral and sacroiliac joint detail.
BASIC: AP, Lateral, Obliques, *AP spot
3. Tilt error: Adequate visualization depends on the CR
passing through the plane of the lumbosacral disc,
which can be established from the lateral film. In general, weight-bearing studies and female patients tend
to have greater lordoses and increased lumbosacral
angles, sometimes requiring a greater degree of tube
angulation to achieve the correct view.
Clinicoradiologic Correlations: For low back pain investigation this is probably the single most important
view for assessing the lumbosacral junction, sacrum, and
sacroiliac joints. (Fig. 1-22, D and E) If upright AP lumbar
films are performed this view is an important diagnostic
supplement.
1. Alignment: The sacral base should be straight and horizontal with the L5 inferior endplate in parallel. Note
the relationship of the L4 disc relative to the level of
the iliac crests (intercrestal line), which often is at or
above in women and below in men. Lateral deviation
of the coccyx can be identified.
2. Bone: The L5 vertebral arch is shown to advantage and
may demonstrate pedicle abnormalities, defects of the
pars interarticularis, fractures, anomalies of facet orientation (tropism), and various forms of union of the
transverse process with the sacral ala (transitional segment). (18,25) At the sacrum four key landmarks are
the sacral pedicles, sacral crest, sacral body endplates,
and cortical margins of each sacral foramen (arcuate
or foraminal lines). (26)
3. Cartilage: The L5–S1 disc space can be established
between the anterior sacral promontory and inferior
L5 endplate. The L5–S1 facet joint space if sagittally
orientated will be apparent as a thin lucency between
the surfaces of the facets. The sacroiliac joint appearance is complex with overlapping anterior and poste-
rior components. The anterior joint cavity is synovial;
it is laterally placed and curved in appearance with
smooth surfaces and a uniform joint space. It begins
approximately 1 inch below the sacral ala and extends to the pelvic inlet cortical surface. The posterior
joint space lies medial and has three sections of
about 1 cm in length each: inferior, which is usually
vertical; middle, which has an L-shaped deviation in its
midcourse; and superior, which merges toward the
anterior joint. (21)
4. Soft tissue: Apparent radiolucent bone lesions, particularly of the pelvis, from superimposed gas will move
superiorly with tube angulation, whereas intrinsic bone
lesions will remain unchanged in position. The same
applies to soft tissue masses and calcifications.
Specialized Projections: Additional views are occasionally employed for clarification.
1. PA view: Performed upright or prone, the tube is tilted
caudad 20°, with the CR passing through the L5 spinous process. It has been argued that despite sacral
magnification the angle of the sacroiliac joints allows
the diverging x-ray beam to pass through the joint
and its surfaces, producing clear definition of the joint
superior to that of the AP view.
2. Oblique views: Oblique views are performed AP
(supine) or PA (prone). (a) Supine: the side to be
demonstrated is elevated 25–30° off the table with
the CR 1 inch medial to the elevated ASIS. (b)
Prone: the pelvis is also rotated 25–30° degrees off
the table with the CR at the posterior superior iliac
spine (PSIS) of the side closest to the table. These
views are seldom required, because the AP–PA tilt
view is usually sufficient for joint assessment. (21)
63
OPTIONAL: Lateral, Lumbosacral lateral
spot, Flexion, Extension, Lateral bending
LUMBAR SPINE: AP Lumbosacral
Spot Projection
Normal Anatomy (Figure 1-22C )
Figure 1-22 C. AP Lumbosacral Spot.
1.
2.
3.
4.
5.
64
Spinous process of L5.
First sacral tubercle.
Sacral ala.
Medial posterior ilium.
First sacral foramina.
6.
7.
8.
9.
Sacroiliac joint.
Posterior superior iliac spine.
Sacral endplate.
Transverse process of L5.
BASIC: AP, Lateral, Obliques, *AP spot
Clinicoradiologic Correlations (Figure 1-22, D and E )
Figure 1-22 D. AP Lumbosacral Spot, Sacroiliitis. One sacroiliac joint demonstrates widening of the joint and prominent subchondral sclerosis of the iliac margin (arrow). This was caused by psoriatic sacroiliitis and was not detectable
on the weight-bearing AP view because of the effect of the lumbar lordosis. E. AP Lumbosacral Spot, Lumbosacral
Transitional Segment. The L5 transverse processes are enlarged and form accessory articulations with the sacral ala
(arrows).
65
OPTIONAL: *Lateral lumbosacral spot,
Flexion, Extension, Lateral bending
LUMBAR SPINE: Lateral
Lumbosacral Spot Projection
Positioning (Figure 1-23, A and B)
Collimation: 8 × 10 inch (24 × 30 cm) field.
Side Marker: In a corner of the film.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Underexposure: Allowance for the effect of the
superimposed pelvis must be made with exposure calculations.
2. Gonadal shielding: Should be applied wherever possible given the higher radiation of the exposure.
3. Lateral flexion artifact: Care must be made not to induce any lateral flexion or rotation, which will distort
the appearance of the lumbosacral disc.
Clinicoradiologic Correlations: This is a supplemental
view obtained when the lumbosacral joint is underexposed
on the routine lateral lumbar film. (13,14) (Fig. 1-23, D–F )
Figure 1-23 LATERAL LUMBOSACRAL SPOT. A. Patient
Position. B. Collimation and Central Ray.
Demonstrates: L5 vertebra and disc, upper sacrum, and
adjacent soft tissues. (2,3,27) (Fig. 1-23C)
Measure: 1 inch below the iliac crests.
kVp: 90 (85 to 95).
Film Size: 8 × 10 inches (18 × 24 cm), vertical orientation.
Grid: Yes.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Upright lateral or lateral recumbent.
(Fig. 1-23A)
Part Position: True lateral position, with CR entering midway between the anterior superior iliac spine (ASIS) and
posterior superior iliac spine (PSIS).
CR: 1 inch below the iliac crest level. Center film to the
CR. (Fig. 1-23B)
1. Alignment: The relationship of L5 to the sacral base
can be assessed for retrolisthesis or anterolisthesis
(spondylolisthesis). The angle of the sacral base to the
horizontal can be measured (sacral base angle). The
coccygeal alignment relative to the sacrum is often
demonstrated.
2. Bone: The L4 and L5 vertebral bodies and neural arches
are identifiable. Note how the intervertebral foramen
at L5–S1 appears smaller than that at L4–L5, because it
is orientated inferiorly and more posteriorly. The upper
sacrum is usually seen, especially the sacral promontory. The superimposed iliac wings are discernible as
curved outlines over the L4 or L5 vertebrae.
3. Cartilage: The L5–S1 intervertebral disc is primarily evaluated for its height and for demonstrating changes at
the adjacent endplates.
4. Soft tissue: The presacral soft tissues are usually visible
outlined by gas in the rectum. Calcification within the
iliac arteries may be visible.
Specialized Projections:
1. Lumbosacral foraminal view: From the lateral position
the body is rotated 30° toward the bucky, the tube is
angled 15–30° caudad, and the CR is at the iliac crest
through L5–S1. This will demonstrate the intervertebral
foramen at L5–S1 of the side closest to the bucky. (28)
Figure 1-23 D. Lateral Lumbosacral Spot, Ventral Hemivertebra. The L4 vertebra (4) is wedge shaped and deficient
posteriorly with smooth opposing endplates. This anomaly was partially obscured on the routine lateral owing to the
overlying iliac crest. E. Lateral Lumbosacral Spot, Spondylolisthesis. The L5 vertebra lies anterior to the sacrum, determined by aligning the posterior body lines of L5 and the upper sacrum. Also observe that the L5–S1 disc space is greatly
reduced in height secondary to degenerative disc disease. F. Lateral Lumbosacral Spot, Metastases. The L4 vertebral
body is densely sclerotic (ivory vertebra) and the L5 vertebral body is predominantly destroyed by an osteolytic process
with loss of the normal bony outlines. There is also disease in the L3 vertebra and upper sacrum.
66
BASIC: AP, Lateral, Obliques, AP spot
Normal Anatomy (Figure 1-23C )
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Body.
Pedicle.
Superior articular process.
Pars interarticularis (isthmus).
Inferior articular process.
Lamina.
Intervertebral foramina.
Intervertebral disc.
Vertebral endplate.
Sacral promontory.
Superior articular process of the sacrum.
Transverse process.
Figure 1-23 C. Lateral Lumbosacral Spot.
Clinicoradiologic Correlations (Figure 1-23, D–F )
67
SACRUM: AP Sacrum Projection
Positioning (Figure 1-24, A and B)
Figure 1-24 AP SACRUM. A. Patient Position. B. Collimation and
Central Ray.
Synonyms: Ferguson’s, Hibbs’, Chamberlain’s, or
Barsony’s projection; lumbosacral tilt; semi-axial AP projection. (1–3)
Demonstrates: Sacrum, sacroiliac joints, coccyx, and
lumbosacral joint. (4–8) (Fig. 1-24, C and D)
Measure: At the CR.
kVp: 80 (75 to 85).
Film Size: 10 × 12 inches (24 × 30 cm), vertical orientation.
Grid: Yes.
TFD: 40 inches (102 cm); must reduce TFD 1 inch for
every 5° of tube tilt.
Tube Tilt: 15° cephalad; depends on sacral position.
Ultimately, the CR should be perpendicular to the body
of the sacrum.
Patient Position: Supine or upright. (Fig. 1-24A)
Part Position: Patient is centered to the midline.
CR: Midway between the pubic symphysis and the umbilicus. Center film to the CR. (Fig. 1-24B)
Collimation: 10 × 12 inch (24 × 30 cm) field.
68
Side Marker: In the corner of the film.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Underexposure: At least a doubling of the mAs is necessary to obtain adequate exposure.
2. Undercollimation: Strict four-sided collimation must
be employed to reduce image-degrading scatter and
optimize sacral and sacroiliac joint detail.
3. Tilt error: Adequate visualization depends on the CR
passing perpendicular to the plane of the sacrum,
which can be established from the lateral film. In
general, weight–bearing studies and female patients
tend to have greater lordoses and increased sacral tilt,
thus sometimes requiring a greater degree of tube
angulation to achieve the correct view.
Clinicoradiologic Correlations: A preceding enema and
voiding of the bladder should be performed to reduce the
confusing overlying densities of gas, feces, and urine. (7)
For low back pain investigation this is probably the single
most important view to be obtained to assess the lumbosacral junction, sacrum, and sacroiliac joints. (Fig. 1-24,
E and F ) If upright AP lumbar films are performed this
view is an important diagnostic supplement.
BASIC: *AP, Lateral
1. Alignment: The sacral base should be straight and
horizontal with the L5 inferior endplate in parallel.
Note the relationship of the L4 disc relative to the level
of the iliac crests (intercrestal line), which often is at or
above in women and below in men. Lateral deviation
of the coccyx can be identified.
2. Bone: The L5 vertebral arch is shown to advantage and
may demonstrate pedicle abnormalities, defects of the
pars interarticularis, fractures, anomalies of facet orientation (tropism), and various forms of union of the
transverse process with the sacral ala (transitional segment). (8,9) At the sacrum four key landmarks are the
sacral pedicles, sacral crest, sacral body endplates, and
cortical margins of each sacral foramen (arcuate or
foraminal lines). (9,10)
3. Cartilage: The L5–S1 disc space can be established
between the anterior sacral promontory and inferior
L5 endplate. The L5–S1 facet joint space if sagittally
orientated will be apparent as a thin lucency between
the surfaces of the facets. The sacroiliac joint appearance is complex, with overlapping anterior and posterior components. The anterior joint cavity is synovial, laterally placed, and curved in appearance with
smooth surfaces and a uniform joint space. It begins
approximately 1 inch below the sacral ala and extends to the pelvic inlet cortical surface. The posterior
joint space lies medial and has three sections of
about 1 cm in length each: inferior, which is usually
vertical; middle, which has an L-shaped deviation in its
midcourse; and superior, which merges toward the
anterior joint. (2) The joint space is 1–2 mm wide in
adults and bilaterally symmetrical.
4. Soft tissue: Apparent radiolucent bone lesions, particularly of the pelvis, from superimposed gas will move
superiorly with tube angulation, whereas intrinsic bone
lesions will remain unchanged in position. The same
applies to soft tissue masses and calcifications.
69
SACRUM: AP Sacrum Projection
Normal Anatomy (Figure 1-24, C and D)
Figure 1-24 C. AP Sacrum. D. Specimen Radiograph, Sacrum.
1.
2.
3.
4.
70
First sacral tubercle.
Sacral ala.
Superior articular process of the sacrum.
Second sacral foramen.
5.
6.
7.
8.
Sacral–coccygeal junction.
Coccyx.
Sacroiliac joint.
Third sacral tubercle.
BASIC: *AP, Lateral
Clinicoradiologic Correlations (Figure 1-24, E and F )
Figure 1-24 E. AP Sacrum, Sacral Metastases. There is diffuse destruction of the lower half of the sacrum
as evidenced by the loss of the foraminal cortices, pedicles, and sacral bodies. F. AP Sacrum, Sacral
Fracture. The ventral sacral foraminal cortices show displacement from S1 to S3 (arrows). Compare with
the normal contralateral foraminal lines.
71
SACRUM: Lateral Projection
Positioning (Figure 1-25, A and B)
Figure 1-25 LATERAL, SACRUM. A. Patient Position. B. Collimation
and Central Ray.
Demonstrates: Sacrum, lumbosacral joint, coccyx, and
presacral soft tissues. (4–7) (Fig. 1-25, C and D)
Measure: At the CR.
kVp: 80 (75 to 85).
Film Size: 10 × 12 inches (24 × 30 cm), vertical orientation.
Grid: Yes.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Lateral recumbent or upright. (Fig.
1-25A)
Part Position: Place patient in the lateral position, with
the hips and knees flexed for support, if recumbent.
Center the sacrum over the midline of the table.
CR: At the anterior superior iliac spine (ASIS) level, 2 inches
anterior to the posterior sacral surface. Center film to CR.
(Fig. 1-25B)
Collimation: 10 × 12 inch (24 × 30 cm) field.
Side Marker: In the corner of the film.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Overexposure: The lower half of the sacrum is often
overexposed and may require a repeat exposure
lowering the factors.
72
2. Clipped anatomy: In acute sacral angulation the lower
half of the sacrum may not be placed on the film and
may require horizontal placement of the cassette.
Clinicoradiologic Correlations: The complex anatomy
of the sacrum makes structural identification difficult in
this projection. Careful attention to systematic evaluation
will assist in determining these structures.
1. Alignment: Note the position of the coccyx in relation
to the sacrum, which is subject to wide variation and
does not correlate with coccygodynia. (11,12) Similarly,
note the sacral base angle.
2. Bone: Identify the sacral base, promontory, crest, and
canal. Follow the continuous scalloped contour of the
anterior and posterior surfaces. (Fig. 1-25, E and F )
Variations in sacral curvature are common and may
be flat (sacrum planum) or markedly curved (sacrum
arcuatum). Note the relative lucency of each sacral
body from the superimposed foramina.
3. Cartilage: Check the lumbosacral disc, rudimentary
sacral discs, and the sacrococcygeal joint.
4. Soft tissue: The soft tissue area between the sacrum
and rectum (presacral space) should be measured
(normal = < 2 cm). A space > 2 cm is a sign of rectal
or sacral disease associated with a soft tissue mass
(tumor, infection, etc.).
BASIC: AP, *Lateral
Normal Anatomy (Figure 1-25, C and D)
1.
2.
3.
4.
5.
6.
7.
8.
Sacral promontory.
Second sacral segment.
First sacral tubercle.
Sacral crest.
Sacral canal.
Auricular surface.
Sacrococcygeal joint.
Superior articular process,
sacrum.
Figure 1-25 C. Lateral, Sacrum.
D. Specimen Radiograph,
Sacrum.
Clinicoradiologic Correlations (Figure 1-25, E and F )
Figure 1-25 E. Lateral, Sacrum,
Fracture. There is offset of the
anterior cortex of the second
sacral segment at the site of fracture (arrow). The fracture can also
be seen to pass through the sacral
body posteriorly. F. Lateral,
Sacrum, Malignant Tumor. There
is an area of irregular bone destruction with cortical destruction
in the posterior aspects of the S3
and S4 sacral bodies (arrow). The
anterior sacral cortex is sclerotic
and thickened as a result of underlying Paget’s disease.
73
COCCYX: AP Projection
Positioning (Figure 1-26, A and B)
Figure 1-26 AP COCCYX. A. Patient Position. B. Collimation and Central Ray.
Demonstrates: Coccyx and lower sacrum. (1–3) (Fig.
1-26, C and D)
Measure: At the CR.
kVp: 80 (75 to 85).
Film Size: 8 × 10 inches (18 × 24 cm), vertical orientation.
Grid: Yes.
TFD: 40 inches (102 cm); reduce the TFD by 2 inches
for tube tilt.
Tube Tilt: 10° caudad. Tilt depends on coccygeal position. Ultimately, the CR should be perpendicular to the
ventral surface of the coccyx.
Patient Position: Supine or upright. (Fig. 1-26A)
Part Position: Centered to the bucky.
CR: Enters at a point 2.5 inches above the symphysis
pubis. Center film to the CR. (Fig. 1-26B)
Collimation: 5 × 5 inch field.
Side Marker: In an open space.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Bowel superimposition: Overlying gas and feces often
obscure the coccyx and/or lower sacrum and an enema
may be of assistance. (Fig. 1-26, E and F )
74
2. Tube tilt: There is wide variation in sacrococcygeal inclination, and it may be helpful to expose and develop
the lateral radiograph first, to most accurately determine the necessary tube tilt for the AP spot projection. Upright exposures may require < 10° tube tilt
or a straight tube.
Clinicoradiologic Correlations: Because trauma is the
most common problem with the coccyx, technically excellent views are required to depict subtle lesions. (Fig. 1-26,
E and F)
1. Alignment: There is wide variation in alignment of the
coccyx either at the sacrococcygeal joint or between
coccygeal segments. (4,5)
2. Bone: Evaluate the lower sacrum by tracing its lateral
margins, sacral body endplates, sacral hiatus, and foraminal lines. Identify the upswept lateral processes
(cornu) of the first coccygeal segment. There may be
between one and four flattened oval-shaped coccygeal segments visible distally.
3. Cartilage: The sacrococcygeal and intercoccygeal joints
can be seen.
4. Soft tissue: The overlying bladder silhouette may be
visible.
BASIC: *AP, Lateral
Normal Anatomy (Figure 1-26, C and D)
1.
2.
3.
4.
5.
6.
7.
8.
First sacral tubercle.
Sacral ala.
Second sacral foramen.
Sacral pedicle.
Sacral hiatus.
Sacrococcygeal junction.
Coccyx.
Cornu of the coccyx.
Figure 1-26 C. AP Coccyx. D. Specimen Radiograph, Sacrum and Coccyx.
Clinicoradiologic Correlations (Figure 1-26, E and F)
Figure 1-26 E. AP Coccyx, Gas and Fecal Superimposition. In the midline, overlying the lower sacrum and
coccyx, the combined density of colonic gas and feces within the rectum obscures the bony anatomic details.
F. AP Coccyx, Postevacuation. A short time later, with the obscuring feces removed by rectal evacuation, the
lower sacrum and coccyx can be seen.
75
COCCYX: Lateral Projection
Positioning (Figure 1-27, A and B)
Figure 1-27 LATERAL, COCCYX. A. Patient Position. B. Collimation and
Central Ray.
Demonstrates: Coccyx and lower sacrum. (1–3) (Fig. 127, C and D)
Measure: At the CR.
kVp: 80 (75 to 85).
Film Size: 8 × 10 inches (18 × 24 cm), vertical orientation.
Grid: Yes.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Lateral recumbent or upright lateral.
(Fig. 1-27A)
Part Position: Lateral position, with the coccyx centered
over the midline of the bucky.
CR: Directed through the sacrococcygeal junction, 2 inches
anterior to the posterior body surface. Center film to the
CR. (Fig. 1-27B)
Collimation: 8 × 8 inch field.
Side Marker: Place laterally.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Overexposure: The exposure is at least half the mAs
of the sacrum. Placement of lead vinyl at the skin
76
surface shadow on the cassette will greatly improve
image quality by scatter reduction.
2. Gonad shielding: Apply if possible, given the gonad
proximity.
Clinicoradiologic Correlations: The coccyx is a difficult area to evaluate radiographically and may require a
nuclear bone scan to confirm an abnormality such as
fracture.
1. Alignment: Note the position of the coccyx in relation
to the sacrum, which is subject to wide variation and
does not correlate with coccygodynia or post-traumatic
subluxation. (4,5)
2. Bone: The number of coccygeal segments varies considerably from one to four. Fractures are usually recognized by cortical offset. (Fig. 1-27E)
3. Cartilage: The sacrococcygeal joint is identified as the
first separated level of the lower sacrum. The joint
surfaces are usually concave–convex.
4. Soft tissue: The presacral soft tissue space behind the
rectum should be < 2 cm.
Specialized Projections:
1. Motion studies: Mobility of the coccyx can be demonstrated by seated and recumbent studies; altered
mobility is often linked to coccygodynia. (5)
BASIC: AP, *Lateral
Normal Anatomy (Figure 1-27, C and D)
1. Sacrococcygeal joint.
2. First coccygeal
segment.
3. Auricular surface.
4. Sacral crest.
5. Sacral canal.
6. Fifth sacral segment.
7. Distal coccygeal
segment.
8. Ischial tuberosity.
9. Ischial spine.
Figure 1-27 C. Lateral, Coccyx.
D. Specimen Radiograph, Sacrum
and Coccyx.
Clinicoradiologic Correlations
(Figure 1-27E )
Figure 1-27 E. Lateral Coccyx, Fracture.
The first coccygeal segment is displaced anteriorly relative to the sacrum; the fracture line is
visible with cortical offset (arrow).
77
PELVIS: AP Projection
Positioning (Figure 1-28, A and B)
Figure 1-28 AP PELVIS. A. Patient Position. B. Collimation and
Central Ray.
Demonstrates: Both innominates, sacrum, coccyx, and
proximal femurs and the sacroiliac, symphysis, and hip
joints. (1–5) (Fig. 1-28C)
Measure: At the CR.
kVp: 80 (75 to 85).
Film Size: 14 × 17 inches (35 × 43 cm), horizontal orientation.
Common Pitfalls:
1. Limb rotation: If the feet are not internally rotated, the
femoral necks will appear foreshortened and their anatomic details and relationships will be obscured. (6)
2. Uneven exposure: Due to thin cortical bone mass at
the iliac fossa these regions, including the iliac crests,
may be overexposed.
Grid: Yes.
Clinicoradiologic Correlations:
TFD: 40 inches (102 cm).
1. Alignment: Trace the cortex of the pelvic inlet from left
to right, noting any disruptions at the sacroiliac, acetabular, and pubic regions. Follow the inferior margin
of the superior pubic ramus and note the smooth continuity with the medial femoral neck (Shenton’s line).
Note the smooth contour from the lateral ilium across
the acetabulum onto the lateral femoral neck (iliofemoral line). These visual guidelines should be compared bilaterally for symmetry and can be indicators of
hip joint disease. (Fig. 1-28D)
Tube Tilt: None.
Patient Position: Supine or upright. (Fig. 1-28A)
Part Position: Center the midsagittal plane of the
body to the midline. Internally rotate the feet about 15°
(heels apart and big toes together), and use sandbags to
stabilize.
CR: Midway between the symphysis pubis and iliac crest.
Center film to the CR. (Fig. 1-28B)
Collimation: 14 × 17 inch (35 × 43 cm) field.
Side Marker: At a corner of the film.
Breathing Instructions: Suspended expiration.
78
2. Bone: Identify all structures systematically, including
the ilium, pubis, ischium, proximal femur, sacrum, and
lumbosacral spine. The “teardrop” at the medial acetabulum is a key landmark and should be identified as a
marker of acetabular bone disease. (3) (Fig. 1-28E )
BASIC: *AP
3. Cartilage: All joints (sacroiliac, symphysis pubis, hip,
lumbosacral) are inspected for alignment, joint space,
and articular contours.
at the knee with the hip in the neutral position and
the left leg again supports the weight. A variation is
standing views on each leg.
4. Soft tissue: Identify the bladder outline and, at its lateral margins, the fat line of the obturator internus
muscle. Identify gas and feces by colonic haustrations,
air–fluid levels and air crescents and position—medial
to the properitoneal fat, which should be symmetrical
and lie close to the adjacent acetabulum; if displaced,
this can be a sign of hip disease. (7,8) The margins of
the lateral abdominal wall is composed of alternating
soft tissue–radiolucent fat layers (flank stripe). Round
calcifications above the superior pubic ramus are
commonly seen and represent clinically insignificant
calcified venous thromboses (phleboliths).
2. Weight-bearing view: Demonstration of degenerative
hip disease changes with loss of joint space and lateral subluxation of the femur can be enhanced with
weight bearing and may reveal changes when nonweight-bearing views are normal. The same changes
can be used with hip replacements to demonstrate
polyethylene joint wear. (10)
Specialized Projections:
1. Flamingo (Chamberlain’s, stork) views: To demonstrate pubic instability two views are performed PA
collimated to the pubic symphysis. (9) The first film is
taken with the right leg hanging dependently nonweight-bearing and the contralateral leg supporting
the weight. In the second view the right leg is flexed
3. Inlet–outlet views: To show fractures and dislocations
of the pelvic ring, the CR is angled caudally 40° (inlet)
and cephalad (outlet).
4. Obturator view: To show the pubic rami, body of the
pubis, obturator foramen, and symphysis, perform an
AP study with the tube angled cephalad 25° centered
to the lower symphysis. (11)
5. Lateral pelvis view: This can be performed erect or
supine as a cross-table lateral with a horizontal tube
in which the hips will be superimposed or by angling
the tube 25° off horizontal to show both hips. (12)
79
PELVIS: AP Projection
Normal Anatomy (Figure 1-28C )
Figure 1-28 C. AP Pelvis.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
80
First sacral tubercle.
Anterior sacral foramina.
Sacroiliac joint.
Anterior superior iliac spine (ASIS).
Anterior inferior iliac spine (AIIS).
Ischial spine.
Pelvic brim.
Gas in the colon overlying the iliac fossa.
Sacral ala.
Posterior surface of the ilium.
Acetabular rim.
Fovea capitis centralis of the femoral head.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
Superior pubic ramus.
Inferior pubic ramus.
Obturator foramen.
Quadrilateral plate of the acetabulum (Köhler’s
teardrop).
Greater trochanter of the femur.
Lesser trochanter of the femur.
Pubic symphysis.
First coccygeal segment.
Iliac fossa.
Iliac crest.
Ischial tuberosity.
BASIC: *AP
Clinicoradiologic Correlations (Figure 1-28, D and E )
Figure 1-28 D. AP Pelvis, Congenital Hip Dislocation. Observe that both femoral heads lie cephalad posterior
to the iliac wings and that the acetabuli bilaterally are shallow and lack the characteristic landmark of the
sclerotic roof. E. AP Pelvis, Paget’s Disease. Abnormal changes are visible throughout all bones with increased
density, cortical thickening, and trabecular accentuation. Note specifically the involvement of the anatomic
landmarks of the pubic bones, pelvic (Köhler’s) teardrop, iliac wings, sacral foraminal lines, and proximal femurs.
81
FULL SPINE: AP Projection
Positioning (Figure 1-29, A and B)
Figure 1-29 AP FULL SPINE. A. Patient Position, Collimation, and
Central Ray: Without Compensating Filtration. B. Patient Position,
Collimation, and Central Ray: With Compensating Filtration (arrows).
Demonstrates: Pelvis and lumbar, thoracic, and cervical
spine. (1–4) (Fig. 1-29, C and D)
Measure: AP at the lumbosacral joint.
kVp: 90 (85 to 95).
Film Size: 14 × 36 inches (14 × 91 cm), vertical orientation.
Grid: Yes.
TFD: 84 inches (200 cm) optimum; no less than 72 inches
(183 cm).
Tube Tilt: None.
Patient Position: Upright. (Fig. 1-29, A and B)
Part Position: Spine centered to bucky. Film placed 1 inch
below inferior gluteal fold.
CR: To the film.
Collimation: To exclude the eyes and include the ischial
tuberosities. Laterally to the anterior superior iliac spine
(ASIS) bilaterally.
Side Marker: Place adjacent to and above the shoulder.
82
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Equipment requirements: Unless strict technical parameters are adhered to (high-frequency generators,
patient selection, immobilization, high grid ratio, tight
collimation, filtration, rare earth screens, etc.) singleexposure, full-spine radiography should be avoided. (5)
(Fig. 1-29, C and D) A compensating filter such as the
Baulin system should be used to prevent overexposure
to the upper third of the film. (5–10) Patients with AP
measurements > 28 cm should not have a single, AP,
full-spine projection. (Fig. 1-29B)
2. Diagnostic limitations: The large field of view generates significant scatter and image degradation. Lateral,
full-spine radiographs have significantly reduced film
quality and can be used only for postural analysis, not
for pathologic evaluation. (11) Whenever possible sectional studies are preferred to single, full-spine lateral exposures. Diminished anatomic detail is common
owing to tissue thickness differences, overlap of structures (such as the mandible over the upper cervical
spine), and effects of the sagittal curves (especially of
the lumbosacral junction and sacrum). (5,11,12)
BASIC: *AP
3. Interpretive demands: The large area of exposure
requires all structures included on the film to be adequately interpreted, including soft tissues of the abdomen and chest.
4. Gonad shielding: Given the high exposures, gonad
shielding should be used.
Clinicoradiologic Correlations:
1. Alignment: Observe for pelvic unleveling, scoliosis,
intersegmental rotation, lateral wedging, or listhesis.
2. Bone: All skeletal structures must be evaluated, including each vertebral segment, the pelvis, each rib, and
the shoulder girdles.
3. Cartilage: All joints (sacroiliac, pubic, discs, facets,
costal, etc.) need to be studied carefully, despite their
less-than-adequate demonstration.
4. Soft tissue: Many paraspinal structures are included
and need to be carefully assessed: (a) abdomen: psoas,
kidney, liver, spleen, gas shadows, etc.; (b) chest: paraspinal lines, lung fields, heart, great vessels, etc.; and
(c) neck: trachea, vasculature, and muscles.
Normal Anatomy (Figure 1-29, C and D)
Figure 1-29 C. AP Full Spine:
With Wedge Filtration.
D. AP Full Spine: With Wedge
Filtration and T Collimation.
COMMENT: Both C and D are
male patients with an AP
measurement of 24 cm. Technical parameters were 76 kVp,
50 mAs, using a 1200-speed
system (Kodak Lanex Fast
Screens, T-Mat H Film) 72-inch
FFD and using an HCMI
100-kHz high-frequency generator x-ray machine.
(Courtesy of Todd A. Ryan,
MEd, DC, Logan College of
Chiropractic, St. Louis,
Missouri.)
83
HIP: AP Projection
Positioning (Figure 1-30, A and B)
Figure 1-30 AP HIP. A. Patient Position. B. Collimation and Central Ray.
Demonstrates: Acetabulum, adjacent pelvis, joint
space, femoral head, neck, trochanters, and proximal diaphysis. (1–5) (Fig. 1-30, C and D)
Measure: At the CR.
kVp: 80 (75 to 85).
Common Pitfalls:
1. Foot position: If the feet are not internally rotated at
least 15° the femoral necks will appear foreshortened
and their anatomic details and relationships will be
obscured. (5)
Film Size: 10 × 12 inches (24 × 30 cm), vertical orientation.
2. Gonad shield: Use gonadal shielding and collimate to
at least the film.
Grid: Yes.
Clinicoradiologic Correlations:
TFD: 40 inches (102 cm).
1. Alignment: Apply the lines and measurements of the
hip (Shenton’s line, iliofemoral line, femoral angle,
Skinner’s line, Klein’s line, etc.). (See Chapter 2.)
Tube Tilt: None.
Patient Position: Supine or upright. (Fig. 1-30A)
Part Position: The leg is internally rotated 15°. (4) The
femoral neck is centered to the midline.
CR: Make an imaginary line between the anterior superior iliac spine (ASIS) and symphysis pubis and locate its
midpoint. From the midpoint, move away from the umbilicus 2 inches to locate the center point. The femoral
artery passes over the femoral head and can be used as
the marker for the CR. (Fig. 1-30B)
Collimation: 10 × 12 inch (24 × 30 cm) field.
Side Marker: In a corner of the film.
Breathing Instructions: Suspended expiration.
84
2. Bone: Identify all structures systematically, including
the ilium, pubis, ischium, and proximal femur. Acetabular anatomy is complex: Superiorly the cortex is thick
and distinct to support weight bearing; the acetabular notch then causes a distinct indentation—which
should not be confused with joint erosion—and inferiorly lateral to the pelvic teardrop the cortex appears
slightly convex. The trabecular pattern in the femoral
neck forms a radiolucent zone (Ward’s triangle): The
primary compressive trabeculae curves up from the inferior femoral neck, the secondary compressive group
arcs obliquely across the intertrochanteric zone, and
the third group superiorly is the principal tensile trabeculae. (Fig. 1-30, E–G)
BASIC: *AP, Frog leg
3. Cartilage: At the hip, note the joint space (superior =
4 mm; axial = 4 mm; and medial = 8 mm) and smooth
articular contours. Do not mistake the fovea capitis of
the femoral head for a bone lesion.
4. Soft tissue: Identify the bladder outline and, at its lateral margins, the fat line of the obturator internus
muscle, which lies in close proximity to the superior
pubic ramus. (3,6) The fascial fat line separating the
gluteus medius and minimus can be seen lateral to
the femoral neck and medially to the psoas. (6)
3. Judet views: Two views are taken of one hip. Elevating
the hip by 45° (anterior oblique) shows the posterior
acetabular margin, superior pubic ramus attachment
to the anterior acetabulum (anterior column), and
obturator foramen. Elevating the contralateral hip by
45° (posterior oblique) shows the iliac wing, posterior
acetabulum, and its fusion with the ischial ramus
(posterior column). (7)
Specialized Projections:
4. Iliac wing view: To demonstrate the iliac wing and
fossa, ASIS, and anterior inferior iliac spine (AIIS), elevate the contralateral side 40°.
1. Bilateral hips: In bilateral hip studies a crosswise film
of suitable size can be used and positioned appropriately. Generally, for children younger than 12 years of
age both hips are done for comparison.
5. AP femur: Thigh extended with the limb internally rotated by 15°, CR directed to include at least one joint
(usually the hip), collimated to a 7 × 17 inch (18 ×
43 cm) film.
2. External rotation view: With the femur externally rotated the lesser trochanter will come into profile.
85
HIP: AP Projection
Normal Anatomy (Figure 1-30, C and D)
Figure 1-30 C. AP Hip. D. Specimen Radiograph, Proximal Femur.
1.
2.
3.
4.
5.
6.
7.
8.
9.
86
Femoral head.
Femoral neck.
Fovea capitis centralis of the femoral head.
Intertrochanteric crest.
Greater trochanter.
Lesser trochanter.
Shaft of the femur.
Ischial tuberosity.
Superior pubic ramus.
10.
11.
12.
13.
14.
15.
16.
17.
18.
Inferior pubic ramus.
Obturator foramen.
Acetabular rim.
Anterior inferior iliac spine (AIIS).
Anterior superior iliac spine (ASIS).
Iliac fossa.
Sacroiliac joint.
Sacral ala.
Pelvic teardrop (Köhler’s teardrop).
BASIC: *AP, Frog leg
Clinicoradiologic Correlations (Figure 1-30, E–G )
Figure 1-30 E. AP Hip, Intertrochanteric Fracture of the Femur. A non-displaced oblique fracture is present, extending through the intertrochanteric region of the proximal femur. F. AP Hip, Protrusio Acetabuli in Rheumatoid
Arthritis. Note that there is uniform loss of joint space of the entire hip, with medial bulging of the acetabular floor
(arrow). G. AP Hip, Osteoblastic Metastases Obliterating the Teardrop. Observe the focal increase in bone density at
the medial acetabulum, which has obscured the Köhler’s teardrop.
87
HIP: Frog-Leg Projection
Positioning (Figure 1-31, A and B)
Figure 1-31 FROG LEG, HIP. A. Patient Position (Recumbent). B. Collimation
and Central Ray.
Synonyms: Oblique view.
Demonstrates: Acetabulum, adjacent pelvis, joint space,
femoral head, neck, trochanters, and proximal diaphysis.
(1–3,5,8) (Fig. 1-31, C–F)
Measure: At the CR.
kVp: 80 (75 to 85).
Film Size: 10 × 12 inches (24 × 30 cm), vertical orientation.
Grid: Yes.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Supine or upright. (Fig. 1-31A)
Part Position: The femoral neck is centered to the midline of the table. The hip and knee are flexed until the
foot reaches the level of the opposite knee. The flexed
lower extremity is then abducted as far as possible.
CR: Draw an imaginary line between the anterior superior iliac spine (ASIS) and symphysis pubis, and locate its
midpoint. From this midpoint, move away from the umbilicus 2 inches to locate the center point. (Fig. 1-31B)
from the sagittal plane. Incomplete hip abduction will
foreshorten the neck and not project it adequately.
Clinicoradiologic Correlations: To examine a hip with
only an AP view is an incomplete examination and inclusion of this view should be routine.
1. Alignment: Use Shenton’s and Klein’s lines in this position. The coverage of the femoral head by the acetabulum can be gauged and the relative relationships of
the neck to the head can be assessed.
2. Bone: Structures of the acetabulum, femoral head,
neck, and trochanters depicted in a different plane.
Many subtle lesions, such as fracture and tumors, will
be visible only in this projection. Both lesser and greater
trochanters will be seen in profile and not superimposed on the femoral necks. A thin linear cortical
density can often be seen on this view adjacent to the
lesser trochanter (called the calcar femorale). (9)
3. Cartilage: The hip joint space is well depicted where
the medial joint space is twice as thick as the axial
and superior compartments.
4. Soft tissue: The fat lines between the gluteus medius
and minimus, psoas, and obturator internus are visible and should be identified for position and contour.
Collimation: 10 × 12 inch (24 × 30 cm) field.
Side Marker: In the corner of the film.
Specialized Projections:
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Bilateral frog-leg view (modified Cleaves): Taken
with the cassette placed crosswise and with no tube
angulation.
1. Pelvic rotation: The pelvis should be maintained in the
true AP position and the hip abducted at least to 40°
2. Cleaves’ method: Bilateral frog-leg position with 40°
cephalad tube angulation.
88
BASIC: AP, *Frog leg
3. Lateral hip: (a) Lauenstein’s method: rotate the pelvis
to 45°, abduct and flex the thigh with the CR at the
hip. (b) Hickey’s method: the Lauenstein view with 25°
cephalad tube tilt.
4. Lorenz view: For children with suspected hip dysplasia
or Perthes disease; bilateral frog-leg view with the femurs abducted and perpendicular to the midsagittal
plane.
5. Van Rosen view: For children with congenital hip dysplasia; the lower limbs are kept straight, hips abducted
to 45° and internally rotated 25°.
6. Lateral femur: With the patient in the lateral position
the superior leg is flexed forward, leaving the lower leg
extended and in contact with the cassette. The CR is
directed to the midfemur when it is collimated to the
film and includes the knee joint on the lower end of
the film.
7. Appa’s view: A modification of the supine technique
may enable a satisfactory radiograph to be obtained in
the upright position. (Fig. 1-31, C and D) The patient
grasps a stabilizing object and places the hip into a
flexed, abducted, and externally rotated position.
The CR is directed to 2 inches below the mid-inguinal
point.
Normal Anatomy (Figure 1-31, C–F)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Femoral head.
Greater trochanter.
Lesser trochanter.
Intertrochanteric line.
Femoral neck.
Acetabular rim.
Inferior pubic ramus.
Superior pubic ramus.
Pelvic rim.
Sacroiliac joint.
Anterior superior iliac
spine (ASIS).
Anterior inferior iliac
spine (AIIS).
Obturator
foramen.
Ischial
tuberosity.
Inferior acetabular
fossa (Köhler’s
teardrop).
Figure 1-31 C. Frog Leg, Patient Positioning (Erect, Appa’s View). D. Appa L. Anderson DC,
DACBR. (With such a first name, “AP-PA” it’s clear she was destined to become a radiologist.)
E. Frog Leg, Hip. F. Specimen Radiograph, Proximal Femur.
89
KNEE: AP Projection
OPTIONAL: Obliques
Positioning (Figure 1-32, A and B)
Figure 1-32 AP KNEE. A. Patient Position. B. Collimation and
Central Ray.
Demonstrates: Distal femur, proximal tibia and fibula,
femorotibial joint space, and patella. (1–3) (Fig. 1-32, C
and D)
Measure: At the CR.
kVp: 60 (55 to 65).
Film Size: 8 × 10 inches (18 × 24 cm), vertical orientated.
Grid: Yes, if the knee measures > 10 cm; if < 10 cm, a
non-grid technique is used.
TFD: 40 inches (102 cm); must correct TFD to 39 inches
(99 cm) for 5° tube tilt.
Tube Tilt: 5° cephalad (CR coincident with tibial surface).
Patient Position: Supine or upright. (Fig. 1-32A)
Part Position: Internally rotate the leg slightly (5°) so
that the knee is in a true AP position. Sandbag the ankle
and foot.
CR: 1 cm inferior to the apex of the patella. Center film
to the CR. (Fig. 1-32B)
Collimation: Collimate to area of radiographic interest.
Side Marker: In the corner of the film.
Breathing Instructions: Suspended expiration.
90
Common Pitfalls:
1. Gonad shielding: The proximity to the pelvis generates potential gonad exposure.
2. Tube tilt: Failure to angle the tube cephalad will not
allow a tangential and accurate view of the joint space.
3. CR placement: The joint space usually lies < 1 inch
below the apex of the patella and is the CR entry
point.
Clinicoradiologic Correlations: A true AP may not
be obtainable if the knee is unable to be fully extended.
The AP is an integral view that cannot be omitted in knee
studies. (4) (Fig. 1-32, C and D)
1. Alignment: The medial and lateral margins of the
femoral condyles and opposing tibial condyles should
be in vertical alignment. The patella should lie centrally
over the distal femur. The fibula head is overlapping
the tibial condyle.
2. Bone: All components of the distal femur (femoral
shaft, medial and lateral epicondyles, medial and lateral condyles, intercondylar notch, adductor tubercle),
proximal tibia (intercondylar eminences, medial and
BASIC: *AP, Lateral, Intercondylar, Tangential
lateral condyles), fibula (head and neck of the fibula,
styloid process), and patella (superior and inferior
poles) need to be located. The lateral femoral condyle
is broader and shorter, whereas the medial condyle is
narrower and longer. Because the tibial plateau angles
posteriorly at about 15° it will not be clearly seen in
entirety on this view.
3. Cartilage: Medial and lateral femorotibial joint compartments should be equal in width with smooth articular contours with a joint space of 4–6 mm. The
patellofemoral and tibiofibular joints are not clearly
visible in this projection.
4. Soft tissue: The fabella (sesamoid bone in the lateral
head of the gastrocnemius) will be present superimposed over the lateral femoral condyle above the
joint space. The thickness of the soft tissue overlying
the femoral–tibial condyles may indicate obesity or
effusion. Loss of or a blurred subcutaneous radiolucent
fat line adjacent to the medial joint line may indicate
medial collateral ligament injury with edema.
Specialized Projections:
1. Weight-bearing view: Upright views frequently identify
joint space narrowing, femorotibial subluxation and/
or varus–valgus instability when non-weight-bearing
views appear normal. (5,6)
2. Rosenburg’s view: Performed upright, PA with 10°
of caudal tube tilt and the knees flexed to 45°. This
demonstrates the weight-bearing surfaces of the femoral condyles in tangential projection to show degenerative sclerosis, cysts, and osteochondral defects
(including osteochondritis dissecans). In addition this
is the most accurate view for detecting degenerative
loss of joint space. (7) The intercondylar notch begins
to appear in this view.
3. Tibial plateau view: Angling the tube 15° cephalad
will provide a tangential view of the tibial plateau, especially useful in trauma to investigate depression of
the articular surface and fractures. (8)
4. Varus–valgus stress views: With the femur stabilized
by a third person (who wears lead gloves and gown)
studies taken at varus (medial to lateral stress) and
valgus (lateral to medial stress). (9) The width of the
joint space is assessed for opening (normally < 5–7°)
and femorotibial shift (normally < 1 mm) is assessed
as sign of collateral ligament stability. Bilateral studies are performed for comparison.
5. Internal–external oblique views: The leg is rotated
internally and then externally by 45°, again with 5°
cephalad tube tilt. (10) The femoral condylar surface,
tibial plateau, tibial spines, and patella have improved
structural visibility. The medial oblique shows the
tibiofibular joint to advantage and avulsion fractures
of the head of the fibula and lateral tibial condyle
(Segond’s fracture).
6. Patella views: PA views are preferred to improve detail. The lateral view is supplemented with 45° internal
and external rotation obliques, halving the mAs and
collimating for the patella to show it in better exposure
and detail.
7. AP tibia–fibula: With the leg straight and the ankle
dorsiflexed with the ankle malleoli equidistant from
the film, preferable for including both the knee and
ankle in the field.
91
KNEE: AP Projection
OPTIONAL: Obliques
Normal Anatomy (Figure 1-32, C and D)
Figure 1-32 C. AP Knee. D. Specimen Radiograph, Distal Femur.
1.
2.
3.
4.
5.
6.
7.
8.
92
Femoral shaft.
Medial epicondyle.
Lateral epicondyle.
Medial condyle.
Lateral condyle.
Intercondylar notch.
Intercondylar eminences (tibial spines).
Medial condyle of the tibia.
9.
10.
11.
12.
13.
14.
15.
16.
Lateral condyle of the tibia.
Head of the fibula.
Neck of the fibula.
Adductor tubercle.
Medial joint space.
Lateral joint space.
Tibial shaft.
Patella.
BASIC: *AP, Lateral, Intercondylar, Tangential
Clinicoradiologic Correlations (Figure, 1-32 E–G)
Figure 1-32 E. AP Knee, Fracture of the Tibial Plateau. Vertical fractures are visible through the medial (arrowheads)
and lateral tibial plateau (arrow). Note the offset of the lateral femoral and tibial condyles owing to fragment displacement. F. AP Knee, Degenerative Joint Disease. The medial femorotibial joint space is decreased, with osteophytes and sclerosis of the femoral and tibial condylar surfaces. There is widening of the lateral femorotibial joint
(varus deformity) and lateral subluxation of the tibia, marked by the malalignment at the lateral margins of the
femoral and tibial condyles. G. AP Knee, Osteochondroma of the Femur. A cortical exostosis projects off of the distal
metaphysis of the femur. Note its calcified cartilaginous cap.
93
KNEE: Lateral Projection
OPTIONAL: Obliques
Positioning (Figure 1-33, A and B)
Figure 1-33 LATERAL, KNEE. A. Patient Position. B. Collimation and
Central Ray.
Demonstrates: Distal femur, proximal tibia and fibula,
patella, and patellofemoral and tibiofemoral joint
spaces. (1–3,11,12) (Fig. 1-33, C and D)
Measure: At the CR.
kVp: 60 (55 to 65).
Film Size: 8 × 10 inches (18 × 24 cm), vertical orientation.
Grid: Yes. Can be done non-bucky if part measures
< 10 cm.
TFD: 40 inches (102 cm).
Tube Tilt: Optional; 5° cephalad tilt may be used to superimpose the inferior aspects of the medial and lateral
femoral condyles and allow an uninterrupted depiction
of the femorotibial joint space.
Patient Position: Lateral recumbent. (Fig. 1-33A)
Part Position: Place the patient on the table with the
side of the leg being examined down. Flex the lower leg
about 45° to traction the patella in place. Cross the opposite leg over the leg being examined and support, if
necessary, to prevent pelvic rotation. Center the long
axis of the femur to the midline of the film. Only when
the posterior surface of the buttocks is perpendicular
to the film will a true lateral view of the distal femur
be ensured.
94
CR: Enters 1 cm distal to the medial epicondyle. Center
the film to CR. (Fig. 1-33B)
Collimation: To film size.
Side Marker: In the corner of the film.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Correct knee flexion: Between 30° and 45° of flexion
is optimum. Flexing the knee > 45° will project the
patella into the joint space and compress the suprapatellar pouch, which will hinder the diagnosis of effusions. With (< 30°) knee pain, flexion may not be
possible and interpretations will be limited.
2. True lateral view: By elevating and supporting the calcaneus a true lateral position is obtained. Using the
5° cephalad tube angulation will superimpose the
condylar surfaces.
Clinicoradiologic Correlations: The lateral view is an
integral view that cannot be omitted in knee studies. (4)
(Fig. 1-33, E–G)
1. Alignment: The position of the patella is assessed relative to the femorotibial joint. Normally the length
of the patella is equal to the length of the patella
tendon with 20% variation. (13) A low-lying patella
BASIC: AP, *Lateral, Intercondylar, Tangential
(patella baja) may be the result of quadriceps tendon
rupture or quadriceps weakness; a high-riding patella
(patella alta) can be caused by rupture of the patella
tendon or associated with chondromalacia patellae.
The fibula head should partially overlap the posterior
tibia.
2. Bone: The distal femoral cortex thins with the transition to the metaphysis. Superimposed over the
condyles is a distinct radiolucency (Ludloff’s lucency), with the lowest oblique margin corresponding
to the roof of the intercondylar notch (Blumensaat’s
line). The anterior convex surface represents the floor
of the femoral trochlea (sulcus), which is the femoral
surface of the patellofemoral joint. (14) The medial
condyle is larger and extends more inferiorly than
the lateral condyle, with both surfaces smooth and
convex in congruity with the opposing concave tibial
condylar surfaces. The tibial articular surface is tilted
15° posteriorly. The tibial lateral condyle posterior surface is inferiorly oblique; the medial is horizontal and
squared. The medial tibial spine is the highest bony
projection from the tibia. A small bony bump (Parson’s
knob) can often be seen anterior to the tibial spines; it
enlarges with osteoarthritis. (15) The proximal fibula
is expanded with a tapered tip (styloid process). The
patella is thinner at the inferior pole and obliquely tapered. The anterior and posterior cortices are prominent, producing a trilaminar appearance.
3. Cartilage: The femorotibial joint is the space between
the convex femoral and concave tibial condyle surfaces. The patellofemoral articulation lies between the
concave margin of the retropatellar surface and anterior cortex of the trochlear groove of the femur. The
tibiofibular joint will not be visible.
4. Soft tissue: Identify the infrapatellar fat (Hoffa’s fatpad), which occupies the soft tissue below the patella
anteriorly, is roughly triangular in shape, is radiolucent,
has sharp margins at the interfaces with the patellar
tendon and joint margins, and has a well-defined
acute inferior recess between the tibial tuberosity and
the patellar tendon. The normal suprapatellar pouch
is visible as a thread-like shadow bounded anteriorly
by a small triangular fat-pad that is continuous with
the superior pole of the patella and posteriorly by fat
abutting the femur. Thickening of the pouch is a sensitive sign of joint effusion; a 10-mm pouch thickness
contains 10 mL of joint fluid. (16) Bright lighting the
anterior soft tissues will demonstrate the patellar tendon as an opaque, uniform structure, 4–6 mm in
thickness with sharp margins attaching to the patella
and tibial tuberosity. The quadriceps tendon can also
be clearly seen attaching to the superior patellar pole.
The sesamoid bone within the lateral head of the
gastrocnemius muscle (fabella) is usually triangular
and lies adjacent to the posterior surface of the lateral femoral condyle.
Specialized Projections:
1. Cross-table lateral: The patient’s knee is fully extended. An exposure with the mAs reduced by at
least 50% and a horizontal beam may demonstrate a
fat–blood interface effusion (FBI sign) in the suprapatellar pouch as a marker of lipohemarthrosis. This
is caused by an often unrecognized intra-articular
fracture that produces bleeding and the release of
fatty bone marrow into the joint space. (17)
2. Tibial tuberosity view: Slight internal rotation of the
tibia by 5° with lowered kVp and mAs will assist in
demonstrating the anatomic details of the distal
patellar tendon, infrapatellar fat, tendo-osseous junction, and surface of the tibial tuberosity. (18)
3. Weight-bearing view: The patella is stabilized by use
of a support device and the knee is flexed to 15° in full
weight bearing; a horizontal beam is used. Anterior
translation of the tibia by > 5 mm is a sign of a deficient anterior cruciate ligament. (19)
4. Quadriceps contraction view: Performed supine as a
cross-table lateral with a horizontal beam. A 30° knee
bolster is placed in the popliteal fossa, a 15-lb weight
is suspended from the ankle, and the patient is instructed to fully extend the knee; then the exposure
is taken. Anterior tibial displacement of > 4 mm is a
sign of anterior cruciate ligament rupture. (20)
5. Lateral tibia and fibula: The leg is placed in the true lateral position with the knee slightly flexed; the CR is directed to the midleg with collimation to the film (7 ×
17 inch; 18 × 43 cm) to include the knee and ankle.
95
KNEE: Lateral Projection
OPTIONAL: Obliques
Normal Anatomy (Figure 1-33, C and D)
Figure 1-33 C. AP Knee. D. Specimen Radiograph, Proximal Tibia and Fibula.
1.
2.
3.
4.
5.
6.
96
Anterior intercondylar area.
Posterior intercondylar area.
Tibial tuberosity.
Tibial shaft.
Head of fibula.
Fabella (sesamoid bone in the head of the lateral
gastrocnemius tendon; arrowhead ).
7.
8.
9.
10.
11.
12.
13.
Patella.
Lateral condyle.
Femoral shaft.
Superior pole, patella.
Inferior pole, patella.
Infrapatellar fat (Hoffa’s fat-pad).
Suprapatellar fat, femoral surface.
BASIC: AP, *Lateral, Intercondylar, Tangential
Clinicoradiologic Correlations (Figure 1-33, E–G )
Figure 1-33 E. Lateral, Knee, Suprapatellar Joint Effusion. There is a large fluid effusion in the suprapatellar pouch (arrows). Note the preservation of the fat anterior to the femur, which borders the posterior border of the pouch. F. Lateral, Knee, Paget’s Disease of the Patella and Tibia. The patella and tibia
are both increased in density, have thickened cortices, and are enlarged. Observe the transverse fracture
of the patella. G. Lateral, Knee, Degenerative Joint Disease of the Patellofemoral Joint. The patellofemoral joint space is decreased in thickness so that there is almost bone–bone contact between the
patella and the femur. There has been a mechanical erosion of the anterior femoral cortex owing to
chronic patella impingement (arrow).
97
OPTIONAL: Obliques
KNEE: Intercondylar (Tunnel) Projection
Positioning (Figure 1-34, A–C )
A
B
C
Figure 1-34 INTERCONDYLAR (TUNNEL), KNEE. A. Patient Position, Prone. B. Patient Position, Kneeling. C. Collimation
and Central Ray, Kneeling.
Synonyms: Tunnel view, notch view, intercondylar fossa
view, Holmblad view.
Demonstrates: Intercondyloid fossa, distal femur, proximal tibia, tibial eminences, proximal fibula, and joint space.
(1–3,21,22) (Fig. 1-34, D and E )
Measure: At the CR.
kVp: 60 (55 to 65).
Film Size: 8 × 10 inches (18 × 24 cm), vertical orientation.
Grid: Yes. Can be done non-bucky if the knee measures
< 10 cm.
TFD: 40 inches (102 cm); must correct TFD to 35 inches
(89 cm) for tube tilt.
Tube Tilt: Prone position: 45° caudal angulation.
CR: (a) Prone: the CR is angled 25° caudad and enters the
knee joint at the popliteal depression. Center film to the
CR. (b) Kneeling (Holmblad’s view): no tube tilt is used
and the CR passes through the knee joint. Center film to
the CR. (22,23) (Fig. 1-34C )
Collimation: Collimate closely to the skin line.
Side Marker: In the corner of the film.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Patella projected into the joint: This is caused by the
knee being incompletely flexed.
2. Uneven exposure: The distal femur is usually relatively
underexposed, which is tolerable; however, the condyles should be properly exposed.
Patient Position: Prone or kneeling.
Part Position: (a) Prone: the patient is prone on the table.
The knee is flexed approximately 45°, with the lower leg
and ankle supported. (Fig. 1-34A) (b) Kneeling (Holmblad’s
view): the patient is on the table in the kneeling position
and then leans forward so that the shaft of the femur
will form a 25° angle with the CR. (22,23) (Fig. 1-34B) The
unaffected knee is brought forward so that the majority
of the weight of the torso is on that knee.
98
Clinicoradiologic Correlations: This view depicts the
intercondylar notch; the femoral condylar surfaces, especially for osteochondral lesions (osteochondritis dissecans);
and the tibial spines. Intra-articular loose bodies, not visible on any other view, may be shown to lie within the
notch. (Fig. 1-34, F and G)
1. Alignment: The femur and tibia maintain normal alignment at their margins.
BASIC: AP, Lateral, *Intercondylar, Tangential
2. Bone: The medial femoral condyle is more convex and
narrower; the lateral condyle is broader. At the femoral
lateral epicondyle a distinct groove comes into profile
where the tendon for the popliteus muscle passes. The
intercondylar notch is clearly shown in its entirety as an
arch-like concavity with smooth borders where the
anterior and posterior cruciate ligaments attach. The
tibial spines are shown to advantage.
3. Cartilage: The femorotibial joint space is not clearly
demonstrated, because the incident beam is not tangential to the tibial surface. The fabella remains superimposed over the lateral femoral condyle. The patellofemoral joint is not demonstrated. The tibiofibular joint
can be discerned.
4. Soft tissue: The soft tissues overlying the distal femur
appear more radio-opaque owing to knee flexion and
the relationship to the incident beam; do not confuse
with swelling or mass.
Specialized Views:
1. Supine view: With the patient’s knee flexed to 30° the
CR is perpendicular to the tibia. (22,23)
2. Standing notch view: The patient stands on one leg;
the knee to be examined is placed on a stool and
flexed to 70°; the CR enters PA to the popliteal fossa
with no tube angulation. (23)
99
OPTIONAL: Obliques
KNEE: Intercondylar (Tunnel) Projection
Normal Anatomy (Figure 1-34, D and E)
Figure 1-34 D. Intercondylar (Tunnel), Knee. E. Specimen Radiograph, Distal Femur.
1.
2.
3.
4.
5.
6.
7.
8.
100
Femoral shaft.
Adductor tubercle.
Medial condyle.
Lateral condyle.
Medial epicondyle.
Lateral epicondyle.
Popliteal groove.
Intercondylar notch.
9.
10.
11.
12.
13.
14.
15.
Intercondylar eminences (tibial spines).
Medial condyle, tibia.
Lateral condyle, tibia.
Styloid process, fibula.
Neck of fibula.
Tibial shaft.
Patella.
BASIC: AP, Lateral, *Intercondylar, Tangential
Clinicoradiologic Correlations (Figure 1-34, F and G )
F
G
Figure 1-34 F. Intercondylar (Tunnel), Knee, Osteochondritis Dissecans. A
single loose body is visible within the intercondylar notch (arrowhead ). It has
originated from the medial condyle, where the defect can be seen (arrow ).
G. Intercondylar (Tunnel), Knee, Chondroblastoma. A well-defined radiolucent lesion is present within the medial femoral condyle (arrows). This lesion
was almost non-detectable on the routine AP view but is shown more clearly
on the intercondylar view, because the femoral surface is less tangential to the
incident beam.
101
KNEE: Tangential
(Skyline, Sunrise) Projection
OPTIONAL: Obliques
Positioning (Figure 1-35, A and B)
A
B
Figure 1-35 TANGENTIAL, KNEE. A. Patient Position. B. Collimation and
Central Ray.
Synonyms: Skyline projection, sunrise view, sunset view,
patellofemoral joint view, or Settegast’s view.
Demonstrates: Patella and patellofemoral joint space.
(1-3,24–27) (Fig. 1-35, C and D)
Measure: At the CR.
kVp: 60 (55 to 65).
Film Size: 8 × 10 inches (18 × 24 cm), vertical orientation.
Grid: Yes. May be done non-grid if part measures
< 10 cm.
TFD: 40 inches (102 cm); must correct TFD to 38 inches
(96 cm) for tube tilt.
Tube Tilt: 10° cephalad.
Patient Position: Prone. (Fig. 1-35A)
Part Position: The knee is fully flexed. If the patient is
unable to fully flex the knee, angle the CR cephalad so
that a 45° angle exists between the lower leg and the CR.
CR: Set the CR between the patella and the femoral
condyles. Center film to the CR. (Fig. 1-35B)
Collimation: 4 × 4 inch field.
Side Marker: In the corner of the film.
Breathing Instructions: Suspended expiration.
102
Common Pitfalls:
1. Non-tangential projection: When the incident beam
is not parallel to the retropatellar surface the patellofemoral joint space will not be clearly shown. In overangulation the shape of the patella is narrowed and
of increased depth.
2. Exposure: Commonly overexposed because of thin
part thickness.
3. Gonad shielding: Apply routinely, because angling
body parts and the incident beam will often expose
the gonads.
4. Quadriceps contraction: The quadriceps muscles
should be relaxed at the time of exposure, because
contraction can mask patellofemoral instability.
Clinicoradiologic Correlations: This view is particularly
useful for assessing the patella position (subluxation, dislocation), patellofemoral joint pain (chondromalacia,
arthritis), retropatellar surface (fracture), and depth of the
trochlear groove (dysplasia). (7,14) (Fig. 1-35, E and F )
1. Alignment: The patella should lie in a congruous manner relative to the trochlear groove of the femur. The
apex of the patellar articular surface lies directly above
the deepest part of the groove.
BASIC: AP, Lateral, Intercondylar, *Tangential
2. Bone: There is a wide variation in patellar shape. (27)
The retropatellar surface of the patella has three
facets. (a) Lateral facet: largest and broadest, with
the thickest subchondral cortex. (b) Medial facet:
shorter and more obliquely vertical with a diminishing
cortical thickness. (c) Odd facet: at the superior margin of the medial facet; often absent. The patellar
apex (median ridge) is the peak of the articular surface that separates the lateral and medial facets and
lies within the deepest point of the trochlear groove.
The internal patellar trabeculae are vertically orientated. The superior surface of the patella is often irregular and perforated by numerous radiolucent vascular grooves. The opposing trochlear groove (sulcus)
is congruous with the patella with the lateral condyle
broader.
3. Cartilage: The depth of the patellofemoral joint space
is assessed by the ratio of the joint space at the patellar apex to the lateral joint depth—usually ≤ 1. (28)
The surfaces of the femoral trochlea and patella
should be smooth.
4. Soft tissue: The overlying skin line lies in close apposition to the anterior patella. A triangular extra-articular
fat-pad can often be seen between the medial patella
and the femoral condyle. (29)
Specialized Views: There are numerous views available
to demonstrate the patellofemoral joint. (7)
1. Hughston’s view: Prone position with leg flexed
50–60°; the tube is angled cephalad, parallel to the
patellofemoral joint. (30)
2. Knutsson’s view: In the supine position with the knee
flexed to at least 60°; the beam is horizontal to the
film.
3. Merchant’s view: Supine position with the knee
flexed to 45° over the table edge; the tube is angled
caudally, parallel to the patellofemoral joint. (31)
4. Reversed merchant view: Supine position with the
knee flexed to 45° over the table edge; the tube is
angled cephalad, parallel to the patellofemoral joint
with the patient holding the film cassette. (28)
5. Ficat’s views: Same as the reversed Merchant view,
except three films are performed at 30°, 60°, and 90°
of flexion. The 30° view is best for patellar subluxation; the 60° is best for contact joint space.
103
KNEE: Tangential
(Skyline, Sunrise) Projection
OPTIONAL: Obliques
Normal Anatomy (Figure 1-35, C and D)
D
C
Figure 1-35 C. Tangential, Knee. D. Specimen Radiograph, Patella.
1.
2.
3.
4.
5.
6.
7.
8.
104
Odd facet of the patella.
Medial facet of the patella.
Lateral facet of the patella.
External cortical surface of the patella.
Patella.
Head of the fibula.
Tibiofibular articulation.
Patellofemoral articulation.
9.
10.
11.
12.
13.
14.
15.
Medial condyle.
Lateral condyle.
Groove for the popliteus tendon.
Intercondylar (trochlear) notch.
Medial epicondyle.
Lateral epicondyle.
Adductor tubercle.
BASIC: AP, Lateral, Intercondylar, *Tangential
Clinicoradiologic Correlations (Figure 1-35, E and F)
Figure 1-35 E. Tangential, Patella, Dislocation. The patella (P) has dislocated laterally relative to the femur
(F). There is a small fracture fragment adjacent to the lateral femoral condyle (arrows). F. Tangential,
Patella, Osteochondritis Dissecans. A separating bone fragment is visible from the retropatellar surface
involving the majority of the lateral facet and a small part of the medial facet (arrow).
105
OPTIONAL: Lateral oblique, Stress studies
ANKLE: AP Projection
Positioning (Figure 1-36, A and B)
Figure 1-36 AP ANKLE. A. Patient Position. B. Collimation and
Central Ray.
Synonyms: AP talocrural view.
Common Pitfalls:
Demonstrates: Distal tibia and fibula, talus, and ankle
joint. (1–3) (Fig. 1-36, C and D)
1. Inadequate dorsiflexion: If the foot is not dorsiflexed,
the tibiotalar joint space and lateral malleolus will
not be clearly visualized, because of overlap from the
calcaneus. (3)
Measure: AP at the ankle mortise.
kVp: 55 (50 to 60).
Film Size: 10 × 12 inches (24 × 30 cm), horizontal orientation. Divide in half; the other half is for the medial
oblique.
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Supine. (Fig. 1-36A)
Part Position: The ankle is slightly dorsiflexed so that the
plantar surface of the foot is perpendicular to the film,
which brings the weight-bearing talar surface into optimum tangential projection. Internally rotate the lower leg
so that a line through the malleoli is parallel with the film
surface.
CR: Center halfway between the medial and lateral malleolus. (Fig. 1-B)
Collimation: 6 × 10 inch field.
Side Marker: In the corner of the film.
Breathing Instructions: Suspended expiration.
106
2. Lack of internal rotation: Failure to internally rotate
the ankle a few degrees will not show the malleoli adequately and will result in overlap of the fibula with
the talus.
3. Plaster cast technique: Increase the kVp by at least 5 to
achieve improved penetration.
4. Long bone inclusion: Demonstration of the distal tibia
and fibula should be included when clinical symptoms
are proximal to the ankle joint.
Clinicoradiologic Correlations: All three views of the
basic series must be performed for adequate evaluation;
consider including the lateral oblique view in cases of
trauma. The most common injury of the ankle is an inversion injury with fracture of the lateral malleolus.
Associated fractures may require supplemental views:
the talar dome with an AP ankle plantar flexion view, the
base of the fifth metatarsal with a medial oblique foot
view, and an AP view of the proximal fibula
(Maisonneuve fracture). (Fig. 1-36, E–G)
1. Alignment: The opposing articular surfaces of the distal tibia (plafond) and talar dome should be parallel
and congruous; although up to 6° of tibiotalar tilt is
within the realm of normal variation. (4)
BASIC: *AP, Medial oblique, Lateral
2. Bone: The distal tibial diaphysis gradually expands to
the metaphysis, marked by progressive thinning of
the cortex. The medial malleolus curves inferiorly with
a groove visible at its tip, which houses the deep
flexor tendons. The inferior articular surface of the
tibia is called the plafond (French; “ceiling”). The
residuals of the growth plate (physeal scar) can often
be seen parallel to the plafond. The lateral malleolus
is bulbous toward its distal end and has a distinct
groove (peroneal groove) at its tip for the peroneal
tendons to pass. It extends about 1 cm lower than
the medial malleolus and slightly overlaps the talus in
this view. The talar dome has three articular facets:
the trochlea for the articulation with the tibial plafond, and the medial and lateral facets for articulation with the adjacent malleoli.
3. Cartilage: The joint is often referred to as the mortise
because of its similarity to a carpenter’s joint; the talus
is the tenon (a piece of wood with a projection), which
fits into a slot (the mortise) formed by the lateral and
medial malleoli. The joint space is congruent for the entire articulation from medial to lateral. The space between the medial malleolus and medial talar dome
(medial clear space) and lateral malleolus and lateral
talar dome (lateral clear space) should be the same distance as that at the superior joint and is about 5 mm.
4. Soft tissue: Note the close proximity of the overlying
skin line to the underlying malleoli.
Specialized Projections:
1. Plantar flexion view (lazy AP view): For subtle fractures of the talar dome, including osteochondritis dissecans, plantar flexion will often demonstrate the
fracture site as the posterior articular surface comes
into view. (5)
2. Inversion–eversion stress views: The stress is induced
by a third person, who wears lead gloves and lead
apron, or by the patient, who holds a strap that is
looped around the sole of the foot. The views should
be performed and measurements compared bilaterally. (6) The magnitude of tibiotalar tilt is assessed by
measuring the surface angles between the talar
dome and tibial plafond and is abnormal if > 10°,
which is an indicator of lateral ligament injury. (6,7)
3. Weight-bearing AP view: Performed AP and weight
bearing with a horizontal beam. This is especially
valuable in showing degenerative decreased joint
space and chronic instability with lateral talar tilt or
lateral shift. Diastasis of the distal tibiofibular syndesmosis may also be more apparent as a widened
joint with lack of tibiofibular overlap.
107
ANKLE: AP Projection
OPTIONAL: Lateral oblique, Stress studies
Normal Anatomy (Figure 1-36, C and D)
Figure 1-36 C. AP Ankle. D. Specimen Radiograph, Distal Tibia and Fibula.
1.
2.
3.
4.
5.
108
Tibia.
Fibula.
Medial malleolus, tibia.
Lateral malleolus, fibula.
Plafond of the tibia.
6.
7.
8.
9.
Lateral surface of the tibia.
Dome of the talus.
Neck of the talus.
Posterior malleolus.
BASIC: *AP, Medial oblique, Lateral
Clinicoradiologic Correlations (Figure 1-36, E–G )
Figure 1-36 E. AP Ankle, Bimalleolar Fracture. Fractures of both the lateral and medial malleolus are
visible (arrows). Observe also that the talus with the fractured malleoli has subluxed laterally. F. AP Ankle,
Osteochondritis Dissecans. A small bony fragment separated from the medial talar dome is demonstrated
(arrow). G. AP Ankle, Multiple Osteochondromas. Bony exostoses are present in the distal tibia and fibula.
The tibiotalar joint is angled laterally, owing to altered growth (tibiotalar slant deformity).
109
OPTIONAL: Lateral oblique, Stress views
ANKLE: Medial Oblique
Projection
Positioning (Figure 1-37A)
Collimation: 6 × 10 inch field.
Side Marker: In the corner of the film.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Inadequate dorsiflexion: The calcaneus will overlap
the lateral malleolus.
2. Incorrect medial rotation: The ankle joint space will
not be seen in its entirety. The medial malleolus overlaps the medial clear space with over-rotation and the
lateral malleolus overlaps the lateral clear space with
under-rotation.
3. Inclusion of tibia and fibula: Fractures, especially of the
fibula, may exist well above the joint; thus, adequate
demonstration of the distal shafts should be obtained.
Clinicoradiologic Correlations: This is an important
view in the assessment of the post-traumatic ankle for detecting subtle fractures of the distal fibula, posterior tibia,
talar dome, and base of the fifth metatarsal. The amount
of medial rotation is open to variation, with some advocating views at 20°, 35°, and 45° to demonstrate the
mortise. (Fig. 1-37, C–E)
Figure 1-37 MEDIAL OBLIQUE, ANKLE.
A. Patient Position, Collimation and
Central Ray
Synonyms: Internal oblique view, mortise view.
Demonstrates: Distal tibia–fibula, talus, and ankle joint.
(1–3,8) (Fig. 1-37B)
Measure: AP at the ankle mortise.
kVp: 55 (50 to 60).
Film Size: 10 × 12 inches (24 × 30 cm). Divide in half; the
other half is for the AP projection. Horizontal orientation.
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
1. Alignment: The opposing articular surfaces of the tibia
and talar dome should be parallel but may diverge up
to 6°. (4) The joint remains the same depth throughout
its length of approximately 5 mm.
2. Bone: Both lateral and medial malleoli are clearly
shown, as is the talocrural joint space, talus, and tibial
plafond. The overlap of the distal tibia and fibula is
reduced on this view. The calcaneus, navicular, cuboid,
and proximal metatarsals and their respective joints will
be visible. Given the common tandem fractures of the
base of the fifth metatarsal and cuboid with ankle inversion injuries, these should all be examined carefully.
3. Cartilage: The view is called the mortise view because
the entire joint space is visible in one view. The key
change from the AP is the clear demonstration of the
distal tibiofibular joint separation of 2 mm. A measurement > 5 mm indicates diastasis. The subtalar joint
(talocalcaneal) can be seen partially in this view.
4. Soft tissue: Note the close proximity of the overlying
skin line to the underlying malleoli and the concave
contour below the malleolar tips.
Patient Position: Supine. (Fig. 1-37A)
Part Position: The ankle is slightly dorsiflexed so that the
plantar surface of the foot is perpendicular to the film.
The lower leg is then internally rotated so that the intermalleolar line forms an angle of 35° with the film.
CR: Center halfway between the medial and lateral malleolus. Center film to the CR.
110
Specialized Projections:
1. Internal 45° oblique: The posterior subtalar joint, talus,
lateral malleolus, and tibia are shown to advantage.
2. External 45° oblique: The tibia is shown in different
profile and offers an especially good view of the anterior tibia and lateral malleolus.
BASIC: AP, *Medial oblique, Lateral
Normal Anatomy (Figure 1-37B)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
Tibia.
Fibula.
Lateral malleolus, fibula.
Medial malleolus, tibia.
Plafond of the tibia.
Lateral surface of the tibia.
Posterior malleolus.
Body of the talus.
Neck of the talus.
Head of the talus.
Sinus tarsi (sulcus calcanei).
Anterior tubercle, calcaneus.
Calcaneus.
Navicular.
Lateral cuneiform.
Cuboid.
Fifth metatarsal base.
Figure 1-37 B. Medial Oblique, Ankle.
Clinicoradiologic Correlations (Figure 1-37, C–E )
Figure 1-37 C. Medial Oblique, Ankle, Fracture of the Distal Fibula. An oblique fracture is visible through the lateral
malleolus (arrow). A medial talar dome fracture (osteochondritis dissecans) is also shown (arrowhead), which was not
visible on the routine AP and lateral projections, underscoring the importance of this mortise view. D. Medial Oblique,
Ankle, Chondromyxoid Fibroma. A well-defined round lesion is present within the tibia. This view, taken by rotating
the tibial metaphysis, allows assessment of all the lesion’s features. E. Medial Oblique, Ankle, Chronic Osteomyelitis.
There is increased bone density (sclerosis) and thickening of the cortex (arrow) in the distal tibia above the joint, exemplifying why adequate sections of the distal long bones must be included for proper assessment. The separation of the
distal tibia and fibula confirm that this is a medially rotated view.
111
OPTIONAL: Lateral oblique, Stress views
ANKLE: Lateral Projection
Positioning (Figure 1-38A)
2. Bone: The fibula overlaps the tibia and talar dome.
The divisions of the talus can be recognized as the
dome (which forms the talocrural joint), neck (which
is the narrowed segment anterior to the joint), and
head (which has a convex surface to articulate with
the navicular). The posterior and plantar surface of the
calcaneus is usually very dense and thick, as a normal
compressive stress reaction. Observe the normal trabecular patterns that pass upward to the subtalar
joint. (Fig. 1-38, D–F)
3. Cartilage: The surface of the convex talus should be
congruent with the reciprocal concave surface of the
tibial plafond. The talocalcaneal (subtalar) joint is visible in its midsection, where the sinus tarsi is found.
The talonavicular joint is a uniform convex shape.
Figure 1-38 LATERAL ANKLE. A. Patient Position,
Collimation, and Central Ray.
Demonstrates: Distal tibia and fibula, ankle joint talus,
and calcaneus. (1–3,9,10) (Fig. 1-38, B and C)
Measure: Transversely through the malleoli.
kVp: 55 (50 to 60).
Film Size: 8 × 10 inches (18 × 24 cm). Vertical orientation.
4. Soft tissue: Posterior to the tibia there is a triangular
radiolucent region of the pre-Achilles fat-pad. It is
bounded by the Achilles tendon posteriorly, deep
flexor muscles of the calf anteriorly, and the superior
border of the calcaneus. The Achilles tendon can be
identified as a thin 4- to 6-mm soft tissue band. The
heel pad is often mottled in appearance owing to thick
fibrous septae. The attachment of the plantar fascia
at the inferior calcaneal surface can usually be seen.
At the anterior talotibial joint margin, a small fat-pad
can occasionally be located, below which effusions of
5 mL may be seen. (11) Note the thickness of the skin
overlying the calcaneus posteriorly and on the plantar surface.
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Lateral recumbent. (Fig. 1-38A)
Part Position: The lateral surface of the ankle is in contact with the film, with the foot slightly dorsiflexed. Cross
the opposite leg over the leg being examined, and support the opposite knee to avoid rotation of the ankle.
CR: Directed to the medial malleolus. Center film to
the CR.
Collimation: 8 × 10 inch field.
Side Marker: In the corner of the film.
Breathing Instructions: Suspended expiration.
Clinicoradiologic Correlations:
1. Alignment: Note the position of the tibia on the talus.
The angle of the calcaneus is upward and is referred to
as the calcaneal pitch. The configuration of the calcaneus, tarsals, and downward-sloping metatarsals form
the longitudinal arch of the foot.
112
Specialized Projections:
1. Drawer view: A third person, who wears lead gloves
and a lead apron, stabilizes the tibia and pulls the hind
foot forward. Anterior translation of > 2 mm of the
talus relative to the tibia is a sign of instability.
2. Flexion–extension (dancer views): These can be performed with or without weight bearing with the foot
on maximal plantar and then dorsiflexion for demonstrating bony impaction anteriorly and posteriorly as
a sign of impingement syndromes.
3. Lunge’s view: Performed weight bearing in plantar
flexion, the view demonstrates the degree of impaction
of the anterior tibial margin to the neck of the talus,
as part of the assessment for anterior impingement
syndrome.
4. Lazy lateral: The posterior tibial margin is a frequent
site of fracture and can be best demonstrated in an
off-lateral projection, with slight external rotation of
the foot. (10) In addition, signs of posterior impingement syndrome can be shown to advantage at the
posterior talus and os trigonum.
BASIC: AP, Medial oblique, *Lateral
Normal Anatomy (Figure 1-38, B and C )
Figure 1-38 B. Lateral, Ankle. C. Specimen Radiograph, Distal Tibia and Fibula.
1.
2.
3.
4.
5.
Tibia.
Fibula.
Plafond of the tibia.
Posterior malleolus, tibia.
Lateral malleolus, fibula.
6.
7.
8.
9.
10.
Talar dome.
Neck of talus.
Head of talus.
Navicular.
Cuboid.
11.
12.
13.
14.
Anterior tubercle, calcaneus.
Middle tubercle, calcaneus.
Posterior tubercle, calcaneus.
Posterior surface, calcaneus.
Clinicoradiologic Correlations (Figure 1-38, D–F )
Figure 1-38 D. Lateral, Ankle, Talar Neck Fracture. The cortical offset and radiolucent fracture line can be seen
traversing the neck of the talus (arrow). E. Lateral, Ankle, Paget’s Disease. Both the talus and calcaneus are increased in density (sclerotic), have expanded, and demonstrate thickened trabeculae. The talocrural and subtalar
joints were normal. F. Lateral, Ankle, Osteochondral Loose Bodies. Multiple calcified round intra-articular loose
bodies are present anterior to the talocrural joint. These are partially calcified cartilaginous masses often found
in degenerative joints. Note the unequal talocrural joint space, a manifestation of degenerative joint disease.
113
FOOT: Dorsoplantar Projection
Positioning (Figure 1-39, A and B)
Figure 1-39 DORSOPLANTAR, FOOT. A. Patient Position. B. Collimation
and Central Ray.
Demonstrates: Phalanges, metatarsals, cuneiforms,
cuboid, and navicular. (1–5) (Fig. 1-39, C and D)
Measure: Through the tarsometatarsal junction at the
base of the third metatarsal.
kVp: 55 (50 to 60).
Film Size: 10 × 12 inches (24 × 30 cm), vertical orientation. Divide in half lengthwise; the other half is for the
medial oblique projection.
Grid: No.
TFD: 40 inches (102 cm); must correct TFD to 38 inches
(96 cm) for tube tilt.
Tube Tilt: 10° cephalad.
Patient Position: Supine with knee flexed, or standing.
(Fig. 1-39A)
Part Position: The knee is flexed so that the plantar surface of the foot is resting on the film.
CR: Centered to base of third metatarsal. Center film to
the CR. (Fig. 1-39B)
Collimation: 5 × 12 inch field.
Side Marker: In the corner of the film.
114
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Uneven exposure: A compensating wedge filter can
be used to prevent overexposure of the metatarsal
heads and toes while adequately exposing the tarsals,
filtering from the midshaft of the metatarsals distally.
If a wedge filter is not available, optimally expose the
region of concern.
2. No tube tilt: Tube tilt improves visualization of the
intertarsal and tarsometatarsal articulations. The flatter
the longitudinal arch (pes planus), the less the tube tilt
required; the higher the arch (pes cavus), the greater
the tilt necessary.
3. Toe flexion–extension: When the toes are flexed or
extended the intervening joint spaces will not be depicted and the phalanges appear end-on as circles; for
optimum demonstration keep them straight in plane
with the film as much as possible.
Clinicoradiologic Correlations: This is an integral view
in evaluation of foot pain. (Fig. 1-39, E and F)
1. Alignment: In general each metatarsal–phalangeal unit
(ray) is in straight longitudinal alignment; all joints of
BASIC: *Dorsoplantar, Medial oblique, Lateral
each ray should be visible. The spaces between each
metatarsal shaft are generally equidistant to each
other. A number of other relationships can be assessed:
(a) Hallux abductus angle: the angle between the shafts
of the first metatarsal and proximal phalanx (0–15°).
(b) Intermetatarsal angle: angle between the first and
second metatarsal shafts (14°). (c) Metatarsal angle:
tangential lines drawn along the articular surfaces of
the first to second and fifth to second metatarsal heads
(140°). (6)
2. Bone: All bones displayed should be identified. The
first metatarsal is the shortest; the second, the longest.
The metatarsal heads are expanded relative to the
metaphyses, have thin cortices, and are normally quite
radiolucent. Only two phalanges occur at the great
toe, which also has two sesamoid bones on the plantar surface superimposed over the first metatarsal
head. Each phalanx has expanded ends, which are also
relatively radiolucent. The expanded distal end of the
distal phalanges are referred to as the terminal or ungula tufts.
3. Cartilage: Identify all joints and note the width of
the joint cavity and the smooth articular surfaces.
The articulations between the first and the third tarsometatarsal junctions, cuneiforms, and cuboid are
often not well seen on this view. The tarsometatarsal
joint is known as Lisfranc’s joint; the joint through
the talonavicular and calcaneocuboid articulations
is called Chopart’s joint. The tarsometatarsal joint
spaces are uniform and about 1 mm from the first to
fifth joints; widening—especially at the first and second joints—is a subtle sign of a ligamentous
(Lisfranc’s) injury. Many people have congenital fusion of the fifth distal interphalangeal joint.
4. Soft tissue: The skin line lies in close apposition to each
toe and over the medial and lateral midfoot of the
metatarsals.
Specialized Projections:
1. Weight-bearing view: The beam is angled 15° cephalad to optimize the depiction of the intertarsal joints.
Common deformities that are increased with gravity
effects include hallux valgus and splayed foot.
115
FOOT: Dorsoplantar Projection
Normal Anatomy (Figure 1-39, C and D)
Figure 1-39 C. Dorsoplantar, Foot. D. Anatomic Specimen, Foot.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
116
Medial malleolus, tibia.
Calcaneus.
Cuboid.
Head of talus.
Navicular.
First cuneiform (medial).
Second cuneiform (intermediate).
Third cuneiform (lateral).
Base of fifth metatarsal (styloid process).
Base of fourth metatarsal.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Shaft of third metatarsal.
Neck of second metatarsal.
Head of first metatarsal.
First metatarsal phalangeal articulation.
Medial sesamoid in tendon of flexor hallucis brevis.
Lateral sesamoid in tendon of flexor hallucis brevis.
Proximal phalanx of the fourth toe.
Middle phalanx of the third toe.
Distal phalanx of the second toe.
Distal ungual tuft of the first toe.
BASIC: *Dorsoplantar, Medial oblique, Lateral
Clinicoradiologic Correlations (Figure 1-39, E and F)
Figure 1-39 E. Dorsoplantar, Foot, Fracture–Dislocation of the Tarsometatarsal
Joint (Lisfranc’s Injury). The second through fifth metatarsals are dislocated laterally, with widening of the first to second intermetatarsal space. A small avulsed
bone fragment from the medial base of the second metatarsal at the site of ligamentous insertion is visible (arrow). F. Dorsoplantar, Foot, Stress Fracture.
Surrounding the neck of the second metatarsal is a prominent collar of callus (arrows). The actual fracture line is not visible.
117
FOOT: Medial Oblique Projection
Positioning (Figure 1-40, A and B)
Figure 1-40 MEDIAL OBLIQUE, FOOT. A. Patient Position.
B. Collimation and Central Ray.
Synonyms: Internal oblique view.
Collimation: 5 × 12 inch field.
Demonstrates: Phalanges, metatarsals, cuboid, third
cuneiform, navicular, and distal calcaneus. (1–7) (Fig.
1-40, C and D)
Side Marker: In the corner of the film.
Measure: Tarsometatarsal junction at the base of the
third metatarsal.
kVp: 55 (50 to 60).
Film Size: 10 × 12 inches (24 × 30 cm), vertical orientation. Divide in half; other half is for the dorsoplantar
projection.
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: 10° cephalad.
Patient Position: Supine with knee flexed, or standing.
(Fig. 1-40A)
Part Position: Begin with the knee flexed so that the
foot rests flat on the film. The leg is rotated medially so
that the plantar surface of the foot forms an angle of approximately 35° with the plane of the film; the fifth digit
will be elevated from the film surface.
CR: Center to the base of the third metatarsal. Center film
to the CR. (Fig. 1-40B)
118
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Uneven exposure: A compensating wedge filter can
be used to prevent overexposure of the metatarsal
heads and toes while adequately exposing the tarsals,
filtering from the midshaft of the metatarsals distally.
If a wedge filter is not available, optimally expose the
region of concern.
2. No tube tilt: Tube tilt improves visualization of the
intertarsal and tarsometatarsal articulations.
Clinicoradiologic Correlations: This is an extremely
important view in the assessment of lateral foot pain to
show the cuboid and fifth metatarsal, common sites of
fracture which are not seen well on other views. (Fig.
1-40, E and F)
1. Alignment: Joint relationships, especially of the toes,
can be well appreciated in this plane to show latent
dislocations not visible on the dorsoplantar view.
Alignment of the intertarsal joints can also be assessed.
2. Bone: The metatarsals are rotated to show a different
surface, as are the phalanges. The greatest asset of this
BASIC: Dorsoplantar, *Medial oblique, Lateral
view is the clear depiction of the tarsal bones, especially
the cuboid, cuneiforms, and navicular and the adjacent
metatarsal bases (especially the fifth). The third
through fifth metatarsals are separated on this view,
which are superimposed on the dorsoplantar study.
The sesamoid bones at the great toe are displaced medially, with the most medial being clear of the undersurface of the first metatarsal. Always scrutinize the
ankle, because the talus and malleoli are displayed in a
different plane, allowing the detection of other injuries.
3. Cartilage: The intertarsal joints, especially the talonavicular and calcaneocuboid joints, are clearly depicted.
The tarsometatarsal joints, especially the third through
fifth, are more clearly demonstrated as is the sinus tarsi.
This is an excellent view for detecting bony bridging
across joints, either acquired (ankylosis) or congenital
bars (tarsal coalition). (8) The great toe– sesamoid joint
spaces also come into profile and can be evaluated.
4. Soft tissue: The skin line lies in close apposition to
each toe and over the medial and lateral midfoot.
Specialized Projections:
1. Navicular view: Foot is laterally rotated 15°, the CR is
at the navicular, and the tube is not tilted, allowing
display of subtle bone lesions of the navicular and
talonavicular arthritis. (9)
2. Lateral oblique: Foot is laterally rotated 60° and the
great toe is elevated from the film. The CR is to the
midfoot at the third–fourth metatarsal bases; there
is no tube tilt. The view will show to advantage medial structures, including the first metatarsal, medial
cuneiform, navicular, talus, and the intervening joints.
3. Plantar–dorsal view (Grashey’s method ): This view
is suited to demonstrate details of the metatarsals,
which are close to and parallel with the film. The
patient is prone, the foot is plantar flexed, and the
CR enters the midfoot with no tube tilt. Medial rotation of 30° will show the first and second metatarsals; lateral rotation of 20° displays the second
through fifth metatarsals.
119
FOOT: Medial Oblique Projection
Normal Anatomy (Figure 1-40, C and D)
Figure 1-40 C. Medial Oblique, Foot. D. Anatomic Specimen, Foot.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
120
Calcaneus.
Head of talus.
Navicular.
First cuneiform (medial).
Second cuneiform (intermediate).
Third cuneiform (lateral).
Cuboid.
Calcaneocuboid joint.
Base of fifth metatarsal (styloid process).
Base of fourth metatarsal.
Shaft of third metatarsal.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Neck of second metatarsal.
Head of first metatarsal.
First metatarsal phalangeal articulation.
Bipartite medial sesamoid in tendon of flexor hallucis
brevis.
Lateral sesamoid in tendon of flexor hallucis brevis.
Proximal phalanx of the fourth toe.
Middle phalanx of the third toe.
Distal phalanx of the second toe.
Distal ungual tuft of the first toe.
BASIC: Dorsoplantar, *Medial oblique, Lateral
Clinicoradiologic Correlations (Figure 1-40, E and F )
Figure 1-40 E. Medial Oblique, Foot, Tarsal Coalition. Bony processes from both the calcaneus and the navicular
converge, at irregular, sclerosed joint surfaces, where there is a fibrous coalition (arrow). Note how clearly this view
displays the joint surfaces and bones of the tarsus, sinus tarsi, and metatarsal bases. F. Medial Oblique, Foot, Fifth
Metatarsal Fracture. A transverse fracture is present at the base of the fifth metatarsal (arrow). This view lays out the
anatomy at this region of the lateral foot; this fracture would be obscured on the routine dorsoplantar view.
121
FOOT: Lateral Projection
Positioning (Figure 1-41, A and B)
Figure 1-41 LATERAL, FOOT. A. Patient Position. B. Collimation and
Central Ray.
Synonyms: Mediolateral foot view.
Demonstrates: Distal tibia and fibula, tarsals, ankle joint,
metatarsals, and phalanges. (1–5) (Fig. 1-41C)
Measure: Navicular to fifth metatarsal.
kVp: 55 (50 to 60).
Film Size: 8 × 10 inches (18 × 24 cm) or 10 × 12 inches
(24 × 30 cm) for large feet, horizontal orientation.
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Lateral recumbent or standing. (Fig.
1-41A)
Part Position: Cross the unaffected leg over and forward for patient stability. The affected foot is placed in
true lateral projection, with the fifth metatarsal in contact with the film. The plantar surface of the foot should
be perpendicular to the film.
CR: At the navicular, medial to lateral. (Fig. 1-41B)
Collimation: To the film.
Side Marker: In the corner of the film.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Foot over-rotation: Care must be taken to achieve a
true lateral of the foot.
122
Clinicoradiologic Correlations: The view is an integral
part of a foot series and should not be omitted. (Fig. 1-40,
D–F)
1. Alignment: Note the curvature of the longitudinal arch
and its maximum depth at its apex, usually located at
the level of the navicular. The plane of angulation of
the first metatarsal normally continues proximally to
intersect the medial cuneiform, navicular, and head of
talus. The calcaneus is angled cephalad relative to the
plane of the forefoot and midfoot (calcaneal pitch). (5)
Note the position of the tibia on the talus.
2. Bone: The talus, calcaneus, navicular, and cuboid are
clearly visible. Of the metatarsals, only the base of the
fifth metatarsal is well demonstrated. The first metatarsal is recognized by being the shortest and broadest with the largest head. The divisions of the talus
are the dome, which forms the talocrural joint; the
neck, which is the narrowed segment anterior to the
joint; and the head, which has a convex surface to
articulate with the navicular. The posterior and plantar surface of the calcaneus is usually very dense and
thick, owing to a normal compressive stress reaction.
Observe the normal calcaneal trabecular patterns that
pass upward to the subtalar joint.
3. Cartilage: The surface of the convex talus should be
congruent with the reciprocal concave surface of
the tibial plafond. The talocalcaneal (subtalar) joint
is visible in its midsection, where the sinus tarsi is
found. The talonavicular joint forms a uniform convex–
BASIC: Dorsoplantar, Medial oblique, *Lateral
concave reciprocating shape, as does the adjacent
distal naviculocuneiform joint. The calcaneocuboid
joint is visible inferiorly. The tarsometatarsal joints
are usually obscured, as are the metatarsophalangeal
joints—except those of the first metatarsal, which,
because of its larger size, can be discerned.
4. Soft tissue: Posterior to the tibia there is a triangular radiolucent region of the pre-Achilles fat-pad. It is
bounded by the Achilles tendon posteriorly, deep flexor
muscles of the calf anteriorly, and superior border of
the calcaneus. The Achilles tendon can be identified
as a thin 4–6mm soft tissue band. The heel pad often
is mottled in appearance owing to thick fibrous septae.
The attachment of the plantar fascia at the inferior
calcaneal surface can usually be seen. At the anterior
talotibial joint margin a small fat-pad can occasionally
be located, below which effusions of 5 mL may be
seen. (10) Note the thickness of the skin overlying the
calcaneus posteriorly and on the plantar surface.
Specialized Projections:
1. Lateromedial foot view: In the absence of acute pain,
prominent hallux valgus, prominent medial malleolus,
or significant foot deformity, this lateral view is preferred because when placed with the first metatarsal
in contact with the film, the foot will adapt a natural
lateral position and is prone to rotational distortion.
2. Weight-bearing lateral: Performed bilaterally for comparison of the longitudinal arch.
123
FOOT: Lateral Projection
Normal Anatomy (Figure 1-41C)
Figure 1-41 C. Lateral, Foot.
1.
2.
3.
4.
5.
6.
7.
124
Tibia.
Dome of talus.
Neck of talus.
Head of talus.
Navicular.
Cuneiforms (superimposed on each other).
Cuboid.
8.
9.
10.
11.
12.
13.
14.
Base of fifth metatarsal.
Styloid process, fifth metatarsal.
Calcaneus.
Anterior tubercle, calcaneus.
Middle tubercle, calcaneus.
Posterior tubercle, calcaneus.
Os trigonum.
BASIC: Dorsoplantar, Medial oblique, *Lateral
Clinicoradiologic Correlations (Figure 1-41, D–F )
Figure 1-41 D. Lateral, Foot, Tarsal Ankylosis. There is obliteration and bony fusion of the normal joint spaces
between the navicular and the medial cuneiform (arrow). The naviculocuboid joint is also fused, and the tarsometatarsal joints are narrowed. This has occurred secondary to inflammatory arthritis, in this case psoriatic arthritis.
E. Lateral, Foot, Osteosarcoma of the Calcaneus. At the posterior aspect of the calcaneus there is dense new bone
formation that, on this view, is demonstrated to be extending superiorly into the pre-Achilles fat, which has been
opacified owing to tumor mass and edema. F. Lateral, Foot, Paget’s Disease of the Talus and Calcaneus. Both bones
are increased in density and show trabecular accentuation and bone enlargement. In addition, there is a pathological fracture through the neck of the talus (arrowhead) and destruction of bone at the superior aspect of the
posterior calcaneus (arrow) caused by malignant degeneration to osteosarcoma. Neither fracture nor malignant
changes were visible on the dorsoplantar images, demonstrating the supplemental roles of routinely obtaining
orthogonal views.
125
OPTIONAL: Axial (sesamoids)
TOES: Dorsoplantar Projection
Positioning (Figure 1-42A)
Side Marker: In the corner of the film.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Toe flexion–extension: When the toes are flexed or
extended the intervening joint spaces will not be depicted and the phalanges appear end-on as circles. For
optimum demonstration keep toes straight in plane
with the film as much as possible.
2. Overexposure: Use of foot exposure factors will result
in overexposure, requiring at least a 50% decrease
in mAs. Use fine-detail film–screen combinations if
available.
Clinicoradiologic Correlations: These structures are
best evaluated on a separate film from the foot to ensure
improved exposure and detail often necessary to demonstrate subtle pathology. (Fig. 1-42, D–G)
1. Alignment: Note any deviation of the digits (flexion,
axial). The phalanges should generally be congruous
at their joint surfaces. The hallux sesamoids should
overlap the first metatarsal head.
Figure 1-42 DORSOPLANTAR, TOES. A. Patient Position,
Collimation, and Central Ray.
Demonstrates: Phalanges, distal metatarsals, and interphalangeal and metatarsophalangeal joints. (1–4) (Fig.
1-42, B and C )
Measure: At the proximal interphalangeal joints. For the
great toe, at the interphalangeal joint.
kVp: 55 (50 to 60).
Film Size: 8 × 10 inches (18 × 24 cm). Divide in half; the
other half is for the oblique projection. Horizontal orientation.
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Supine or sitting on the tabletop. (Fig.
1-42A)
Part Position: The knee is flexed so the foot is placed
flat on the film.
CR: At the proximal interphalangeal joint.
Collimation: If a general evaluation of the toes is required, all of the toes should be exposed. If a specific toe
is being evaluated, then appropriate collimation should
be performed.
126
2. Bone: Each phalanx is examined. There are only two
phalanges at the great toe. The phalanges become
progressively smaller laterally, with the fifth toe having
the smallest. The expanded metaphyses appear relatively radiolucent as the cortex thins from the diaphysis.
The distal ends of the proximal and middle phalanges
are more squared in their appearance. The distal ends
of the distal phalanges are expanded and often slightly
irregular in outline and density; these are called the
distal tufts, terminal tufts, or ungual tufts.
3. Cartilage: The metatarsophalangeal joints are convex–
concave in configuration, whereas the interphalangeal
joints are more planar, though the interphalangeal
joint of the great toe has a small trochlea centrally.
Note how the metatarsophalangeal joints have relatively wide joint spaces. Because of flexion of the
digits all phalangeal joints may not be observed. A
common variant is fusion of the fifth distal interphalangeal joint.
4. Soft tissue: Carefully follow the skin outlines and soft
tissue density for any swelling. Often the nail can be
identified. At the metatarsophalangeal joint of the
medial great toe it is usually possible to see the subcutaneous fat in profile as a radiolucent line beneath
the skin, which is often altered or lost in diseases of
the joint.
Specialized Projections:
1. Collimated around-the-clock views: If a selected toe
is involved, it should be radiographed in sequential
around-the-clock views (AP, PA, oblique, and lateral).
Use of a separating pad between the toes to help stabilize and minimize superimposition can be helpful.
BASIC: *Dorsoplantar, Obliques
Normal Anatomy (Figure 1-42, B and C )
1. Medial sesamoid bone in tendon
of flexor hallucis brevis.
2. Lateral sesamoid bone in tendon
of flexor hallucis brevis.
3. First metatarsal head.
4. Proximal phalanx, fourth toe.
5. Middle phalanx, third toe.
6. Distal phalanx, second toe.
7. Distal ungual tuft, first toe.
8. Metatarsal phalangeal joint,
second toe.
9. Interphalangeal joint.
10. Distal interphalangeal joint,
third toe.
Figure 1-42 B. Dorsoplantar, Toes. C. Anatomic Specimen, Toes.
Clinicoradiologic Correlations (Figure 1-42, D–G )
Figure 1-42 D. PA Toes, Septic Arthritis, Metatarsophalangeal Joint. At the third joint there is loss of the normal
articular cortical bone of both the metatarsal head and base of the proximal phalanx (arrowhead). Observe the localized loss of bone density (osteopenia) of these same bones. Compare these changes with the adjacent unaffected joints
(arrows). E. PA Toes, Arthritis Mutilans, Psoriasis. Erosive changes are visible at the proximal phalanx of the great toe
(arrow). Joint fusion has occurred at the proximal interphalangeal joints of the second and third toes (arrowheads).
Notice how the toes are extended at the metatarsophalangeal joints, with erosion and deformity of the metatarsal
heads and bases of the proximal phalanges. F. PA Toes, Phalangeal Synostosis. A common normal variation is congenital fusion of the distal interphalangeal joint of the little toe (arrow). Note the lack of joint space and cortical articular
cortex; the bony trabeculae is continuous across where the joint should lie. A small accessory ossicle adjacent to the
distal interphalangeal articulation of the great toe is also visible (arrowhead). G. PA Great Toe, Gout. Multiple erosive
defects are present at the first metatarsal head (arrowhead) and base of the proximal phalanx (arrow, crossed arrow).
Also observe the increase in soft tissue density surrounding the joint, the medial soft tissue displacement, and the loss
of the subcutaneous fat secondary to urate crystal deposition and edema.
127
OPTIONAL: Axial (sesamoids)
TOES: Oblique Projection
Positioning (Figure 1-43, A–C )
Figure 1-43 OBLIQUE, TOES. A. Patient Position, Toes 1–3. B. Patient
Position, Toes 4 and 5. C. Collimation and Central Ray.
Demonstrates: Phalanges, distal metatarsals, and interphalangeal and metatarsophalangeal joints. (1–4) (Fig.
1-43, D and E)
Measure: At interphalangeal joints.
kVp: 55 (50 to 60).
Film Size: 8 × 10 inches (18 × 24 cm). Divide in half; the
other half is for the dorsoplantar projection. Horizontal
orientation.
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Supine or sitting on the tabletop.
Part Position: The knee is flexed so the foot is placed
flat on the film. (a) Medial toes 1–3: elevate the fifth metatarsal region so the foot forms a 45° angle with the film.
(Fig. 1-42A) (b) Lateral toes 4 and 5: elevate the great toe
region so the foot forms a 45° angle with the film. (Fig.
1-43B)
CR: At the proximal interphalangeal joint. (Fig. 1-43C)
Collimation: If a general evaluation of the toes is required, all of the toes should be exposed. If a specific toe
is being evaluated, then appropriate collimation should
be performed.
Side Marker: In the corner of the film.
128
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Inadequate obliquity: Because lateral views are often
difficult to obtain, oblique views are used instead,
so enough rotation must be induced to see the posterior bony surface.
2. Overexposure: Use of foot exposure factors will result
in overexposure, requiring at least a 50% decrease
in mAs. Use fine-detail film–screen combinations if
available.
Clinicoradiologic Correlations: These structures are best
evaluated on a separate film from the foot to ensure improved exposure and detail. (Fig. 1-43, F–H) If a selected
toe is involved, it should be radiographed in sequential
around-the-clock views (AP, PA, oblique, and lateral).
1. Alignment: Toe deformities, subluxation, and dislocation can often be seen on these views when not visible
on the AP views.
2. Bone: Each phalanx is examined; note the diaphyseal
constriction, expanded articular ends, and ungual
tuft. The hallux sesamoids are often seen in profile, although they are best shown on an axial projection. (4)
3. Cartilage: Because of flexion of the digits all phalangeal
joints may not be observed. Note how the metatarsophalangeal joints have relatively wide joint spaces.
4. Soft tissue: Carefully follow the skin outlines of each
digit.
BASIC: Dorsoplantar, *Obliques
Normal Anatomy (Figure 1-43, D and E )
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
Base of second metatarsal.
Shaft of first metatarsal.
Neck of second metatarsal.
Head of third metatarsal.
Proximal phalanx, fifth toe.
Middle phalanx, fourth toe.
Distal phalanx, third toe.
Distal tuft (ungual), second toe.
Proximal phalanx, first toe.
Interphalangeal joint, first toe.
Distal phalanx, first toe.
Metatarsal phalangeal
articulation, second toe.
Proximal interphalangeal
joint, fifth toe.
Distal interphalangeal joint,
second toe.
Medial sesamoid bone in the
Figure 1-43 D. Oblique, Toes. E. Specimen Radiograph, Toes.
tendon of flexor hallucis brevis.
Lateral sesamoid bone in the
tendon of flexor hallucis brevis.
Clinicoradiologic Correlations (Figure 1-43, F–H )
Figure 1-43 F. Oblique Medial, Toes, Avascular Necrosis. The head of the third metatarsal is flattened
and collapsed owing to underlying bone necrosis. This change was very subtle on the AP view, yet is
clearly demonstrated here because the collapsed cortex comes into tangential projection. G. Oblique
Medial, Toes, Enchondroma. Within the medullary space of the base of the proximal phalanx of the
second toe there is loss of bone density, a small fleck of internal calcification, and bone expansion.
The tumor has not destroyed the articular cortex. H. Oblique Lateral, Toes, Fracture. A non-displaced
oblique fracture extends through the diaphysis of the proximal phalanx of the fifth toe (arrow). Note
also the congenital fusion of the distal interphalangeal joint of the fifth toe.
129
CALCANEUS: Axial Projection
Positioning (Figure 1-44, A and B)
Common Pitfalls:
1. Uneven exposure: The posterior subtalar joint should
be visible. To avoid overexposure of the calcaneus on
one view, it may be necessary to use a wedge filter;
otherwise two exposures may be necessary.
2. Inadequate dorsiflexion: A looped strap can be placed
around the ball of the foot and grasped by the patient
to maximize dorsiflexion of the foot.
Clinicoradiologic Correlations: The axial view depicts
the body and its posterior aspect; the anterior calcaneus
needs to be evaluated on the lateral and oblique views.
Failure to do this view in the evaluation of heel pain will
overlook fractures in the calcaneal body and subtalar
coalition at the posterior and medial joints. (Fig. 1-44E )
1. Alignment: The opposing surfaces of the posterior
and medial subtalar joints should be congruous and
smooth.
Figure 1-44 AXIAL, CALCANEUS. A. Patient Position.
B. Collimation and Central Ray.
Synonyms: Plantar-dorsal view.
Demonstrates: Body and posterior calcaneus, posterior
subtalar joint. (1,2) (Fig. 1-44, C and D)
Measure: Through the central ray.
kVp: 55 (50 to 60).
Film Size: 8 × 10 inches (18 × 24 cm), horizontal orientation. Divide in half; the other half is for the lateral
projection.
Grid: No.
TFD: 40 inches (102 cm); must correct TFD to 33 inches
(84 cm) for tube tilt.
Tube Tilt: 35–40° cephalad.
2. Bone: The body of the calcaneus and posterior tuberosity are seen in profile. Both the medial and lateral cortices need to be carefully followed to identify often
subtle cortical offset of fractures. Normally the calcaneus is 30–35 mm in width, a measurement that
commonly increases with fractures. (3) The posterior
surface of the calcaneus is smooth but often lacks a distinct cortex. The sustentaculum tali is a broad shelf-like
projection from the anteromedial calcaneus that supports the facet for the medial subtalar joint and houses
the tendon of the flexor hallucis longus inferiorly. It is
readily identifiable and can fracture, often with displacement. Scrutinize the triangular base of the fifth
metatarsal, as this is also a common site of fracture.
3. Cartilage: The posterior subtalar joint is seen transverse
to the plane of the calcaneus on the fibular side of the
calcaneus. The medial subtalar joint is on the tibial side
of the calcaneus, anterior to the sustentaculum tali.
4. Soft tissue: The skin line is closely opposed to the contour of the calcaneus. Irregularity of the posterior calcaneal surface is often seen as a result of calcification
in the insertion of the Achilles tendon.
Patient Position: Supine with legs extended. (Fig. 1-44A)
Part Position: Foot is dorsiflexed such that the plantar
surface is perpendicular to the film.
CR: Enters 2 inches up from the back of the heel. (Fig. 144B)
Collimation: To the size of the calcaneus, approximately
5 × 5 inches.
Side Marker: In the corner of the film.
Breathing Instructions: Suspended expiration.
130
Specialized Projections:
1. Axial dorsoplantar: Taken with the patient prone and
the film perpendicular to the table on the plantar surface of the foot. The tube is angled caudad 40°.
2. Harris-Beath views: Essentially the same as the routine
plantar-dorsal, except it is exposed using a higher kVp
technique to demonstrate the subtalar joints; it may
require multiple views with 5° increments in tube
angulation. (2)
BASIC: *Axial, Lateral
3. Weight-bearing coalition view: The patient stands on
the film with the knee slightly flexed and the foot
minimally dorsiflexed. The tube is tilted toward the
foot at 45°.
4. Subtalar joint views: The joint is made up of anterior
and posterior compartments that require multiple
views for demonstration. (a) Anterior and posterior
joints combined (sinus tarsi view): the foot is overrotated anteriorly from the lateral position, elevating
the heel by 3–4 cm. The CR enters at the ankle joint,
with a double tube angulation of 5° anteriorly and 23°
distally. Both anterior and posterior joints are demonstrated, separated by the circular sinus tarsi. (b)
Posterior joint view (Broden’s method): with the foot
dorsiflexed and supported by a looped strap held by
the patient, the ankle is rotated medially by 45°. Four
views are obtained at 10° increments, beginning at
10° cephalad through to 40°. The CR enters 2–3 cm
below and anterior to the lateral malleolus. (4) (c)
Anterior joint view: from the medial oblique position
of the foot, rotate it to 45° oblique; with a straight
tube place the CR 2 cm anterior and distal to the lateral malleolus. (5)
Normal Anatomy (Figure 1-44, C and D)
1.
2.
3.
4.
5.
6.
Calcaneus.
Medial process, calcaneus.
Tuberosity, calcaneus.
Lateral process, calcaneus.
Sustentaculum tali, calcaneus.
Trochlear process, calcaneus.
Figure 1-44 C. Axial, Calcaneus.
D. Anatomic Specimen, Calcaneus.
Clinicoradiologic Correlations (Figure 1-44E )
Figure 1-44 E. Axial, Calcaneus, Osteomyelitis
(Brodie’s Abscess). The localized area of bone
destruction in the posterior calcaneus, which
contains an isolated bone fragment (sequestrum; arrow) is shown to advantage.
131
CALCANEUS: Lateral Projection
Positioning (Figure 1-45A)
Figure 1-45 LATERAL, CALCANEUS. A. Patient Position,
Collimation, and Central Ray.
Demonstrates: Calcaneus, talus, subtalar joints, and
Achilles tendon. (1,2) (Fig. 1-45, B and C)
Measure: At the CR.
kVp: 55 (50 to 60).
Film Size: 8 × 10 inches (18 × 24 cm). Divide in half; the
other half is for the axial projection.
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Lateral recumbent. (Fig. 1-45A)
Part Position: The unaffected leg is crossed over and
anterior for patient stability. The lateral side of the foot
contacts the film, with the plantar surface perpendicular
to the film.
CR: Mid-calcaneus; 1.5 inches up from the plantar surface of the heel and 2 inches from the posterior surface
of the heel.
132
Collimation: To the calcaneus size (5 × 5 inches).
Side Marker: In the corner of the film.
Breathing Instructions: Suspended expiration.
Clinicoradiologic Correlations: The calcaneus and its
articulations are seen optimally in this projection.
1. Alignment: Boehler’s angle should be carefully
measured.
2. Bone: All bones and their components should be
identified.
3. Cartilage: The tibiotalar, talocalcaneal (subtalar), talonavicular, and calcaneocuboid joints should be isolated;
their joint spaces defined; and their smooth surfaces
noted. The subtalar joint is usually partially obscured in
its midportion.
4. Soft tissue: The pre-Achilles fat-pad and heel pad can
be identified.
BASIC: Axial, *Lateral
Normal Anatomy (Figure 1-45, B and C )
Figure 1-45 B. Lateral, Calcaneus. C. Anatomic Specimen, Calcaneus.
1.
2.
3.
4.
5.
6.
7.
Tibia.
Dome of the talus.
Body of the talus.
Head of the talus.
Navicular.
Cuneiforms (superimposed on each other).
Cuboid.
8.
9.
10.
11.
12.
13.
14.
Anterior tuberosity of the calcaneus.
Subtalar joint.
Posterior tuberosity of the calcaneus.
Calcaneus.
Posterior surface of the calcaneus.
Calcaneocuboid joint.
Neck of the talus.
133
OPTIONAL: Transaxial, Lateral scapula
SHOULDER: AP Internal
Rotation Projection
Positioning (Figure 1-46A)
Figure 1-46 AP INTERNAL ROTATION, SHOULDER.
A. Patient Position, Collimation, and Central Ray.
Demonstrates: Proximal humerus, scapula, clavicle, rib
cage, and lung. (1–6) (Fig. 1-46, B and C)
Side Marker: In the corner of the film, above the
humeral head.
Measure: Between the coracoid process and scapula.
Breathing Instructions: Suspended expiration.
kVp: 75 (70 to 80).
Common Pitfalls:
Film Size: 10 × 12 inches (24 × 30 cm), vertical orientation.
1. Obscured glenohumeral joint space: The plane of the
glenohumeral joint is approximately 45°, and to clearly
see the joint the trunk must be rotated this amount
(Grashey’s view).
Grid: Yes.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Upright or supine. (Fig. 1-46A)
Part Position: The patient is rotated to be at 30° to the
bucky. The coracoid is centered to the bucky and the
arm internally rotated until the elbow epicondyles are
perpendicular to the film.
CR: To the coracoid process.
Collimation: To film size.
134
2. Insufficient internal humeral rotation: A comfortable
positioning alternative for the patient with an acute
shoulder is to allow 90° of elbow flexion and then
rest the forearm against the abdomen.
3. Tennis racquet appearance: Superimposition of the
humeral head on the metaphysis in this position creates
the impression of the presence of a cyst in the humeral
head (pseudocyst, tennis racquet appearance). If this
artifact persists on external rotation it may be a sign of
posterior humeral dislocation. The greater tuberosity
often appears decreased in density, because it is a thin
structure with a fine cortex. (7)
BASIC: *Internal rotation, External rotation, Abduction (baby arm)
4. Uneven exposure: Overexposure of the acromioclavicular joint, distal clavicle, acromion, and greater tuberosity is common; specific exposure factors to show these
will have to be selected, unless a filter is employed.
Clinicoradiologic Correlations: With internal rotation,
the greater tuberosity is seen en face and the posterior
surface of the humeral shaft comes into profile (Fig. 1-46,
D and E )
1. Alignment: Assess the position of the humeral head
relative to the glenoid fossa by tracing the smooth
transition from the medial humerus across the glenoid
fossa to the axillary border of the scapula, creating
a smooth continuous arc (Maloney’s arch, scapulohumeral arch). Additional landmarks are the distance
between the undersurface of the acromion and the
opposing humeral head (acromiohumeral space, normally 10 mm) and glenohumeral joint space. The alignment of the acromion with the distal clavicle across
the acromioclavicular joint is normally without displacement or separation.
2. Bone: Specifically outline the greater and lesser tuberosities. The distal clavicle, scapula, and upper ribs are also
visible.
3. Cartilage: The joint space of the glenohumeral articulation may not be clearly seen, but the opposing articular cortices can usually be discerned. The acromioclavicular joint also may not be clearly displayed, but
both the surfaces should be smooth and congruous.
4. Soft tissue: A curvilinear fat line representing two layers
of fat surrounding the subdeltoid bursa can often be
seen arcing over the lateral humeral head and beneath
the acromion process; it is referred to as the subdeltoid
bursal fat line. Carefully look around the greater
tuberosity for evidence of abnormal soft tissue calcification. Screen the lung fields for any masses (Pancoast
tumor), pleural thickening, or pneumothorax.
Specialized Projections: There is no general consensus
as to what constitutes a shoulder series. A bare minimum
should include AP with internal and external rotations.
Supplemental views are employed in addition to these for
use in specific clinical situations; at least 15 radiographic
projections of the shoulder have been described.
1. Grashey’s view (glenoid cavity view): The body is rotated 45° toward the affected side, with the CR at
the coracoid process. The glenoid joint cavity is seen
clearly along with a tangential depiction of the articular surfaces. It can be performed in internal and external rotation.
2. Apical oblique: The body is rotated 45° degrees, as
for the Grashey view, and the tube is angled caudally 45°. (8) This view is useful for demonstrating
fractures of the glenoid rim, dislocation, and impaction fractures of the humeral head (Hill-Sachs
defect). (7,8)
3. Subacromial impingement view: An AP view with 30°
caudad tube angulation and no body rotation will
allow depiction of the undersurface of the acromion
for spurs and abnormal shape variations, as a factor
in impingement of the supraspinatus tendon. (9)
135
SHOULDER: AP Internal
Rotation Projection
OPTIONAL: Transaxial, Lateral scapula
Normal Anatomy (Figure 1-46, B and C )
Figure 1-46 B. AP Internal Rotation, Shoulder. C. Anatomic Specimen, Humerus.
1.
2.
3.
4.
5.
136
Coracoid process, scapula.
Acromion, scapula.
Glenoid fossa.
Axillary border, scapula.
Subscapular fossa.
6.
7.
8.
9.
Lesser tuberosity, humerus.
Greater tuberosity, humerus.
Humeral head.
Pectoralis groove.
BASIC: *Internal rotation, External rotation, Abduction (baby arm)
Clinicoradiologic Correlations (Figure 1-46, D and E)
Figure 1-46 D. Internal Rotation, Shoulder, Osteochondroma. The internal rotation has profiled a posteriorly
placed humeral shaft osteochondroma, which was virtually indiscernible on the external rotation view. E. Internal
Rotation, Shoulder, Paget’s Disease. The bone density is increased, and the cortex is thickened. There is a transverse pathologic fracture in the midshaft.
137
OPTIONAL: Transaxial, Lateral scapula
Positioning (Figure 1-47A)
SHOULDER: AP External
Rotation Projection
Common Pitfalls:
1. Obscured glenohumeral joint space: The plane of the
glenohumeral joint is approximately 45°, and to clearly
see the joint the trunk must be rotated this amount
(Grashey’s view).
2. Insufficient external humeral rotation: Failure to
achieve maximum external rotation will impair visualization, especially of the greater tuberosity, its pathology, and adjacent soft tissue changes. Greater external rotation may be induced by allowing 90° of elbow
flexion, with the patient maximally externally rotating
the forearm.
3. Uneven exposure: Overexposure of the acromioclavicular joint, distal clavicle, acromion, and greater
tuberosity is common, and specific exposure factors
to show these will have to be selected unless a filter
is employed.
Clinicoradiologic Correlations: This is an especially useful view for demonstrating calcific tendinitis of the supraspinatus and fractures of the greater tuberosity. (10)
Figure 1-47 AP EXTERNAL ROTATION, SHOULDER.
A. Patient Position, Collimation, and Central Ray.
Demonstrates: Proximal humerus (especially the greater
tuberosity), scapula, clavicle, rib cage, and lung. (1–6) (Fig.
1-47, B–D)
Measure: Between the coracoid process and the scapula.
kVp: 75 (70 to 80).
Film size: 10 × 12 (24 × 30 cm), vertical orientation.
Grid: Yes.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Upright or supine. (Fig. 1-47A)
Part Position: The patient is rotated to 30° to the bucky.
The coracoid is centered to the bucky, and the arm externally rotated until the elbow epicondyles are parallel to
the film.
CR: To the coracoid process.
Collimation: To film size.
Side Marker: In the corner of the film, above the humeral
head.
Breathing Instructions: Suspended expiration.
138
1. Alignment: Elevation of the humerus within the glenoid fossa is a sign of rotator cuff tendon tear.
Normally there is a smooth transition from the medial
humerus across the glenoid fossa to the axillary border
of the scapula, which creates a smooth continuous arc
(Maloney’s arch, scapulohumeral arch). Additional
landmarks are the distance between the undersurface of the acromion and the opposing humeral
head (acromiohumeral space, normally 10 mm) and
glenohumeral joint space (4–6 mm). The distal clavicle is aligned with the acromion process at the
acromioclavicular joint.
2. Bone: The greater tuberosity is shown in profile as a
sharply angular bony shelf. The lesser tuberosity lies
immediately medially with the intertubercular groove
interposed between them. The global density of the
humeral head, neck, and tuberosities is reduced relative to the humeral shaft. Frequently, a remnant of the
humeral growth plate (physeal scar) is visible at the
anatomic neck as an oblique radio-opaque line extending up from the medial humeral head. The surgical neck lies inferior to the tuberosities, where the constricting zone of metaphyseal–diaphyseal transition occurs. The scapula landmarks of the glenoid fossa, coracoid, acromion process, and scapular spine can be
identified, as can the distal clavicle and upper ribs.
3. Cartilage: The joint space of the glenohumeral articulation may not be clearly seen unless the thorax is
rotated to 45°, but the anterior cavity can usually be
discerned between the humeral and the scapular cortices. The acromioclavicular joint also may not be
clearly displayed, but both surfaces should be smooth
and congruous.
4. Soft tissue: A curvilinear fat line representing two layers of fat surrounding the subdeltoid bursa can often
be seen arcing over the lateral humeral head and beneath the acromion process; it is referred to as the sub-
BASIC: Internal rotation, *External rotation, Abduction
deltoid bursal fat line. Carefully look around the apex
of the greater tuberosity for evidence of abnormal
soft tissue calcification. Screen the lung fields for
any masses (Pancoast’s tumor), pleural thickening,
or pneumothorax. (Fig. 1-47C)
Specialized Projections: There is no general consensus as
to what constitutes a shoulder series. A bare minimum
should include AP with internal and external rotations.
Supplemental views are employed in addition to these for
use in specific clinical situations; at least 15 radiographic
projections of the shoulder have been described.
1. Grashey’s view (glenoid cavity view): The body is rotated 45° toward the affected side with the CR at
the coracoid process. The glenoid joint cavity is seen
clearly along with a tangential depiction of the articular surfaces. It can be performed in internal and
external rotation.
Normal Anatomy (Figure 1-47, B–E )
Figure 1-47 B. AP External Rotation, Shoulder. C. AP External Rotation, Shoulder, Lung
Carcinoma. D. Specimen Radiograph, Humerus. E. Specimen Radiograph, Scapula.
COMMENT: This case demonstrates why at least one view of the shoulder and the lung field
should be included and screened for a mass (arrows in C). (Courtesy of Robert L. Wohlert, DC,
Iowa Falls, Iowa.)
1.
2.
3.
4.
5.
6.
7.
Coracoid process, scapula.
Acromion, scapula.
Distal clavicle.
Glenoid fossa.
Spine of scapula.
Superior angle, scapula.
Vertebral border, scapula.
8.
9.
10.
11.
12.
13.
14.
Axillary border, scapula.
Inferior angle, scapula.
Posterior rib.
Anterior rib.
Acromioclavicular joint.
Glenohumeral articulation.
Humeral head.
15. Greater tuberosity, humerus.
16. Lesser tuberosity, humerus.
17. Intertubercular groove,
humerus.
18. Anatomic neck, humerus.
19. Surgical neck, humerus.
20. Shaft of the humerus.
139
OPTIONAL: Transaxial, Lateral scapula
SHOULDER: Abduction Projection
Positioning (Figure 1-48A)
2. Obscured glenohumeral joint space: The plane of the
glenohumeral joint is approximately 45°; to clearly
see the joint, the trunk must be rotated this amount
(Grashey’s view). Rotation of the thorax to achieve
this will compromise depiction of the upper thorax
and lung field.
3. Insufficient abduction: Failure to abduct the humerus
at least to 90° will not stress the rotator cuff sufficiently
to show impingement.
Clinicoradiologic Correlations: This view serves five
functions: (a) to provide an additional view of the
humerus, scapula, thoracic cage, and cervicothoracic
spine; (b) to allow dynamic assessment of the humeral
position, which may elevate and impinge the rotator cuff
beneath the acromion process (acromiohumeral distance); (c) to allow dynamic assessment of the acromioclavicular joint; (d ) to provide the best view of the
scapula, which is obscured in other views; and (e) to
demonstrate the upper lobe of the lung.
Figure 1-48 AP ABDUCTION, SHOULDER. A. Patient
Position, Collimation, and Central Ray.
Synonyms: Baby arm view, Cleopatra’s view, active abduction veiw, scapular neck view, stop sign view,
Bennett’s projection.
Demonstrates: Proximal humerus, scapula (especially the
coracoid and acromion), acromioclavicular joint, upper rib
cage, clavicle, and lung apex. (1–5)
Measure: Between the coracoid process and the posterior shoulder.
kVp: 75 (70 to 80).
Film size: 10 × 12 inches (24 × 30 cm), horizontal orientation.
Grid: Yes.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Upright or supine. (Fig. 1-48A)
Part Position: The patient’s back is flat to the bucky.
The arm is abducted to 90°, the elbow is flexed to 90°,
and the palm of the hand faces the tube.
CR: At the midclavicular line at the level of the coracoid
process.
Collimation: To film size.
Side Marker: In the corner of the film, above the
humerus.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Lung apex: Given that disease processes of the cervicothoracic spine, upper ribs, and apex of the lung may
cause shoulder pain, they should be included in at
least one view of the shoulder. By placing the cassette
horizontally this should be obtainable.
140
1. Alignment: Elevation of the humerus within the glenoid is a sign of rotator cuff tendon tear and is accentuated more in this view than in any other projection;
it is judged abnormal when the space is < 5 mm
(acromiohumeral distance). (11) The distal clavicle
and acromion should be aligned.
2. Bone: The greater and lesser tuberosities are superimposed and approximate the undersurface of the
acromion. At the scapula the glenoid rim, scapula neck,
axillary border, acromion, coracoid, and spine can all be
identified. The clavicle in this view is distinctly curved
and concave on its under surface. The upper posterior
ribs slope inferiorly and laterally; the anterior ribs are
broader and directed inferomedially.
3. Cartilage: The joint space of the glenohumeral articulation may not be clearly seen, but the anterior cavity
can usually be discerned. The acromioclavicular joint is
often seen very clearly, unless body rotation obscures it.
4. Soft tissue: Carefully look around the greater tuberosity for evidence of abnormal soft tissue calcification.
Screen the lung fields for any abnormal mass. The
lung apex should be checked bilaterally for aeration
and symmetry. Note the trachea to be midline. The
pulmonary vasculature can be seen branching in the
lung field. In cases of trauma, search for signs of
pneumothorax over the apex.
Specialized Projections: Many views have been developed to assess for different anatomic details and pathologies of the shoulder girdle complex.
1. Axillary view: With the patient seated, the arm is
abducted, the cassette placed in the axilla, and the
beam positioned to pass from superior to inferior
through the joint. This view shows the anterior and
posterior glenoid rims and the relative positions of the
humerus, coracoid, and acromion processes.
2. Westpoint view: A variant axillary view that demonstrates the glenoid margins (Bankart’s lesion) and
humeral head (Hill-Sach lesion) and assesses the po-
BASIC: Internal rotation, External rotation, *Abduction (baby arm)
sition of the humerus. The patient is in the prone
position with the head turned away; a 3-inch pad is
placed under the shoulder to slightly elevate it off
the table. With the elbow flexed, the forearm is
hung over the edge of the table and the humerus
abducted to 90°. A vertical cassette is placed against
the superior aspect of the shoulder, and the tube
angled 25° medially and 25° anteriorly, with the CR
to exit the glenoid cavity. (12)
3. Bicipital groove: The patient is supine with the
humerus externally rotated. A cassette is placed
at the superior aspect of the shoulder; the tube is
angled 15° inferior, with the CR directed at the
humeral head. (13)
4. Stryker notch: The patient is supine or erect, and the
hand is placed on the back of the head with the
elbow flexed and directed anterior; the elbow is at
least at the level of the top of the head. The CR is directed to the axilla with 10° of cephalad tube tilt. This
is a useful view for showing a postdislocation compression fracture of the humeral head (Hill-Sach lesion) and avulsions of the anterior–inferior glenoid
margin (Bankart’s lesion)
5. Trans-thoracic lateral projection (Lawrence’s method):
The patient stands in a true lateral position with the
shoulder to be radiographed flush against the bucky
and hanging down with the arm rotated so the
palm of the hand rests on the thigh. The humerus
should be brought anterior to lie projected between
the sternum and spine. The unaffected humerus is
elevated by placing the hand on their head. (14)
6. AP scapula view: The body is rotated 10–15° to the
affected side, with the arm abducted in the baby
arm position; the tube is horizontal with the CR 2–3
inches below the coracoid process.
7. Lateral scapula (Y) view: The patient faces the bucky,
and the torso is rotated to 60° (anterior oblique); the
CR is directed to the vertebral border of the scapula.
The scapula on the film is depicted as the letter Y,
with the upper limbs formed by the coracoid and the
acromion and the stem formed by the body of the
scapula. It is important to note that the normal
humeral head lies at the projected intersection of both
upper and lower limbs. (15) The scapulothoracic joint,
subscapular surface, and ribs can be assessed.
8. Coracoid process view: The patient is supine or erect;
the CR is directed to the coracoid process, with the
tube angled 15–45°, though 30° is optimum. (16)
9. Outlet (tunnel) views: The patient faces the bucky
and the body is rotated 30–45° (anterior oblique).
The tube is angled inferiorly 10°, with the CR directed
to the superior angle of the scapula. This view demonstrates the coracoclavicular space where the supraspinatus exits, the undersurface of the acromion (to
assess for spurs), and the acromiohumeral joint space,
all important factors for demonstrating rotator cuff
impingement.
10. Scapula notch view: The suprascapular notch is where
the suprascapular nerve passes through and may
be compressed by fractures or other abnormalities.
The notch is demonstrated by 40° body rotation and
20° cranial tube tilt.
Normal Anatomy (Figure 1-48B )
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
Coracoid process, scapula.
Acromion, scapula.
Distal clavicle.
Superior angle, scapula.
Spine of scapula.
Glenoid fossa.
Greater and lesser tuberosities
(superimposed).
Intertubercular groove, humerus.
Surgical neck, humerus.
Shaft, humerus.
Posterior fifth rib.
Anterior first rib.
Axillary border, scapula.
Acromioclavicular joint.
Coronoid tubercle, clavicle.
Transverse process, T1.
Figure 1-48 B. Abduction (Baby Arm), Shoulder.
141
CLAVICLE: PA Projection
Positioning (Figure 1-49, A and B)
Figure 1-49 PA CLAVICLE. A. Patient Position. B. Collimation
and Central Ray.
Demonstrates: Clavicle, upper ribs, scapula, and lung.
(1–3) (Fig. 1-49, C and D)
Measure: At coracoid process.
kVp: 70 (65 to 75).
Film Size: 10 × 12 inches (24 × 30 cm), horizontal orientation.
Grid: Yes.
TFD: 38 inches (100 cm); corrected TFD for tube tilt.
Tube Tilt: (a) PA: 10° caudad. (b) AP: 10° cephalad.
Patient Position: Upright. (Fig. 1-49A)
Part Position: (a) PA: facing the bucky, with no body rotation, the head is turned away from the side being evaluated. The midpoint of the clavicle is centered to the
midline of the bucky. (b) AP: Facing the tube, with no
body rotation. The midpoint of the clavicle is centered to
the midline of the bucky.
CR: (a) PA: Through the midclavicle and 1 inch above the
level of the clavicle at the patient’s back. (b) AP: Through
the midclavicle. (Fig. 1-49B)
Collimation: Top to bottom, 8 inches; side to side, 12
inches.
142
Side Marker: Above the humeral head.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Overexposure of the distal clavicle: In many muscular
patients, because they are thicker through the coracoid
region, overexposure of the distal clavicle is common
and may require a specific view with mAs reduced by
at least 25–50%.
2. Clipped medial clavicle: The entire length of the clavicle
including the sternoclavicular joint should be displayed.
Clinicoradiologic Correlations: The PA projection is
preferred over the AP view for anatomic detail and in
kyphotic patients.
1. Alignment: Observe the position of the clavicle with
the acromion (acromioclavicular joint) and sternum
(sternoclavicular joint), as well as the acromiohumeral
and coracoclavicular spaces.
2. Bone: The clavicle is broader medially than laterally and
is curved in shape. Adjacent to the coracoid process,
the undersurface of the clavicle is often irregular at the
site of the coracoclavicular ligament insertion. The distal 1–2 inches of the clavicle are more radiolucent and
BASIC: AP (cephalad angulation), *PA (caudad angulation)
have a thin cortex. Details of the scapula can be
identified, including the acromion, coracoid, spine,
glenoid, superior and inferior angles, and vertebral
and axillary borders. The humeral head, surgical
neck, and proximal shaft are visible, though the
tuberosities may be obscured. The upper ribs from the
costovertebral joints to the costochondral junctions are
depicted.
3. Cartilage: The sternoclavicular, acromioclavicular,
glenohumeral, and costal joints can all be identified.
4. Soft tissue: Note the skin line of the trapezius muscle.
A thin, soft tissue line parallel to the superior surface
of the clavicle is usually visible (companion shadow).
The adjacent lung field, including the pleura, bronchovascular markings, upper lobe parenchyma, aorta, trachea, and upper mediastinum should always be identified. The lung apex should be checked bilaterally for
aeration and symmetry. In cases of trauma, search the
apex for signs of pneumothorax.
Specialized Projections:
1. AP axial view: The standing patient can be placed
leaning back on the bucky in an AP lordotic position,
with the tube angled 15–25° cephalad. Alternatively,
the patient is in the supine position and a tangential
view can be obtained by angling the tube 15–25°
cephalad. These views are especially useful for detecting undisplaced clavicular fractures.
2. Apical oblique view: The patient is placed AP and
rotated away 45° (posterior oblique), with the affected side against the bucky; the tube is angled 20°
cephalad. This view is well suited to the detection of
undisplaced fractures of the clavicle in neonates and
children.
Normal Anatomy
(Figure 1-49, C and D)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Coracoid process, scapula.
Acromion, scapula.
Distal clavicle.
Superior angle, scapula.
Superior border, scapula.
Axillary border, scapula.
Medial clavicle.
Sternoclavicular joint.
Rhomboid fossa; clavicle.
Midportion, clavicle.
Glenoid fossa.
Posterior third rib.
Anterior second rib.
Humeral head.
Shaft of the humerus.
Figure 1-49 C. PA Clavicle. D. Specimen Radiograph, Clavicle.
143
ACROMIOCLAVICULAR JOINT: AP Projection
Positioning (Figure 1-50, A and B)
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Body rotation: The joint space will not be accurately
demonstrated.
2. Film identification: If weights are applied the film
should be marked “with weights” or similar. Care
should be taken not to place markers over the joint
or bony structure.
Clinicoradiologic Correlations: Numerous disorders
affect the distal clavicle and acromioclavicular joints and
this specific view is necessary for their diagnosis. (Fig. 150, D and E) The purpose of comparing non-weightbearing and weight-bearing views is to attempt to assess
the integrity of the acromioclavicular and costoclavicular
ligaments. (5–6)
Figure 1-50 AP ACROMIOCLAVICULAR JOINT. A. Patient
Position. B. Collimation and Central Ray.
Demonstrates: Distal clavicle and acromioclavicular
joint. (1–3) (Fig. 1-50C)
Measure: At the coracoid process; use half the mAs, as
calculated from the shoulder exposure factors.
kVp: 70 (65 to 75).
Film Size: 8 × 10 inches (18 × 24 cm), horizontal orientation.
Grid: Yes.
TFD: 38 inches (100 cm); corrected TFD for tube tilt.
Tube Tilt: 5° cephalad.
Patient Position: Upright. (Fig. 1-50A)
Part Position: AP position, with no body rotation and
the acromioclavicular joint centered to the bucky. The
same position is done with and without the patient holding 10- to 15-lb weights. (4) Slight external rotation of
the humerus is suggested to show the greater tuberosity, which is commonly fractured with acromioclavicular
joint trauma and may mimic pain at this joint.
CR: Through the acromioclavicular joint. (Fig. 1-50B)
Collimation: To the film.
Side Marker: In an upper corner of the film, above the
humeral head.
144
1. Alignment: There should be a smooth transition
across the acromioclavicular joint, with the distal clavicle aligned with the acromion.
2. Bone: The distal 1–2 inches of the clavicle are more
radiolucent with a thin cortex. The distal third is normally curved in contour, which is reduced with the
cephalad tube tilt. The clavicular articular cortex is
thin and smooth, and the adjacent acromial articular
surface is often thicker and more prominent. The distal clavicular surface is often noticeably concave. (5)
The acromion is variable in shape: flat (17%), curved
(43%), and hooked (40%). (7)
3. Cartilage: The acromioclavicular joint space is variable
in depth, sometimes being capacious in young patients. On weight bearing the joint frequently widens
up to 2 mm as a variant of normal. Comparison with
the asymptomatic side should be performed with
l < 2 mm right to left difference in normal patients.
4. Soft tissue: The skin line over the distal clavicle and
acromioclavicular joint (companion shadow) should
be smooth without any bulge. The lung apex should
be checked bilaterally for aeration and symmetry. In
cases of trauma, search for signs of pneumothorax
over the apex.
Specialized Projections:
1. Bilateral simultaneous anteroposterior comparison
views: Single exposure of both joints can be obtained
with a 7 × 17 inch (18 × 43 cm) film, horizontally orientated. The view is discouraged, unless appropriate
shielding of the thyroid is used.
BASIC: *Without weights, *With weights
Normal Anatomy (Figure 1-50C )
Figure 1-50 C. AP Acromioclavicular Joint.
1.
2.
3.
4.
Coracoid process, scapula.
Acromion, scapula.
Distal clavicle.
Superior angle, scapula.
5. Superior border, scapula.
6. Acromioclavicular joint.
7. Humeral head.
Clinicoradiologic Correlations (Figure 1-50, D and E)
Figure 1-50 D. AP Acromioclavicular Joint, Post-Traumatic Osteolysis of the Clavicle. The articular cortex is irregular
with resorption of the distal bone matrix (arrow). E. AP Acromioclavicular Joint, Subluxation. There is elevation of
the distal clavicle relative to the acromion process (arrow) with slight widening of the joint space.
145
ELBOW: AP Projection
Positioning (Figure 1-51, A and B)
Figure 1-51 AP ELBOW. A. Patient Position.
B. Collimation and Central Ray.
Demonstrates: Distal humerus, proximal ulna, proximal
radius, and elbow joint. (1–3) (Fig. 1-51, C and D)
Side Marker: Adjacent to the humerus at the edge of
the film.
Measure: AP through the elbow at the epicondyles.
Breathing Instructions: Suspended expiration.
kVp: 55 (50 to 60).
Common Pitfalls:
Film Size: 10 × 12 inches (24 × 30 cm), horizontal orientation. Divide in half; the other half is for the medial
oblique projection (cover with lead vinyl).
1. Incomplete supination: There will be overlap of the
radius and ulna and some obscuring of the elbow
joint space.
Grid: No.
2. Incomplete extension: The radial head and neck and
the elbow joint space will not be clearly defined and
are often underexposed if the anterior brachial muscles enter the exposure field.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Seated, with body rotated away from
the table. Apply a lead half apron for gonad protection.
(Fig. 1-51A)
Part Position: Arm fully extended, and the hand supinated. If the elbow cannot be extended, two APs are
done, one with the forearm on the film and the second
with the humerus on the film.
CR: To the elbow, between and 1 inch below the level
of the epicondyles. (Fig. 1-51B)
Collimation: To the arm.
146
3. Scatter control: Lead vinyl must be applied to the half
of the film not being exposed. Lead vinyl should be
placed beneath the cassette to reduce primary and
secondary radiation to the patient.
Clinicoradiologic Correlations: Because of the complexity of the joint and often subtle nature of many fractures,
multiple views—preferably all four—should be obtained.
This view is especially suited to disorders of the radial
head, distal humerus, and joint space. (Fig. 1-51, E and F)
1. Alignment: The axial relationships of the humerus
to the ulna (carrying angle) should be assessed. Note
BASIC: *AP, Medial oblique, Lateral, Tangential
that the radial head is aligned with the capitellum
and that the olecranon lies within the olecranon fossa
of the humerus.
2. Bone: The distal humerus at the cortical surfaces of
the metaphysis (supracondylar ridges) is often indistinct and not to be interpreted as a sign of disease.
Within the medullary cavity the trabeculae are thick
and form a V-shaped configuration (herring bone or
chevron sign). The medial epicondyle is the largest
projection from the humerus (the origin of the common flexor tendon); the lateral epicondyle (the origin
of the common extensor tendon) is smaller and less
distinct at the cortex. The olecranon fossa is superimposed over the ventrally sited coronoid fossa, which
is visible as a distinctive triangular lucency. The olecranon process overlaps the reciprocating fossa as a
trapezoid opacity before expanding as the coronoid
process. The radial head is the expanded oval structure, and the concave joint surface is congruent with
the opposing capitellum. The radial neck constricts
with smooth concave cortices just proximal to the eccentrically located radial tuberosity, which commonly
overlaps the adjacent ulna.
3. Cartilage: The elbow is considered as having three
joints all contained within a single synovial-lined cavity: (a) Radiohumeral joint: lies laterally between the
rounded capitellum and concave surface of the radial
head and gives the capacity for multidirectional movements, including rotation. (b) Ulnohumeral joint: the
principal joint, acting as the ginglymus or hinge joint
that allows flexion and extension. It is contiguous
medially between the angular trochlea and the reciprocating sigmoid notch of the ulna. Between the
capitellum and the trochlea is a depression called
the capitellotrochlear sulcus; the central sulcus
within the trochlea is called the trochlear groove. The
combined medial and lateral compartments should
exhibit the same depth of joint space. (c) Proximal
radioulnar joint: lies between the radial head and the
proximal adjacent ulna.
4. Soft tissue: Muscle bellies of the biceps and brachialis
make up the soft tissue of the brachium, and the extensor and flexors of the antebrachium can be discerned to cross the elbow.
Specialized Projections:
1. Forearm views: With the palm supinated and the
wrist and elbow extended, an AP view is obtained to
include the elbow and wrist. For the lateral projection
the elbow is flexed to 90° with the thumb side up.
2. Humerus views: AP and lateral views are obtained
when study of the full length of the humerus is required. For the AP view the arm is slightly abducted
with the forearm supinated. For the lateral view the
elbow is flexed, the arm slightly abducted, and the
hand placed over the iliac fossa.
147
ELBOW: AP Projection
Normal Anatomy (Figure 1-51, C and D )
Figure 1-51 C. Radiograph, Anteroposterior Elbow. D. Specimen Radiograph, Elbow.
1.
2.
3.
4.
5.
6.
7.
148
Shaft of the humerus.
Olecranon fossa, ulna.
Medial epicondyle, humerus.
Lateral epicondyle, humerus.
Capitellum, humerus.
Trochlea, humerus.
Supracondylar ridge, humerus.
8.
9.
10.
11.
12.
13.
14.
Radial head.
Neck of the radius.
Radial tuberosity.
Shaft of the radius.
Coronoid process, ulna.
Ulna.
Olecranon process, ulna.
BASIC: *AP, Medial oblique, Lateral, Tangential
Clinicoradiologic Correlations (Figure 1-51, E and F )
Figure 1-51 E. AP Elbow, Fracture of the Radial Head. A linear fracture line is visible extending from the articular
surface distally (arrow). F. AP Elbow, Giant Cell Tumor of the Radius. Within the radial head and extending into
the radial neck is a loss of bone density, bone expansion, and thinning of the cortex caused by a slowly growing
tumor.
149
OPTIONAL: Radial head
ELBOW: Medial Oblique Projection
Positioning (Figure 1-52, A and B )
CR: 1 inch below the epicondyles. (Fig. 1-52B)
Collimation: To the arm.
Side Marker: Adjacent to the humerus at the edge of
the film.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Under-rotation: If the coronoid process is not projected free of overlap with the radius, the obliquity is
< 45°.
2. Scatter control: Lead vinyl must be applied to the half
of the film not being exposed. Lead vinyl should be
placed beneath the cassette to reduce primary and
secondary radiation to the patient.
Clinicoradiologic Correlations: The elbow is projected
in a different plane, which is especially useful for depicting the tip of the coronoid and olecranon processes of
the ulna, trochlea, coronoid process, and medial epicondyle. (Fig. 1-52D)
1. Alignment: The radial head is aligned with the capitellum and the olecranon lies within the olecranon fossa
of the humerus.
Figure 1-52 MEDIAL OBLIQUE, ELBOW. A. Patient
Position. B. Collimation and Central Ray.
Synonyms: AP Internal Oblique.
Demonstrates: Distal humerus, proximal ulna, proximal
radius, and elbow joint. (1–3) (Fig. 1-52C)
Measure: At the CR.
kVp: 55 (50 to 60).
2. Bone: Close scrutiny of the ulnar-placed structures—
including the medial supracondylar ridge, medial epicondyle, olecranon, trochlea, and coronoid process—
needs to be performed, because abnormalities of
these may be displayed only in this position.
3. Cartilage: The olecranon process should lie closely
within the fossa. The fossa needs to be closely examined for the presence of calcified loose bodies. The
ulnohumeral joint space is shown clearly as a sharp
indentation of the trochlea sulcus and the articulating
sigmoid notch of the ulna.
Grid: No.
4. Soft tissue: The origin of the common flexor tendon,
from the medial epicondyle, is determined by the appearance of the increasing soft tissue density and bulk
inferior to the structure. At the lateral epicondyle, the
common extensor tendon margin can usually be seen
with a clear subcutaneous fat–muscle interface.
TFD: 40 inches (102 cm).
Specialized Projections:
Tube Tilt: None.
1. Lateral oblique view: From the true AP position the
extended elbow is rotated externally by 45°, with the
movement occurring at the shoulder. The view optimizes visualization of the radially sited structures, including the lateral supracondylar ridge, lateral epicondyle, radiohumeral joint, and lateral margin of the
radial head.
Film Size: 10 × 12 inches (24 × 30 cm), horizontal orientation. Divide in half; the other half is for the AP projection (cover with lead vinyl).
Patient Position: Seated, with body rotated away from
the table. Apply a lead half apron for gonad protection.
(Fig. 1-52A)
Part Position: Arm fully extended and the forearm
pronated.
150
BASIC: AP, *Medial oblique, Lateral, Tangential
Normal Anatomy (Figure 1-52C )
Clinicoradiologic Correlations
(Figure 1-52D )
Figure 1-52 C. Medial Oblique, Elbow.
1.
2.
3.
4.
5.
6.
7.
8.
Shaft of the humerus.
Olecranon fossa, humerus.
Medial epicondyle, humerus.
Lateral epicondyle, humerus.
Supracondylar ridge.
Olecranon process, ulna.
Coronoid process, ulna.
Radial head.
Figure 1-52 D. Medial Oblique, Elbow, Fracture of the
Radial Neck. A subtle non-displaced fracture is present
through the cortex of the radial neck (arrow). This fracture was not visible on other views, underscoring the
importance of performing all views.
151
ELBOW: Lateral Projection
OPTIONAL: Radial head
Positioning (Figure 1-53A)
Figure 1-53 LATERAL VIEW, ELBOW. A. Patient
Position, Collimation, and Central Ray.
Demonstrates: Distal humerus, proximal ulna, proximal
radius, and elbow joint. (1–3) (Fig. 1-53, B and C)
Side Marker: In the corner of the film, adjacent to the
olecranon.
Measure: At the CR.
Breathing Instructions: Suspended expiration.
kVp: 55 (50 to 60).
Common Pitfalls:
Film Size: 10 × 12 inches (24 × 30 cm), horizontal orientation. Divide in half; the other half is used for the tangential projection (cover with lead vinyl).
1. Humerus elevation: Failure to place the humerus flat
and in plane with the film will obscure the joint and
distort the bony structures. Humeral rotation will particularly project the large medial epicondyle across
the joint or posteriorly.
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Seated, with the body rotated away
from the table. Apply a lead half apron for gonad protection. (Fig. 1-53A)
Part Position: Elbow flexed to 90°, with the ulnar surface of the forearm flat on the film. The hand is in the
true lateral position. The humerus must also be parallel
to the film plane, with the shoulder abducted to 90°.
2. Forearm rotation: The ulna will not be seen in true
lateral and may obscure fractures and even dislocations of the olecranon. Stabilization with a sandbag
helps maintain the position.
3. Scatter control: Lead vinyl must be applied to the half
of the film not being exposed. Lead vinyl should be
placed beneath the cassette to reduce primary and
secondary radiation to the patient.
CR: Mid-elbow joint, just anterior to the lateral epicondyle.
Clinicoradiologic Correlations: This is a useful view for
evaluating the post-traumatic elbow for fracture. It is this
view that will demonstrate joint effusion, which is often
a marker for subtle fracture or effusions.
Collimation: To the arm, 10 inches along the forearm
axis and 6 inches top to bottom.
1. Alignment: The plane of the radius passes through the
middle of the capitellum (radiocapitellar line). Note that
152
BASIC: AP, Medial oblique, *Lateral, Tangential
the humeral condyles are slightly angled forward in
relation to the plane of the humeral shaft. In children
a line parallel and contacting the anterior humerus
should intersect the middle third of the capitellum
(anterior humeral line).
2. Bone: The distal humerus exhibits an X configuration,
formed by a confluence of cortices of the olecranon
and coronoid fossae. The olecranon process hooks
posteriorly behind the humerus; the coronoid process
curves anteriorly. The radial head cortex is distinctly
concave, and the ventral surface of the radial neck lies
in profile.
the humeral surfaces (positive fat-pad sign). (4) (Fig.
1-52D) In trauma, up to 90% of positive fat-pad cases
have an intra-articular fracture, most commonly of the
radial head. The normal thin radiolucent supinator fat
line can be identified close and parallel to the head
and neck of the radius, which when fractured will invariably obliterate the fat, because of edema, or displace it ventrally. (5)
Specialized Projections:
3. Cartilage: The radiohumeral and humeroulnar articulations are superimposed, but their surfaces are usually congruous across the respective compartments
and may be able to be recognized. The joint space
between the olecranon and trochlea is usually visible.
1. Radial head capitellum view: With the elbow flexed
to 90° and in the true lateral position, the tube is angled 45° toward the radial head. (6) This provides a
magnified view of the radial head, which is projected
clear of the ulna and humerus and is useful in the detection of a joint effusion and fractures of the radial
head, coronoid process, and capitulum.
4. Soft tissue: Anterior and posterior to the distal humeral
surfaces are pericapsular fat layers interposed between
the joint synovium and fibrous joint capsule (fatpads). Normally they are imperceptible, though the
anterior fat-pad can occasionally be just visible. If displaced away from the humerus because of joint distension (blood, effusion, pus) they will be visible on
the lateral view as triangular radiolucencies close to
2. Radial head views: Multiple views in various degrees
of rotation can be used to profile the entire circumference of the radial head. Divide a 10 × 12 inch (24
× 30 cm) film into four vertical sectors and collimate
to the radial head for each view. In the lateral position the forearm is slightly supinated, then in true
lateral, then with palm down, and finally in extreme
internal rotation with the thumb down.
153
OPTIONAL: Radial head
ELBOW: Lateral Projection
Normal Anatomy (Figure 1-53, B and C )
Figure 1-53 B. Lateral, Elbow. C. Specimen Radiograph, Elbow.
1.
2.
3.
4.
5.
154
Shaft of the humerus.
Capitellum and trochlea (superimposed).
Olecranon process, ulna.
Coronoid process, ulna.
Radial head.
6.
7.
8.
9.
10.
Neck of the radius.
Radial tuberosity.
Coronoid fossa, humerus.
Olecranon fossa, humerus.
Supinator fat line (arrow).
BASIC: AP, Medial oblique, *Lateral, Tangential
Clinicoradiologic Correlations (Figure 1-53D )
Figure 1-53 D. Lateral, Elbow, Positive Fat-Pad Sign. The anterior and posterior fat-pads are
elevated away from the humeral surface as a result of joint effusion or hemarthrosis (arrows) associated with a subtle impaction fracture of the radial neck, evidenced only by a sharp, angular
change in the contour of the ventral cortex (arrowhead).
155
ELBOW: Tangential (Jones) Projection
OPTIONAL: Radial head
Positioning (Figure 1-54, A and B )
Figure 1-54 TANGENTIAL, ELBOW. A. Patient Position.
B. Collimation and Central Ray.
Synonyms: Jones view, axial view, acute flexion view,
inferior-to-superior projection.
2. Forearm rotation: The elbow joint and olecranon will
not be clearly seen.
Demonstrates: Olecranon, ulnar groove, trochlea, and
radial head. (1–3,7) (Fig. 1-54C)
3. Scatter control: Lead vinyl must be applied to the half
of the film not being exposed. Lead vinyl should be
placed beneath the cassette to reduce primary and
secondary radiation to the patient.
Measure: 2 inches above the olecranon tip.
kVp: 55 (50 to 60).
Film Size: 10 × 12 inches (24 × 30 cm), horizontal orientation. Divide in half; the other half is used for the lateral projection (cover with lead vinyl).
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Elbow is fully flexed and the humerus
is placed parallel to the film. Apply a lead half apron for
gonad protection. (Fig. 1-53A)
CR: 2 inches above the olecranon tip. (Fig. 1-53B)
Collimation: 6 × 6 inches.
Side Marker: In the corner of the film, adjacent to the
olecranon.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Incomplete elbow flexion: The olecranon and joint
space will not be clearly shown in profile.
156
Clinicoradiologic Correlations: The selective visualization of the olecranon–trochlear joint compartment is useful for detecting intra-articular loose bodies and degenerative osteophytes. (8) The ulnar groove, in which lies the
ulnar nerve, is also well seen. Lead vinyl must be placed
beneath the cassette to reduce primary and secondary
radiation to the patient.
1. Alignment: Assess the relationship of the olecranon
with the humerus.
2. Bone: The trochlea is distinctive as the angular contributor to the joint line with the opposed sigmoid
notch of the olecranon. The surface of the capitellum
is profiled to advantage, as are the epicondyles. The
radial head is often obscured.
3. Cartilage: The ulnohumeral joint cavity is of equal
depth, slightly widening laterally. Since the radius has
moved ventrally, the radiohumeral joint space does
not show on this view.
BASIC: AP, Medial oblique, Lateral, *Tangential
4. Soft tissue: The soft tissue of the common tendon
origins should be of uniform density with no calcification or cortical irregularity. “Hot lighting” the skin
line over the olecranon reveals it closely, opposed to
the olecranon process.
and after reduction, to assess axial position. Fractures
of the epicondyles and subtle tendon calcifications
can also be shown to advantage. Angling the beam
20° distally is helpful.
2. Cubital tunnel view: From the tangential position,
with the elbow fully flexed, the forearm is externally
rotated 15° to bring the cubital tunnel into profile,
where the ulnar nerve is sited. Medial trochlear lip
osteophytes and osteoarthritis of the medial trochlea–
olecranon joint, clearly shown in this view, are frequently associated with ulnar nerve compression in
the cubital tunnel. (8)
Specialized Projections:
1. Superior-to-inferior view: With the elbow flexed to
about 110° the forearm is placed on the cassette in a
supine position with the beam passing through the
distal humerus to the proximal forearm. This is often
used in cases of supracondylar fractures, both before
Normal Anatomy (Figure 1-54C )
Figure 1-54 C. Tangential, Elbow.
1.
2.
3.
4.
Olecranon process.
Trochlea.
Head of the radius.
Neck of the radius.
5.
6.
7.
8.
Tuberosity, radius.
Medial epicondyle, humerus.
Olecranon fossa.
Ulnar groove.
157
OPTIONAL: Carpal tunnel, Scaphoid, Lateral oblique (pisiform)
WRIST: PA
Projection
Positioning (Figure 1-55)
Figure 1-55 PA WRIST. A. Patient Position,
Collimation, and Central Ray.
Synonyms: Dorsal-palmar view.
Demonstrates: Carpal bones and joints, distal radius,
and ulna. (1–4) (Fig. 1-55, B and C)
Measure: PA at the level of the wrist.
kVp: 55 (50 to 60).
Film Size: 10 × 12 inches (24 × 30 cm), vertical orientation. Divide into quarters; the other quarters are used for
the other basic projections (cover with lead vinyl).
Grid: No.
Tube Tilt: None.
Patient Position: Seated. Apply lead half apron for gonad
protection. (Fig. 1-55A)
Part Position: Forearm pronated, with a loosely closed
fist and the wrist flat on the film.
CR: To the midcarpal region.
Collimation: To the wrist, approximately 6 inches.
Side Marker: In a corner of the film.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Wrist position: The third metacarpal should be aligned
with the long axis of the radius, the metacarpals
should not be overlapped, and the scapholunate space
should be clearly visible.
2. Scatter control: Lead vinyl must be applied to the three
quarters of the film not being exposed. Lead vinyl
should be placed beneath the cassette to reduce primary and secondary radiation to the patient.
3. Cassette orientation: Care must be taken not to rotate
the cassette between exposures, ensuring that all four
views remain in the same orientation.
158
Clinicoradiologic Correlations: A wrist series should include a minimum of four views—PA, PA oblique, lateral,
and PA with ulnar flexion. The PA view is especially useful for assessing fractures (Fig. 1-55, D and E ) Specialized projections should be employed for specific clinical
situations.
1. Alignment: Three arcs of alignment can be followed
within the carpus: (a) proximal surface: scaphoid–
lunate–triquetrum, (b) distal surface: scaphoid–lunate–
triquetrum, (c) proximal surface: capitate–hamate. (5)
2. Bone: All carpal bones, proximal metacarpals, and distal radius and ulna should be identified. The scaphoid
is foreshortened in this view, because it lies ventrally
tilted at its proximal end by about 20°. The distal
scaphoid tubercle can usually be identified. The trapezium articulates with the thumb (first metacarpal). The
pisiform overlaps the triquetrum. The capitate is the
largest carpal. The hook of the hamate is a distinctive
landmark, as a round corticated density over the body
of the hamate. The head of the ulna continues in alignment with the radius joint cortex (normal ulnar variance), and the ulnar styloid should not be in contact
with the triquetral bone. The ulnar styloid should be
small (1–3 mm) with a rounded distal contour and a
thin cortex.
3. Cartilage: Joint compartments are described according to location: carpometacarpal, midcarpal, radiocarpal, ulnocarpal, and distal radioulnar joints. The joint
spaces between the carpal bones are congruous at
1–2 mm. The scapholunate space should also be
1–2 mm; it commonly widens with rupture of the
scapholunate ligament, precipitating scapholunate instability, and thus should always be assessed in cases
of wrist pain. (5) The distal radioulnar joint is visible,
with a joint space also of 1–2 mm.
BASIC: *PA, PA ulnar flexion, Medial oblique, Lateral
4. Soft tissue: A fat line (navicular fat stripe) can be seen
running parallel to the scaphoid in > 90% of wrist
radiographs. (6) If absent or displaced, there usually
is an associated fracture of the scaphoid. Within the
ulnar compartment lies the triangular fibrocartilage
complex (TFC), which consists of a fibrocartilage disc
with attachments to the ulnar styloid and radius; it is
not normally visible on plain films.
Specialized Projections:
1. AP view: May be an alternative view for patients unable to extend the elbow or pronate the hand. The
intercarpal joint spaces are usually projected wider
than on the PA view and may provide improved visualization of the scapholunate joint space.
2. Flat hand technique: When the patient is unable to
make a fist, a flat hand on the cassette can be used,
which allows improved visualization of the distal carpus, carpometacarpal joints, and proximal metacarpals.
3. Closed fist view: A firmly closed fist allows closer
wrist–film contact and may accentuate any ligamentous disruption within the carpus, especially the scapholunate space. (7) The AP view is better than the
PA view for scapholunate disassociation. (8)
4. Scapholunate space view: The scapholunate space is
best depicted with 10° of tube tilt from the ulna toward the radius. (9) Fluoroscopic positioning may be
the only method for accurate placement.
5. Radiocarpal joint view: Angling the tube cephalad
25–30° will improve depiction of the radiocarpal joint.
6. Capitate view: Tilting the tube 25–30° toward the
fingers will show the capitate more clearly. Fractures
and other bony lesions of the capitate and capitate–
scaphoid arthritis are shown to advantage.
7. Carpal bridge view: With the wrist AP, maximal palmar
flexion is induced. The beam is angled 45° toward the
elbow and is tangent to the dorsal surface of the wrist.
This view is used to show abnormalities of the dorsum
of the wrist, including calcifications, foreign bodies,
ganglions, carpal bossing, and fractures of the scaphoid, lunate, and triquetral bones. (10–12)
8. Carpal tunnel view (Gaynor-Hart view): With the wrist
PA, maximal dorsiflexion is induced. The beam is
angled 25–30° toward the elbow, tangential to the
center of the palmar surface. (12,13) This view displays the tunnel-like arrangement of the trapezium,
scaphoid, capitate, hook of the hamate, triquetrum,
and pisiform. (14)
159
OPTIONAL: Carpal tunnel, Scaphoid, Lateral oblique (pisiform)
Normal Anatomy (Figure 1-55, B and C )
Figure 1-55 B. PA Wrist. C. Anatomic Specimen, Wrist.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
160
Styloid process, radius.
Metaphysis, distal radius.
Metaphysis, distal ulna.
Styloid process, ulna.
Scaphoid.
Lunate.
Triquetrum.
Pisiform.
Trapezium.
Trapezoid.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Capitate.
Hamate.
Base, fifth metacarpal.
Shaft, fourth metacarpal.
Neck, third metacarpal.
Hook of the hamate.
Radioulnar joint.
Radiocarpal joint.
Ulnocarpal joint.
Navicular fat stripe.
WRIST: PA
Projection
BASIC: *PA, PA ulnar flexion, Medial oblique, Lateral
Clinicoradiologic Correlations (Figure 1-55, D and E )
Figure 1-55 D. PA Wrist, Fracture of the Radial Styloid Process. A non-displaced fracture is seen as a radiolucent line
through the base of the styloid process of the radius (arrow). E. PA Wrist, Septic Arthritis (Tuberculosis). The definition of all articular cortices of the carpals, metacarpal bases, and distal radius has been lost. There is also narrowing
of all joint spaces and decreased bone density (osteopenia) of all involved structures, as manifestations of chronic
joint infection.
161
OPTIONAL: Carpal tunnel, Scaphoid, Lateral oblique (pisiform)
Positioning (Figure 1-56A)
WRIST: PA Ulnar
Flexion Projection
2. Scatter control: Lead vinyl must be applied to the
three quarters of the film not being exposed. Lead
vinyl should be placed beneath the cassette to reduce
primary and secondary radiation to the patient.
3. Cassette orientation: Care must be taken not to rotate the cassette between exposures, ensuring that
all four views remain in the same orientation.
Clinicoradiologic Correlations: This view enhances visualization of scaphoid and radial styloid fractures by distracting the fracture line, which may not be visible on
the neutral study. (Fig. 1-56C)
1. Alignment: Three arcs can be followed within the carpus: (a) proximal surface: scaphoid–lunate–triquetrum,
(b) distal surface: scaphoid–lunate–triquetrum,
(c) proximal surface: capitate–hamate (5). There is
radial rotation of the proximal carpal row, but the
scaphoid still maintains contact with the radius. There
may be very slight intercarpal displacements owing to
normal motion.
Figure 1-56 PA ULNAR FLEXION, WRIST. A. Patient
Position, Collimation, and Central Ray.
Synonyms: Ulnar deviation view.
Demonstrates: Carpal bones and joints, distal radius,
and ulna. (1–4) The view is especially good for assessing
the scaphoid. (15,16) (Fig. 1-56B)
Measure: PA at the level of the wrist.
kVp: 55 (50 to 60).
Film Size: 10 × 12 inches (24 × 30 cm), vertical orientation. Divide into quarters; the other quarters are used for
the other basic projections (cover with lead vinyl).
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Seated. Apply lead half apron for
gonad protection. (Fig. 1-56A)
Part Position: Forearm pronated with the wrist moved
into ulnar deviation and placed flat on the film.
CR: To the midcarpal region.
Collimation: To the wrist, approximately 6 inches.
Side Marker: In a corner of the film.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Incomplete ulnar flexion: Patients with a scaphoid
fracture tend to hold the wrist in radial flexion, which
foreshortens the scaphoid and can obscure the fracture. Maximal ulnar flexion should be induced within
the patient’s tolerance, with the third metacarpal–
radius alignment visibly angulated.
162
2. Bone: All carpal bones and proximal metacarpals and
the distal radius and ulna should be identified. Careful
scrutiny of the radial surface of the waist of the scaphoid for fracture should be performed. The scaphoid
will often appear elongated in this projection, because
it rotates into a horizontal plane parallel with the film,
showing the waist to advantage, and may distract the
fracture line to become more visible.
3. Cartilage: The joint spaces between the carpal bones
is 1–2 mm. (5) The distal radioulnar joint is visible,
with a joint space also of 1–2 mm, and is unchanged
from the neutral position. The ulnar styloid should
not contact the triquetral bone, but the pisiform may
migrate proximally 1–4 mm.
4. Soft tissue: A radiolucent fat line (navicular fat stripe)
can be seen parallel to the scaphoid in > 90% of wrist
radiographs. (6) If absent or displaced, there usually is
an associated fracture of the scaphoid.
Specialized Projections:
1. Radial deviation: The ulnar carpal bones and their intervening joints (lunate–triquetral–pisiform) are shown to
advantage. Widening of the lunate–triquetral joint
space may indicate (lunate–triquetral) interosseous
ligament disruption. Assessment of ulnar styloid fractures and their stability can be assessed.
2. Scaphoid views: Fracture of the scaphoid is the most
common fracture of the wrist and is frequently not visible on the PA view (occult fracture). It is commonly
complicated by non-union and avascular necrosis, especially if not appropriately immobilized. At least seven
specific views of the scaphoid have been described. (17)
a. Semipronated 45° oblique in ulnar deviation: From
the PA position the wrist is rotated 45°, raising
the radius off the film with maximal ulnar deviation;
no beam angulation with the CR at the scaphoid.
b. Semipronated 30° oblique: From the PA position the
wrist is rotated 30°, raising the radius off the film;
no beam angulation with the CR at the scaphoid.
BASIC: PA, *PA ulnar flexion, Medial oblique, Lateral
c. Semipronated 60° oblique: From the PA position the
wrist is rotated 60°, raising the radius off the film;
no beam angulation with the CR at the scaphoid.
d. Lateral scaphoid: From the lateral position the
wrist is extended about 10°.
e. Stecher position: The hand is placed flat onto a
cassette, which is angled 20° so that the wrist is
extended; no beam angulation with the CR
directed to the scaphoid. (18)
f. Ulnar oblique: From the PA position the wrist is
rotated 45°, raising the ulna off the film with
ulnar deviation; no beam angulation with the CR
at the scaphoid.
g. Elongated view: From the PA position the wrist is
rotated 20°, raising the radius off the film; the
beam is angled 35° toward the elbow with the
CR at the scaphoid.
Normal Anatomy (Figure 1-56B)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Styloid process, radius.
Metaphysis, distal radius.
Metaphysis, distal ulna.
Styloid process, ulna.
Scaphoid.
Lunate.
Triquetrum.
Pisiform.
Trapezium.
Trapezoid.
Capitate.
Hamate.
Hook of the hamate.
Shaft, fourth metacarpal.
Shaft, third metacarpal.
Base, fifth metacarpal.
Radioulnar joint.
Radiocarpal joint.
Ulnocarpal joint.
Navicular fat stripe.
Figure 1-56 B. PA Ulnar Flexion, Wrist.
Clinicoradiologic Correlations (Figure 1-56C )
Figure 1-56 C. PA Ulnar Flexion, Fracture of the Scaphoid. With
ulnar flexion the scaphoid fracture becomes wider and more
apparent. Note how the entire proximal carpal row has moved
radialward and that the fracture of the ulnar styloid has also
migrated in the same direction.
163
OPTIONAL: Carpal tunnel, Scaphoid, Lateral oblique (pisiform)
WRIST: Medial
Oblique Projection
Positioning (Figure 1-57A)
2. Scatter control: Lead vinyl must be applied to the other
three quarters of the film not being exposed. Lead vinyl
should be placed beneath the cassette to reduce primary and secondary radiation to the patient.
3. Cassette orientation: Care must be taken not to rotate
the cassette between exposures, ensuring that all four
views remain in the same orientation.
4. Pseudo-soft tissue swelling: The thenar pad density
can be prominent over the radial side of the wrist and
should not be confused with effusion or soft tissue
swelling.
Figure 1-57 MEDIAL OBLIQUE, WRIST. A. Patient
Position, Collimation, and Central Ray.
Synonyms: PA semipronated oblique view.
Demonstrates: Carpal bones and joints, distal radius,
and ulna. (1–4,19) (Fig. 1-57, B and C)
Measure: Laterally, between radial and ulnar styloid
processes.
kVp: 55 (50 to 60).
Film Size: 10 × 12 inches (24 × 30 cm), vertical orientation. Divide into quarters; the other quarters are used for
the other basic projections (cover with lead vinyl).
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Seated. Apply lead half apron for
gonad protection. (Fig. 1-57A)
Part Position: Forearm semipronated so the dorsum
of the wrist is 45° to the film (see “Hand, Oblique
Projection”).
CR: To the midcarpal area.
Collimation: To the wrist, approximately 6 inches.
Side Marker: In a corner of the film.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Patient motion: Place a 45° wedge sponge to support
the hand and wrist.
164
Clinicoradiologic Correlations: This view is critical in
the assessment of the scaphoid, because it shows to advantage the waist and tubercle, which are common sites
of fracture that can be obscured on other views. It also
offers additional views of the thumb and distal forearm.
(Fig. 1-57, D and E )
1. Alignment: The first metacarpal–trapezium alignment
is shown as well as within the carpus.
2. Bone: The radially based structures are best depicted:
the base of the first metacarpal, trapezium, scaphoid,
and radius. In particular, the waist and tubercle of
the scaphoid, trapezium, and articular surface of the
radius and ulnar styloid are clearly demonstrated.
3. Cartilage: The radially placed joints are shown clearly:
the first metacarpal–trapezium, trapezioscaphoid, and
radiocarpal articulations. Other joints can be discerned
if looked for carefully.
4. Soft tissue: A radiolucent fat line (navicular fat stripe)
can be seen parallel to the scaphoid in > 90% of wrist
radiographs. (6) If absent or displaced, there usually is
an associated fracture of the scaphoid. Identify the
soft tissue density of the thenar pad.
Specialized Projections:
1. Semisupinated (AP) oblique view (pisiform view): The
wrist is rotated from the AP position to 45° to the
film; no beam angulation with the CR at the radiocarpal joint. The pisiform and the pisiform–triquetral
joint are shown to advantage.
2. Semipronated 45° oblique in ulnar deviation: From the
PA position the wrist is rotated 45°, raising the radius
off the film with maximal ulnar deviation; no beam
angulation with the CR at the scaphoid. Primarily used
to show subtle fractures of the scaphoid.
BASIC: PA, PA ulnar flexion, *Medial oblique, Lateral
Normal Anatomy (Figure 1-57, B and C )
Figure 1-57 B. Medial Oblique, Wrist. C. Anatomic Specimen, Wrist.
1.
2.
3.
4.
5.
6.
7.
Styloid process, radius.
Metaphysis, distal radius.
Metaphysis, distal ulna.
Styloid process, ulna.
Scaphoid.
Lunate.
Triquetrum.
8.
9.
10.
11.
12.
13.
Pisiform.
Trapezium.
Trapezoid.
Capitate.
Hamate.
Base, fifth metacarpal.
14.
15.
16.
17.
18.
19.
Shaft, fourth metacarpal.
Shaft, first metacarpal.
Radioulnar joint.
Radiocarpal joint.
Ulnocarpal joint.
Navicular fat stripe.
Clinicoradiologic Correlations (Figure 1-57, D and E )
Figure 1-57 D. Oblique, Wrist, Giant Cell Tumor of the
Radius. Observe that the distal radius is expanded and
the cortex is thinned, osteopenic, and deformed as a result of a slow-growing tumor. E. Oblique, Wrist, Fracture
of the Trapezium. A longitudinal fracture is present within
the trapezium, which was not visible on the PA view in a
patient suspected clinically of a scaphoid fracture.
165
OPTIONAL: Carpal tunnel, Scaphoid, Lateral oblique (pisiform)
WRIST: Lateral
Projection
Positioning (Figure 1-58A)
in line with the dorsal surface of the triquetrum. The
third metacarpal and radius are in coaxial alignment.
Clinicoradiologic Correlations: The relationships of
the carpal bones to each other, the radiocarpal joint (especially the lunate), and the distal radius after trauma
are best analyzed on this view. (Fig. 1-58, C and D)
Figure 1-58 LATERAL, WRIST. A. Patient Position,
Collimation, and Central Ray.
Demonstrates: Carpal bones, distal radius, and ulna.
(1–4) (Fig. 1-58B)
Measure: Laterally, between the radial and the ulnar
styloids.
kVp: 55 (50 to 60).
Film Size: 10 × 12 inches (24 × 30 cm), vertical orientation. Divide into quarters; the other quarters are used for
the other basic projections (cover with lead vinyl).
1. Alignment: The plane through the long axes of the radius, lunate, capitate, and third metacarpal usually
does not deviate more than 10°. The articular surface
of the distal radius is tilted ventrally 10–15°. The distal radius projects 1–3 mm beyond the ulna, and there
should be superimposition of the radius and ulna.
2. Bone: The lunate, distal radius, and ulna are well depicted. The pisiform overlies the distal scaphoid. The
dorsal surface of the triquetrum can also be identified.
The bases of the metacarpals, especially the first, can
be seen.
3. Cartilage: The radiolunate and capitate –lunate joints
are readily identified. The articulations of the thumb,
including the first metacarpal–trapezium and
scaphoid–trapezium are well displayed.
CR: To the midcarpal area.
4. Soft tissue: The fat line of the pronator quadratus is
usually seen lying close to and parallel to the ventral
surface of the distal radius. Practically all fractures of
the distal radius result in displacement or obliteration
of the pronator quadratus fat line. (20) At the wrist
dorsum, the skin subcutaneous fat should be visible
as a 1-mm radiolucent transition zone that is straight
or undulating; it becomes convex or locally obliterated
when there is adjacent edema emanating from the
extensor tendons or dorsal bone surfaces. (21)
Collimation: To the wrist, approximately 6 inches.
Specialized Projections:
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Seated. Apply lead half apron for gonad
protection. (Fig. 1-58A)
Part Position: Forearm is in true lateral position.
Side Marker: In a corner of the film.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Patient motion: A sandbag placed over the forearm is
a useful adjunct for immobilization.
2. Scatter control: Lead vinyl must be applied to the
three quarters of the film not being exposed. Lead
vinyl should be placed beneath the cassette to reduce
primary and secondary radiation to the patient.
3. Cassette orientation: Care must be taken not to rotate the cassette between exposures, ensuring that
all four views remain in the same orientation.
4. Pseudo-lateral positioning: The radius and ulna should
be fully superimposed, with the ulnar styloid process
166
1. The 5° angled view: Tilting the tube 5° toward the
elbow may demonstrate the radiocarpal joint slightly
better than will a non-angulated tube.
2. Lateral with flexion–extension: Two views are obtained in the lateral position, with dorsal extension
and with volar flexion, to assess scapholunate instability patterns and carpal bossing. (22)
3. Modified carpal boss: Non-union of the secondary
growth center at the base of the second or third metacarpal adjacent to the capitate and trapezium can produce a painful bony swelling at the dorsum of the
wrist, which is difficult to demonstrate on routine wrist
and hand views. From the true lateral position the wrist
is pronated to 30–60°, and 20–30° of ulnar flexion is
induced. (11,23)
BASIC: PA, PA ulnar flexion, Medial oblique, *Lateral
Normal Anatomy (Figure 1-58B)
Figure 1-58 B. Lateral, Wrist.
1.
2.
3.
4.
5.
Posterior lip, radius.
Anterior lip, radius.
Styloid process, ulna.
Shaft of the radius.
Shaft of the ulna.
6.
7.
8.
9.
Lunate.
Capitate.
Scaphoid.
Pisiform.
10. Trapezium.
11. Base, first metacarpal.
12. Fat line, pronator quadratus
(arrow).
Clinicoradiologic Correlations (Figure 1-58, C and D)
Figure 1-58 C. Lateral, Wrist, Lunate Dislocation. The
lunate is tilted and dislocated ventrally relative to the
radius and capitate (arrow). D. Lateral, Wrist, Distal
Radius Fracture with Angulation. The fracture of the
distal radius is marked by a break in the cortex (arrow).
The distal segment of the radius is angulated dorsally
(Colle’s fracture).
167
OPTIONAL: Norgaard (Ball catcher)
HAND: PA Projection
Positioning (Figure 1-59A)
3. Wrist flexion–extension: The wrist should be flat onto
the cassette, otherwise the carpal bones and their
joints will be distorted.
Clinicoradiologic Correlations: A hand series should
consist of a minimum of three views: PA, PA oblique,
and lateral.
1. Alignment: Each phalanx and metacarpal for a single
digit is called a ray in which all components should be
aligned. The long axes of each individual ray should
diverge uniformly from the adjacent ray(s). Note the
gradual shortening of each metacarpal so that the
third to fifth heads are aligned tangentially.
Figure 1-59 PA HAND. A. Patient Position, Collimation,
and Central Ray.
Synonyms: Dorsal-palmar view.
Demonstrates: Distal radius and ulna, carpals, metacarpals, phalanges, and joints. (1–3) (Fig. 1-59, B and C)
Measure: Posteroanterior through metacarpals.
kVp: 55 (50 to 60).
Film Size: 8 × 10 inches (18 × 24 cm), vertical orientation.
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Seated. Apply lead half apron for
gonad protection. (Fig. 1-59A)
Part Position: Hand is placed palm down on the film
with the fingers extended.
CR: Third metacarpal head.
Collimation: To hand size.
Side Marker: In the corner of the film.
2. Bone: Each proximal and middle phalanx has a head,
shaft, and base. The distal phalanx has a base, neck,
and expanded distal (ungual) tuft. The bone density
of the ends of each phalanx displays relatively less
radiographic density owing to the thinner cortex of
these regions. Small vascular channels are frequently
seen at the distal aspect of the phalanges as thin,
oblique, radiolucent lines. Each metacarpal exhibits a
base, shaft, and rounded head. At the head small
grooves occur laterally, referred to as valleculae. The
cortices of the shaft when added together normally
equal the thickness of the medullary cavity (corticomedullary ratio). Note that the thumb has only two
phalanges and the sesamoid bones are present at the
ventral aspect of the metacarpophalangeal joint. The
carpus and distal radius and ulna are displayed.
3. Cartilage: The interphalangeal joints are characterized
by a slightly concave proximal surface and convex distal surface. The metacarpophalangeal joint spaces are
thicker than the interphalangeal joints and lie between
convex–concave articular surfaces. The metacarpal–
carpal, intercarpal, radiocarpal, and distal radio–ulnar
joints are displayed.
4. Soft tissue: The skin line over each digit should be followed; note any deviation, especially near a joint, as
evidence of swelling. The interface between the subcutaneous fat and tendon sheaths is usually visible as
a 1-mm lucency below the skin line. Note the contour of the distal fingertip and the distance between
the soft tissue pulp and ungual tuft surface. In goodquality films the nail and skin folds at the joints can
be discerned.
Specialized Projections:
Breathing Instructions: Suspended expiration.
1. AP view: The palm is turned into supination and is used
when the patient is unable to pronate the forearm.
Common Pitfalls:
1. Joint flexion pseudo-fusion artifact: Failure to
straighten the digits at the time of exposure will prevent clear definition of the joint spaces.
2. Metacarpal views: Perform PA, AP, oblique, and lateral projections with tight collimation to the individual metacarpal being examined.
2. Scatter control: Lead vinyl should be placed beneath
the cassette to reduce primary and secondary radiation to the patient.
168
3. Brewerton projection: The dorsum of the fingers are
placed flat onto the cassette with the metacarpophalangeal joints flexed approximately 45° and the dorsum of the hand elevated off the cassette. The view is
BASIC: *PA, Obliques
useful for detecting lesions of the metacarpal heads
and joint erosion from inflammatory arthritis within
the valleculae and heads. (4–6)
4. Skeletal (bone age): A PA view of the left hand is performed and the time of occurrence and changes in
the morphology of the epiphyses, bone components,
and sesamoid bones are matched to female and male
standards displayed in the Greulich and Pyle Atlas to
determine the relative skeletal age. (7) This is compared with the chronological age of the patient to assess relative skeletal maturity.
Normal Anatomy (Figure 1-59, B and C )
Figure 1-59 B. PA Hand. C. Anatomic Specimen.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Styloid process, radius.
Metaphysis, radius.
Metaphysis, ulna.
Styloid process, ulna.
Scaphoid.
Lunate.
Triquetrum.
Pisiform.
Trapezium.
10.
11.
12.
13.
14.
15.
16.
17.
Trapezoid.
Capitate.
Hamate.
Metacarpal base.
Metacarpal shaft.
Metacarpal neck.
Metacarpal head.
Metacarpophalangeal joint.
18.
19.
20.
21.
22.
Proximal phalanx.
Middle phalanx.
Distal phalanx.
Distal (ungual) tuft.
Sesamoid bone (flexor pollicis
brevis, adductor pollicis).
23. Vallecula, metacarpal head.
24. Metacarpal styloid process.
169
OPTIONAL: Norgaard’s (Ball catcher)
HAND: Oblique Projection
Positioning (Figure 1-60A)
2. Finger flexion: Some advocate keeping the fingers and
thumb extended to prevent foreshortening of the phalanges and allowing improved depiction of the interphalangeal joints. (9) If adopted, a 45° oblique foam
support is necessary to minimize motion artifact.
3. Scatter control: Lead vinyl should be placed beneath
the cassette to reduce primary and secondary radiation
to the patient.
Clinicoradiologic Correlations: The oblique film is
especially useful in depicting fractures of the metacarpals
and dislocations of the finger joints. (Fig. 1-59C)
1. Alignment: The first metacarpal–trapezium (thumb)
and the fourth and fifth metacarpal joints with the
hamate are shown to advantage, which is useful in detecting fractures and dislocations of this region easily
overlooked on PA views. (10)
Figure 1-60 OBLIQUE, HAND. A. Patient Position,
Collimation, and Central Ray.
Demonstrates: Distal radius and ulna, carpals, metacarpals, phalanges, and joints. (1–3,8) (Fig. 1-60B)
Measure: Through the CR.
kVp: 55 (50 to 60).
Film Size: 8 × 10 inches (18 × 24 cm), vertical orientation.
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Seated. Apply lead half apron for gonad
protection. (Fig. 1-60A)
Part Position: Hand is semipronated to 45° to the film.
For stability, the fingers are flexed to touch the film and to
be projected free from each other (see “Wrist, Oblique
Projection”), or they may be placed on a foam rubber
positioning aid.
CR: Between the second and third metacarpal heads.
Collimation: To hand size.
Side Marker: In the corner of the film.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Exaggerated obliquity: Over-rotation of the hand will
superimpose the metacarpals and limit the demonstration of each metacarpal along its entire length.
Proper rotation has been obtained when the dorsal
rim of the distal radius overlaps the ulna at the distal
radioulnar joint.
170
2. Bone: Begin the bony assessment proximally and proceed distally. The distal radius and ulna are both
depicted, especially the ulnar styloid. The scaphoid, trapezium, and trapezoid are now clearly seen, with
the scaphoid waist laid out for detection of fractures.
The dorsal surface of both the triquetrum and the hamate are shown almost tangentially, and subtle avulsion fractures can be demonstrated. Each metacarpal
and phalanx is curved at the inferior surface with slight
ventral tilt distally of the head. The sesamoid bone
often seen at the ventral surface of the second metacarpophalangeal joint is usually visible in this view.
3. Cartilage: The interphalangeal joints are characterized by a slightly concave proximal surface and convex distal surface. The metacarpophalangeal joint
spaces are thicker than the interphalangeal joints and
lie between convex–concave articular surfaces. The
metacarpal–carpal, intercarpal, radiocarpal, and radio–
ulnar joints are displayed. The thumb joints are often
clearly seen, especially if the thumb is kept straight
rather than flexed.
4. Soft tissue: The skin line over each digit should be followed, observing any deviation, especially near a joint,
as evidence of swelling. The interface between the
subcutaneous fat and tendon sheaths is usually visible as a 1-mm lucency below the skin line. Note the
contour and subcutaneous fat interface of the skin over
the ulnar styloid and dorsum of the wrist for evidence
of swelling. The muscle bulk of the thenar pad is often
accentuated as a soft tissue density and should not
be misconstrued as evidence for soft tissue swelling
or mass.
Specialized Projections:
1. Norgaard’s (ball catcher, champagne toast, semisupinated) projection: The hands are placed supine
(AP) with thumb and fingers rotated up 45°, maintaining contact to the cassette with the ulnar aspect
BASIC: PA, *Oblique
of the wrist. (11,12) The CR is directed to the midshafts of the metacarpals. The mAs should be reduced from the PA factors by about 25% to avoid
overexposure. The view is exceptionally useful for detecting early erosive inflammatory arthritis, such as
rheumatoid arthritis, to display erosions of the valleculae, metacarpal heads, base of the proximal phalanges, and pisiform. (11,12) In trauma, fractures and
dislocations at the bases of the fourth and fifth
metacarpals and the hamate may be shown only on
this view. (10)
Normal Anatomy (Figure 1-60B)
2. Reversed PA oblique projection: From the PA position
the ulnar side of the hand is elevated 45°. All bone
surfaces are profiled differently from the routine views
and may show cortical disruptions, including fractures
that are otherwise hidden. The bases of the fourth and
fifth metacarpals, the hamate, and the pisiform are
similarly shown to advantage.
3. Lateral projection: With the hand in the true lateral
position the fingers are progressively flexed. The metacarpals are superimposed but the thumb is shown in
PA projection.
Clinicoradiologic Correlations
(Figure 1-60C )
Figure 1-60 C. Oblique, Hand, Metacarpal Fractures.
Fractures are present through the shaft of the third and
fourth metacarpals as well as the proximal phalanx of
the fifth digit.
Figure 1-60 B. Oblique, Hand.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Styloid process, radius.
Metaphysis, radius.
Metaphysis, ulna.
Styloid process, ulna.
Scaphoid.
Lunate.
Triquetrum.
Pisiform.
Trapezium.
Trapezoid.
Capitate.
Hamate.
13.
14.
15.
16.
17.
18.
19.
20.
21.
Base, second metacarpal.
Shaft, third metacarpal.
Neck, fourth metacarpal.
Head, fifth metacarpal.
Metacarpophalangeal
joint.
Proximal phalanx.
Middle phalanx.
Distal phalanx.
Sesamoid bones (flexor
pollicis brevis, adductor
pollicis).
171
FINGERS: PA, Oblique, and Lateral Projections
Positioning (Figure 1-61, A–C )
Figure 1-61 FINGERS. A. PA, Patient Position, Collimation, and
Central Ray. B. Oblique, Patient Position, Collimation, and Central Ray.
C. Lateral, Patient Position, Collimation, and Central Ray.
Demonstrates: Phalanges, metacarpal heads, and interphalangeal joints. (1–4) (Fig. 1-61, D–G)
Measure: At the metacarpal head.
2. Scatter control: Lead vinyl must be applied to the two
thirds of the film not being exposed. Lead vinyl should
be placed beneath the cassette to reduce primary and
secondary radiation to the patient.
kVp: 55 (50 to 60).
Film Size: 8 × 10 inches (18 × 24 cm), horizontal orientation. Divided in thirds; the other thirds are used for the
other basic views (covered with lead vinyl).
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Seated. Apply lead half apron for
gonad protection.
Part Position: (a) Posteroanterior: hand prone, with affected finger centered. (Fig. 1-61A) (b) Oblique: hand
semiprone to 45° with the film; the exposed finger is extended, with the other fingers slightly flexed and spread
apart. (Fig. 1-61B) (c) Lateral: hand in true lateral position, affected finger is extended, with the remaining fingers flexed. (Fig. 1-61C)
CR: At the proximal interphalangeal joint.
Collimation: To include only the affected digit.
Side Marker: In a corner of the film, adjacent to fingertip for one view only.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Finger flexion: The finger joints must be extended as
much as possible to allow accurate profiling of the
articular surfaces and joint space. (5)
172
Clinicoradiologic Correlations: Given the shape and
size of each phalanx the emphasis must be on bone detail, which can be achieved only by performing all three
views for the digit examined with close collimation, finedetail film–screen combinations, and accurate exposure.
(6,7) (Fig. 1-61, H–J)
1. Alignment: Each joint needs to be assessed for alignment. The plane through the long axes of each phalanx and metacarpal usually does not deviate > 10° in
the extended position.
2. Bone: Each proximal and middle phalanx has a head,
shaft, and base. The distal phalanx has a base, neck,
and expanded distal (ungual) tuft. The bone density of
the ends of each phalanx displays relatively less radiographic density, owing to the thinner cortex of these
regions. Small vascular channels are frequently seen
at the distal aspect of the phalanges as thin, oblique,
radiolucent lines. Each metacarpal exhibits a base,
shaft, and rounded head. At the head small grooves
occur laterally, referred to as valleculae. The cortices
of the shaft when added together normally equal
the thickness of the medullary cavity (corticomedullary
ratio). The articular cortices of opposing phalanges
are concave–convex in the lateral projection, with the
upper portion designated as the dorsal plate and the
undersurface component as the ventral or volar plate;
these are common sites of avulsion fracture, which is
demonstrated only on the lateral view.
BASIC: *PA, *Oblique, *Lateral
3. Cartilage: The interphalangeal joint surfaces on the
frontal projection often demonstrate a biconcave contour with a central sulcus ridge arrangement and a relatively narrow joint space. The metacarpophalangeal
joints, however, have a smooth concave–convex relationship and a wider joint cavity.
4. Soft tissue: The skin line over each digit should be followed, observing any deviation, especially near a joint,
as evidence of swelling. The subcutaneous fat interface should be visible over the entire length of the
digit, and there is uniform density of the soft tissue of
the entire digit, except proximally at the metacarpophalangeal joints, where there is a gradual transition
to increased density. Note the contour of the distal
fingertip, and in good–quality films identify the nail.
Specialized Projections:
1. Internal oblique view: Elevating the ulnar side of the
wrist may show fractures of the phalanges better
than will the routine external oblique. (6)
2. Metacarpal views: Perform PA, AP, oblique, and lateral
views with tight collimation to the individual metacarpal being examined.
3. Tea cup (OK, fan) view: To obtain a lateral view of all
fingers simultaneously the hand is placed in the lateral position, the thumb and index finger are opposed and touching each other at their tips, with the
remaining fingers progressively less flexed so they are
not superimposed on each other. The little finger remains extended. Use of a stepped 45° foam pad will
assist in digital stabilization, as will a sandbag across
the forearm.
4. Off-lateral views: Superimposition of the metacarpals
largely obscures them in the lateral position; 10° of
pronation will show the second and third metacarpals
and 10° of supination profiles the fourth and fifth metacarpals. (8)
173
FINGERS: PA, Oblique, and Lateral Projections
Normal Anatomy (Figure 1-61, D–G)
Figure 1-61 D. PA Finger. E. Specimen Radiograph, PA Finger. F. Lateral, Finger. G. Specimen Radiograph,
Lateral Finger.
1.
2.
3.
4.
5.
6.
174
Distal (ungual) tuft.
Distal phalanx.
Distal interphalangeal joint.
Middle phalanx.
Proximal interphalangeal joint.
Proximal phalanx.
7.
8.
9.
10.
11.
12.
Metacarpophalangeal joint.
Head, metacarpal.
Vallecula.
Neck, metacarpal.
Shaft, metacarpal.
Base, metacarpal.
BASIC: *PA, *Oblique, *Lateral
Clinicoradiologic Correlations (Figure 1-61, H–J )
Figure 1-61 H. PA Finger, Enchondroma. The bone is expanded at the base of the proximal phalanx with
associated soft tissue swelling. I. Lateral, Finger, Enchondroma. The bone expansion is predominantly ventral with deformity of the articular cortex. J. Lateral, Finger, Avulsion Fracture of the Dorsal Plate. A small
bone fragment is present at the dorsal aspect of the distal interphalangeal joint owing to an avulsion fracture with flexion of the joint (mallet finger).
175
OPTIONAL: Obliques
THUMB: AP and Lateral Projections
Positioning (Figure 1-62, A and B)
Figure 1-62 THUMB. A. AP Patient Position,
Collimation, and Central Ray. B. Lateral Patient
Position.
Demonstrates: Phalanges, first metacarpal, trapezium,
scaphoid, and intervening joints. (1–4) (Fig. 1-62, C–E )
Measure: At the metacarpophalangeal joint.
kVp: 55 (50 to 60).
Film Size: 8 × 10 inches (18 × 24 cm), horizontal orientation. Divide in half; the other half is used for the other
projection (cover with lead vinyl).
Grid: No.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Seated. Apply lead half apron for
gonad protection.
Part Position: (a) AP (Robert’s projection): the hand is
rotated internally until the posterior surface of the
thumb contacts the film. (Fig 1-62A) (b) Lateral: the
hand is placed prone and the thumb is brought to a lateral position. This is assisted by slightly flexing of the
metacarpophalangeal joints. (Fig 1-62B)
CR: Through the first metacarpophalangeal joint.
Collimation: To thumb size.
Side Marker: In a corner of the film adjacent to the
thumb tip.
Breathing Instructions: Suspended expiration.
Common Pitfalls:
1. Underexposure: If the thumb is not extended the
flexion at the metacarpal–trapezium joint will often
cause overlap of the thenar muscle pad and produce
underexposure of the joint. A specific collimated view
should be performed if underexposed on the routine
study, with an adjusted increase in exposure of at least
25% mAs.
2. Thumb rotation: Care should be employed to get a
true frontal view to clearly depict the base of the first
176
metacarpal and the concave surface of the saddle joint
of the trapezium as fractures, dislocation, and arthritis
of this joint are relatively frequent and subtle. (5)
3. Scatter control: Lead vinyl must be applied to the half
of the film not being exposed. Lead vinyl should be
placed beneath the cassette to reduce primary and
secondary radiation to the patient.
Clinicoradiologic Correlations: Depiction of the
thumb on routine hand views is inadequate, particularly for the base of the first metacarpal and its joint;
these specific views should be employed for adequate
examination.
1. Alignment: When the joints are in anatomic extension the bones should be congruously aligned across
the joint spaces. If there is more joint flexion more on
the lateral view, there may be anterior translation
of the proximal phalanx on the metacarpal head. Considerable mobility exists at the first metacarpotrapezial
joint and pseudo-subluxation is common.
2. Bone: There are only two phalanges of the thumb.
Each phalanx has a head, shaft, and base. The distal
phalanx has a base, neck, and expanded distal (ungual) tuft. The bone density of the ends of each phalanx displays relatively less radiographic density because of the thinner cortex of these regions. The first
metacarpal exhibits a base and shaft and a flatter but
still rounded head. Valleculae are not present at the
head. At the base a medial sharp angular bony projection can often be seen on the lateral view, which
is referred to as the styloid process. There is commonly cortical irregularity at the undersurface of the
distal phalanx, seen on the lateral projection.
3. Cartilage: The interphalangeal, metacarpophalangeal,
and first metacarpotrapezial joints are evaluated for
BASIC: *AP, *Lateral
joint space and articular contours. The interphalangeal
joint surfaces on the frontal projection often demonstrate a biconcave contour with a central sulcus ridge
arrangement and a relatively narrow joint space. The
metacarpophalangeal joint is concave–convex, though
less so than the corresponding finger joints. At the
ventral surface of the metacarpophalangeal joint lie
two sesamoid bones within the tendons of the flexor
pollicis brevis and adductor pollicis; the joint surfaces
are continuous with the adjacent joint. The metacarpotrapezial joint is a saddle joint with a convex–concave
shape that is best profiled on the frontal projection.
4. Soft tissue: The skin line over the thumb should be followed observing any deviation, especially near a joint,
as evidence of swelling. On the lateral projection the
skin line is closely apposed to the bones, whereas it is
three times thicker ventrally. The subcutaneous fat
interface should be visible over the entire length of
the digit; there is uniform density of the soft tissue
of the entire digit, except proximally at the metacarpotrapezial joint, where there is a gradual transition to
increased density from the thenar pad.
Specialized Projections:
1. PA view: In this position the thumb is elevated away
from the cassette, creating magnification and loss of
detail. It is usually performed when the patient is unable to tolerate the AP position.
2. Burman’s AP view: The view is specific for the first
metacarpotrapezial joint. From the AP position with
the thumb on the cassette surface, the wrist is extended as much as possible, the thumb is extended in
parallel with the fingers, the tube is angled 45° toward
the wrist, and the CR is aimed at the thenar pad. (6)
3. Oblique view: With the hand in the neutral PA position, the thumb is in a natural oblique position.
Collimate to the thumb and including the adjacent
carpus and radial styloid process.
4. Stress views: In the AP or PA position the patient
stresses the thumb with the contralateral hand using
the contralateral thumb as the fulcrum, which is
placed at the margin of the metacarpophalangeal
joint. Exposures are made in radial and ulnar flexion
to assess the collateral ligamentous stability of the
joint (gamekeeper’s thumb). (7)
Normal Anatomy (Figure 1-62, C–E )
Figure 1-62 C. AP Thumb. D. Lateral,
Thumb. E. AP Anatomic Specimen.
1.
2.
3.
4.
Distal (ungual) tuft.
Distal phalanx.
Distal interphalangeal joint.
Proximal phalanx.
5.
6.
7.
8.
Metacarpophalangeal joint.
Metacarpal head.
Metacarpal shaft.
Metacarpal base.
9. Trapezium.
10. Sesamoid bones (flexor pollicis
brevis, adductor pollicis).
177
OPTIONAL: Anterior oblique (45°), Posterior oblique (45°), Tangential
RIBS: AP and
PA Projections
Positioning (Figure 1-63A)
Figure 1-63 AP AND POSTEROANTERIOR RIBS.
A. Patient Position, Collimation, and Central Ray.
Demonstrates: Ribs (anterior and posterior), thoracic
spine. (1–5) (Fig. 1-63, B–E )
Measure: AP chest at CR.
kVp: 80 (75 to 85); low for ribs above diaphragm, high
for ribs below diaphragm.
Film Size: 14 × 17 inches (35 × 43 cm).
Grid: Yes.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Upright or recumbent. (Fig. 1-63A)
Part Position: (a) AP: if rib lesion is posterior, centered
to the bucky. (b) PA: if rib lesion is anterior, centered to
the bucky.
CR: To the area of complaint.
Collimation: To the film.
Side Marker: In a corner of the film.
Breathing Instructions: Above-diaphragm rib projection:
suspended full inspiration. Below-diaphragm rib projection: suspended full expiration.
Common Pitfalls:
1. Breathing: To prevent movement artifact, respiration
must be suspended for the duration of the exposure.
2. Exposure difficulties: Ribs above and below the diaphragm will require different exposures; those above
need reduced mAs (usually by 25–50%).
178
3. Inadequate views: Multiple oblique views at varying
angles may be necessary to demonstrate rib fractures
because of the curved contour of each rib. If the suspected lesion is located anteriorly, the obliques are
taken PA; if posterior, they are taken AP.
Clinicoradiologic Correlations: Because of normal overlying anatomy, the positioning, exposure, and interpretation of rib radiographs are extremely difficult. (6,7) Placing
a radio-opaque skin marker over the site of pain can be a
useful interpretive tool to focus the analysis.
1. Alignment: Compare the intercostal spaces for symmetry, tracing them from posterior to anterior. Widened
intercostal spaces can be a sign of tension pneumothorax, previous thoracotomy, and intercostal mass;
they are common on the convex side of scoliosis. Compare the vertebral origins of all posterior ribs, as extra
ribs may occur with spinal hemivertebrae. Narrowed
intercostal spaces may be found in myopathy, lung
collapse, skeletal dysplasia with broad ribs, and on the
concave side of scoliosis.
2. Bone: The posterior ribs are narrowed, gradually
widening and becoming broader anteriorly. The cortices of the posterior ribs are usually uniform and readily seen though the inferior margins; especially at the
seventh to twelfth ribs, they are often irregular and
may even appear absent where the subcostal groove
is situated. Anteriorly, the cortices are thin and become indistinct, with the lengths prone to variation.
3. Cartilage: Identify the costotransverse and costovertebral joints. The gradual transition of the anterior ribs
BASIC: *AP or PA
into the costal cartilages may make the ends appear
frayed and indistinct and frequently cupped. The costochondral transitional zones are frequently calcified; in
males this is often peripheral in the cartilage as two
parallel linear calcifications, whereas in females this is
displayed as more central tongue-like calcifications.
(8) The first costochondral junction is invariable and
calcified, which can be bulbous, dense, and pseudopathologic in appearance.
4. Soft tissue: Trace carefully the bone–lung interface
adjacent to each rib, because it represents the pleura,
which is normally adherent to the periosteum. If it appears locally thick or is convex away from the rib this
may be a sign of rib fracture with hematoma, bone
destruction with soft tissue mass, or primary pleural
disease. Visible retraction of the visceral pleura from
the rib is a sign of pneumothorax. For lower rib fractures, look at the outline of the spleen and liver for
signs of rupture or hematoma. Look systematically at
the lung fields, aeration, vascularity, and lung volumes
and the sharp outlines of the cardiovascular silhouette,
diaphragm, and acute costophrenic angles.
Specialized Projections:
1. Bilateral and unilateral ribs: Depending on clinical circumstances, collimated views to the area of interest
will optimize film quality and is the preferred method.
Bilateral views are often obtained as part of skeletal
surveys or in the initial assessment of trauma but may
require subsequent spot views for better depiction of
the abnormality.
2. Obliques: For posterior ribs, place the affected side
against the bucky (posterior oblique) and rotate the
thorax 45°, with the CR passing through the anterior
chest lateral to the sternum. The anterior ribs are best
displayed with the affected side away from the bucky
(anterior oblique) and rotated 45°, with the CR passing through the posterior chest on the same side lateral to the spine.
3. Tangential: Turn the patient until the required rib lies
tangential to the beam, preferably as close to the
bucky as possible.
4. Ribs 1–3: An AP projection with 10–15° cephalad tube
tilt will improve the demonstration of the upper ribs.
5. Costovertebral joints: In the AP position the tube is
angled cephalad at 20°, with the CR passing through
the sixth thoracic vertebra. Increase the tube angulation 5–10° for patients with increased kyphosis.
179
RIBS: AP and
PA Projections
OPTIONAL: Anterior oblique (45°), Posterior oblique (45°), Tangential
Normal Anatomy (Figure 1-63, B and C )
Figure 1-63 B. AP Ribs. C. Oblique, Ribs.
1.
2.
3.
4.
180
Anterior rib.
Posterior rib.
Rib tubercle.
Costotransverse joint.
5.
6.
7.
8.
Rib head.
Transverse process.
Superior angle, scapula.
Distal clavicle.
9.
10.
11.
12.
Transverse aorta.
Pulmonary artery.
Peripheral pulmonary vessel.
Heart.
BASIC: *AP or PA
Normal Anatomy (Figure 1-63, D and E)
Figure 1-63 D and E. Specimen Radiographs.
1. Anterior rib.
2. Posterior rib.
3. Rib tubercle.
4. Costotransverse joint.
5. Rib head.
181
OPTIONAL: Lordotic, Obliques
CHEST: PA Projection
Positioning (Figure 1-64, A and B)
centered to the midline of the bucky. Cassette positioned so that its superior border is 2 inches above the
shoulders.
CR: To the film. (Fig. 1-64B)
Collimation: To the film.
Side Marker: In a corner of the film, above the shoulder.
Breathing Instructions: Suspended deep inspiration.
Common Pitfalls:
1. Adequate inspiration: A good inspiratory effort has
been achieved when seven anterior ribs or ten posterior ribs are visible above the diaphragm.
2. Correct exposure: The thoracic spine should be just visible through the density of the heart and mediastinum.
3. Patient rotation: The medial clavicles should be equidistant from the upper thoracic spinous processes.
4. Shoulder retraction: The shoulders must be rotated
anteriorly to remove the scapulae from the lung fields;
be sure to keep the hands and forearms low over the
pelvis and removed from the primary beam.
5. Pectus excavatum: Depression of the sternum obscures
the right heart border and may mimic lung disease.
Clinicoradiologic Correlations: The role of a chest
radiograph in skeletal disorders is broad and often a very
necessary component of diagnosis and management. In
thoracic spine disorders it often plays a crucial role.
Figure 1-64 PA CHEST. A. Patient Position.
B. Collimation and Central Ray.
Demonstrates: Lung fields, heart, great vessels, ribs,
shoulder girdles, thoracic spine, and upper abdomen.
(1–4) (Fig. 1-64C)
Measure: Anteroposterior at greatest diameter in full,
deep inspiration.
kVp: 110 (100 to 120).
Film Size: 14 × 17 inches (35 × 43 cm), vertical orientation.
Grid: No.
1. Alignment: Observe for scoliosis, elevated shoulder, diaphragm, tracheal position, and mediastinal–
cardiovascular silhouette positions.
2. Bone: Evaluate the bony thorax, including the shoulder girdles, spine, and ribs.
3. Cartilage: The joints of the shoulder girdles (glenohumeral, acromioclavicular, sternoclavicular), spine
(discs), and ribs (costotransverse, costovertebral) can
be identified.
4. Soft tissue: Look systematically at the lung fields, aeration, vascularity, minor fissure, trachea, bronchi, cardiovascular silhouette, diaphragm, and costophrenic angles. Outline visible structures of the upper abdomen
(liver, colonic gas, stomach air bubble).
TFD: 72 inches (183 cm).
Specialized Projections:
Tube Tilt: None.
1. Expiration view: Performed in an identical manner to
the inspiratory PA film, except the exposure is made
at the end of suspended expiration. Used to enhance
the visualization of pneumothorax, bronchial obstruction, emphysema, and diaphragmatic paralysis.
Patient Position: Upright. (Fig. 1-64A)
Part Position: PA, chin elevated, hands placed over
buttocks, and shoulders rolled forward. Thoracic spine
182
BASIC: *PA, Lateral
Normal Anatomy (Figure 1-64C)
Figure 1-64 C. PA Chest.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Right atrial border.
Left ventricular border.
Left atrial border.
Pulmonary trunk.
Transverse aorta (aortic knob).
Ascending aorta.
Left pulmonary hilus.
Right pulmonary hilus.
Right pulmonary vessel.
Right cardiophrenic angle.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Left cardiophrenic angle.
Right costophrenic angle.
Left costophrenic angle.
Right lung apex.
Breast.
Right hemidiaphragm.
Left hemidiaphragm.
Liver.
Gastric air bubble (magenblase).
Humeral head.
21.
22.
23.
24.
25.
26.
27.
28.
29.
Axillary border, scapula.
Coracoid process, scapula.
Acromion, scapula.
Superior angle, scapula.
Clavicle.
Spinous process, T2.
Tracheal air shadow.
Manubrium.
Thoracic spine.
183
OPTIONAL: Lordotic, Obliques
CHEST: Lateral Projection
Positioning (Figure 1-65A)
CR: To the film.
Collimation: To patient size.
Side Marker: Left marker placed anterior to the sternum or behind the upper thoracic spine.
Breathing Instructions: Suspended deep inspiration.
Common Pitfalls:
1. Arm elevation: If the arms are not elevated the upper
and anterior lung fields will be obscured and the
scapulae will be superimposed on the posterior lung
fields.
2. Body rotation: The posterior ribs will come into view,
causing overlap with the spine; the posterior costophrenic sulci will be distorted and the diaphragms will
not be shown in true profile.
3. Scatter control: In larger patients a grid technique may
need to be employed.
Clinicoradiologic Correlations: Left laterals are routinely
performed to reduce cardiac magnification. Without a lateral the mediastinum and lesion localization cannot be
adequately assessed.
Figure 1-65 LATERAL, CHEST. A. Patient Position,
Collimation, and Central Ray.
1. Alignment: Measure the degree of thoracic kyphosis
present and ensure anatomic vertebral alignment.
Observe the contour of the sternum.
2. Bone: Evaluate the bony thorax, including the shoulder
girdles, spine, and ribs.
Demonstrates: Lung fields, heart, great vessels, ribs,
sternum, and thoracic spine. (5–7) (Fig. 1-65B)
Measure: Transversely, under the axilla, at the T6 level.
kVp: 110 (100 to 120).
Film Size: 14 × 17 inches (35 × 43 cm), vertical orientation.
Grid: No.
TFD: 72 inches (183 cm).
Tube Tilt: None.
Patient Position: Upright. (Fig. 1-65A)
Part Position: Left lateral position, with no rotation.
Both arms elevated and crossed on top of the head.
Cassette position is 2 inches above the shoulders.
184
3. Cartilage: The joints of the shoulder girdles (glenohumeral), spine (discs, facets), and ribs (costotransverse, costovertebral) can be identified.
4. Soft tissue: Look systematically at the lung fields, aeration, vascularity, fissures (major, minor), trachea,
bronchi, cardiovascular silhouette, diaphragm, and
costophrenic angles; observe for any masses. Outline
visible structures of the upper abdomen (liver, colonic
gas, stomach air bubble). The aorta should only just
cross the thoracic spine. The right hemidiaphragm is
usually higher than the left, and beneath the left hemidiaphragm lies the gastric air bubble.
BASIC: PA, *Lateral
Normal Anatomy (Figure 1-65B)
Figure 1-65 B. Lateral, Chest.
1.
2.
3.
4.
5.
6.
7.
8.
Right ventricular border.
Ascending aorta.
Aortic arch.
Descending aorta.
Left atrial border.
Left ventricular border.
Hilus.
Pulmonary vessels.
9.
10.
11.
12.
13.
14.
15.
Retrosternal space.
Retrocardiac space.
Body of sternum.
Manubriosternal joint.
Manubrium.
Axillary borders, scapulae.
Vertebral body.
16.
17.
18.
19.
20.
21.
22.
Intervertebral foramen.
Posterior rib.
Spinous process.
Trachea.
Diaphragm.
Posterior costophrenic sulcus.
Breast shadow.
185
OPTIONAL: *Lordotic, Obliques
CHEST: Lordotic Projection
Positioning (Figure 1-66, A–C )
Figure 1-66 LORDOTIC, CHEST. A. AP Patient Tilt, Patient Position.
B. AP Tube Tilt, Patient Position. C. Collimation and Central Ray.
Demonstrates: Lung apices, right middle lobe, and lingular segments. (8–11) (Fig. 1-66D)
Measure: Through the CR.
kVp: 110 (100 to 120).
Film Size: 14 × 17 inches (35 × 43 cm), vertical orientation.
Grid: No.
TFD: (a) AP patient tilt: 72 inches (183 cm); (b) AP tube tilt:
72 inches (183 cm); must correct for tube tilt, 66 inches
(167 cm).
Tube Tilt: (a) AP patient tilt: No tilt. (b) AP tube tilt: 30°.
Patient Position: Upright.
Part Position: (a) AP patient tilt: patient stands 1 foot
from the bucky and leans back, with shoulders, neck,
and back of the head against bucky. (Fig.1-66A)
Tube Tilt: (b) AP tube tilt: alternatively, the patient stands
straight upright and tube is angled cephalad 30°. The film
is placed 2 inches above the shoulders. (Fig. 1-66B)
2. Expiration: With elevation of the hemidiaphragms the
heart is enlarged and the trachea deviates. The heart
size should not be assessed on this view.
Clinicoradiologic Correlations: This is an optional view
that is excellent for delineating lung disease involving the
apices, middle lobe, and lingula. (12,13)
1. Alignment: Note if the trachea is displaced and the
symmetry of clavicular orientation. The intercostal
spaces should be symmetrical, with the ribs bilaterally
aligned.
2. Bone: The bones of the shoulder girdle (humerus,
clavicle, scapula) and cervicothoracic spines are displayed. Note how the posterior ribs are horizontal, as
are the clavicles.
3. Cartilage: The costovertebral joints of the ribs, cervicothoracic disc spaces, and shoulder girdle articulations
can be seen.
Collimation: To the film.
4. Soft tissue: The lung fields are assessed for symmetry of
aeration or masses, vascularity, fissure, and trachea position, especially of the upper and middle lobes, as well
as the lingula. The lung–rib interface is marked by the
normally 1- to 2-mm-thick and smooth pleural surface.
Side Marker: In the corner of the film, above the
shoulder.
Specialized Projections:
CR: To the film. (Fig. 1-66C)
Breathing Instructions: Suspended full inspiration.
Common Pitfalls:
1. Inadequate angulation: The clavicles will overlie the
apices, obscuring the detail.
186
1. Lordotic grid technique: To evaluate dense parenchymal lesions and lesions with calcium or to demonstrate
bone lesions, including fractures or tumor destruction
of the ribs and upper thoracic vertebrae, use a grid
with reduced kVp of 75–85 to improve depiction.
BASIC: PA, Lateral
Normal Anatomy (Figure 1-66D )
Figure 1-66 D. Lordotic, Chest.
1.
2.
3.
4.
5.
Left ventricular border.
Left pulmonary vessels.
Aortic arch (aortic knob).
Superior vena cava.
Right pulmonary vessels.
6.
7.
8.
9.
Posterior fifth rib.
Humeral epiphysis.
Coracoid process.
Acromion process.
10.
11.
12.
13.
Clavicle.
T1 vertebra.
Trachea.
Physis.
187
OPTIONAL: PA, Erect, Decubitus
ABDOMEN: AP (KUB) Projection
Positioning (Figure 1-67, A and B )
Figure 1-67 AP ABDOMEN. A. Patient Position. B. Collimation
and Central Ray.
Synonyms: Kidneys–urinary bladder (KUB)
Breathing Instructions: Suspended expiration.
Demonstrates: Kidneys, urinary bladder, liver, spleen,
large bowel, psoas shadow, pelvis, lumbar spine, and
lower ribs. (1–3) (Fig. 167C)
Common Pitfalls:
Measure: At the iliac crest.
kVp: (a) 70 (65 to 75) for calcific densities; (b) 100 (95
to 105) for soft tissue detail.
Film Size: 14 × 17 inches (35 × 43 cm), vertical orientation.
Grid: Yes.
TFD: 40 inches (102 cm).
Tube Tilt: None.
Patient Position: Supine. (Fig. 1-67A)
Part Position: Spine positioned to the midline.
CR: At the top of the iliac crests. (Fig. 1-67B)
Collimation: To film size.
Side Marker: In top corner of the film.
188
1. Inadequate coverage: The lung bases through to the
symphysis pubis should be included on the exposure.
Exceptionally tall patients may be exposed during a
deep inspiration to ensure the abdominal contents
from diaphragm to pubic symphysis are included on
the radiograph.
2. Patient motion: Breathing must be suspended in expiration to prevent the abdominal organs moving and
losing their definition.
Clinicoradiologic Correlations: The role of an abdominal radiograph in skeletal disorders is broad and often
a very necessary component of diagnosis and management. In thoracolumbar spine, pelvic, and hip disorders it
often plays a crucial role.
1. Alignment: Observe for scoliosis, the position of the
liver, the lower level of the right kidney, the gastric air
bubble, and the distribution of bowel gas.
BASIC: *AP
2. Bone: The spine, pelvis, sacrum, and lower ribs can all
be identified.
3. Cartilage: Joints, including the disc spaces, sacroiliac,
pubic, hips, and lower costals, can all be seen.
4. Soft tissue: Many soft tissue outlines of abdominal viscera can be determined because of their density and
outlines of capsular fat. The kidneys are tilted medially
at their superior poles parallel to the plane of the divergent psoas muscles and span three vertebral levels,
including their discs. The urinary bladder is dense because urine has a high specific gravity and the structure is surrounded by perivesical fat. The lower lobe of
the liver passes obliquely across the left upper quadrant, often depressing the transverse colon and hepatic flexure. Occasionally a variant tongue-like lower
right lobe of the liver extends into the right iliac fossa,
known as the Reidel lobe. The spleen abuts the stomach and can be seen at its lower pole. The large bowel
is recognized by the mucosal folds (haustra) being
widely separated. Semifluid feces in the right colon are
often speckled because they are a mixture of fluid and
gas. Solid feces in the transverse colon through to the
rectum form opaque rounded densities surrounded by
crescents of air. The layers of the abdominal wall—
including muscle and fascial and peritoneal fat—form
the flank stripe at the lateral abdominal margins.
Specialized Projections:
1. PA view: Obese patients should be examined PA to
compress the body tissues and decrease the time of
exposure.
2. Erect AP view: In bowel obstruction the presence of
air–fluid levels will be shown only on erect studies.
Pneumoperitoneum from a perforated hollow viscus
will also be demonstrated by accumulating beneath
the hemidiaphragms. Postural ptosis of the liver and
kidneys is common, with the right lobe of the liver
often lying in the right iliac fossa.
3. Decubitus views: This alternative to an erect study in
acutely ill patients will help show bowel obstruction
and pneumoperitoneum.
Normal Anatomy (Figure 1-67C )
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Liver.
Right kidney.
Gas in splenic flexure.
Solid feces in colon.
Semifluid feces in colon.
Haustra, descending colon.
Psoas margin.
Flank stripe.
T12 vertebral body.
Sacral ala.
Sacroiliac joint.
Iliac fossa.
Iliac crest.
Anterior superior iliac spine.
Femoral head.
Köhler’s teardrop.
Symphysis pubis.
Superior pubic ramus.
Cecum
Ascending colon
Figure 1-67 C. AP Abdomen.
189
190
I Yochum & Rowe’s Essentials of Skeletal Radiology
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192
I Yochum & Rowe’s Essentials of Skeletal Radiology
21. Dihlmann W: Diagnostic Radiology of the Sacroiliac Joints.
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SACRUM
1. Ferguson AB: The clinical and roentgenographic interpretation of lumbosacral anomalies. Radiology 22:548, 1934.
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3. Hibbs RA, Swift WE: Developmental abnormalities at the
lumbo-sacral juncture causing pain and disability: A report of
147 patients treated by spine fusion operation. Surg Gynec
Obst 48:604, 1929.
4. Christenson PC: The radiologic study of the normal spine:
Cervical, thoracic, lumbar, and sacral. Radiol Clin North Am
15:133, 1977.
5. Hoing M: A new technic of coccyxography. Xray Technol
7:68, 1935.
6. Zochert RW: The sacrum and coccyx: Location and technic
for radiography. Xray Technol 4:118, 1933.
7. Turner ML, Mulhern CB, Dalinka MK: Lesions of the
sacrum: Differential diagnosis and radiological evaluation.
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8. Amorosa JK, Wintraub S, Amorosa LF, et al.: Sacral destruction: Foraminal lines revisited. AJR 145:773, 1985.
9. Jackson H, Burke JT: The sacral foramina. Skeletal Radiol
11:282, 1984.
10. Yochum TR, Guebert GM, Kettner NW: The tilt-up view:
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11. Postacchini F, Massobrio M: Idiopathic coccygodynia:
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12. Maigne JY, Guedj S, Straus C: Idiopathic coccygodynia.
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COCCYX
1. Christenson PC: The radiologic study of the normal spine:
Cervical, thoracic, lumbar, and sacral. Radiol Clin North Am
15:133, 1977.
2. Hoing M: A new technic of coccyxography. Xray Technol
7:68, 1935.
3. Zochert RW: The sacrum and coccyx: Location and technic
for radiography. Xray Technol 4:118, 1933.
4. Postacchini F, Massobrio M: Idiopathic coccygodynia:
Analysis of fifty-one operative cases and a radiographic study
of the normal coccyx. J Bone Joint Surg 65A:1116, 1983.
5. Maigne JY, Guedj S, Straus C: Idiopathic coccygodynia.
Spine 19:930, 1994.
PELVIS
1. Bridgman CF: Radiography of the hip bone. Med Radiogr
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2. Liliequist B: Roentgenologic examination of the acetabular
part of the os coxae. Acta Radiol Diagn 4:289, 1966.
3. Armbuster TG: The adult hip: An anatomic study. Part I:
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4. Katz JF: Precise identification of radiographic acetabular
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5. Bowerman JW, Sena JM, Chang R: The teardrop shadow
of the pelvis: Anatomy and clinical significance. Radiology
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6. Mitton KL, Auringer EM: Roentgenological study of the
femoral neck. AJR 66:639, 1951.
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8. Guerra J, Armbuster TG, Resnick D, et al.: The adult hip: An
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9. Chamberlain WE: The symphysis pubis in the roentgen examination of the sacroiliac joint. AJR 24:621, 1930.
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12. Berkebile RD, Fischer DL, Albrecht LF: The gull wing sign:
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the acetabular rim and posterior dislocation of the femoral
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FULL SPINE
1. Farren J: Routine radiographic assessment of the scoliotic
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2. Davies WG: Radiography in the treatment of scoliosis and in
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3. Sausser WS: Achievement—Entire body x-ray technic perfected. ACA J Chiro 4(2):17, 1935.
4. Young LW, Oestreich AE, Goldstein LA: Roentgenology in
scoliosis: Contribution to evaluation and management. AJR
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5. Taylor JAM: Full-spine radiography: A review. J Manipulative
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6. Field TJ, Buehler MT: Improvements in chiropractic full
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8. Merkin JJ, Sportelli L: The effects of two new compensating filters on patient exposure in chiropractic full spine radiography.
J Manipulative Physiol Ther 5:25, 1982.
9. Gray JE, Hoffman AD, Peterson NA: Reduction of radiation
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10. Bhatnagar JP: X-ray doses to patients undergoing full-spine
radiographic examination. Radiology 138:231, 1981.
11. Greko PJ: Evaluation of quality of lateral full spine radiographs: A statistical study. J Manipulative Physiol Ther 15:217,
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HIP
1. Bridgman CF: Radiography of the hip joint. Med Radiogr
Photogr 26:2, 1950.
1 Normal Skeletal Anatomy and Radiographic Positioning I
2. Bridgman CF: Radiography of the hip joint. Med Radiogr
Photogr 27:2, 1951.
3. Bridgman CF: Radiography of the hip joint. Med Radiogr
Photogr 28:38, 1952.
4. Hooper AC, Ormond DJ: A radiographic study of hip rotation. Ir J Med Sci 144:25, 1975.
5. Armbuster TG: The adult hip: An anatomic study. Part I:
The bony landmarks. Radiology 128:1, 1978.
6. Guerra J, Armbuster TG, Resnick D, et al.: The adult hip: An
anatomic study. Part II. The soft tissue landmarks. Radiology
128:11, 1978.
7. Judet R, Judet S, Letournel E: Fractures of the acetabulum:
Classification and surgical approaches to open reduction.
J Bone Joint Surg 46A:1615, 1964.
8. Mitton KL, Auringer EM: Roentgenological study of the
femoral neck. AJR 66:639, 1951.
9. Stiles RG, Laverina CJ, Resnick D, Convery R: The calcar
femorale: An anatomic, radiologic, and surgical correlative
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21.
22.
23.
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25.
26.
27.
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KNEE
1. Larsen RM: Radiography of extremities. Xray Technol 12:215,
1941.
2. Harris J: Radiography of the lower limb. Radiography 31:235,
1965.
3. Funke T: Radiography of the knee joint. Med Radiogr Photogr
36:1, 1960.
4. Cockshott WP, Racoveanu NT, Burrows DA: Use of radiographic projections of knee. Skeletal Radiol 13:131, 1985.
5. Leach RE, Gregg T, Ferris JS: Weight-bearing radiography
in osteoarthritis of the knee. Radiology 97:265, 1970.
6. Thomas R, Resnick D, Alazraki N, et al.: Compartmental
evaluation of osteoarthritis of the knee: A comparative study of
available diagnostic modalities. Radiology 116:585, 1975.
7. Rosenburg TD, Paulos LE, Parker RD, et al.: The forty-five
degree posteroanterior flexion weight-bearing radiograph of
the knee. J Bone Joint Surg 70A:1479, 1988.
8. Moore TM, Harvey JP: Roentgenographic measurement of
tibial plateau depression due to fracture. J Bone Joint Surg
56A:155, 1974.
9. McPhee IB, Fraser JG: Stress radiography in acute ligamentous injuries of the knee. Injury 12:383, 1981.
10. Daffner RH, Tabas JH: Trauma oblique radiographs of the
knee. J Bone Joint Surg 69A:568, 1986.
11. Vaughan FMA: Lateral knees. Radiography 16:75, 1950.
12. Alexander OM: Routine lateral radiography of the knee and
ankle joints. Radiography 17:10, 1951.
13. Insall J, Salvati E: Patella position in the normal knee joint.
Radiology 101:101, 1971.
14. Pfirrmann CWA, Zanetti M, Romero J, Hodler J: Femoral
trochlear dysplasia: MR findings. Radiology 216:858, 2000.
15. Brossmann J, White LM, Stabler A, Preidler KW, et al.:
Enlargement of the third intercondylar tubercle of Parsons as
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16. Hall FM: Radiographic diagnosis and accuracy in knee joint
effusions. Radiology 115:49, 1975.
17. Lee JH, Weissman BN, Nikpoor N, et al.: Lipohemarthrosis
of the knee: A review of recent experiences. Radiology 173:189,
1989.
18. Scotti DM, Sadhu VK, Heimberg F, et al.: Osgood-Schlatter’s
disease: An emphasis on soft tissue changes in roentgen diagnosis. Skeletal Radiol 10:21, 1979.
19. Egund N, Friden T, Hjarbaek J, et al.: Radiographic assessment of sagittal knee instability in weight bearing. Skeletal
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20. Franklin JL, Rosenburg TD, Paulos LE, France EP:
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Camp JD, Coventry MB: Use of special views in roentgenography of the knee joint. US Naval Med Bull 42:56, 1944.
Holmblad EC: Postero-anterior x-ray view of the knee in
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Turner GW, Burns CB, Previtte RG: Erect positions for
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Settegast AL: Typische roentgenbilder von normalen menschen. Lahmanns Med Atlanten 5:211, 1921.
Hughston JC: Subluxation of the patella. J Bone Joint Surg
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Laurin CA, Dussault R, Levesque HP: The tangential x-ray
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Wiberg G: Roentgenographic and anatomic studies on the
femoropatellar joint. Acta Orthop Scand 12:319, 1941.
Laurin CA, Dussaulty R, Levesque HP: The tangential
x-ray investigation of the patellofemoral joint: X-ray technique, diagnostic criteria and their interpretation. Clin Orthop
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Engelstad BL, Friedman EM, Murphy WA: Diagnosis of
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Hughston JC: Subluxation of the patella. J Bone Joint Surg
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Merchant AC, Mercer RL, Jacobsen RH, Cool CR:
Roentgenologic analysis of the patellofemoral joint congruence. J Bone Joint Surg 56A:1391, 1974.
ANKLE
1. Larsen RM: Radiography of extremities. X-ray Technol 12:215,
1941.
2. Harris J: Radiography of the lower limb. Radiography 31:235,
1965.
3. Goergen TG, Danzig LA, Resnick D, et al.: Roentgenographic
evaluation of the tibiotalar joint. J Bone Joint Surg 59A:874,
1977.
4. Rowe LJ: Imaging of the ankle. In: AL Logan, ed, The Foot
and ankle. Clinical Applications. Gaithersburg, MD, Aspen
Publishers, 1995.
5. Thompson JP, Loomer RL: Osteochondral lesions of the
talus in a sports medicine clinic. A new radiographic technique
and surgical approach. Am J Sports Med 12(6):460, 1984.
6. Laurin CA, Ouellet R, St. Jaques R: Talar and subtalar tilt:
an experimental investigation. Can J Surg 11:270, 1968.
7. Sausser DD, Nelson RC, Lavine MH, Wu CW: Acute injuries
of the lateral ligaments of the ankle: Comparison of stress radiography and arthrography. Radiology 148:653, 1983.
8. Hutter CG Jr, Scott W: Tibial torsion. J Bone Joint Surg
31A:511, 1949.
9. Alexander OM: Routine lateral radiography of the knee and
ankle joints. Radiography 17:10, 1951.
10. Mandell J: Isolated fracture of the posterior tibial lip at the
ankle as demonstrated by an additional projection, the “poor”
lateral view. Radiology 101:319, 1971.
11. Jacobsen JA, Andresen R, Jaovisidha S, et al.: Detection of
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FOOT
1. Larsen RM: Radiography of extremities. Xray Technol
12:215, 1941.
2. Harris J: Radiography of the lower limb. Radiography
31:235, 1965.
3. Meschan I: Radiology of the normal foot. Semin Roentgenol
15:327, 1970
4. Graham D, Rorrison J: Radiography of the tarsal bones.
Radiography 28:156, 1962.
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5. Santora PJ: Anteroposterior view of the ankle joint and foot.
AJR 45:127, 1941.
6. Rowe LJ: Imaging of the ankle. In: AL Logan, ed, The Foot
and ankle. Clinical Applications. Gaithersburg, MD, Aspen
Publishers, 1995.
7. Piotrowski Brother D: Oblique view of the ankle joint and
foot. AJR 45:127, 1938.
8. Sartoris DJ, Resnick DL: Tarsal coalition. Arthritis Rheum
28(3):331, 1985.
9. Pavlov H, Torg SS, Freiberger RH: Tarsal navicular stress
fracture: Roentgen evaluation. Radiology 148:641, 1983.
10. Jacobsen JA, Andresen R, Jaovisidha S, et al.: Detection of
ankle effusions: Comparison study in cadavers using radiography, sonography and MR imaging. AJR 170: 1231, 1998.
TOES
1. Larsen RM: Radiography of extremities. Xray Technol 12:215,
1941.
2. Harris J: Radiography of the lower limb. Radiography 31:235,
1965.
3. Meschan I: Radiology of the normal foot. Semin Roentgenol
5:327, 1970.
4. Rowe LJ: Imaging of the ankle. In: AL Logan, ed, The Foot
and Ankle. Clinical Applications. Gaithersburg, MD, Aspen
Publishers, 1995.
CALCANEUS
1. Burdick AV: Calcaneus. Xray Technol 23:276, 1952.
2. Harris RI, Beath T: Etiology of peroneal spastic flat foot.
J Bone Joint Surg 30B:624, 1948.
3. Bohler L: Diagnosis, pathology, and treatment of fractures of
the os calcis. J Bone Joint Surg Am 13:75, 1930.
4. Broden B: Roentgen examination of the subtaloid joint in
fractures of the calcaneus. Acta Radiol 31:85, 1949.
5. Isherwood I: A radiological approach to the subtalar joint.
J Bone Joint Surg 43B:566, 1961.
SHOULDER
1. Lawrence WS: New position in radiographing the shoulder
joint. AJR 2:728, 1915.
2. Freedman E: Radiography of the shoulder. Radiogr Clin
Photogr 10:8, 1934.
3. Jones ML: Radiographic examination of the shoulder. Xray
Technol 7:104, 1936.
4. Blackett CW, Healy TR: Roentgen studies of the shoulder.
AJR 37:760, 1937.
5. Knutsson F: An axial projection of the shoulder joint. Acta
Radiol 30:214, 1948.
6. Stripp WJ: Radiographs of the scapulothoracic region. Xray
Focus 4:8, 1963.
7. Helms CA. Pseudocysts of the humerus. AJR 131:287, 1978.
8. Garth WP, Slappey CE, Ochs CW: Roentgenographic
demonstration of instability of the shoulder: The apical oblique
projection. J Bone Joint Surg 66A:1450, 1984.
9. Kilcoyne RF, Reddy PK, Lyons F, et al: Optimal plain film
imaging of the shoulder impingement syndrome. AJR 153:795,
1989.
10. ViGario GD, Keats TE: Localization of calcific deposits in
the shoulder. AJR 108:806, 1970.
11. Bloom RA: The active abduction view: A new manoeuvre in
the diagnosis of rotator cuff tears. Skeletal Radiol 20:255,
1991.
12. Rokous JR, Feagin JA, Abott HG: Modified axillary
roentgenogram. Clin Orthop 82:84, 1972.
13. Fisk C: Adaptation of the technique for radiography of the
bicipital groove. Radiol Technol 34:47, 1965.
14. Lawrence WS: A method of obtaining an accurate lateral
roentgenogram of the shoulder. AJR 5:193, 1918.
15. Rubin SA, Gray RL, Green WR: The scapular “Y”: A diagnostic aid in shoulder trauma. Radiology 110:725, 1974.
16. Kwak DL, Espiniella JL, Kattan JL: Angled anterposterior
views of the shoulder. Radiol Technol 53:590, 1982.
CLAVICLE
1. Quesada F: Technique for the roentgen diagnosis of fractures
of the clavicle. Surg Gynecol Obstet 42:424, 1926.
2. Stripp WJ: The clavicle and the acromioclavicular joint.
Xray Focus 4:21, 1963.
3. Zanca P: Shoulder pain: Involvement of the acromioclavicular joint. Analysis of 1000 cases. AJR 112:493, 1971.
ACROMIOCLAVICULAR JOINTS
1. Alexander OM: Radiography of the acromioclavicular joint.
Radiography 54:139, 1948.
2. Alexander OM: Radiography of the acromioclavicular articulation. Med Radiogr Photogr 30:34, 1954.
3. Zanca P: Shoulder pain: Involvement of the acromioclavicular joint. Analysis of 1000 cases. AJR 112:493, 1971.
4. Rockwood CA, Green DP: Fractures. Vol 1. Philadelphia,
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5. Bossart PJ: Lack of efficacy of “weighted” radiographs in
diagnosing acute acromioclavicular separation. Ann Emerg
Med 17:20, 1988.
6. Keats TE, Pope TL Jr: The acromioclavicular joint: normal
variation and the diagnosis of dislocation. Skeletal Radiol
17:159, 1988.
7. Edelson JG, Taitz C: Anatomy of the coraco-acromial arch.
J Bone Joint Surg 74B:589, 1992.
ELBOW
1. Buxton D: A radiographic survey of normal joints: The elbow
joint. Br J Radiol 29:395, 1924.
2. Rogers LF: Fractures and dislocations of the elbow. Semin
Roentgenol 13:97, 1978.
3. Holly EW: Radiography of the radial head. Med Radiogr
Photogr 32:13, 1956.
4. Bledsoe RC, Izenstark JL: Displacement of fat pads in disease
and injury to the elbow: A new radiographic sign. Radiology
73:717, 1959.
5. Rogers SL, MacEwan DW: Changes due to trauma in the fat
plane overlying the supinator muscle: A radiographic sign.
Radiology 92:954, 1969.
6. Greenspan A, Norman A: Radial head—capitulum view: An
expanded imaging approach to elbow injury. Radiology
164:272, 1987.
7. Jones R: A note on the treatment of injuries about the elbow.
Prov Med J 14:28, 1895.
8. St. John JN, Palmaz JC: The cubital tunnel in ulnar entrapment neuropathy. Radiology 158:119, 1986.
WRIST
1. Buxton D: A radiographic survey of normal joints: The wrist
joint and hand. Br J Radiol 32:199, 1927.
2. Roderick JF: The roentgenographic examination of the carpus.
Xray Technol 18:8, 1946.
3. Alexander OM: Radiography of the wrist. Radiology 4:181,
1938.
4. DeSmet AA, Martin NL, Fritz SL, et al.: Radiographic projections for the diagnosis of arthritides of the hands and wrists.
Radiology 139:577, 1981.
5. Gilula LA: Carpal injuries: Analytic approach and case exercises. AJR 133:503, 1979.
6. Terry DW Jr, Ramin JE: The navicular fat stripe: A useful
roentgen feature for evaluating wrist trauma. AJR 124:25, 1975.
7. Gilula LA Weeks PM: Post-traumatic ligamentous instabilities of the wrist. Radiology 129:641, 1978.
8. Jones WA: Beware the sprained wrist: The incidence and diagnosis of scapholunate instability. J Bone Joint Surg 70B:293,
1988.
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9. Kindynis P, Resnick D, Kang HS, et al.: Demonstration of
the scapholunate space with radiography. Radiology 175:278,
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10. Lentino W, Lubetsky HW, Jacobsen HG, Poppel MH: The
carpal bridge view. J Bone Joint Surg 39A:88, 1957.
11. Conway WF, Destouet JM, Gilula LA, et al.: The carpal boss:
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12. Gruber L: Practical approaches to obtaining hand radiographs
and special techniques in hand radiology. Hand Clin 7:1, 1991.
13. Hart VL, Gaynor V: Roentgenographic study of the carpal
canal. J Bone Joint Surg 23A:382, 1941.
14. Abbitt PL, Riddervold HO: The carpal tunnel view: Helpful
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15. Bridgman CF: Radiography of the carpal navicular bone.
Med Radiogr Photogr 25:104, 1949.
16. Fodor J, Malott JC: Radiography of the carpal navicular.
Radiol Technol 52:175, 1980.
17. Gilula LA, Yin Y: Imaging of the Wrist and Hand.
Philadelphia, WB Saunders, 1996.
18. Stecher WR: Roentgenography of the carpal navicular bone.
AJR 37:307, 1937.
19. Lewis RW: Oblique views in roentgenography of the wrist.
AJR 50:119, 1943.
20. MacEwan DW: Changes due to trauma in the fat plane of
the pronator quadratus muscle: A radiologic sign. Radiology
82:879, 1964.
21. Carver RA, Barrington NA: Soft tissue changes accompanying scaphoid fractures. Clin Radiol 36:423, 1985.
22. Gilula LA Weeks PM: Post-traumatic ligamentous instabilities of the wrist. Radiology 129:641, 1978.
23. Cuono CB, Watson HK: The carpal boss: Surgical treatment
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HAND
1. Buxton D: A radiographic survey of normal joints: The wrist
joint and hand. Br J Radiol 32:199, 1927.
2. DeSmet AA, Martin NL, Fritz SL, et al.: Radiographic projections for the diagnosis of arthritides of the hands and wrist.
Radiology 139:577, 1981.
3. Yeh HC, Wolf BS: Radiographic anatomical landmarks of
the metacarpophalangeal joints. Radiology 122:353, 1977.
4. Brewerton DA: A tangential radiographic projection for
demonstrating involvement of the metacarpal heads in rheumatoid arthritis. Br J Radiol 40:233, 1967.
5. Lane CS: Detecting occult fractures of the metacarpal head:
The Brewerton view. J Hand Surg 2:131, 1977.
6. Kaye JJ, Lister GD: Another use for the Brewerton view.
J Hand Surg (Am) 3:603, 1978.
7. Greulich WW, Pyle SI: Radiographic Atlas of Skeletal
Development of the Hand and Wrist, ed 2. Stanford, CA,
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8. Gramiak R: Oblique radiography of the hands. Med Radiogr
Photogr 42:28, 1966.
9. Gilula LA, Yin Y: Imaging of the Wrist and Hand.
Philadelphia, WB Saunders, 1996.
10. Fisher MR, Rogers LF, Hendrix RW: Systematic approach to
identifying fourth and fifth carpometacarpal joint dislocations.
AJR 140:319, 1983
11. Norgaard F: Earliest roentgenological changes in polyarthritis of the rheumatoid type: Rheumatoid arthritis. Radiology
85:325, 1965.
12. Norgaard F: Earliest roentgenological changes in polyarthritis of the rheumatoid type. Radiology 92:299, 1969.
FINGERS
1. Buxton D: A radiographic survey of normal joints: The wrist
joint and hand. Br J Radiol 32:199, 1927.
195
2. DeSmet AA, Martin NL, Fritz SL, et al.: Radiographic projections for the diagnosis of arthritides of the hands and wrists.
Radiology 139:577, 1981.
3. Yeh HC, Wolf BS: Radiographic anatomical landmarks of
the metacarpophalangeal joints. Radiology 122:353, 1977.
4. Reichmann S, Deichgraber E, Strid KG, et al.: Soft-tissue
radiography of finger joints. Acta Radiol 15:439, 1974.
5. Gilula LA, Yin Y: Imaging of the Wrist and Hand.
Philadelphia, WB Saunders, 1996.
6. Street JM: Radiographs of phalangeal fractures: Importance
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7. De Smet AA, Doherty MP, Norris MA, et al.: Are oblique
views needed for trauma radiography of the distal extremities? AJR 172:1561, 1999.
8. Conway WF, Destouet JM, Gilula LA, et al.: The carpal boss:
An overview of radiographic evaluation. Radiology 156:29,
1985.
THUMB
1. Buxton D: Radiographic survey of normal joints: The wrist
joint and hand. Br J Radiol 32:199, 1927.
2. DeSmet AA, Martin NL, Fritz SL, et al.: Radiographic projection for the diagnosis of arthritides of the hands and wrists.
Radiology 139:577, 1981.
3. Kaye JJ: Fractures and dislocations of the hand and wrist.
Semin Roentgenol 13:109, 1978.
4. Jones RP, Leach RE: Fracture of the ulnar sesamoid bones
of the thumb. Am J Sports Med 8:446, 1980.
5. Bennett EH: On fracture of the metacarpal bone of the
thumb. Clin Orthop 220:3, 1987.
6. Burman M: Anteroposterior projection of the carpometacarpal joint of the thumb by radial shift of the carpal tunnel view. J Bone Joint Surg 40A:1156, 1958.
7. Downey EF, Curtis DJ: Patient-induced stress test of the first
metacarpophalangeal joint: A radiographic assessment of collateral ligament injuries. Radiology 158:679, 1986.
RIBS
1. Bartsch GW: Radiographic examination of the ribs. Xray
Technol 14:18, 1942.
2. Rogers NJS: A technique of x-ray examination of the ribs.
Radiography 9:7, 1943.
3. Bridgeman CF, Holly EW, Zariquiey MO: Radiography of
the ribs and costovertebral joints. Med Radiogr Photogr 32:38,
1956.
4. Hohmann D, Gasteiger W: Roentgen diagnosis of the costovertebral joints. Fortschr Roentgenstr 112:783, 1970.
5. Morris L, Bailey J: A simple method to demonstrate the ribs
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7. Guttentag AR, Salwen JK: Keep your eyes on the ribs: The
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CHEST
1. Pesauera GS: The evolution of chest roentgenographic technique. AJR 40:405, 1938.
2. Kattan KR, Wiot JF: How was this roentgenogram taken,
AP or PA? AJR 117:843, 1973.
3. Bauer RG: High kilovoltage chest radiography with an air
gap. Radiol Technol 42:10, 1970.
4. Kattan K: High kilovoltage oblique roentgenography of the
chest: Its advantage in differential diagnosis of the lung and
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5. Proto AV, Speckman JM: The left lateral radiograph of the
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I Yochum & Rowe’s Essentials of Skeletal Radiology
6. Riggs W Jr, Parvey L: Differences between right and left lateral chest radiographs. AJR 127:997, 1976.
7. Bachman DM, Ellis K, Austin JH: The effects of minor degrees of obliquity on the lateral chest radiograph. Radiol Clin
North Am 16:465, 1978.
8. Bray HA: A suggestion for improving the visibility of the apical field on the chest radiogram. AJR 8:602, 1921.
9. Lavner G, Copelman B: The anteroposterior lordotic projection in the roentgenographic examination of the lungs.
Radiology 43:135, 1944.
10. Zinn B, Monroe J: The lordotic position in fluoroscopy and
roentgenography of the chest. AJR 75:682, 1956.
11. Jacobson G, Sargent EN: Apical roentgenographic views of
the chest. AJR 104:822, 1968.
12. Baum F, Black LT: The importance of the apical roentgenogram in pulmonary tuberculosis. Am Rev Tuber 12:228,
1925.
13. Flaxman AJ: Apical tuberculosis with roentgen technique.
Am Rev Tuber 54:1, 1946.
ABDOMEN
1.
2.
3.
Williams FH: X-ray examination of the abdomen. Boston
Med Surg J 23:20, 1900.
Kelly JF, Dowell DH: The value of the preliminary film without opaque media in the diagnosis of abdominal conditions.
Radiology 29:104, 1937.
Miller RE: The technical approach to the acute abdomen.
Semin Roentgenol 8:267, 1973.
Measurements in
Skeletal Radiology
2
Lindsay J. Rowe and Terry R. Yochum
INTRODUCTION
CORRECTION OF GEOMETRIC
DISTORTION
SKULL
VASTINE-KINNEY METHOD OF PINEAL
GLAND LOCALIZATION
SELLA TURCICA SIZE
BASILAR ANGLE
MCGREGOR’S LINE
CHAMBERLAIN’S LINE
MACRAE’S LINE
DIGASTRIC LINE
HEIGHT INDEX OF KLAUS
BOOGARD’S LINE AND ANGLE
ANTERIOR ATLANTO-OCCIPITAL
DISLOCATION MEASUREMENT
CERVICAL SPINE
ATLANTODENTAL INTERSPACE
METHOD OF BULL
GEORGE’S LINE
POSTERIOR CERVICAL LINE
SAGITTAL DIMENSION OF THE CERVICAL
SPINAL CANAL
ATLANTOAXIAL ALIGNMENT
CERVICAL GRAVITY LINE
CERVICAL LORDOSIS
STRESS LINES OF THE CERVICAL SPINE
PREVERTEBRAL SOFT TISSUES
THORACIC SPINE
COBB’S METHOD OF SCOLIOSIS EVALUATION
RISSER-FERGUSON METHOD OF
SCOLIOSIS EVALUATION
THORACIC KYPHOSIS
THORACIC CAGE DIMENSION
LUMBAR SPINE
INTERVERTEBRAL DISC HEIGHT
LUMBAR INTERVERTEBRAL DISC ANGLES
LUMBAR LORDOSIS
LUMBOSACRAL LORDOSIS ANGLE
SACRAL INCLINATION
LUMBOSACRAL ANGLE
LUMBOSACRAL DISC ANGLE
STATIC VERTEBRAL MALPOSITIONS
LUMBAR GRAVITY LINE
MACNAB’S LINE
HADLEY’S S CURVE
VAN AKKERVEEKEN’S MEASUREMENT OF
LUMBAR INSTABILITY
DEGENERATIVE LUMBAR SPINAL INSTABILITY:
FLEXION–EXTENSION
DEGENERATIVE LUMBAR INSTABILITY:
LATERAL BENDING
LATERAL-BENDING SIGN
MEYERDING’S GRADING METHOD IN
SPONDYLOLISTHESIS
ULLMANN’S LINE
INTERPEDICULATE DISTANCE
EISENSTEIN’S METHOD FOR SAGITTAL CANAL
MEASUREMENT
CANAL TO BODY RATIO
INTERCRESTAL LINE
LENGTH OF LUMBAR TRANSVERSE PROCESSES
LOWER EXTREMITY
TEARDROP DISTANCE
INTRODUCTION
Since the time of the first roentgen image, measurements have
been used to evaluate normal and abnormal skeletal relationships. Many measurements have been determined through astute
observation and appropriate statistical evaluation.
In all analytical assessments of skeletal spatial relationships,
the outcome depends on the quality of the radiographic data
collected and on its correct interpretation. Any attempt to measure and quantify the human frame has inherent uncontrolled
error. The major errors arising in the mensuration process in-
HIP JOINT SPACE WIDTH
ACETABULAR DEPTH
CENTER–EDGE ANGLE
SYMPHYSIS PUBIS WIDTH
PRESACRAL SPACE
ACETABULAR ANGLE
ILIAC ANGLE AND INDEX
MISCELLANEOUS MEASUREMENTS OF
THE GROWING HIP
MEASUREMENTS OF PROTRUSIO ACETABULI
SHENTON’S LINE
ILIOFEMORAL LINE
FEMORAL ANGLE
SKINNER’S LINE
KLEIN’S LINE
AXIAL RELATIONSHIPS OF THE KNEE
PATELLAR POSITION
PATELLAR MALALIGNMENT
AXIAL RELATIONSHIPS OF THE ANKLE
HEEL PAD MEASUREMENT
BOEHLER’S ANGLE
UPPER EXTREMITY
AXIAL RELATIONSHIPS OF THE SHOULDER
GLENOHUMERAL JOINT SPACE
ACROMIOHUMERAL JOINT SPACE
ACROMIOCLAVICULAR JOINT SPACE
AXIAL RELATIONSHIPS OF THE ELBOW
RADIOCAPITELLAR LINE
AXIAL RELATIONSHIPS OF THE WRIST
METACARPAL SIGN
REFERENCES
clude (a) image unsharpness, (b) projectional geometric distortion,
(c) inconsistency in patient positioning, (d ) individual anatomic
variation, (e) imprecision in locating standard reference points, and
( f ) observer error. (1–4)
Additional confusion exists around the issues of clinical interpretation of measurements and their application to treatment protocols. This is highlighted in the spine and pelvis, where small
measurements derived from various systems of analysis have often
exerted a strong influence on treatment regimes. Among the various systems of analysis there appears to be little correlation in
the results obtained. (1,5–7) Many measurements have been used
to evaluate spinal segmental motion abnormalities from static
radiographs, which inadequately reflect motion biomechanics.
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In general, any measurement is meaningless unless it is performed accurately and correlated clinically. (8,9) Too often it is
the x-ray that is treated, not the patient. To rely on a radiographic
measurement as the sole criterion for a particular treatment method
is a frail approach to patient care.
In this chapter each measurement is described according to synonyms, optimum projections, landmark reference points, normal
values, special considerations, and significance. Whenever numerical data are given, they have been rounded for simplicity. Unless
otherwise stated, the measurements are film image sizes and are
not corrected for true anatomic dimensions. References to the literature are included so the reader may seek further information.
Medicolegal Implications
RADIOGRAPHIC MEASUREMENTS
•
•
•
•
•
•
•
• The application of standard lines and measurements to radiographs often allows the
detection of subtle abnormalities and assists
in avoiding misdiagnosis.
Comparison of studies is facilitated. This may allow regression or progression of the disorder to be recognized
and the response to therapy quantified.
Inherent errors in skeletal measurements are well recognized and must be minimized. The major errors arising in
the mensuration process include (a) image unsharpness
(image quality), (b) projectional geometric distortion,
(c) inconsistency in patient positioning, (d ) individual
anatomic variation, (e) imprecision in locating standard
reference points, and (f ) observer error. (1–4)
The normal range within a population for age and sex
must be known as well as the significance of an abnormal
measurement.
Applying a measurement or line analysis system does not
replace a pathologic evaluation of radiographs. Measurements and lines should be applied only after the film
has been pathologically evaluated. No films should be
obtained purely for a line or angular analysis.
Accurate measurements cannot be made on poor-quality
or poorly positioned radiographs.
Drawing on radiographs should be done only with a
medium that can be readily removed without defacing
the image, in case the need arises. Lines and angles should
be marked on radiographs as sparingly as is clinically
practicable.
Any measurement made should not be the sole criterion
for a diagnosis or for establishing a treatment regime. All
measurements must be correlated clinically.
CORRECTION OF
GEOMETRIC DISTORTION
Numerous methods can be used to determine the anatomic dimensions demonstrated on a given radiograph. These include nomograms and algebraic formulations. (1,2) The roentgen image is
always larger than the true anatomic size because of the effect of
diverging rays on a structure not in close contact with the film.
To algebraically arrive at the correct object size (O), three
values must be known: (Fig. 2-1)
• Film image dimension (cm) (I)
• Target film distance (cm) (D)
• Object film distance (cm) (d)
Initially, a correction factor (CF ) is calculated:
CF =
D−d
D
The film image dimension (I) is then multiplied by this correction factor:
O = I × CF
Anode
D–d
D
O
d
I
Figure 2-1 GEOMETRIC DISTORTION IN IMAGE PRODUCTION.
2
Measurements in Skeletal Radiology I
SKULL
Vastine-Kinney Method
of Pineal Gland Localization
Synonyms. None.
Technique
Projection. Lateral skull.
Landmarks. The pineal gland must be visible as a result of calcium deposition before the following four measurements are
made: (1) (Fig. 2-2)
A. The greatest distance from the pineal gland to the inner
table of the frontal bone
B. The greatest distance from the pineal gland to the inner
aspect of the occipital bone
C. The greatest distance from the pineal gland to the inner
table of the skull vertex
D. The greatest distance from the pineal gland to the
posterior margin of the foramen magnum
Normal Measurements. Measurements A and B are used to assess anterior or posterior pineal displacement, whereas measurements C and D are used to assess superior or inferior displacement.
• Anteroposterior (AP) position. Measurement A is plotted
against the sum of A and B and should fall within the
specified range.
• Superoinferior position. Measurement C is plotted against
the sum of C and D and also should fall within a specified
range. (2)
Special Considerations. An alternative and more accurate method
for pineal gland localization is the Pawl-Walter method. (3)
Significance. A pineal shift may be caused by a space-occupying
mass, such as a tumor, hemorrhage, or localized atrophic cerebral
disease. The most accurate means by which to locate the pineal
gland is the MRI scan.
Figure 2-2 VASTINE-KINNEY METHOD OF PINEAL
LOCALIZATION. A and B. See text.
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Sella Turcica Size
Basilar Angle
Synonyms. Pituitary fossa size.
Technique
Projection. Lateral skull.
Landmarks. Two measurements are made: the greatest AP diameter and the greatest vertical diameter. The AP value is the widest
distance between the anterior and posterior surfaces of the pituitary
fossa. The vertical dimension is between the fossa floor and the
plane between the opposing surfaces of the anterior and posterior
clinoid processes. (4,5) (Fig. 2-3)
Normal Measurements. The AP dimension averages about
11 mm, with a normal range of 5–16 mm. The vertical measurement averages about 8 mm, with a normal range of 4 –12 mm.
(4–6) (Table 2-1) In children these values will be progressively
smaller with decreasing chronologic age.
Synonyms. Welcker’s basilar angle, Martin’s basilar angle,
sphenobasilar angle.
Technique
Projection. Lateral skull.
Landmarks. Three points are located and joined together by two
lines; the subsequent angle is measured. The three points are the
nasion (frontal–nasal junction), the center of the sella turcica (midpoint between the clinoid processes), and the basion (anterior
margin of the foramen magnum). (Fig. 2-4)
Normal Measurements. The average normal angle subtended
by these two lines is 137°, with a normal variation of 123–152°.
(8) (Table 2-2)
Table 2-2
Table 2-1
Normal Values for Sella Turcica Size
Diameter
Average
(mm)
Minimum
(mm)
Maximum
(mm)
Anteroposterior
Vertical
11
8
5
4
16
12
Special Considerations. All lateral flexion and rotation of the
skull should be eliminated for these measurements to be accurate.
Significance. The finding of a small sella is of debatable significance. (7) However, an enlarged sella may be associated with a
pituitary neoplasm, empty sella syndrome, or extrapituitary mass
(neoplasm, aneurysm); it may even be a normal variant.
Average (°)
137
Normal Values for Basilar Angle
Minimum (°)
123
Maximum (°)
152
Special Considerations. None.
Significance. The measurement is an index of the relationship
between the anterior skull and its base. The angle will increase
beyond 152° in platybasia, in which the base is elevated in relation to the rest of the skull. This may or may not be associated
with basilar impression. The deformity may be congenital (isolated impression, occipitalization) or acquired (Paget’s disease,
rheumatoid arthritis, fibrous dysplasia).
Figure 2-3 LATERAL MEASUREMENTS OF THE SELLA
TURCICA. A and B. See text.
Figure 2-4 BASILAR ANGLE. A and B. See text.
2
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201
McGregor’s Line
Synonyms. Basal line.
Technique
Projection. Lateral skull; lateral cervical spine.
Landmarks. A line is drawn from the posterosuperior margin of
the hard palate to the most inferior surface of the occipital bone.
(9) The relationship of the odontoid apex to this line is then
examined. (Fig. 2-5)
Normal Measurements. In 90% of individuals the odontoid
apex should not lie above this line > 8 mm in males and > 10 mm
in females. (9) In children younger than 18 years, these maximum values diminish with decreasing chronologic age.
Special Considerations. Of all methods used to evaluate for basilar impression on the lateral projection, McGregor’s line appears
to be the most accurate and reproducible. (10)
Significance. An abnormal superior position of the odontoid
indicates basilar impression. Common precipitating causes include
platybasia, atlas occipitalization, and bone-softening diseases of
the skull base (e.g., Paget’s disease, osteomalacia, and fibrous
dysplasia). Occasionally, rheumatoid arthritis may also precipitate this deformity.
Figure 2-5 MCGREGOR’S LINE. A and B. Normal Line. See
text. C. Abnormal Line. Note the tip of the odontoid
(retouched) is well above the line owing to basilar invagination from Paget’s disease.
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Chamberlain’s Line
Macrae’s Line
Synonyms. Palato-occipital line.
Technique
Projection. Lateral skull; lateral cervical spine.
Landmarks. A line is constructed from the posterior margin of
the hard palate to the posterior aspect of the foramen magnum. The
relationship of this line to the tip of the odontoid process is then
assessed. (11) (Fig. 2-6)
Normal Measurements. In the majority of patients the tip of the
odontoid process should not project above this line; however, a
normal variation of 3 mm above this line may occur. (8) A measurement of ≥ 7 mm is definitely abnormal.
Special Considerations. This relationship can also be evaluated
on lateral cervical views but is best done on lateral skull films,
preferably with computed tomography (CT). To locate the
posterior aspect of the foramen magnum, identify the inner table
of the occipital bone, follow it anteriorly, and observe for an
oblique cortical white line crossing the diploe to merge with the
outer table. This should be found slightly posterior to the plane of
the atlas spinolaminar junction.
Significance. An abnormal superior position of the odontoid
indicates basilar impression. Common precipitating causes include platybasia, atlas occipitalization, and bone-softening diseases of the skull base (e.g., Paget’s disease, osteomalacia, and
fibrous dysplasia). Occasionally, rheumatoid arthritis may also
precipitate this deformity.
Synonyms. Foramen magnum line.
Technique
Projection. Lateral skull.
Landmarks. A line is drawn between the anterior ( basion) and
posterior (opisthion) margins of the foramen magnum. Two assessments are then made in relation to this line: (a) the occipital
bone and (b) the odontoid process. (Fig. 2-7)
Normal Measurements. The inferior margin of the occipital
bone should lie at or below this line. In addition a perpendicular
line drawn through the odontoid apex should intersect this line in
its anterior quarter. (10,12)
Special Considerations. A true lateral view with no lateral flexion distortion should be obtained for this positional line to be
applied.
Significance. If the inferior margin of the occipital bone is
convex in a superior direction and/or lies above this line, then basilar impression is present. Predisposing causes include platybasia,
occipitalization, rheumatoid arthritis, and bone-softening diseases
(e.g., Paget’s disease, osteomalacia, and fibrous dysplasia). If the
odontoid apex does not lie in the ventral quarter of this line, a dislocation of the atlanto-occipital joint or a fracture or dysplasia of
the dens may be present.
Figure 2-7 MACRAE’S LINE. A and B. See text.
Figure 2-6 CHAMBERLAIN’S LINE. A and B. See text.
2
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203
Digastric Line
Height Index of Klaus
Synonyms. Biventer line.
Technique
Projection. AP open mouth.
Landmarks. The digastric groove medial to the base of the mastoid process is located on each side and a line is drawn between
them. The vertical distance to the odontoid apex and atlantooccipital joints is then measured. (Fig. 2-8)
Normal Measurements. The digastric line–odontoid apex measurement averages 11 mm but may range between 1 and 21 mm.
The odontoid should not project above this line. The digastric
line–atlanto-occipital joint average measurement is 12 mm, with
a normal range between 4 and 20 mm. (10,13) (Table 2-3)
Synonyms. None.
Technique
Projection. Lateral skull; lateral cervical spine.
Landmarks. A line is drawn from the tuberculum sellae to the internal occipital protuberance. The vertical distance between this
line and the apex of the odontoid is measured. (14) (Fig. 2-9)
Normal Measurements. See Table 2-4.
Table 2-4
Average (mm)
40–41
Normal Values for Height Index of Klaus
Minimum (mm)
30
Normal Values for Digastric Line
Table 2-3
Measure
Digastric line–
odontoid apex
Digastric line–
atlanto-occipital
joint
Average
(mm)
Minimum
(mm)
Maximum
(mm)
11
1
21
12
4
20
Special Considerations. None.
Significance. A measurement < 30 mm indicates basilar impression. Values between 30 and 36 mm reflect a tendency toward
basilar impression. (10,14) The wide range of normal variation
casts doubt on the usefulness of this measurement. (12)
Special Considerations. Computed tomography (CT) evaluation
is the most accurate method for obtaining clear visualization of
the necessary anatomic landmarks.
Significance. Both measurements will decrease in basilar
impression owing to platybasia, occipitalization, and bonesoftening diseases (e.g., Paget’s disease, osteomalacia, and fibrous
dysplasia).
Figure 2-9 HEIGHT INDEX OF KLAUS. See text.
Figure 2-8 DIGASTRIC LINE. See text.
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Boogard’s Line and Angle
Synonyms. None.
Technique
Projection. Lateral skull; lateral cervical spine.
Landmarks
• Boogard’s line. A line is drawn connecting the nasion to
the opisthion. (15) (Fig. 2-10A)
• Boogard’s angle. (a) A line is drawn between the
basion and the opisthion (Macrae’s line). (b) A second line
is drawn from the dorsum sellae to the basion along the
plane of the clivus. (c) The angle between these two lines
is measured. (15) (Fig. 2-10B)
Normal Measurements
• Boogard’s line. The basion should lie below this line.
• Boogard’s angle. See Table 2-5.
Table 2-5
Normal Values for Boogard’s Angle
Average (°)
Minimum (°)
Maximum (°)
122
119
135
Special Considerations. None.
Significance. Both measurements will be altered in basilar
impression—the basion will be above Boogard’s line, and the
angle will be > 135°.
Figure 2-10 BOOGARD’S LINE AND ANGLE. A. Boogard’s
Line. See text. B. Boogard’s Angle. See text.
2
Anterior Atlanto-Occipital
Dislocation Measurement
Synonyms. Power’s index.
Technique
Projection. Lateral cervical spine; lateral skull.
Landmarks. Four osseous landmarks are located: the basion,
opisthion, and anterior and posterior arches of the atlas. Two
measurements are then made: The first is the distance between
the basion and the posterior arch at the spinolaminar junction
Measurements in Skeletal Radiology I
205
(B–P), and the second is the distance between the opisthion and
the posterior margin of the anterior arch (O–A). The ratio of these
two measurements (B–P:O–A) is then calculated. (16) (Fig. 2-11)
Normal Measurements. In the normal individual the ratio is
always < 1.
Special Considerations. This relationship can be assessed only
when there are no associated fractures or dislocations of the atlas
and odontoid process.
Significance. When the ratio is ≥ 1, then an anterior atlantooccipital dislocation probably exists.
Figure 2-11 ATLANTO-OCCIPITAL RELATIONSHIP. A. Normal Relationship. B. Anterior Dislocation. See text. Observe the
posterior arch fracture of C1 (arrow). (Courtesy of Steven B. Wasserman, DC, Long Beach, California.)
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CERVICAL SPINE
Atlantodental Interspace (ADI)
Synonyms. Atlas–odontoid space, predental interspace, atlas–
dens interval.
Technique
Projection. Lateral neutral; flexion–extension cervical spine.
Landmarks. The distance measured is between the posterior margin of the anterior tubercle and the anterior surface of the odontoid.
(Fig. 2-12)
Normal Measurements. A small, insignificant difference exists
between males and females. The measurement is slightly increased
in normal children. (1,2) (Table 2-6) In flexion the shape of the interspace takes on a V configuration, whereas in extension it has an
inverted V pattern. (3,4)
Special Considerations. Flexion is the optimum view to assess
the interspace, because in this position the most stress is placed
on the transverse ligament of the atlas.
Figure 2-12 ATLANTODENTAL INTERSPACE. A. Normal
Adult Interspace. The interspace measures < 3 mm (arrows ).
B. Abnormal Interspace. On flexion a patient with rheumatoid arthritis exhibits anterior translation of the atlas by
5 mm (arrows ). C. Normal Childhood Interspace. The inter-
Table 2-6
Normal Values for Atlantodental
Interspace
Age
Minimum (mm)
Maximum (mm)
Adults
Children
1
1
3
5
Significance. There are numerous disorders that may alter the
interspace. A decreased space is to be expected with advancing age
because of degenerative joint disease of the atlantodental joint. A
more significant change is an abnormally widened space with reduction in the neural canal size. (5) The most frequent causes
include trauma, occipitalization, Down’s syndrome, pharyngeal infections (Grisel’s disease), and inflammatory arthropathies
(e.g., ankylosing spondylitis, rheumatoid arthritis, psoriatic
arthritis, and Reiter’s syndrome). (5,6)
space measures < 5 mm (arrows). D. CT Scan, Abnormal
Interspace. In this patient with rheumatoid arthritis, the atlantodental interspace is increased (arrowheads). Note the
erosion at the posterior surface of the odontoid at the site
of synovial tissue beneath the transverse ligament (arrow).
2
Measurements in Skeletal Radiology I
207
Method of Bull
George’s Line
Synonyms. None.
Technique
Projection. Lateral skull; lateral cervical spine.
Landmarks. Two lines are drawn and the resultant angle measured. The first line is drawn from the posterior aspect of the
hard palate to the posterior margin of the foramen magnum
(Chamberlain’s line). The second line is drawn through the midpoints of the anterior and posterior tubercles of the atlas (atlas
plane line). The angle formed posteriorly is then measured. (7)
(Fig. 2-13)
Normal Measurements. The posterior angle formed by these
two lines should be 13°. If this angle is > 13°, it is abnormal. (2)
Special Considerations. The accuracy of this measurement is affected in individuals with acute neck pain owing to muscular
spasm.
Significance. The angle will increase if the odontoid is tilted
posteriorly because of congenital malformation or fracture displacement. In some individuals the atlas may be altered in position, which changes this angle even in the absence of odontoid abnormality.
Synonyms. Posterior vertebral alignment line, posterior
body line.
Technique
Projection. Lateral cervical spine.
Landmarks. The posterior vertebral body surfaces are connected
with a continuous line that traverses the intervertebral disc. A
straight line cannot be drawn because of the normal concavity of
the posterior surface. The key landmarks are the alignment of the
superior and inferior posterior body corners. (Fig. 2-14)
Normal Measurements. Normally, there is a smooth vertical
alignment of each posterior body corner.
Special Considerations. Flexion and extension films are especially useful in determining disruptions in George’s line. (8,9) The
posterior body line can be incorporated with other complex measuring systems to assess stability. (10,11) Care should be taken to
eliminate positional rotation, because this will create a projectional
disruption of the line at consecutive levels (stair stepping). This
line can be applied throughout the entire spine.
Significance. In 1919 George called attention to the relevance
of ascertaining alignment to detect post-traumatic cervical injuries. (12,13) Proper alignment of the posterior vertebral bodies
signified no fracture, dislocation, or ligamentous laxity. In burst
fractures of the vertebral body, a posteriorly displaced fragment
of bone will lie behind the line. (14,15) If an anterolisthesis or
retrolisthesis is present, this may be a radiologic sign of instability caused by fracture, dislocation, ligamentous laxity, or degenerative joint disease.
Figure 2-13 METHOD OF BULL. A and B. See text. The
posterior angle is measured (double-headed arrow).
Figure 2-14 GEORGE’S LINE. A. Normal Line. See text.
B. Abnormal Line. The abnormality is the result of traumatic
bilateral facet dislocation (arrow).
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Posterior Cervical Line
Synonyms. Spinolaminar junction line, arch–body line.
Technique
Projection. Lateral cervical spine (neutral, flexion, extension).
Landmarks. The cortical white line of the spinolaminar junction
is first identified at each level C1 to C7. Each spinolaminar junction will be curved slightly anteriorly from superior to inferior. For
consistency, the most anterior part of the convexity is compared
between levels. (Fig. 2-15)
Normal Measurements. When each spinolaminar junction
point is joined, a smooth arc-like curve results. At the C2 level,
the spinolaminar junction line in children should not be > 2 mm
anterior to this line.
Special Considerations. None.
Significance. If the drawn curve is discontinuous at any level,
then an anterior or posterior displacement may be present. This line
is especially useful for detecting subtle odontoid fractures and
atlantoaxial subluxation (anterior), which otherwise may be easily overlooked. (16) A disruption in the middle to lower cervical
spine may also be a sign of anterolisthesis, retrolisthesis, or frank
dislocation.
Figure 2-15 POSTERIOR CERVICAL LINE. A. Normal Line. See text. B. Abnormal Line. The abnormality is caused by posterior
displacement of the atlas secondary to os odontoideum.
2
Sagittal Dimension of
the Cervical Spinal Canal
Synonyms. None.
Technique
Projection. Lateral cervical (neutral, flexion, extension).
Landmarks. The sagittal diameter is measured from the posterior surface of the midvertebral body to the nearest surface of
the same segmental spinolaminar junction line. (17) (Fig. 2-16)
Normal Measurements. Measurements vary according to the
cervical level. (18) (Table 2-7) Values will be altered in children.
(17,19)
Table 2-7
Measurements in Skeletal Radiology I
209
Special Considerations. None.
Significance. Narrowing of the canal (stenosis) may be present
when the measurement is < 12 mm, which can be assessed on plain
film, CT, and MRI. (20) If degenerative posterior osteophytes
are present, the measurement can be made from their tip to examine the magnitude of the stenotic effect. The degree of stenosis
from these spurs is best measured on extension films. (18) An
abnormally widened canal may be associated with a spinal cord
neoplasm or syringomyelia.
The most accurate measurement is by the ratio of the sagittal dimension of the canal and vertebral body (canal to body ratio,
Pavlov’s ratio). (21,22) A ratio of less than 0.82 is significant for
spinal stenosis. (21) The benefit of this method is that it removes
the effects of radiographic magnification.
Normal Sagittal Diameters
for the Cervical Spine
Level
Average (mm)
Minimum (mm)
Maximum (mm)
C1
C2
C3
C4
C5
C6
C7
22
20
18
17
17
17
17
16
14
13
12
12
12
12
31
27
23
22
22
22
22
Figure 2-16 CERVICAL SPINAL CANAL. A and B. Sagittal Dimensions. The dimensions at two levels are shown (arrows). See text.
C and D. Dry Specimens. Specimen correlation demonstrating the distance being evaluated (arrows).
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Atlantoaxial Alignment
Cervical Gravity Line
Synonyms. Spread of the atlas.
Technique
Projection. AP open mouth; cervical spine.
Landmarks. The lateral margins of the atlas lateral masses are
compared to the opposing lateral corner of the axis articular surface. (Fig. 2-17)
Normal Measurements. These two landmarks should be in vertical alignment.
Special Considerations. None.
Significance. If the lateral margin of the atlas lateral mass lies
lateral to the lateral axis margin, this may be a radiologic sign of
Jefferson’s fracture, odontoid fracture, alar ligament instability, or rotatory atlantoaxial subluxation. (23,24) If there is overhang of the lateral mass in combination with a laterally tilted dens
of > 5°, there is at least a 70% probability a fracture of the odontoid is present. (25) In children up to 4 years of age, overhang of
the atlas may be a normal variant resulting from accelerated growth
of the atlas ( pseudo-spread ). (24,26)
Synonyms. None.
Technique
Projection. Lateral cervical spine (neutral).
Landmarks. A vertical line is drawn through the apex of the odontoid process. (27) (Fig. 2-18)
Normal Measurements. This line should pass through the
C7 body.
Special Considerations. None.
Significance. The line allows a gross assessment of where the
gravitational stresses are acting at the cervicothoracic junction.
Figure 2-18 CERVICAL GRAVITY LINE. See text.
Figure 2-17 ATLANTOAXIAL ALIGNMENT. A. Normal Alignment. B. Abnormal Alignment. The abnormality (arrow) is the
result of a Jefferson’s fracture of the atlas.
2
Cervical Lordosis
Synonyms. Angle of the cervical curve, cervical (lordotic) angle.
Technique
Projection. Cervical spine, neutral.
Landmarks. Numerous methods have been devised. (28–35)
Some are described here.
• Depth of cervical curve. A line is drawn from the superior
posterior aspect of the odontoid to the posterior inferior
corner of C7. The greatest transverse distance between this
line and the posterior vertebral bodies is measured. (32)
(Fig. 2-19A)
• Method of Jochumsen. A line is drawn from the anterior
border of the atlas anterior tubercle to the anterosuperior
corner of the C7 body. The distance from this line to the
anterior border of the C5 body is then measured. (33)
(Fig. 2-19B)
• Angle of cervical curve. Two lines are drawn, one through
and parallel to the inferior endplate of the C7 body and the
other through the midpoints of the anterior and posterior
tubercles of the atlas (atlas plane line). Perpendiculars are
then constructed to the point of intersection; the resultant
angle is measured. (34) (Fig. 2-19C)
• Method of Gore. A line is drawn through the posterior
surface of the C2 body and another through the posterior
surface of the C7 body. The angle formed by these two
lines is measured. (28)
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• Method of Drexler. This is a laborious but accurate
method. Each individual segment is assessed by drawing
lines along the body endplates and measuring the resultant
angle. The lordosis value is the cumulative total of each
intersegmental measurement. (35)
Normal Measurements. See Table 2-8.
Table 2-8
Normal Values for Cervical Lordosis
Method
Depth (mm)
Jochumsen’s
method (mm)
Angle (°)
Drexler’s method (°)
Average
Minimum
Maximum
12
3–8
7
1
17
9
40
40
35
16
45
60
Special Considerations. The position of the head is a critical
factor in determining the lordosis. If the chin is lowered, tucked
downward, or retracted 1 inch, the effect is to straighten the lordosis. (36–38)
Significance. Many authors have stressed the lack of correlation
between altered cervical curvature and clinical symptomatology
and its limitations as a prognostic indicator. (31,39) However, a
reduced or reversed curve may be observed following trauma,
muscle spasm, and degenerative spondylosis. (31,32,36,37,40)
In patients with myelopathy caused by degenerative stenosis, response to laminectomy is diminished when the lordosis is reversed
or straightened. (41)
Figure 2-19 CERVICAL LORDOSIS. A. Depth Measurement. B. Method of Jochumsen. C. Angle of the Cervical Curve. See text.
Areas of measurement are shown (double-headed arrows).
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Stress Lines of the Cervical Spine
Synonyms. Ruth Jackson’s lines.
Technique
Projection. Lateral cervical spine (flexion, extension).
Landmarks. Two lines are constructed on each film. The first line
is drawn along the posterior surface of the axis. The second line is
drawn along the posterior surface of the C7 body until it intersects
the axis line. (40) (Fig. 2-20)
Normal Measurements
• Flexion. These lines normally should intersect at the level
of the C5–C6 disc or facet joints.
• Extension. These lines normally should intersect at the
level of the C4–C5 disc or facet joints.
Special Considerations. None.
Significance. The value of these lines has not been established.
The intersection point represents the focus of stress when the cervical spine is placed in the respective positions. (40) The point of
intersection does not appear to correlate with the level of degenerative disc disease. (42) Muscle spasm, joint fixation, and disc
degeneration may alter the stress point.
Figure 2-20 CERVICAL STRESS LINES. A. Flexion. See text. B. Extension. See text.
2
Prevertebral Soft Tissues
Synonyms. Retropharyngeal interspace (RPI), retrolaryngeal
interspace (RLI), retrotracheal interspace space (RTI).
Technique
Projection. Lateral cervical spine (neutral, flexion, extension).
Landmarks. The soft tissue in front of the vertebral bodies and
behind the air shadow of the pharynx, larynx, and trachea is measured. The bony landmarks are the anterior arch of the atlas; the
inferior corners of the axis and C3; the superior corner of C4; and
the inferior corners of C5, C6, and C7. (43,44) At C2–C3 this is
called the RPI; behind the larynx, the RLI (C4–C5); and behind
the trachea (C5–C7), the RTI. (Fig. 2-21)
Normal Measurements. Measurements will vary according to
the level being measured and the position of the patient at the
time of the exposure. (43,44) (Table 2-9)
Table 2-9
Level
C1
C2
C3
C4
C5
C6
C7
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Special Considerations. The values at the C4 and C5 levels
may alter, depending on the position of the larynx, which may
change with swallowing, screaming, axial rotation, and lateral
flexion. (44) There is no difference between the sexes, and the
values are not altered significantly by radiographic magnification.
(44) Patients > 180 lb (82 kg) may have a space 1 mm greater
than the normal range, and patients older than 70 years have
spaces of 1 mm less than normal. (44) No more than a 1-mm
change occurs in the measurement between flexion and neutral.
(43) Anterior degenerative osteophytes may cause deflection of
the pharyngeal contour.
Significance. Any soft tissue mass may increase these measurements. These include post-traumatic hematoma, retropharyngeal
abscess, and neoplasm from the adjacent bone and soft tissue
structures.
Normal Values for
Cervical Prevertebral Soft Tissues
Flexion (mm)
Neutral (mm)
Extension (mm)
11
6
7
7
22
20
20
10
5
7
7
20
20
20
8
6
6
8
20
19
21
Figure 2-21 PREVERTEBRAL SOFT TISSUE. A and B. Prevertebral Soft Tissues. See text. Areas of measurement are
shown (arrows). C. Abnormal Retropharyngeal Soft Tissue
Measurement. The abnormality is the result of hematoma formation after cervical trauma (arrows). (Courtesy of Norman
W. Kettner, DC, DACBR, St. Louis, Missouri.)
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THORACIC SPINE
Cobb’s Method of Scoliosis Evaluation
Synonyms. Cobb–Lippman method.
Technique
Projection. AP spine.
Landmarks
• End vertebrae. There are two, one each located at the
superior and inferior extremes of the scoliosis. They are
defined as the last segment that contributes to the spinal
curvature. They appear as the last segment at the extreme
ends of the scoliosis, where the endplates tilt to the side of
the curvature concavity.
• Endplate lines. On the superior end vertebra, a line is
drawn through and parallel to the superior endplate. On
the inferior end vertebra, a line is constructed in a similar
manner through and parallel to the inferior endplate.
• Perpendicular lines. At right angles to both endplate lines,
lines are drawn to intersect, and their resultant angle is
measured. (Fig. 2-22)
Special Considerations. This is the preferred method in scoliosis assessment. In patients with double scoliotic curves each
component should be measured. Care should be taken to ensure
that common landmarks are used in progressive evaluations.
Interobserver errors in measurement range up to 10°, which is
a problem because a 5° progression of a scoliosis between two
successive radiographs is considered significant when deciding
on therapeutic options. (1–3)
Significance. This procedure was introduced by Lippman in
1935 and later popularized by Cobb. (4) Essentially, curvatures
< 20° require no bracing or surgical intervention; however, if curvatures < 20° are present in a patient between 10 and 15 years of
age, careful monitoring should be implemented to assess for progression of 5° or more in any 3-month period. (1,5) Curves between 20° and 40° should be braced to prevent progression in the
growth period. Surgical intervention may be contemplated for
cosmetic reasons, underlying anomaly, curvature progression in
an immature spine, or curvature in excess of 40°. (See Chapter 4.)
Risser-Ferguson Method
of Scoliosis Evaluation
Synonyms. None.
Technique
Projection. AP spine.
Landmarks
• End vertebrae. Same as described for Cobb’s method.
• Apical vertebra. This vertebral segment is the most laterally placed in the curve and usually is the most rotated.
• Vertebral body center. For each end vertebra and
apical segment diagonals are drawn from opposing corners
of the body to locate the body center.
• Connecting line. Two lines are constructed connecting the
body centers of the apical segment with each end vertebra,
and the resultant angle is measured. (Fig. 2-23)
Special Considerations. This method gives values approximately
25% lower than those of Cobb’s method (10°), and some investigators have advocated its use for larger curves; but this practice is
to be discouraged. (6) (See Chapter 4.)
Significance. Ferguson first introduced this methodology in the
early 1920s and published his findings in the 1930s and 1940s.
(7,8) Like Cobb’s method, this assesses the degree of scoliosis and
provides data used in the therapeutic decision process.
Figure 2-23 RISSER-FERGUSON METHOD OF SCOLIOSIS
EVALUATION. See text. The angle measured is shown
(double-headed arrow).
Figure 2-22 COBB’S METHOD OF SCOLIOSIS EVALUATION.
See text. The angle measured is shown (double-headed arrow).
2
Thoracic Kyphosis
Synonyms. None.
Technique
Projection. Lateral thoracic spine.
Landmarks. A line is drawn parallel to and through the superior endplate of the T1 body. A similar line is drawn through
the inferior endplate of the T12 body. Perpendicular lines to these
endplate lines are then constructed, and the resultant angle is measured at the intersection of the lines. (Fig. 2-24)
Normal Measurements. Measurements vary according to age
and sex. (9) (Tables 2-10 and 2-11)
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A reduction in the kyphosis (straight back syndrome) may
alter the dynamics of intracardiac blood flow and manifest as an
apparent cardiac murmur. (17,18)
Table 2-10 Degree of Normal Kyphosis in Females
by Age
Age
Mean
2–9
10 –19
20 –29
30 – 39
40 – 49
50 –59
60 – 69
70 –79
24
26
27
28
33
41
45
42
Kyphosis (°)
Standard
Deviation
Minimum
7
7
8
9
7
10
8
9
8
11
7
10
21
22
34
30
Maximum
36
41
40
42
50
53
54
56
Table 2-11 Degree of Normal Kyphosis in Males
by Age
Age
Mean
2–9
10 –19
20 –29
30–39
40 –49
50 –59
60 – 69
70 –79
21
25
26
29
30
33
35
41
Kyphosis (°)
Standard
Deviation
Minimum
8
8
8
8
7
6
5
8
5
8
13
13
17
25
25
32
Maximum
40
39
48
49
44
45
62
66
Special Considerations. Frequently the vertebral bodies at the
ends of the thoracic spine will not be clearly visible. In these
circumstances the first visible segment will suffice but may alter
the angular value. Interobserver measurement errors up to 11°
are common. (2) Physiologic anterior vertebral body wedging
accounts for the natural kyphotic curvature of the thoracic spine.
(10,11) This normal anterior wedging for each vertebral body is
4–5° or 2–3 mm. (11–14) The wedging increases by almost 1 mm
for each successive level, with approximately 45° of thoracic
kyphosis accounted for by this wedging. (11)
Significance. The kyphosis may be altered in many disorders.
An increased kyphosis may be seen in old age, osteoporosis,
Scheuermann’s disease, congenital anomalies, muscular paralysis,
and even cystic fibrosis. (9,15) The degree of kyphosis increases
with age, and the rate of increase is greater in females than in
males. (16)
Figure 2-24 THORACIC KYPHOSIS MEASUREMENT. See text.
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Thoracic Cage Dimension
LUMBAR SPINE
Synonyms. Straight back syndrome evaluation.
Technique
Projection. Lateral chest.
Landmarks. The distance between the posterior sternum and the
anterior surface of the T8 body is measured. (Fig. 2-25)
Normal Measurements. The sagittal dimension will normally
vary slightly. (18) (Table 2-12)
Table 2-12 Normal Sagittal Dimensions of
the Thoracic Cage
Sex
Average (cm)
Minimum (cm)
Maximum (cm)
Male
Female
14
12
11
9
18
15
Special Considerations. None.
Significance. A measured sagittal dimension < 13 cm in males
and < 11 cm in females may indicate the presence of the straight
back syndrome. (Table 2-13) If an abnormal measurement is
found, the chest should be auscultated for a cardiac murmur. If
detected, an organic cause should be searched for, although one
may not be found. The decreased AP diameter may create such a
murmur by creating cardiac compression and altered intracardiac
hemodynamics. (17,18)
Table 2-13 Sagittal Dimensions of the Thoracic Cage
in Straight Back Syndrome
Sex
Average (cm)
Minimum (cm)
Maximum (cm)
Male
Female
11
10
9
8
13
11
Figure 2-25 SAGITTAL THORACIC CAGE DIMENSION IN
STRAIGHT BACK SYNDROME. See text. The dimension
measured is shown (double-headed arrow).
Intervertebral Disc Height
Synonyms. None.
Technique
Projection. Lateral lumbar spine.
Landmarks. A number of methodologies have been described,
but only two are presented. (1,2)
• Hurxthal’s method. The distance between the opposing
endplates at the midpoint between the anterior and the
posterior vertebral body margins is measured. (3)
(Fig. 2-26A)
• Farfan’s method. The anterior disc height (A) and posterior disc height (P) are measured and expressed as a ratio
to disc diameter (D). These two ratios are then reduced to
a ratio of each other. (4) (Fig. 2-26B)
A
D
P
PHR =
D
AHR
DH =
PHR
AHR =
where AHR is anterior height ratio, PHR is posterior height
ratio, and DH is disc height.
Normal Measurements. Considerable variation exists in disc
height, according to the lumbar interspace being assessed.
Special Considerations. When segmental rotation is > 40° or
lateral flexion is > 20°, these methods become unreliable.
Significance. Disc spaces can be altered in many conditions. The
most common causes for a decreased disc height are disc degeneration, postsurgery, postchemonucleolysis, infection, and congenital hypoplasia. There is poor correlation between loss of disc
height and the focus for low back pain. (2,5)
Figure 2-26 INTERVERTEBRAL DISC HEIGHT MEASUREMENT.
A. Hurxthal’s Method. See text. The areas measured are
shown (double-headed arrows). B. Farfan’s Method. See text.
The areas measured are shown (double-headed arrows).
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Lumbar Intervertebral Disc Angles
Lumbar Lordosis
Synonyms. None.
Technique
Projection. Lateral lumbar spine.
Landmarks. Lines are drawn through and parallel to each lumbar body endplate; the lines are extended posteriorly until they
intersect. The angles formed at each interspace are then measured. (Fig. 2-27)
Normal Measurements. Measurements vary according to the
lumbar level. (6) (Table 2-14)
Synonyms. Lumbar curve, lumbar spinal angle, lumbar angle.
Technique
Projection. Lateral lumbar spine.
Landmarks. A line is drawn through and parallel to the superior
endplate of the first lumbar segment. A second line is drawn
through the superior endplate of the first sacral segment. Perpendiculars are then created, and the angle at their intersection is
measured. (Fig. 2-28)
Normal Measurements. A wide variation exists within normal
individuals. However, the average appears to be 50–60°. (6,7)
Special Considerations. Some investigators prefer to use the inferior endplate of the L5 body to eliminate the effects of an altered
sacral position. (8)
Significance. The significance of an altered lumbar curve has
not been delineated. A wide spectrum of opinions has been expressed, from it being of no importance (9) to it being a prime
consideration as it relates to low back pain. (7,10–13) An increase
in lordosis tends to move the nucleus pulposus anteriorly; the significance of this finding is unclear. (14) There is no difference in
lordosis between whites and blacks. (15)
Table 2-14 Normal Values for Lumbar Intervertebral
Disc Angles
Disc Level
Average Angle (°)
L1
L2
L3
L4
L5
8
10
12
14
14
Special Considerations. An alternative method of measurement
includes the vertebral bodies in the calculation. (7)
Significance. The mean angular values will be altered in conditions of antalgia, muscular imbalance, and improper posture.
These measurements may be of assistance in distinguishing the
origins of low back pain. In facet syndrome the angles may be increased, whereas in acute discal injuries a reduction in the angle
may be seen. (7)
Figure 2-28 LUMBAR LORDOSIS MEASUREMENT. See text.
The angle measured is shown (double-headed arrow).
Figure 2-27 LUMBAR INTERVERTEBRAL DISC ANGLES. See
text. The angles measured are shown.
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Lumbosacral Lordosis Angle
Sacral Inclination
Synonyms. None.
Technique
Projection. Lateral lumbar spine.
Landmarks. Two lines are drawn, and the angle formed is measured. For the first line, the centers of the L3 and L5 bodies are
located by intersecting diagonal lines from opposing corners for
each of the two vertebra. A line is then constructed joining the
midpoints of these two bodies. Next the midpoint of the first sacral
segment is located in a similar manner, and a second line is drawn
between the L5 and S1 midpoints. The posterior angle thus formed
is measured. (Fig. 2-29)
Normal Measurements. A wide variation in this angle exists. (16)
(Table 2-15)
Synonyms. Sacral tilt angle.
Technique
Projection. Lateral sacrum, lumbar spine.
Landmarks. Two lines are drawn. First, a tangential line is drawn
parallel to and through the posterior margin of the first sacral segment. Second, a vertical line is drawn, intersecting the tangential
sacral line. The angle formed is then measured. (Fig. 2-30)
Normal Measurements. A wide variation in this measurement
occurs. (16) (Table 2-16)
Table 2-16 Normal Values for Sacral Inclination
Average (°)
46
Minimum (°)
Maximum (°)
30
72
Table 2-15 Normal Values for Lumbosacral Lordosis
Average (°)
146
Minimum (°)
Maximum (°)
124
162
Special Considerations. None.
Significance. This measurement can be used in the assessment of sacral position and provides additional data on the static
mechanics of the low lumbar spine.
Special Considerations. There appear to be small changes in this
angle between the recumbent and the upright positions.
Significance. The role of an excessive or diminished lumbosacral lordotic angle has not been adequately assessed; however,
this is a measurement that can be applied when the upper lumbar
segments are not included in the field of study.
Figure 2-30 SACRAL INCLINATION. See text. The angle measured is shown (double-headed arrow).
Figure 2-29 LUMBOSACRAL LORDOSIS ANGLE. See text.
The angle measured is shown (double-headed arrow).
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Lumbosacral Angle
Lumbosacral Disc Angle
Synonyms. Sacral base angle, Ferguson’s angle.
Technique
Projection. Lateral lumbar spine, lumbosacral.
Landmarks. Two lines are drawn and the resultant angle is measured. First, a horizontal line is made parallel to the bottom edge
of the film. Second, an oblique line is drawn through and parallel
to the sacral base. (17–19) (Fig. 2-31) The posterior angle thus
formed is measured.
Normal Measurements. A wide normal variation in this measurement has been noted. (20) (Table 2-17) The value will increase
from the recumbent to the upright position by 8–12°.
Synonyms. Sacrovertebral disc angle.
Technique
Projection. Lateral lumbar spine, lumbosacral spine.
Landmarks. A line is drawn parallel and through the inferior
endplate of L5 and superior endplate of the first sacral segment.
The anterior angle formed by these lines is then measured. (17)
(Fig. 2-32)
Normal Measurements. The normal range appears to be between 10° and 15°. (7,27)
Special Considerations. None.
Significance. An increase in the lumbosacral disc angle
> 15° has been linked to the presence of low back pain caused
by facet impaction. (27) Also there may be a decrease in the
angle in the presence of acute disc herniation at the L5 disc. (7)
An increased lumbosacral disc angle does not appear to be associated with an increased incidence of spondylolisthesis. (26)
Table 2-17 Normal Values for Lumbosacral Angle
Position
Average
(°)
Standard
Deviation
Minimum
(°)
Maximum
(°)
Upright
41
±7
26
57
Special Considerations. None.
Significance. There is no consensus of opinion on the exact role
and significance of either a decreased or an increased lumbosacral angle. (13,21–23) An increased angle has been implicated
as a mechanical factor in producing low back pain by increasing
shearing and compressive forces on the lumbosacral posterior
joints. (17,24,25) An increased sacral base angle does not appear to
be associated with an increased incidence of spondylolisthesis. (26)
Figure 2-32 LUMBOSACRAL DISC ANGLE. See text. The
angle measured is shown (double-headed arrow).
Figure 2-31 LUMBOSACRAL ANGLE. See text. The angle
measured is shown (double-headed arrow).
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Static Vertebral Malpositions
Synonyms. Static intersegmental subluxations.
Technique
Projection. AP and lateral spine.
Landmarks. Numerous terms have been applied to describe static
vertebral malpositions: (28) (Fig. 2-33)
• Flexion. The endplates of the opposed segments diverge
posteriorly in the lateral view.
• Extension. The endplates of the opposed segments converge
posteriorly more than normal in the lateral view. (Fig. 2-33A)
• Lateral flexion. The endplates of the opposed segments
diverge laterally on one side and converge on the other
side in the AP view. (Fig. 2-33B)
• Rotation. The pedicles are asymmetrical in shape, and the
spinous may be deviated in the AP view. (Fig. 2-33C)
• Anterolisthesis. An anterior displacement of one vertebral
body in relation to the vertebra below. (Fig. 2-33D)
• Retrolisthesis. A posterior displacement of one vertebral
body in relation to the vertebra below. (Fig. 2-33D)
• Laterolisthesis. A sideways displacement of one vertebral
body in relation to the vertebra below. (Fig. 2-33C)
Special Considerations. This classification system and terminology can be used for the entire vertebral column. The position of the
superior vertebra is always described relative to the subadjacent
vertebra; for example, there is a retrolisthesis of C4 on C5.
Significance. These various interbody disrelationships may be
related to degenerative processes, antalgia, or abnormal mechanics; however, the recognition of these displacements does not necessarily confirm a clinically significant finding.
Figure 2-33 STATIC VERTEBRAL MALPOSITIONS. A. Extension. Extension is demonstrated (curved arrows). Of incidental
notation, observe the domed sclerosis at the anteroinferior
aspect of the L3 vertebral body (arrow). This has been called
hemispherical spondylosclerosis. B. Lateral Flexion. Observe
the lateral flexion (arrow). C. Laterolisthesis and Rotation.
Both laterolisthesis (arrow) and rotation (curved arrow) can
be seen. D. Anterolisthesis and Retrolisthesis. This view
demonstrates both anterolisthesis (arrow ) and retrolisthesis
(arrowhead).
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Lumbar Gravity Line
Macnab’s Line
Synonyms. Ferguson’s weight-bearing line, Ferguson’s gravitational line.
Technique
Projection. Lateral lumbar spine.
Landmarks. The center of the L3 body is located by intersecting
diagonals from opposing body corners. A vertical line is then constructed through this point, and the relationship to the upper
sacrum is assessed. (17,18,29) (Fig. 2-34)
Normal Measurements. According to Ferguson, the center of
gravity of the trunk passes through the center of the L3 body and
continues vertically to intersect the sacral base. (17,18)
Special Considerations. The original description was performed
on recumbent lateral lumbar projections; however, some studies
suggest that patient position, whether upright or recumbent, is irrelevant. (7) Some investigators use the intersection point through
L5 as the reference point. (30)
Significance. If this line passes anterior to the sacrum by
> 0.5 inch (> 10 mm), an increase in shearing stresses in an anterior direction between the lumbosacral apophyseal joints may be
occurring. (17) Conversely, it has been suggested that a posterior
shift in this gravity line may indicate increased weight-bearing
forces on these same lumbosacral joints that may also be active
in the production of low back pain. (10,11,24) Increased stress
on the pars interarticularis may also be incurred from this posterior shift in weight bearing, although a direct relationship to
the formation of spondylolysis has not been demonstrated, only
inferred. (25)
Synonyms. None.
Technique
Projection. Lateral lumbar.
Landmarks. A line is drawn through and parallel to the inferior
endplate at the level to be evaluated. The relationship of the adjacent tip of the superior articular process of the vertebra below
is then assessed. (Fig. 2-35)
Normal Measurements. The line should lie above the tip of the
adjacent superior articular process. (31)
Special Considerations. None.
Significance. If the line intersects the superior articulating process, facet imbrication (subluxation) may be present. The effect of
these facets overriding each other is to mechanically infringe on
the size of the intervertebral foramen and lateral recess. The reliability of this line, however, has not been documented. (7) It should
be noted that the original description of this line was with respect
to recumbent radiographs, and its application to weight-bearing
films is uncertain. The relevance of this line is doubtful given the
high incidence in asymptomatic individuals. (29,32)
Figure 2-35 MACNAB’S LINE. See text.
Figure 2-34 LUMBAR GRAVITY LINE. See text.
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Hadley’s S Curve
Synonyms. None.
Technique
Projection. Oblique, AP lumbar spine.
Landmarks. A curvilinear line is constructed along the inferior
margin of the transverse process and down along the inferior articular process to the apophyseal joint space. The line is then continued across the articulation to connect with the outer edge of
the opposing superior articular process. (33,34) (Fig. 2-36)
Normal Measurements. The resultant configuration of this line
will look like the letter S. The key region of the S is the normally
smooth transition across the joint space.
Special Considerations. None.
Significance. An abrupt interruption in the smooth contour of
this line may indicate facet imbrication (subluxation), though
displacements as great as 3 mm may not be visible on plain film
examination. (35,36) A localized wide facet joint has been linked
to disc derangement. (37)
Van Akkerveeken’s Measurement
of Lumbar Instability
Synonyms. None.
Technique
Projection. Lateral lumbar spine (neutral, flexion, extension).
Landmarks. Two lines are drawn through and parallel to opposing segmental endplates until they intersect posteriorly. The distance from the posterior body margins to the point of intersection
is then measured. Alternatively, the displacement can be assessed
by measuring the offset in the opposing body corners. (Fig. 2-37)
Normal Measurements. There should be < 1.5 mm displacement,
as determined by either measurement method. (38)
Special Considerations. This evaluation is best performed on
the extension film, when the most stress is applied to the lower
lumbar discs.
Significance. If there is > 1.5 mm difference in measurement,
then it is likely that nuclear, annular, and posterior ligament damage at the displaced segment is present. Other investigators have
cited 3 mm displacement to be of clinical significance. (39)
Figure 2-37 VAN AKKERVEEKEN’S MEASUREMENT OF
INTERSEGMENTAL INSTABILITY. See text. Observe the vacuum
phenomenon within the L4 disc (arrow).
Figure 2-36 HADLEY’S S CURVE. A. AP Projection. Both normal (arrow) and abnormal (arrowhead) curves are demonstrated. B. Oblique Projection. See text. Normal curves are
demonstrated.
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Degenerative Lumbar Spinal Instability:
Flexion–Extension
Synonyms. Horizontal displacement measurement.
Technique
Projection. Lateral lumbar spine, with flexion and extension.
Landmarks. The landmarks apply on both flexion and extension
films. Two methods of assessment can be made: gross and accurate mensuration. (40)
• Gross assessment. The alignment of the posterior lumbar
bodies is examined by visually observing the relationship
of the opposing posterior body corners (George’s line).
• Accurate measurement—horizontal displacement.
The posterior body corners of each body are located. At
each segment the superior corners are joined by a line. At
the segment that is normal, a line is drawn parallel to the
posterior corner line through the posterior corner of the displaced segment above. The interspace between these two
lines is then measured, which is called the displaced distance (DD). To remove the effects of radiographic magnification, measure the width of the unstable vertebral body
(W) and express the horizontal disrelationship measurement
as a percentage
HD% =
DD
× 100
W
• Accurate measurement—angular displacement. A line is
drawn perpendicular to the posterior corner line at opposing body surfaces, and the subtended angle is measured.
Normal Measurements. During flexion and extension, there
should be no detectable anterior or posterior translation of the
vertebral bodies in relation to each other. This is assessed by noting the alignment of the posterior body corners in both flexion
and extension. (Fig. 2-38) In addition, only one posterior corner
of each vertebra should be seen.
Special Considerations. None.
Significance. Anterior or posterior displacement seen on flexion or extension indicates degenerative or traumatically induced
instability. A similar phenomenon has been demonstrated on
traction–compression radiography. (41) (See Chapter 5.)
More specifically, anterior displacement during flexion denotes
laxity of the posterior ligamentous complex (interspinous, supraspinous, capsular, flaval ligaments, and annular disc fibers). Conversely, a posterior displacement during extension implies an
anterior ligamentous complex failure (anterior longitudinal ligament and annular disc fibers). These may frequently occur together
as a manifestation of total segmental ligamentous failure.
There has been poor correlation between abnormal findings
and clinical symptoms. (42) The combination of sagittal translation and increased posterior opening can be associated with
debilitating symptoms. (43) In spondylolisthesis > 12°, dynamic
angulation or 8% translation on flexion–extension is considered
evidence of instability. (44)
Another sign of instability during flexion–extension is the recognition of intersegmental rotation. This can be identified by the
observation of two posterior body corners at one segment and
implies posterior joint ligamentous instability.
Figure 2-38 FLEXION–EXTENSION INTERSEGMENTAL
INSTABILITY EVALUATION. A. Flexion. Note the alignment
at the L4 level (arrows). B. Extension. Note the degree of
retrolisthesis (R; arrowheads), which indicates extension
instability (arrow).
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Degenerative Lumbar Instability:
Lateral Bending
Synonyms. None.
Technique
Projection. Lateral bending, lumbar spine.
Landmarks. Three structures are evaluated: vertebral body margins, pedicles, and spinous process. (40) (Fig. 2-39)
Normal Measurements. On normal lateral bending, the following should be noted:
• Vertebral body alignment. No lateral segmental displacement (shear) should be seen, and the disc space should be
less on the concave side.
• Pedicle position. Each segment should show progressive
rotation as evidenced by the altered shape of the pedicle
contour along the concave side of the induced curve.
• Spinous position. Similarly, the normal rotational segmental coupling will be shown by gradual spinous deviation of
each successive segment into the concavity of the curve.
Lateral-Bending Sign
Synonyms. None.
Technique
Projection. Right and left lateral bending, lumbar spine.
Landmarks. Transverse lines are drawn on each segment through
either of two locations: (a) the tips of the superior articulating process or (b) the superior border of the pedicles. (Fig. 2-40)
Normal Measurements. On each lateral-bending study the constructed lines will converge toward the bending side in a gradually increasing manner from the lumbosacral junction up. (40)
Special Considerations. None.
Significance. In the presence of appropriate clinical symptoms,
a localized segmental failure to laterally flex may indicate the presence of a posterolateral (axillary) disc herniation. (45) However,
altered biomechanical function of the posterior joints may produce
an identical radiographic appearance. (40)
Special Considerations. None.
Significance. Lateral segmental displacement (shear) usually
indicates laxity of the discal ligaments and is a sign of degenerative lumbar instability. Abnormalities in normal posterior joint
coupling movements, in which there is a lack of or even complete
reversal of rotatory motion (paradoxical motion), indicate ligamentous laxity of the posterior joints or altered joint mechanics. There has been poor correlation among abnormal findings and
clinical symptoms. (42)
Figure 2-40 LATERAL-BENDING SIGN. Observe the failure of
intersegmental lateral flexion at the L4 segment (arrow)
owing to a posterolateral disc herniation.
Figure 2-39 LATERAL FLEXION INSTABILITY EVALUATION.
A. Neutral Position. Three structures are observed: pedicle
position and configuration (A), spinous position (B), and
adjacent vertebral margin alignment (C). B. Lateral Flexion.
The changes in these structures from the neutral to the lateral
flexion position are assessed.
2
Meyerding’s Grading Method
in Spondylolisthesis
Synonyms. None.
Technique
Projection. Lateral lumbar spine, lumbosacral.
Landmarks. The superior surface of the first sacral segment is
divided into four equal divisions. The relative position of the
posterior-inferior corner of the L5 body to these segments is then
made. (46) (Fig. 2-41)
Normal Measurements. The posterior-inferior corner of the L5
body should be aligned with the posterior-superior corner of the
first sacral segment.
Special Considerations. The same assessment can be applied
to other spinal levels by dividing the superior endplate of the
segment below the spondylolisthesis into four equal spaces. In
spondylolisthesis, > 12° dynamic angulation or 8% translation on
flexion–extension views is considered evidence of instability. (44)
Significance. The degree of anterolisthesis of the affected vertebral body can be categorized according to the division in which
the posterior-inferior corner of the body lies. These are designated into grades as follows:
Measurements in Skeletal Radiology I
225
Ullmann’s Line
Synonyms. Garland-Thomas line, right-angle test line.
Technique
Projection. Lateral lumbar spine, lumbosacral.
Landmarks. Two lines are drawn: (a) parallel to and through the
sacral base and (b) perpendicular to the first line at the anterior margin of the sacral base. The relationship of the L5 body
to this perpendicular line is then assessed. (46–48) (Fig. 2-42)
Normal Measurements. The L5 body should lie posterior to or
just contact this perpendicular line.
Special Considerations. None.
Significance. If the anterior margin of the L5 body crosses the
perpendicular line, then anterolisthesis may be present. This is a
useful line for detecting the presence of spondylolisthesis when
there is poor visualization of the pars region. Application of this
line must be interpreted in light of lumbar biomechanics; for
example, a significant loss of the lumbar lordosis may result in a
false-positive finding.
• Grade 1. The posterior-inferior corner is aligned within
the first division.
• Grade 2. The posterior-inferior corner is aligned within
the second division.
• Grade 3. The posterior-inferior corner is aligned within
the third division.
• Grade 4. The posterior-inferior corner is aligned within
the fourth division.
If the vertebral body has completely slipped beyond the sacral
promontory, the condition is called spondyloptosis.
Figure 2-42 ULLMANN’S LINE. Spondylolisthesis of the fifth
lumbar segment demonstrated by the intersection of the
line with the L5 body (arrow).
Figure 2-41 MEYERDING’S CLASSIFICATION OF SPONDYLOLISTHESIS. The grades of spondylolisthesis are shown
(see text).
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Interpediculate Distance
Synonyms. Coronal dimension of the spinal canal.
Technique
Projection. AP cervical spine, thoracic spine, and lumbar spine.
Landmarks. The shortest distance between the inner convex cortical surfaces of the opposing segmental pedicles is measured.
(Fig. 2-43)
Normal Measurements. These vary according to each spinal
level and the patient’s age. (49) (Table 2-18)
Table 2-18 Normal Values for Adult
Interpediculate Distance
Spinal Level
C3
C4
C5
C6
C7
T1
T2
T3
T4
T5
T6
T7
T8
T9
T10
T11
T12
L1
L2
L3
L4
L5
Average
(mm)
Minimum
(mm)
Maximum
(mm)
28
29
29
29
28
24
20
19
18
17
17
17
18
18
19
20
23
25
26
26
27
30
25
26
26
26
24
20
17
16
15
14
14
14
15
15
15
18
19
21
21
21
21
23
31
32
33
33
32
28
24
22
21
21
20
20
21
21
22
24
27
29
30
31
33
36
Special Considerations. None.
Significance. This is a useful measurement applied in the evaluation of spinal stenosis, congenital malformation, and intraspinal
neoplasms. In stenosis the minimum measurement is exceeded;
but for accurate delineation it is best used in combination with other
measurements, such as the sagittal canal dimension (Eisenstein’s
method) and size of the vertebral body (canal to body ratio). The
maximum interpediculate distance may be increased as a result of
pedicular erosion from an expanding spinal cord tumor (ElsebergDyke sign). (50)
Figure 2-43 INTERPEDICULATE DISTANCE. A. AP Lumbar
Spine. B. Specimen Radiograph. C. Schematic Diagram. The
distance to be measured is demonstrated (arrows).
2
Eisenstein’s Method for
Sagittal Canal Measurement
Synonyms. None.
Technique
Projection. Lateral lumbar spine.
Landmarks. For each lumbar level, except the fifth, the sagittal
canal diameter can be determined by measuring between two
points.
• Articular process line. A line is drawn to connect the tips
of the superior and inferior articular processes at each
level.
• Posterior body margin. The measurement point is on
the posterior body margin at the midpoint between the
superior and the inferior endplate. (Fig. 2-44)
• Sagittal canal measurement. This is obtained by determining the distance between the posterior body and the
articular process line.
Measurements in Skeletal Radiology I
227
For determining the sagittal canal dimension of the fifth lumbar
segment, measurement is made between the spinolaminar junction
line and the posterior body. (51)
Normal Measurements. No single measurement should be
< 15 mm (51), though some have suggested 14 mm to be minimum value. (52)
Special Considerations. The actual lowest anatomic measurement found on cadaver specimens has been 12 mm. (51)
Significance. A measurement < 15 mm may indicate the presence of spinal stenosis. This appears to be the single most reliable
measurement on plain radiographs in the assessment of spinal
stenosis. (51) However, before definitive diagnosis is made,
appropriate clinical studies and CT must be performed. (52)
Wire
Figure 2-44 EISENSTEIN’S METHOD FOR SAGITTAL CANAL
MEASUREMENT. A. Lateral Lumbar Spine. See text. B.
Specimen Radiograph. C. Schematic Diagram. Note that the
line will closely approximate the posterior limits of the canal
(metal wire). The dimension to be measured is demonstrated
(double-headed arrow).
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Canal to Body Ratio
Synonyms. Spinal index.
Technique
Projection. AP and lateral lumbar spine.
Landmarks. Four measurements are made, two per film, for each
spinal segment. (53,54) (Fig. 2-45)
• Interpediculate distance (A). This is the smallest distance
between each pedicle.
• Sagittal canal dimension (B). Eisenstein’s method is
applied. A line is drawn from the tips of the superior and
inferior articular processes, and the sagittal distance is
measured adjacent to the midpoint on the posterior body
margin.
• Transverse body dimension (C). The width of the vertebral
body on the AP film is measured at the midpoint between
the endplates.
• Sagittal body dimension (D). The length of the vertebral
body on the lateral film is measured at the midpoint
between the endplates.
Normal Measurements. These four measurements are combined
to provide an index of the canal size in relation to vertebral body
size. This is derived by:
Interpediculate Dimension
× Sagittal Canal Dimension
A× B
or
Transverse Body Dimension
C× D
× Sagittal Body Dimension
The normal range will vary according to the lumbar level. (53)
(Table 2-19)
Table 2-19 Normal Values for the Lumbar Canal
to Body Ratio
Level
Minimum
Maximum
L3
L4
L5
1:3.0
1:3.0
1:3.2
1:6.0
1:6.0
1:6.5
Special Considerations. None.
Significance. The higher the ratio, the smaller the spinal
canal, which is an indicator of possible spinal stenosis; however, this method of spinal canal assessment has been shown
to be unreliable. (51)
Figure 2-45 CANAL TO BODY RATIO. A and B. AP Measurements. Interpediculate distance (A) and transverse body
dimension (C ). C and D. Lateral Measurements. Sagittal
canal dimension (B) and sagittal body
dimension (D).
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229
Intercrestal Line
Length of Lumbar Transverse Processes
Synonyms. None.
Technique
Projection. AP lumbar spine.
Landmarks. A transverse line is drawn connecting the iliac crests.
The relationship of the bodies and discs of the fifth and fourth
lumbar segments to this line is then made. (55) (Fig. 2-46)
Normal Measurements. The relative position of these two segments within the pelvis is variable; however, the most stable position appears to be where the line intersects the bottom half of the
L4 body or disc. It is usually lower in females. (56)
Special Considerations. None.
Significance. This line, along with other skeletal parameters,
may be a useful indicator for predicting the level at which the most
biomechanical stress is occurring in the lumbar spine and the level
at which degenerative changes are most likely to occur. (55) It is
not, however, a reliable predictor for the predisposition to back
pain. (5,56) The criteria for probable L4–L5 degeneration are as
follows:
Synonyms. None.
Technique
Projection. AP lumbar spine.
Landmarks. A vertical line is drawn through the tip of the L3
transverse process. This is done bilaterally. The relationship of the
L5 transverse process to this line is then assessed. (55) (Fig. 2-47)
Normal Measurements. Considerable variation in the length of
the L5 transverse process occurs.
Special Considerations. None.
Significance. A short L5 transverse process may be an inherent structural instability factor at the lumbosacral junction.
Conversely, a long transverse process can be seen as a stabilizing
factor at this level. The length of this transverse process can be
used in combination with other parameters to predict segmental instability (see “Intercrestal Line”).
•
•
•
•
A high intercrestal line passing through the upper half of L4.
Long transverse processes on L5.
Rudimentary rib.
Transitional vertebra.
The criteria for predicting probable L5–S1 degeneration are as
follows:
•
•
•
•
An intercrestal line passing through the body of L5.
Short transverse processes on L5.
No rudimentary rib.
No transitional vertebra.
Figure 2-47 LENGTH OF THE LUMBAR TRANSVERSE
PROCESSES. Area to be assessed is demonstrated (arrows).
See text.
Figure 2-46 INTERCRESTAL LINE. See text.
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LOWER EXTREMITY
Teardrop Distance
Synonyms. Medial joint space of the hip.
Technique
Projection. AP pelvis, hip.
Landmarks. The distance between the most medial margin of
the femoral head and the outer cortex of the pelvic teardrop is
measured. (1–3) (Fig. 2-48)
Normal Measurements. See Table 2-20.
Figure 2-48 TEARDROP DISTANCE. A. Normal. B. Abnormal.
The distance to be measured is demonstrated (doubleheaded arrow). The abnormality is the result of early Legg-
Table 2-20 Normal Values for Teardrop Distance
Average (mm)
Minimum (mm)
Maximum (mm)
9
6
11
Special Considerations. None.
Significance. If the teardrop distance exceeds 11 mm or if there
is more than a 2-mm discrepancy from right to left (Waldenstrom’s
sign), then hip disease is most likely present. Left to right discrepancies of > 1 mm will be present in 90% of hip joint effusions. (2)
This is an especially sensitive sign in early Legg-Calvé-Perthes
disease and may also be seen in septic arthritis or other inflammatory diseases. (1,2)
Calvé-Perthes disease. Observe the crescent sign in the
femoral capital epiphysis (thick arrow).
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231
Hip Joint Space Width
Acetabular Depth
Synonyms. None.
Technique
Projection. AP hip.
Landmarks. Three measurements are made of the joint cavity.
(2) (Fig. 2-49)
Synonyms. None.
Technique
Projection. AP pelvis.
Landmarks. A line is drawn from the superior margin of the
pubis at the symphysis joint to the upper outer acetabular margin. The greatest distance from this line to the acetabular floor is
measured. (5) (Fig. 2-50)
Normal Measurements. There will be slight variations between
males and females. (5) (Table 2-22)
• Superior joint space. This is the space between the most
superior point on the convex articular surface of the femur
and adjacent acetabular cortex.
• Axial joint space. This is the space between the femoral
head and acetabulum immediately lateral to the acetabular
notch.
• Medial joint space (teardrop distance). This is the space
between the most medial surface of the femoral head and
opposing acetabular surface.
Normal Measurements. Notably, the superior and axial compartments are approximately equal (4 mm), whereas the medial
space is twice the distance (8 mm). (4) (Table 2-21)
Table 2-21 Normal Values for Hip Joint Space Width
Space
Average
(mm)
Minimum
(mm)
Maximum
(mm)
Superior
Axial
Medial
4
4
8
3
3
4
6
7
13
Table 2-22 Normal Values for Acetabular Depth
Space
Average
(mm)
Minimum
(mm)
Maximum
(mm)
Male
Female
13
12
7
9
18
18
Special Considerations. None.
Significance. An acetabular depth < 9 mm in females and
< 7 mm in males is considered to be shallow and dysplastic,
which may be a factor in precipitating degenerative joint disease
of the hip.
Special Considerations. None.
Significance. Various disorders may alter normal values; however, changes within the compartments may be associated with
specific entities.
• Superior joint space. The most common cause for a diminished superior joint space is degenerative joint disease.
• Axial joint space. Degenerative arthritis and especially
inflammatory arthritis, such as rheumatoid arthritis, will
diminish this compartment, often with associated loss of
joint space in the other compartments.
• Medial joint space. Narrowing is usually caused by degenerative or inflammatory arthritis; however, widening of the
compartment is a frequent indicator of hip joint effusion
or lateral shift of the femur (Waldenström’s sign).
Figure 2-50 ACETABULUM DEPTH. See text. Area to be
measured is demonstrated (double-headed arrow).
Figure 2-49 HIP JOINT SPACE WIDTH. A and B. Measurements of the Joint Cavity. See text. Note that the medial joint
space (M) is normally twice the width of the superior (S) and
axial (A) compartments (arrows).
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Center–Edge Angle
Symphysis Pubis Width
Synonyms. CE angle, CE angle of Wiberg.
Technique
Projection. AP pelvis, hip.
Landmarks. A vertical line is drawn through the center point of
the femoral head. Another line is constructed through the femoral
head center to the outer upper acetabular margin. The angle formed
is then measured. (6) (Fig. 2-51) This angle can also be measured
on CT. (7)
Normal Measurements. See Table 2-23. (4,6)
Synonyms. None.
Technique
Projection. AP pelvis.
Landmarks. The measured distance is between the opposing
articular surfaces, halfway between the superior and inferior margins of the joint. (Fig. 2-52)
Normal Measurements. A slight variation exists between males
and females. (8) (Table 2-24)
Table 2-23 Normal Values for Center–Edge Angle
Average (°)
36
Minimum (°)
20
Table 2-24 Normal Values for Symphysis
Pubis Width
Sex
Average
(mm)
Minimum
(mm)
Maximum
(mm)
Male
Female
6
5
4.8
3.8
7.2
6
Maximum (°)
40
Special Considerations. None.
Significance. A shallow angle may be related to underlying
acetabular dysplasia, which has been linked to the onset of degenerative joint disease. It provides a measure of coverage of the
femoral head, which means the amount of the acetabulum primarily concerned with weight bearing. (7)
Special Considerations. If alignment is being assessed, using the
inferior margin appears to be most reliable.
Significance. Widening of the symphysis may be the result of
cleidocranial dysplasia, bladder exostrophy, hyperparathyroidism,
post-traumatic diastasis, and inflammatory resorption (e.g., as in
ankylosing spondylitis, osteitis pubis, and gout).
Figure 2-52 SYMPHYSIS PUBIS WIDTH. A. Normal.
B. Abnormal. See text. The distance to be measured is
demonstrated (double-headed arrow). The abnormality
is the result of traumatic diastasis.
Figure 2-51 CENTER–EDGE ANGLE (CE ANGLE OF WIBERG).
A. AP Radiograph, hip. B. Schematic Diagram. See text.
Angle to be measured is demonstrated (double-headed
arrow).
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233
Presacral Space
Acetabular Angle
Synonyms. Retrorectal space.
Technique
Projection. Lateral sacrum.
Landmarks. The gray soft tissue density located between the anterior surface of the sacrum and the posterior wall of the rectum is
assessed. (Fig. 2-53)
Normal Measurements. There is variation between children and
adults. (9,10) (Table 2-25)
Synonyms. None.
Technique
Projection. AP pelvis.
Landmarks. A transverse line is drawn through the right and left
triradiate cartilages at the pelvic rim ( y–y line). A second oblique
line connecting the lateral and medial acetabular surfaces is then
constructed. The angle of intersection is measured. (11) (Fig. 2-54)
Normal Measurements. Slight variation occurs at different ages,
between males and females, and between blacks and whites. (11)
(Table 2-26)
Table 2-25 Normal Values for Presacral Space
Age
Average
(mm)
Minimum
(mm)
Maximum
(mm)
Children (1–15 years)
Adults
3
7
1
2
5
20
Table 2-26 Normal Values for Acetabular Angle
in 1-Year-Olds
Average (°)
20
Special Considerations. None.
Significance. An increase in this measurement signifies the
presence of an abnormal soft tissue mass. This may be caused by
sacral destruction (tumor, infection), sacral fracture and associated hematoma, or inflammatory bowel disease (in which there
is thickening of the intestinal wall).
Minimum (°)
Maximum (°)
12
29
Special Considerations. None.
Significance. An increased acetabular angle is frequently associated with acetabular dysplasia and congenital hip dislocation. A
decreased acetabular angle is seen in Down’s syndrome.
Figure 2-54 ACETABULAR ANGLE. Observe the abnormally
wide angle (double-headed arrows) on the left in association
with congenital hip dislocation. See text.
Figure 2-53 PRESACRAL SPACE. See text. Note the fracture
(arrow); a hematoma has slightly widened the presacral
space (arrowheads).
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Iliac Angle and Index
Synonyms. None.
Technique
Projection. AP pelvis.
Landmarks. A line is drawn through the triradiate cartilage at
the pelvic rim ( y–y line). A second line is constructed tangential
to the most lateral margin of the iliac wing and iliac body. (12)
(Fig. 2-55)
Normal Measurements
• Iliac angle. See Table 2-27.
• Iliac index. This is the sum of both the iliac angles and the
acetabular angles divided by 2. (Table 2-28)
Table 2-27 Normal Values for Iliac Angle
Age
Average (°)
Minimum (°)
Maximum (°)
0 –3 months
3–12 months
44
55
35
43
58
67
Table 2-28 Normal Values for Iliac Index
Age
Average (°)
Minimum (°)
Maximum (°)
0 –3 months
3–12 months
60
81
48
68
87
97
Special Considerations. None.
Significance. The iliac index is most useful in the determination
of Down’s syndrome. When the index is < 60, Down’s syndrome
is probable; when the index is 60–68, the syndrome is possible;
if > 68, the syndrome is unlikely. (13)
Figure 2-55 ILIAC ANGLE. The angle to be measured is
demonstrated (double-headed arrow). See text.
Miscellaneous Measurements
of the Growing Hip
Synonyms. None.
Technique
Projection. AP pelvis.
Landmarks and Normal Measurements. Numerous lines and
angles aid in the assessment of abnormalities of the growing
hip. (14) (Fig. 2-56)
• y–y line. A horizontal line is drawn through the triradiate
cartilage at its junction with the pelvic rim (cotyloid
notch). This is a baseline by which many other angles and
lines are derived.
a. Epiphyseal relationship. The apex of each femoral
epiphysis should be equally above the y–y line.
b. Diaphyseal interval. The distance between the top of
the diaphysis and the y–y line should be bilaterally
equal and not < 6 cm.
c. Pivot point interval. The distance between the apex of
the epiphysis and the inner acetabular margin of the
ilium should not exceed 16 mm.
d. Vertical line of Ombrédanne. A vertical line to the
y –y line is constructed through the outer upper
acetabular margin. The epiphyseal center should lie
below the y–y line and medial to this vertical line.
• Parallelogram of Kopitz. A rectangle is constructed by
drawing lines between four points—the outer and inner
iliac acetabular margins and the corners of the opposing
femoral diaphysis. Normally the angles will be approximately 90° at each corner.
Special Considerations. None.
Significance. The most common cause for alerting the clinician
to these relationships is congenital hip dislocation.
Figure 2-56 MISCELLANEOUS MEASUREMENTS OF THE
GROWING HIP. See text. Various measurements are demonstrated: diaphyseal interval (A), epiphyseal position (B),
vertical line of Ombrédanne (C), and the parallelogram of
Kopitz (D).
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Measurements of Protrusio Acetabuli
Shenton’s Line
Synonyms. Köhler’s Line.
Technique
Projection. AP pelvis, hip.
Landmarks. A line is constructed tangentially to the cortical
margin of the pelvic inlet and outer border of the obturator foramen. The relationship of the acetabular floor to this line is assessed.
(15,16) (Fig. 2-57)
Normal Measurements. The acetabular floor should not cross
this line and usually lies laterally to it.
Special Considerations. None.
Significance. If the acetabular floor crosses the line, then protrusio acetabuli is present. The most common causes are an idiopathic
form, rheumatoid arthritis, and Paget’s disease.
Synonyms. Makka’s line, Menard’s line.
Technique
Projection. AP hip, pelvis.
Landmarks. A curvilinear line is constructed along the undersurface of the femoral neck and is continued across the joint to
the inferior margin of the superior pubic ramus. (14) (Fig. 2-58)
Normal Measurements. The constructed line should be smooth,
especially in the transition zone between the femoral neck and
superior pubic ramus. Occasionally, a small portion of the inferior
femoral head may just cross the line.
Special Considerations. None.
Significance. An interrupted, discontinuous line is useful in the
detection of hip dislocation, femoral neck fracture, and slipped
femoral capital epiphysis.
Figure 2-58 SHENTON’S LINE. A and B. Normal. See text.
C. Hip Dislocation. Note the interruption in the smooth arc
of Shenton’s line.
Figure 2-57 MEASUREMENTS OF PROTRUSIO ACETABULI.
A and B. Normal. See text. C. Protrusio Acetabuli. Observe
the medial displacement of the acetabulum and femoral head
in relation to the line as a result of rheumatoid arthritis.
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Iliofemoral Line
Femoral Angle
Synonyms. None.
Technique
Projection. AP pelvis, hip.
Landmarks. A curvilinear line is constructed along the outer surface of the ilium, across the joint, and onto the femoral neck.
(17) (Fig. 2-59)
Normal Measurements. A small portion of the superior femoral
head may cause a slight convexity in the line. The most important
normal feature is that the line should be bilaterally symmetrical.
Special Considerations. None.
Significance. A discrepancy in symmetry may be the result of
congenital dysplasia, slipped femoral capital epiphysis, dislocation, or fracture.
Synonyms. Femoral angle of incidence, femoral neck angle,
Mikulicz’s angle.
Technique
Projection. AP hip, pelvis.
Landmarks. Two lines are drawn through and parallel to the midaxis of the femoral shaft and femoral neck. The angle subtended
is then measured. (18) (Fig. 2-60)
Normal Measurements. Slight variation occurs between males
and females. (14) (Table 2-29)
Table 2-29 Normal Values for Femoral Angle
Minimum (°)
Maximum (°)
120
130
Special Considerations. For accurate depiction of the femoral
angle, the foot should be medially rotated 15° at the time of radiographic exposure.
Significance. A value < 120° is designated as coxa vara and
> 130° as coxa valga.
Figure 2-59 ILIOFEMORAL LINE. A. AP Radiograph, hip.
B. Schematic Diagram. See text.
Figure 2-60 FEMORAL ANGLE. A and B. Normal. See text. The
angle to be measured is demonstrated (double-headed arrow).
C. Coxa Vara. Decreased angle (double-headed arrow).
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Skinner’s Line
Klein’s Line
Synonyms. None.
Technique
Projection. AP pelvis, hip.
Landmarks. A line is drawn through and parallel to the axis of
the femoral shaft. A second line is constructed at right angles to the
shaft line and tangential to the tip of the greater trochanter. The relationship of the fovea capitis to this trochanteric line is assessed.
(19) (Fig. 2-61)
Normal Measurements. The fovea capitis should lie above or
at the level of the trochanteric line.
Special Considerations. None.
Significance. The fovea lies below this line when there is a
superior displacement of the femur relative to the femoral head.
The most common causes are fracture and conditions leading to
coxa vara.
Synonyms. None.
Technique
Projection. AP and frog-leg, hip, or pelvis.
Landmarks. A line is constructed tangential to the outer margin
of the femoral neck. The degree of overlap of the femoral head
will be apparent. (20) (Fig. 2-62)
Normal Measurements. Comparison should be made with the
opposite side; generally there will be the same degree of overlap
of the femoral head. In most normal hips the outer margin of the
femoral head will be lateral to the line.
Special Considerations. This line can be drawn on both the AP
and frog-leg projections.
Significance. If the femoral head does not overlap the line or if
there is asymmetry from side to side, then slippage of the femoral
capital epiphysis should be suspected. (20)
Figure 2-61 SKINNER’S LINE. A. AP Radiograph, hip.
B. Schematic Diagram. See text.
Figure 2-62 KLEIN’S LINE. A and B. Normal ADOLESCENT
HIP. See text. C and D. Slipped Femoral Capital Epiphysis. AP
and frog-leg projections of the hip in slipped femoral capital
epiphysis. Note the lack of overlap across the line by the
femoral head.
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Axial Relationships of the Knee
Synonyms. None.
Technique
Projection. AP knee.
Landmarks. Four lines and two angles are drawn. (18) (Fig.
2-63)
• Femoral shaft line (A). A line is drawn through and parallel to the midaxis of the femoral shaft.
• Tibial shaft line (B). A line is drawn through and parallel
to the midaxis of the tibial shaft.
• Femoral condyle line (C). A line is drawn through and
tangential to the articular surfaces of the condyles.
• Tibial plateau line (D). A line is drawn through the medial
and lateral tibial plateau margins.
• Femoral angle (FA). This is the angle formed between the
femoral shaft and femoral condyle lines.
• Tibial angle (TA). This is the angle formed between the
tibial shaft and tibial plateau lines.
Normal Measurements. Slight variation exists between males
and females. (Table 2-30)
Table 2-30 Normal Values for Axial Relationships
of the Knee
Angle
Average (°)
Minimum (°)
Maximum (°)
Femoral
Tibial
81
93
75
85
85
100
Special Considerations. None.
Significance. These angles will be altered in fractures and other
deformities about the knee.
Figure 2-63 AXIAL RELATIONSHIPS OF THE KNEE. The
femoral angle (FA) and tibial angle (TA) are demonstrated.
See text.
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Patellar Position
Patellar Malalignment
Synonyms. Patella alta evaluation.
Technique
Projection. Lateral knee (semiflexed). (Fig. 2-64A)
Landmarks
Synonyms. Patellar tracking, patellar subluxation, patellofemoral joint incongruence.
Technique
Projection. Tangential knee (skyline). (Fig. 2-64, B and C)
Landmarks
• Patella apex (C). The patella is centered when its apex is
directly above the deepest section of the intercondylar
sulcus. (23) (Fig. 2-64B)
• Sulcus angle (A–A:B–B). By drawing lines from the highest
points on the medial and lateral condyles to the lowest point
of the intercondylar sulcus, an angle is formed. (Fig. 2-64B)
Normally, this should be 138° ± 6°. (23,24) Larger angles
(shallow intercondylar groove) predispose the individual to
subluxation and dislocation.
• Lateral patellofemoral joint index (C,D). The narrowest
medial joint space measurement is divided by the narrowest
lateral joint space measurement. (Fig. 2-64B) This index is
normally ≤ 1.0. A value > 1.0 is noted in patients with
chondromalacia patellae. (23–27)
• Lateral patellofemoral angle (C–C:D–D). A line tangential to the femoral condyles is intersected by a line joining
the limits of the lateral facet. (23–27) (Fig. 2-64C) The
angle is normally open. In patellar subluxation these lines
are parallel or open medially.
• Lateral patellar displacement (E). A line is drawn tangential to the medial and lateral condylar surfaces. A perpendicular line at the medial edge of the femoral condyle
normally lies ≤ 1 mm medial to the patella. (27)
(Fig. 2-64C)
• Patellar length (PL). This is the greatest diagonal
dimension between the superior and the inferior poles.
• Patellar tendon length (PT). The distance measured is between the insertion points of the posterior tendon surface
at the inferior patellar pole and the notch at the tibial
tubercle. (Fig. 2-64A)
Normal Measurements. Patellar length and patellar tendon
length are usually equal to each other. A normal variation up to
20%, however, is considered insignificant. (21)
Special Considerations. None.
Significance. When the patellar tendon length is > 20%
greater than the patellar length, patella alta is present. (22) This
may be found in association with chondromalacia patellae. A
low-riding patella (patella baja) may be seen in polio, achondroplasia, juvenile rheumatoid arthritis, and tibial tubercle transposition.
Significance. The combined use of these measurements may
reveal contributing causes to patellofemoral joint pain syndromes
and instability. (22,23)
A
E
A
D
B
D
C
C
C
D
E
B
A
B
Figure 2-64 PATELLAR RELATIONSHIPS. A. Patellar Position,
Lateral Projection. B and C. Patellar Malalignment. Various
C
angles and measures are demonstrated (arrows). See text.
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Axial Relationships of the Ankle
Synonyms. None.
Technique
Projection. AP ankle.
Landmarks. Four lines and two angles are constructed. (18)
(Fig. 2-65)
• Tibial shaft line (A). A line is drawn through and parallel
to the tibial shaft.
• Medial malleolus line (B). A line is drawn tangential to
the articular surface of the medial malleolus.
• Lateral malleolus line (C). A line is drawn tangential to
the articular surface of the lateral malleolus.
• Talus line (D). A line is drawn tangential to the articular
surface of the talar dome.
• Tibial angle (I). The angle is formed medially between the
medial malleolus line and talus line.
• Fibular angle (II). The angle is formed laterally between
the lateral malleolus line and talus line.
joint margins. This should be done on varus–valgus stress studies,
on which there should not be > 3 mm difference between the normal and injured sides. (28) Talar tilt is assessed by drawing a line
tangential to the talar dome and another line along the adjacent
tibial surface. In the neutral position, an angle > 6° indicates significant ligamentous injury. On valgus–varus stress views, the
normal range is 5–23°. A difference between right and left of
> 10° also indicates significant ligamentous damage. (29,30) An
anterior drawer of 4 mm is another indicator of instability. (31)
Normal Measurements. Slight variation occurs between males
and females. (18) (Table 2-31)
Table 2-31 Normal Values for Axial Relationships
of the Ankle
Angle
Average (°)
Minimum (°)
Maximum (°)
Tibial (I)
Fibular (II)
53
52
45
43
65
63
Special Considerations. None.
Significance. These angles will be altered in fractures of the
malleoli, ankle mortise instability, and tibiotalar slant deformities.
The tibiotalar joint space is measured at the lateral and medial
Figure 2-65 AXIAL RELATIONSHIPS OF THE ANKLE. The
angles to be measured are demonstrated (double-headed
arrows ). See text.
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241
Heel Pad Measurement
Boehler’s Angle
Synonyms. None.
Technique
Projection. Lateral foot, lateral calcaneus (non-weight bearing).
Landmarks. The shortest distance between the plantar surface
of the calcaneus and external skin contour is measured. (32)
(Fig. 2-66)
Normal Measurements. Variation between sexes does occur.
(33) (Table 2-32)
Synonyms. Axial relationships of the calcaneus, tuber angle.
Technique
Projection. Lateral foot, lateral calcaneus.
Landmarks. The three highest points on the superior surface of
the calcaneus are connected with two tangential lines. The angle
formed posteriorly is then assessed. (Fig. 2-67)
Normal Measurements. The angle formed posteriorly averages
between 30° and 35° in most normal subjects but may range
between 28° and 40°. Any angle < 28° is abnormal. (36)
Special Considerations. None.
Significance. The most common cause for an angle < 28° is a
fracture with displacement through the calcaneus. Dysplastic
development of the calcaneus may also disturb the angle.
Table 2-32 Normal Values for Heel Pad
Measurement
Sex
Average (mm)
Maximum (mm)
Male
Female
19
19
25
23
Special Considerations. Blacks may have a slightly larger heel
pad distance. (34)
Significance. Increased skin thickness, especially of the heel
pad, is a frequent accompanying feature of acromegaly. Achilles
tendon thickness can be assessed on a lateral view at 1–2 cm above
the calcaneus and is normally 4–8 mm in dimension. (35) Edema
from inflammatory arthritis can thicken the ligament.
28 – 40°
Figure 2-66 HEEL PAD MEASUREMENT. See text. The distance
to be measured is demonstrated (double-headed arrow).
Figure 2-67 BOEHLER’S ANGLE. A and B. Normal. The angle
to be measured is demonstrated (double-headed arrow).
C. Calcaneal Fracture. Observe the decrease in the angle
(double-headed arrow).
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UPPER EXTREMITY
Axial Relationships of the Shoulder
Synonyms. Humeral axial angle.
Technique
Projection. AP shoulder with external rotation.
Landmarks
• Humeral shaft line (A). A line is drawn through and
parallel to the humeral shaft. (Fig. 2-68)
• Humeral head line (B). From the apex of the greater
tuberosity a line is drawn toward the medial humeral
surface at the point at which the diaphyseal cortex changes
from a band to a line.
• Humeral angle (HA). This is the inferior angle between
the humeral shaft and head lines.
Glenohumeral Joint Space
Synonyms. None.
Technique
Projection. AP shoulder with external rotation.
Landmarks. The measurements are made at the superior, middle, and inferior aspects of the joint. These are combined and
averaged. Each distance is ascertained between the opposing
articular surfaces. (Fig. 2-69)
Normal Measurements. The average joint space is 4–5 mm. (2)
Special Considerations. None.
Significance. The joint space may be diminished in degenerative arthritis, calcium pyrophosphate dihydrate (CPPD) crystal
disease, and post-traumatic arthritis. A widened space is a frequently associated finding of acromegaly and posterior humeral
dislocation. (3)
Normal Measurements. The average humeral angles are 60°
for males and 62° for females. (1)
Special Considerations. None.
Significance. This relationship may be altered following a fracture, especially in the surgical neck.
Figure 2-69 GLENOHUMERAL JOINT SPACE. See text.
Figure 2-68 AXIAL RELATIONSHIPS OF THE SHOULDER. The
angle to be measured is demonstrated (double-headed
arrow). See text.
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243
Acromiohumeral Joint Space
Acromioclavicular Joint Space
Synonyms. None.
Technique
Projection. AP shoulder.
Landmarks. The distance between the inferior surface of the
acromion and the articular cortex of the humeral head is measured. (Fig. 2-70)
Normal Measurements. See Table 2-33. (4)
Synonyms. None.
Technique
Projection. AP or posteroanterior (PA) shoulder.
Landmarks. The joint space is measured at the superior (S) and
inferior (I) borders, and the two values are averaged. (Fig. 2-71)
Normal Measurements. The average joint space is 3 mm, with
variation between males and females. There should be no more
than 2–3 mm difference between the right and the left joint
spaces. (Table 2-34)
Table 2-33 Normal Values for Acromiohumeral
Joint Space
Average (mm)
Minimum (mm)
Maximum (mm)
9
7
11
Special Considerations. None.
Significance. A measurement < 7 mm indicates a rotator cuff
tear or degenerative tendinitis caused by the unopposed action of
the deltoid, allowing superior subluxation of the humerus. (4) A
measurement > 11 mm may indicate post-traumatic subluxation,
dislocation, joint effusion, stroke, or brachial plexus lesions
(drooping shoulder). (5)
Table 2-34 Normal Values for Acromioclavicular
Joint Space
Sex
Average
(mm)
Minimum
(mm)
Maximum
(mm)
Male
Female
3.3
2.9
2.5
2.1
4.1
3.7
Special Considerations. None.
Significance. A decreased joint space is seen in degenerative
joint disease. An increased joint space may be caused by traumatic
separation or resorption owing to osteolysis in association with
hyperparathyroidism or rheumatoid arthritis following trauma.
Figure 2-70 ACROMIOHUMERAL SPACE. The distance to be
measured is demonstrated (double-headed arrow). See text.
Figure 2-71 ACROMIOCLAVICULAR JOINT SPACE. A. Normal.
B. Abnormal. The measurement is abnormally decreased as a
result of degenerative joint disease (arrowheads).
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Axial Relationships of the Elbow
Radiocapitellar Line
Synonyms. None.
Technique
Projection. AP elbow.
Landmarks. Three lines and three angles are evaluated. (1)
(Fig. 2-72)
Synonyms. None.
Technique
Projection. Lateral elbow.
Landmarks. A line is drawn through the center of and parallel to
the long axis of the radius and is extended through the elbow
joint. (Fig. 2-73)
Normal Measurements. This line should pass through the center
of the capitellum in all stages of flexion of the elbow. (6)
Special Considerations. None.
Significance. This assists in determining the presence of radial
head subluxation (pulled elbow) or dislocation.
• Humeral shaft line (A). A line is drawn through and
parallel to the humeral shaft.
• Ulnar shaft line (B). A line is drawn through and parallel
to the ulnar shaft.
• Humeral articular line (C). A transverse line is drawn tangentially through the most distal surfaces of the trochlea
and capitellum.
• Carrying angle (CA). The angle formed between the
humeral and the ulnar shaft lines is measured.
• Humeral angle (HA). The angle formed between the
humeral shaft and articular lines is measured.
• Ulnar angle (UA). The angle formed between ulnar shaft
line and humeral articular line is measured.
Normal Measurements. Slight variations occur between males
and females. (Table 2-35)
Table 2-35 Normal Values for
Axial Relationships of the Elbow
Angle
Average (°)
Minimum (°)
Maximum (°)
Carrying
Humeral
Ulnar
169
85
84
154
72
72
178
95
99
Special Considerations. The elbow must be fully extended with
no rotation at the humerus.
Significance. These angles may be altered from fractures or
other deformities at the elbow.
Figure 2-72 AXIAL RELATIONSHIPS OF THE ELBOW. See
text. The angles to be measured are demonstrated (arrows,
arrowheads).
Figure 2-73 RADIOCAPITELLAR LINE. The radial shaft line
passes through the center of the capitellum (C). See text.
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Axial Relationships of the Wrist
Metacarpal Sign
Synonyms. None.
Technique
Projection. PA and lateral wrist.
Landmarks of PA Relationships
• Radioulnar articular line (A). A tangential line is drawn
from the tip of the radial styloid to the base of the ulnar
styloid. (Fig. 2-74A)
• Radial shaft line (B). A line is drawn through and parallel
to the shaft of the radius.
• Radioulnar angle (I). The ulnar side angle between the
two lines is measured.
Synonyms. None.
Technique
Projection. PA hand.
Landmarks. A line is drawn tangentially through the articular
cortex of the fourth and fifth metacarpal heads. (Fig. 2-75)
Normal Measurements. The line should pass distal to or just
touch the third metacarpal head. (7)
Significance. A line that passes through the third metacarpal
head is a frequent sign of gonadal dysgenesis (Turner’s syndrome). A fracture deformity may also produce a positive sign.
Landmarks of Lateral Relationships
• Radius articular line (A). A line is drawn across the most
distal points on the articular surface of the radius.
(Fig. 2-74B)
• Radial shaft line (B). A line is drawn through and parallel
to the shaft of the radius.
• Radius angle (II). The palmar angle is measured between
these two lines.
Normal Measurements. See Table 2-36. (1)
Table 2-36 Normal Values for Axial Relationships
of the Wrist
Angle
Average (°)
Minimum (°)
Maximum (°)
PA radioulnar
Lateral radius
83
86
72
79
95
94
Figure 2-75 METACARPAL SIGN. Normal third, fourth, and
fifth metacarpal relationships. See text.
Special Considerations. None.
Significance. These lines and constructed angles aid in the assessment of radioulnar deformities, especially those caused by
displaced fractures.
Figure 2-74 AXIAL RELATIONSHIPS OF THE WRIST. A. Posteroanterior. B. Lateral. The angles to be measured are demonstrated
(double-headed arrows). See text.
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Table 2-37 Lines and Angles of the Skull
Line or Angle
Figure
Number
Vastine-Kinney
2-2
Sella Turcica Size
2-3
Basilar Angle
2-4
McGregor’s Line
2-5
Chamberlain’s Line
2-6
Macrae’s Line
Normal Measurements
Landmarks
Pineal gland to inner
skull margins: frontal,
occipital, vault, and
foramen magnum
Horizontal: widest
diameter; vertical:
fossa floor to clinoids
Average
Minimum
Horizontal:
11 mm
Vertical:
8 mm
137°
Horizontal:
5 mm
Vertical:
4 mm
123°
Below line
—
Hard palate to opisthion
Below line
to 3 mm
above
—
2-7
Basion to opisthion
—
Digastric Line
2-8
Height Index
of Klaus
2-9
Boogard’s Line
2-10A
Right and left digastric
grooves: (a) line to
odontoid; (b) line
to C1-atlantooccipital joint
Tuberculum sellae to
IOP; odontoid to
line distance
Nasion to opisthion
Occipital
bone at
or below
line
11 mm
Boogard’s Angle
2-10B
Anterior Atlantooccipital
Dislocation
2-11
IOP, internal occipital protuberance.
Nasion to center sella
turcica; basion to
center sella turcica
Hard palate to occiput;
note relative
odontoid apex
Dorsum sella to basion;
basion to opisthion;
angle between lines
Basion to C1 posterior
arch; opisthion to
C1 anterior arch; ratio
of these distances
Maximum
40–41 mm
Ratio: < 1
Horizontal:
16 mm
Vertical:
12 mm
152°
Males:
8 mm
Females:
10 mm
7 mm
—
Pituitary and extrapituitary masses
enlarge fossa
Basilar impression
and platybasia
widen angle (> 152°)
Basilar impression
when odontoid more
than maximum
distance above
Basilar impression
when odontoid more
than maximum
distance above
Basilar impression
when odontoid is
above line
1 mm;
odontoid
not above
line
21 mm
Basilar impression
when odontoid is
above line
30 mm
None
Basilar impression
if < 30 mm
Basion
below
line
135°
Basilar impression
if basion above line
—
—
122°
Significance
Intracranial mass or
localized atrophy
when pineal displaced
Consult standard tables
119°
—
—
Basilar impression
if angle > 135°
Atlanto-occipital
dislocation when
ratio ≥ 1
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Table 2-38 Lines and Angles of the Cervical Spine
Line or Angle
Figure
Number
Normal Measurements
Landmarks
Average
Minimum
Maximum
Significance
(a) 3 mm;
(b) 5 mm
(a) Transverse ligament
rupture or instability;
(b) trauma, Down’s syndrome, and inflammatory
arthritis may increase the
measurement
Odontoid malposition if
> 13°
Atlantodental
Interspace
2-12
C1 anterior tubercle to
odontoid for (a) adult and
(b) child
—
Method of Bull
2-13
—
—
George’s Line
2-14
Hard palate to opisthion;
C1 anterior arch to
C1 posterior arch; measure posterior angle
Alignment of posterior
body margins
Aligned
—
—
Posterior
Cervical Line
2-15
Spinolaminar junction lines
Aligned
—
—
Sagittal Canal
Dimension
2-16
Posterior body to spinolaminar junction
See Table 2-7
Atlantoaxial
Alignment
2-17
C1 lateral mass to C2 articular pillar margin alignment
Aligned
—
—
Gravity Line
2-18
Vertical line from
odontoid apex
Passes through
C7 body
—
—
Lordosis Depth
2-19A
Odontoid apex to postC7 body; measure
greatest distance to line
12 mm
7 mm
17 mm
Jochumsen
2-19B
3–8 mm
1 mm
9 mm
Angle
2-19C
C1 anterior tubercle to anterior C7 body; measure distance to anterior C5 body
Atlas plane line and C7 endplates; then intersecting
perpendiculars
Cumulative total of
individual disc angles
C2 and C7 posterior bodies;
note location of intersection on (a) flexion
and (b) extension
40°
35°
45°
40°
16°
60°
Anterior bodies to posterior
air shadow margins:
(a) RPI (C2–C4), (b) RLI
(C4–C5), (c) RTI (C5–C7)
See Table 2-9
Drexler
Stress Lines
2-20
Prevertebral
Soft Tissues
2-21
(a) 1 mm;
(b) 1 mm
13°
—
12 mm
(a) C5–C6
joint;
(b) C4–C5
joint
—
—
(a) 7 mm;
(b) 7–20 mm;
(c) 20 mm
—
AP, anteroposterior; RLI, retrolaryngeal interspace; RPI, retropharyngeal interspace; RTI, retrotracheal interspace.
Anterior to posterior
vertebral malpositions
when line is not smooth
Anterior to posterior
vertebral malpositions
when line is not
smooth; especially at
C1 and C2
Spinal stenosis when
< 12 mm; intraspinal
tumor when enlarged
Jefferson’s or odontoid
fractures or alar ligament
instability when margins
overlap
AP displacement is a gross
indicator of gravitational
stress at the cervicothoracic junction
Role unclear; decreased
after trauma, muscle
spasm, spondylosis, and
patient tucking the chin
at time of exposure
Stress point during these
movements often
altered by muscle
spasm, fixation, and
spondylosis
Soft tissue masses (tumor,
infection, hematoma) increase the measurements
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Table 2-39 Lines and Angles of the Thoracic Spine
Line or Angle
Figure
Number
Method of Cobb
2-22
Risser-Ferguson
2-23
Thoracic Kyphosis
2-24
Thoracic Cage
Dimension
2-25
Normal Measurements
Landmarks
Average
Minimum
Maximum
End vertebral endplate
lines; then intersecting perpendiculars;
measure angle
Centers of end and
apical segments
joined; measure angle
T1 superior endplate to
T12 inferior endplate;
then intersecting perpendiculars; measure
angle
Posterior sternum to
anterior T8 body;
(a) male, (b) female
—
—
—
Scoliosis evaluation
—
—
—
Scoliosis evaluation
See Tables
2-10 and
2-11
—
—
Kyphosis evaluation
(Scheuermann’s
fractures, etc.)
(a) 14 cm;
(b) 12 cm
(a) 11 cm;
(b) 9 cm
(a) 18 cm;
(b) 15 cm
Significance
Straight back syndrome
when distance is
(a) < 13 cm;
(b) < 11 cm
Table 2-40 Lines and Angles of the Lumbar Spine
Line or Angle
Figure
Number
Normal Measurements
Landmarks
Intervertebral
Disc Height
Hurxthal’s Method
2-26A
Endplate to endplate
distance
Farfan’s Method
2-26B
Intervertebral
Disc Angles
2-27
Lordosis
2-28
Lumbosacral
Lordosis
2-29
Sacral Inclination
2-30
Anterior height divided
by disc diameter; posterior height divided
by disc diameter; then
ratio to each other
At each disc endplate
lines are drawn;
measure the angles
L1 endplate to S1 endplate; perpendiculars
and angle formed
Centers of L3, L5, and
S1 bodies found and
joined; measure angle
Posterior surface of S1
to vertical line angle
Lumbosacral
Angle
2-31
Endplate of S1 to horizontal line angle
Lumbosacral
Disc Angle
2-32
Gravity Line
(Lumbar)
2-34
Macnab’s Line
2-35
Angle between opposing endplates of L5
and S1
A perpendicular line
from the center point
of the L3 body
A line along the inferior
endplate
Average
Minimum
Maximum
Variable
—
—
Variable
—
—
See Table
2-14
—
—
50–60°
—
—
146°
124°
162°
46°
30°
72°
41°
26°
57°
10°
15°
—
Intersects
sacral base
—
—
Should be
above
superior
articular
process
—
—
Significance
Decreased disc height
(degeneration,
surgery, infection)
Decreased disc height
(degeneration,
surgery, infection if
by disc diameter)
Altered in various
mechanical
pathologies
Altered in various
mechanical
pathologies
Altered in various
mechanical
pathologies
Altered in various
mechanical
pathologies
Altered in various
mechanical
pathologies
Altered in various
mechanical
pathologies
Altered in various
mechanical
pathologies
Extension malposition,
normal variant
2
Measurements in Skeletal Radiology I
249
Table 2-40 Lines and Angles of the Lumbar Spine—Continued
Line or Angle
Figure
Number
Normal Measurements
Landmarks
Average
Minimum
Maximum
A line along the inferior
surface of the TVP,
AP, and across the
joint
Endplate lines at opposing segments; measure from the posterior body to the point
of intersection
Amount of displacement
on flexion–
extension (see text)
Smooth
across joint
—
—
Equal measurements
—
1.5 mm
difference
Nuclear, annular, and
posterior ligament
damage if < 1.5 mm
difference
—
—
—
(a) Aligned;
(b) Progressive alteration;
(c) Toward
concavity;
(d) Gradually
increase
away from
the sacrum
—
—
—
Flexion instability:
ligamentous failure;
extension instability:
anterior ligamentous
failure; rotational
instability: posterior
joint ligamentous
failure
(a) Disc ligament failure if displaced;
(b) posterior joint ligament laxity; (c) posterior joint ligament
laxity; (d) disc herniation at level failing
to laterally flex
(lateral bending sign)
—
—
Grading severity of
spondylolisthesis
L5 behind the
line
—
—
See Table
2-18
—
—
Detection of subtle
spondylolisthesis
when L5 body
crosses perpendicular line
Widened in intraspinal
tumors; narrowed in
spinal stenosis
Spinal stenosis
suspected when
< 15 mm
Hadley’s S Curve
2-36
Van Akkerveeken’s
Measurement
2-37
Flexion–Extension
2-38
Lateral-Bending
Instability
(a) 2-39;
(d) 2-40
(a) Body alignment;
(b) pedicle position;
(c) spinous position;
(d ) intersegmental
wedging
Meyerding’s
Grading
2-41
Ullmann’s Line
2-42
Sacral base divided into
quarters; relative position of the posterior
body of the L5 is
determined
Endplate line through
S1, perpendicular
from sacral
promontory
Interpediculate
Distance
2-43
Eisenstein’s
Method
2-44
Canal to Body
Ratio
2-45
Intercrestal Line
2-46
Transverse Process
2-47
AP, anteroposterior; TVP, transverse process.
Shortest distance between inner surfaces
of opposing pedicles
Tips of superior and
inferior articular processes joined; distance
between posterior
midbody and line
(except at L5)
Canal size (AP, lateral)
divided by body size:
(a) L3 and L4; (b) L5
Iliac crests joint; relative position of L4
and L5 bodies and
discs
Vertical line through tip
of L3, TVP; L5 TVP
length assessed relative to the line
Variable
15 mm
—
—
(a) 1:3.0;
(b) 1:3.2
(a) 1:6.0;
(b) 1:6.5
—
—
—
—
—
—
Significance
Facet subluxation
Greater than
maximum ratio
denotes a small canal
May predict level of
most stress and subsequent degeneration
May predict level of
most stress and subsequent degeneration
250
I
Yochum & Rowe’s Essentials of Skeletal Radiology
Table 2-41 Lines and Angles of the Lower Extremity
Normal Measurements
Line or Angle
Figure
Number
Teardrop Distance
2-48
Femoral head to
teardrop distance
9 mm
6 mm
11 mm
Hip Joint Space
Width
2-49
Femoral head to acetabulum distance:
(a) superior; (b) axial;
(c) medial
(a) 4 mm;
(b) 4 mm;
(c) 8 mm
(a) 3 mm;
(b) 3 mm;
(c) 4 mm
(a) 6 mm;
(b) 7 mm;
(c) 13 mm
Acetabular Depth
2-50
(a) 13 mm;
(b) 12 mm
(a) 7 mm;
(b) 9 mm
(a) 18 mm;
(b) 18 mm
Center–Edge Angle
2-51
36°
20°
40°
A shallow acetabulum
may precipitate
degenerative joint
disease
Symphysis Pubis
2-52
(a) 6 mm;
(b) 5 mm
(a) 4.8 mm;
(b) 3.8 mm
(a) 7.2 mm;
(b) 6.0 mm
Diastasis and inflammatory joint disease may
widen the joint
Presacral Space
2-53
(a) 3 mm;
(b) 7 mm
(a) 1 mm;
(b) 2 mm
(a) 5 mm
(b) 20 mm
Soft tissue mass (tumor,
infection, hematoma),
if exceeds maximum
distance
Acetabular Angle
2-54
20°
12°
29°
Iliac Angle
2-55
Superior pubis to outer
acetabulum; measure
distance from the
line to the farthest
surface: (a) male;
(b) female
Lines are drawn from
the center of the
femoral head, vertically, and the acetabular edge; measure
the angle
The distance between
opposing articular
surface, halfway
between the superior
and inferior margins:
(a) male; (b) female
Soft tissue density
between the rectum
and anterior sacral
surface: (a) child;
(b) adult
Draw y–y line and line
from medial to lateral
acetabular surface;
measure the angle
Draw y–y line and line
along lateral iliac
wing and iliac body
Add right and left iliac
and acetabular angles
and divide by 2
Pelvic inlet to outer
obturator; acetabulum
should be lateral to
the line
Smooth curvilinear line
along medial femoral
neck and superior
obturator border
Smooth curvilinear line
along ilium and onto
femoral neck; should
be bilaterally
symmetrical
Congenital hip dislocation widens the angle;
Down’s syndrome
decreases the angle
Combined with
acetabular angles to
derive iliac index
Down’s syndrome possible between 60° and
80°; probable < 60°
Protrusio acetabuli
(Paget’s disease, etc.)
when acetabulum is
medial to the line
Femur dislocation or
fracture if line is
interrupted
Iliac Index
Protrusio Acetabuli
2-57
Shenton’s Line
2-58
Iliofemoral Line
2-59
Landmarks
Average
—
Minimum
—
< 68°
68°
Maximum
—
—
—
—
—
—
—
—
—
—
—
Significance
Early Perthes or other
inflammatory joint
disease may widen
the space > 11 mm
or creat a 2-mm
difference from the
normal side
Various joint diseases
decrease these distances: (a) degenerative joint disease;
(b) rheumatoid arthritis; (c) degenerative
and rheumatoid
arthritis
A shallow acetabulum
exists when the
measurement is
(a) < 7 mm or
(b) < 9 mm
Asymmetry may denote
hip joint abnormality
2
Measurements in Skeletal Radiology I
251
Table 2-41 Lines and Angles of the Lower Extremity—Continued
Line or Angle
Figure
Number
Femoral Angle
2-60
Skinner’s Line
2-61
Klein’s Line
2-62
Axial Relationships of the
Knee
Patellar Malalignment
Patella Alta
2-63
Normal Measurements
Landmarks
Average
Lines through the axis
of the femoral shaft
and neck
Femoral shaft line and
perpendicular line
tangential to the hip
of the greater
trochanter
Tangential line to outer
femoral neck; head
just overlaps
laterally
See text; (a) femoral
angle; (b) tibial angle
—
Minimum
Passes
through
or below
fovea
capitis
—
(a) 81°;
(b) 93°
Maximum
130°
120°
—
—
Hip joint abnormality
(fracture, varus, etc.)
if line passes above
the fovea capitis
—
—
Slipped epiphysis suspected if head does
not intersect line
(a) 75°;
(b) 85°
(a) 85°;
(b) 100°
2-64A
Patella length to patella
tendon ratio
1:1 (+ 20%)
—
—
Patella Apex
2-64B
Aligned
—
—
Sulcus Angle
2-64B
Apex to intercondylar
sulcus
Surface of medial and
lateral condyles
Patellofemoral
Joint Index
Lateral PatelloFemoral
Angle
2-64B
1.0
—
—
Open angle
—
—
Lateral Patellar
Displacement
2-64C
Medial and lateral joint
spaces
Tangential lines through
the femoral condyles
and lateral facet of
the patella
Perpendicular line tangential to the lateral
edge of the medial
femoral condyle
—
—
Axial Relationships of the
Ankle
Heel Pad
2-65
See text; (a) tibial angle;
(b) fibular angle
Tangential to
medial
edge of
patella
(a) 53°;
(b) 52°
2-66
Boehler’s
Angle
2-67
Shortest distance
between the calcaneus and plantar skin
surface: (a) male;
(b) female
Three superior points
joined on the calcaneus; measure
posterior angle
2-64C
138°
30–35°
144°
132°
(a) 45°;
(b) 43°
—
(a) 19 mm;
(b) 19 mm
28°
Significance
Coxa vara: < 120°; coxa
valga: > 130°
(a) 65°;
(b) 63°
Deformities (trauma,
congenital, arthritis)
at the knee will alter
these angles
Chondromalacia patellae
factor if the ratio is
exceeded by > 20%
Patella subluxation
Shallow angle (> 144°
predisposes to lateral
subluxation)
Ratio > 1 in chondromalacia patellae
Patellar malalignment
suggested if lines are
parallel or open
medially
Patellar malalignment
—
(a) 25 mm;
(b) 23 mm
Acromegaly produces
skin overgrowth
exceeding the maximum measurement
40°
Calcaneal fractures may
reduce the angle to
< 28°
252
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Yochum & Rowe’s Essentials of Skeletal Radiology
Table 2-42 Lines and Angles of the Upper Extremity
Line or Angle
Figure
Number
Normal Measurements
Minimum
Maximum
Significance
Axial Relationships of the
Shoulder
2-68
Humeral shaft to
humeral head angle
60–62°
—
—
Glenohumeral
Joint
2-69
Average humeral head
to glenoid distance
(superior, middle,
inferior)
4–5°
—
—
Acromiohumeral
Joint Space
2-70
Acromion to humeral
head
9 mm
7 mm
11 mm
Acromioclavicular
Joint Space
2-71
Average acromion to
clavicular distance
(superior, inferior):
(a) male; (b) female
(a) 3.3. mm;
(b) 2.9 mm
(a) 2.5 mm;
(b) 2.1 mm
(a) 4.1 mm;
(b) 3.7 mm
Axial Relationships of the
Elbow
2-72
See text; (a) carrying
angle; (b) humeral
angle; (c) ulnar angle
(a) 169°;
(b) 85°;
(c) 84°
(a) 154°;
(b) 72°;
(c) 72°
(a) 178°;
(b) 95°;
(c) 99°
Radiocapitellar
Line
2-73
Radius axis line through
the elbow joint
Axial Relationships of the
Wrist
2-74
Metacarpal Sign
2-75
See text; (a) PA view:
radioulnar angle;
(b) lateral view:
radius angle
Tangential line through
the fourth and fifth
metacarpal heads;
third head should be
proximal to the line
Passes
through
capitellar
center
(a) 83°;
(b) 86°
Humeral deformities
(fractures, congenital,
etc.) alter these
values
Degenerative and crystal
arthritis diminish the
space; posterior
dislocation may
widen it
Rotator cuff tear decreases distance;
subluxation and
dislocation increase
distance
Degenerative arthritis
decreases distance;
separation and
resorption widens
distance
Elbow deformities
(fractures, congenital,
etc.) alter these
values
Radius subluxation and
dislocation if line
misses the capitellar
center
Wrist deformities
(trauma, congenital,
etc.) alter these
values
Turner’s syndrome, postfracture deformity
PA, posteroanterior.
Landmarks
Average
—
—
(a) 72°;
(b) 79°
—
—
(a) 95°;
(b) 94°
—
2 Measurements in Skeletal Radiology I
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2
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33. Hadley LA: Intervertebral joint subluxation, bony impingement, and
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35. Peters RE: The facet syndrome. J Aust Chiro Assoc 13(3):15, 1983.
36. Swezey RL, Silverman TR: Radiographic demonstration of induced
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38. van Akkerveeken PF, Obrien JP, Park WM: Experimentally
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40. Dupuis PR, Yong-Hing K, Cassidy JD, et al.: Radiologic diagnosis
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47. Capener N: Spondylolisthesis. Br J Surg 19:374, 1932.
48. Garland LH, Thomas SF: Spondylolisthesis: Criteria for more
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49. Hinck VC, Clark WM Jr, Hopkins CE: Normal interpediculate
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50. Elseberg CA, Dyke CG: Diagnosis and localization of tumors of
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51. Eisenstein S: Measurements in the lumbar spinal canal in two racial
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52. Weisz GM, Lee P: Spinal canal stenosis. Concept of spinal reserve
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53. Jones RAC, Thompson JLG: The narrow lumbar canal. J Bone
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54. Williams RM: The narrow lumbar spinal canal. Aust Radiol 19:356,
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55. MacGibbon B, Farfan H: A radiologic survey of various configurations of the lumbar spine. Spine 4(3):258, 1979.
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Measurements in Skeletal Radiology I
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1. Eyring EJ, Bjornson DR, Peterson CA: Early diagnostic and prognostic signs in Legg-Calvé-Perthes’ disease. AJR 93:382, 1965.
2. Sweeney JP, Helms CA, Minagi H, et al.: The widened teardrop
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3. Bowerman JW, Sena JM, Chang R: The teardrop shadow of the
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1982.
4. Armbruster JG, Guerra J, Resnick D, et al.: The adult hip: An
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5. Murray RO: The aetiology of primary osteoarthritis of the hip.
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6. Wiberg G: Studies on dysplastic acetabula and congenital subluxation of the hip joint—With special reference to the complication
of osteoarthritis. Acta Chir Scand (58 Suppl):1, 1939.
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8. Vix VA, Ryu CY: The adult symphysis pubis: Normal and abnormal. AJR 112:517, 1971.
9. Chrispin AR, Fry IK: The presacral space shown by barium enema.
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17. Martin HE: Geometrical-anatomical factors and their significance
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18. Keats TE, Teeslink R, Diamond AE, et al.: Normal axial relationships of the major joints. Radiology 87:904, 1966.
19. Sante LR: Principles of Roentgenological Interpretation, ed 8. Ann
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20. Klein A, Joplin RJ, Reidy JA, et al.: Roentgenographic features
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28. Berquist TH: Radiology of the Foot and Ankle. New York, Raven
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31. Gould N, Seligson D, Glassman J: Early and late repair of lateral
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32. Steinbach HL, Russell W: Measurement of the heel pad as an aid
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34. Puckette SE, Seymour EQ: Fallibility of the heel pad thickness in
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35. Resnick DL, Feingold ML, Curd J, et al.: Calcaneal abnormalities
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UPPER EXTREMITY
1. Keats TE, Teeslink R, Diamond AE, et al.: Normal axial relationship of the major joints. Radiology 87:904, 1966.
2. Petersson CJ, Redlund-Johnell I: Joint space in normal glenohumeral radiographs. Acta Orthop Scand 54:274, 1983.
3. Arndt JH, Sears AD: Posterior dislocation of the shoulder. AJR
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6. Storen G: Traumatic dislocation of the radial head as an isolated
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7. Archibald RM, Finby N, de Vitto F: Endocrine significance of
short metacarpals. J Clin Endocrinol 19:1312, 1959.
Congenital Anomalies and
Normal Skeletal Variants
3
Gary M. Guebert, Lindsay J. Rowe, Terry R. Yochum,
Jeffrey R. Thompson, and Chad J. Maola
INTRODUCTION
ANOMALIES OF THE SKULL BASE
PLATYBASIA
BASILAR IMPRESSION
ARNOLD-CHIARI MALFORMATION
ANOMALIES OF THE ATLAS
OCCIPITALIZATION OF THE ATLAS
OCCIPITAL VERTEBRAE
ANOMALIES OF THE AXIS
OSSICULUM TERMINALE PERSISTENS
(OF BERGMANN)
OS ODONTOIDEUM
HYPOPLASTIC AND AGENETIC
ODONTOID PROCESS
DOWN’S SYNDROME
ANOMALIES OF C3–C7
BLOCK VERTEBRAE
KLIPPEL-FEIL SYNDROME
SPRENGEL’S DEFORMITY
CERVICAL SPONDYLOLISTHESIS
ABSENT PEDICLE OF THE CERVICAL SPINE
CERVICAL RIB
ANOMALIES OF THE THORACIC
AND LUMBAR SPINES
VERTEBRAL BODY ANOMALIES
ANOMALIES OF THE POSTERIOR ARCH
ANOMALIES OF THE THORAX
ANOMALIES OF THE RIBS
ANOMALIES OF THE STERNUM
ANOMALIES OF THE HIP AND PELVIS
DEVELOPMENTAL DYSPLASIA OF THE HIP
COXA VARA AND COXA VALGA
SACRAL AGENESIS
HERNIATION PIT OF THE FEMORAL NECK
ANOMALIES OF THE LOWER
EXTREMITY
BIPARTITE, TRIPARTITE, AND
MULTIPARTITE PATELLAE
DORSAL DEFECT OF THE PATELLA
FONG’S SYNDROME
SESAMOID BONES AND OSSICLES
OF THE KNEE
INTRODUCTION
Congenital anomalies and normal skeletal variants are a common
occurrence in clinical and radiological practice. Congenital anomalies are those conditions that are present at birth. They typically result in a local deformity that may or may not be related to clinical
signs and symptoms. When the condition affects multiple skeletal
regions and potentially other body systems, we use the term skeletal dysplasia, many examples of which are presented in Chapter 8.
Normal skeletal variants encompass a wide spectrum of altered
bone morphology, which may be congenital or acquired, usually
have few clinical implications, but sometimes mimic more sinister
pathologic processes. The challenge of this chapter is to present
samples of the more common and/or clinically pertinent conditions
included under these headings with enough detail for understanding, while avoiding tedious information that is best left to
a more exhaustive textbook dedicated to anomalies and variants.
The importance of this chapter cannot be overemphasized; in
tandem with the knowledge of normal skeletal anatomy, it is the
basis for accurate interpretation of musculoskeletal images on
TARSAL COALITION
VERTICAL TALUS
MORTON’S SYNDROME
SESAMOID BONES AND OSSICLES
OF THE FOOT AND ANKLE
ANOMALIES OF THE UPPER
EXTREMITY
SUPRACONDYLAR PROCESS OF
THE HUMERUS
RADIOULNAR SYNOSTOSIS
MADELUNG’S DEFORMITY
ULNAR VARIANCE
CARPAL COALITION
CARPAL BOSS
POLYDACTYLY
SYNDACTYLY
DIGITAL CURVATURES
ATLAS OF COMMON NORMAL
SKELETAL VARIANTS
REFERENCES
a day-to-day basis, no matter what specialty of practice. The first
part of this chapter focuses on common congenital anomalies
by body region, and the second is a compendium of images that
demonstrate common skeletal variants, presented in anatomic
format with textual comments limited to the figure captions.
ANOMALIES OF THE SKULL BASE
PLATYBASIA
Synonyms. Flat skull base, Martin’s anomaly.
Description. Platybasia is an anthropological term describing
a flattening of the angle between the clivus and body of the
sphenoid. (1)
Clinical Features. Platybasia may occur as an isolated congenital anomaly, in conjunction with skeletal dysplasia such as
achondroplasia, with osteogenesis imperfecta, or secondary to
Paget’s disease or other bone softening disorders. The majority of
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cases are asymptomatic and remain so throughout life. Rarely, the
upward displacement secondary to degenerative changes of the
upper cervical joints and ligaments may precipitate impingement
onto local neural or vascular structures, usually during the 3rd–5th
decades. (2) Neurological complications of the brainstem, including infarction and syrinx formation; cerebellar dysfunction from infarction and gliosis; Chiari malformation; and perfusion disturbances of the vertebrobasilar arterial system may occur. (3,4)
Radiologic Features. On lateral skull radiographs and sagittal
MRI or CT studies, the skull base angle (Martin’s basilar angle)
can be determined by measuring the angle subtended between
lines from the nasion to sella turcica to the anterior foramen magnum. The normal range is 123–152°. Platybasia is designated
when the angle is > 152°. (2) Common associated changes include
basilar invagination and cervical spine anomalies of the atlas, especially occipitalization, block vertebrae, and Klippel-Feil syndrome. If plain film studies suggest platybasia, MRI evaluation is
indicated as part of the necessary neurovascular evaluation.
base. The position of the foramen magnum and the apex of the
dens are assessed by numerous lines and measurements, including the height index of Klaus and Chamberlain’s, McGregor’s,
Macrae’s, and Boogaard’s lines. (2,5–8) (Fig. 3-1) (See Chapter 2.)
Additional signs of the associated bone softening pathology (e.g.,
Paget’s disease, osteomalacia, fibrous dysplasia) and atlas anomalies can also be observed. When basilar impression occurs in
conjunction with occipitalization, atlantoaxial instability may occur
secondary to acquired laxity of the transverse ligament. Flexion–
extension films should be taken. CT is useful for detecting the
underlying bone disease, and sagittal reconstructions are helpful in assessing the dens position in the foramen magnum. MRI
should be considered in most cases to assess for brainstem compression and syrinx formation, and magnetic resonance angiography (MRA) studies can assess for vertebrobasilar anomalies
and perfusion defects.
BASILAR IMPRESSION
Synonyms. Basilar invagination.
Description. Basilar impression describes the condition of a relative cephalad position of the upper cervical vertebra to the base
of the skull. Two types of basilar impression are described: primary
and secondary. (5)
Clinical Features
Primary Basilar Impression. Primary basilar impression is congenital in origin and often is associated with a variety of vertebral
defects, such as occipitalization of the atlas, spina bifida occulta of
the atlas, odontoid anomalies, agenesis or hypoplasia of the atlas,
Klippel-Feil syndrome, and Arnold-Chiari malformation.
Secondary Basilar Impression. Secondary basilar impression is
an acquired condition that results from disease softening of the occipital bone in which the weight of the cranium deforms the base.
The most common bone softening disorders that may precipitate
this deformity are Paget’s disease, osteomalacia, fibrous dysplasia,
and osteogenesis imperfecta. Inflammatory arthropathies cause
cephalic migration of the dens as a result of bone and transverse
ligament destruction. Rheumatoid arthritis is the most common
of the arthritides to cause secondary basilar impression. Other less
common causes include tumor, infections, cretinism, Morquio’s
syndrome, and cleidocranial dysostosis.
A familial incidence of primary basilar invagination has been
recorded. There is no gender predilection. Many cases remain
asymptomatic throughout life, and the percentage that does become symptomatic is unknown. The onset of symptoms typically
begins in the 3rd–4th decades with occipital headaches, neck stiffness, brainstem dysfunction (nystagmus, dysphagia, facial pain,
unsteady gait), and long tract signs of the upper and lower limbs.
Up to 25% of cases may have congenital and acquired disease of
the vertebral arteries at the craniovertebral junction. (3,4) The thoracic kyphosis often increases with an increase in cervical lordosis
secondary to muscular weakness. The diversity of symptoms often
suggests a diagnosis of multiple sclerosis. (2)
Radiologic Features. On lateral plain films of the skull and cervical spine, elevation of the floor of the posterior fossa, an upward
convexity of the posterior aspect of the foramen magnum, and
cephalic migration of the odontoid are the main findings. The dens
does not actually migrate, of course — the skull settles inferiorly
owing to the congenital or acquired intrinsic pathology of the skull
Figure 3-1 BASILAR IMPRESSION WITH OCCIPITALIZATION.
A. Lateral Cervical Spine. There is fusion of the atlas with
the occiput (occipitalization) and congenital fusion of C2–C5
(block vertebrae). The dens lies superiorly within the foramen magnum (basilar impression). Observe closely the position of the anterior atlas arch relative to the dens (atlantodental interval), which is abnormally increased to > 3 mm
owing to laxity of the atlas transverse ligament (atlantoaxial
instability). B. Tomogram, Lateral Upper Cervical Spine. The
odontoid process (O) lies well above McGregor’s line (M),
confirming basilar impression. The increased atlantodental
interval is also demonstrated as a manifestation of acquired
atlantoaxial instability.
3
Medicolegal Implications
PLATYBASIA AND BASILAR IMPRESSION
•
•
•
•
• Basilar impression can be complicated by
sudden hearing loss, pyramidal tract signs,
posterior column signs, and wasting of the
upper limbs. Abnormalities in somatosensory-evoked potentials and abnormal brainstem auditory-evoked potentials may also be noted. (9)
Platybasia has been associated with syringomyelia. (10)
The high incidence of vertebral artery abnormalities
may be a risk factor for vertebrobasilar vascular complications. (3,4)
Lethal spinal cord injury following hyperextension of
the cervical spine was reported in a patient with basilar
impression and occipitalization of C1. (11)
On recognition of the presence of basilar impression or
platybasia, consider MRI or MRA studies of the craniocervical junction to assess for neurological and vascular
complications.
ARNOLD-CHIARI MALFORMATION
Synonyms. Type I: tonsillar herniation or tonsillar ectopia.
Type II: none.
Description. In 1891 Chiari (1) and later Arnold (1894) described the morphologic changes of the hindbrain that now bear
A
B
Figure 3-2 ARNOLD-CHIARI TYPE I MALFORMATION WITH
HOLOCORD SYRINX. This 25-year-old male patient presented
with cervical spine pain in extension. A thorough neurological examination revealed a unilateral decreased pinwheel
sensation on the right in a shawl-like distribution. A. T1Weighted MRI, Sagittal Cervical Spine. B. T1-Weighted MRI,
Axial Cervical Spine. There is caudal displacement of the
cerebellar tonsils several millimeters below the foramen
magnum (arrow). Observe the large size of the spinal cord
(arrowheads) secondary to the huge central canal (stars).
Congenital Anomalies and Normal Skeletal Variants I
259
their names, the Arnold-Chiari malformation. The brain changes
are characterized by downward displacement or elongation of
the brainstem and cerebellar tonsils through the foramen magnum. Hydrocephalus is variably present and mild. There are two
main presentations.
Clinical Features
Type I Malformation. Type I Arnold-Chiari malformation patients usually present in adulthood with mild brain changes, mild
hydrocephalus, and variable syringomyelia (30 –56%). Females
are predominantly affected 3:2. (2) The presenting symptoms in
type I patients are sometimes vague or bizarre and may initially
suggest a psychiatric disorder. (3) Common complaints include
headache and cervical pain.
Type II Malformation. The symptoms of the type II malformation are more severe and present in infancy or childhood. Stridor,
apnea, and feeding problems may be seen early. Older children
may demonstrate nystagmus and cranial nerve palsies. (3) The
hydrocephalus is severe. Dorsal kinking of the medulla at the cervicomedullary junction is commonly present, and there is upward displacement of the upper cervical nerves. Spina bifida and
meningomyelocele are also associated with type II Arnold-Chiari
malformation.
Type III Arnold-Chiari malformation is rare and is not discussed here. Associated skeletal abnormalities include occipitalization of the first cervical vertebra, platybasia and basilar
impression, cervical block vertebrae, cervical ribs and fused
thoracic ribs, and syringomyelia. (2)
Treatment for type I disease is usually posterior fossa and
upper cervical decompression (suboccipital craniectomy and
cervical laminectomy). If a syrinx is also present, a shunt may be
placed within the cavity (spinal myelotomy) to effect spinal cord
decompression.
C
D
Note the low signal intensity of the central canal, which contains cerebrospinal fluid (CSF). The cephalad portion of the
syrinx extends to the C1–C2 level. C. Gradient-Echo MRI,
Sagittal Cervical Spine. The low signal intensity CSF becomes
hyperintense on this pulse sequence. The thin margins of the
spinal cord are obscured by the large amount of CSF within
the syrinx. D. T1-Weighted MRI, Sagittal Thoracic Spine.
The caudal extent of the syrinx terminates in the conus
medullaris (arrow). (Courtesy of Mark L. Taylor, DC,
Las Vegas, Nevada.)
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Radiologic Features. Plain radiographs are typically not
helpful in making this diagnosis but are capable of showing
the associated skeletal malformations. Myelography and CT myelography were used before the advent of MRI to make the diagnosis of Arnold-Chiari malformation. MRI currently is the key
to making a definitive diagnosis. Low-lying, triangular-shaped
cerebellar tonsils and elongation or kinking of the fourth ventricle with a sharp clivoaxial angle are classic findings. Syringomyelia is easily demonstrated by MRI as a spinal cord cavitation.
This cavity may be focal, usually cervical or cervicodorsal, or
holocord. (Fig. 3-2)
Medicolegal Implications
ARNOLD-CHIARI MALFORMATION
• Autonomic disturbances such as sexual disorders (reduced potency or impotency),
dyspnea, anhidrosis, hyperhidrosis, and constipation have been reported. (4)
• An association between perinatal accidents and syringomyelia has been reported. (5)
• Patients who have decompressive surgery for ArnoldChiari type II malformation may be at risk for postsurgical
cervical spine instability. (6)
• An association of progressive scoliosis and syrinx with
Arnold-Chiari malformation has been reported. (7)
ANOMALIES OF THE ATLAS
OCCIPITALIZATION OF THE ATLAS
Synonyms. Atlas assimilation, atlanto-occipital fusion,
block atlas.
Description. Occipitalization is a congenital synostosis of the
atlas to the occiput caused by a failure of segmentation and separation of the most caudal occipital sclerotome during the first
few weeks of fetal life. It is the most cephalic block vertebra of
the spine and the most common anomaly of the craniovertebral
junction. (1) In 1577 Columbo first described the condition,
followed by Rokitansky in 1844 and Macalister in 1892; the
first radiological demonstration was performed by Schüller in
1911. (2,3)
Clinical Features. A short neck, low hair line, and restricted
neck motion is found in more than two thirds of cases. (4) Local
symptoms include nuchal and facet joint pain. (5) There is a male
dominance of up to 5:1, with a population incidence as high as
0.75–3%. (3,4,6) Generally, young patients will be asymptomatic,
but the risk for significant neurological dysfunction increases with
age, usually beginning in the 3rd–4th decades of life. Premature
and severe degenerative joint disease at C1–C2 and C2–C3 are
common. Repetitive microtrauma, a minor injury, or even a trivial event such as sneezing may initiate symptoms in the 2nd–
3rd decades of life. (4,7) Neck and throat infections are also
known precipitants for the onset of symptoms. (4) Torticollis
may herald atlantoaxial instability from failure of the transverse
ligament. Sudden death has been reported. (8) Brainstem and
cerebellar changes include altered gait, ataxia, incoordination,
Horner’s syndrome, cranial nerve palsy, limb weakness, and bladder and bowel dysfunction. (9) Up to 40% of symptomatic cases
will be misdiagnosed as multiple sclerosis. (9)
Manual therapy should be approached with care. (10) Therapy options need to be evaluated as to effectiveness and risk before being performed. Extension and rotational maneuvers may
place the spinal cord and vertebral arteries at risk. (10 –13)
Pathophysiological mechanisms include mechanical compression of the ventral spinal artery, the cerebrospinal fluid (CSF) outflow foramina, and the medulla and proximal spinal cord as the
odontoid process protrudes through the foramen magnum. Degenerative stenosis at the atlantoaxial joints or loss of integrity of
the transverse ligament of the atlas may compress the cord between
the atlas and dens ( guillotine mechanism), causing vertebrobasilar
ischemia and infarction. (14)
Known associations of occipitalization include anomalies
of the jaw, nose, ear, and palate; cervical ribs; platybasia; basilar impression; deformity of the foramen magnum; ArnoldChiari malformation (type I); odontoid anomalies; C2–C3 block
vertebra; Sturge-Weber syndrome; Klippel-Feil syndrome; renal
anomalies; and vertebrobasilar anatomic variations. (3,6,11,
15,16) Atlantoaxial instability has been reported in as many as
40 –66% of cases, with attendant risk of neurovascular insult
(1,2,4,17,18)
Radiologic Features. Plain films supplemented with CT will
define bony abnormalities. In symptomatic cases MRI is used to
evaluate for abnormalities of the brainstem, and posterior fossa
with MRA is employed to detect accompanying vertebrobasilar
anomalies.
A spectrum of non-segmentation patterns is encountered, ranging from complete to incomplete forms. Complete fusion is manifested by fusion of the anterior and posterior arches with the
occiput as well as bilateral atlanto-occipital joint fusion. Examples
of incomplete forms (hemi-occipitalization) are isolated fusion of
the anterior or posterior arch to the adjacent occiput and fusion
or asymmetry of the C0–C1 articulations.
In virtually all cases the anterior arch will be fused to the anterior margin (basion) of the foramen magnum, and the transverse
process of the atlas will be either absent or fused to the occiput. (1)
A rare variant is fusion of the atlas anterior arch to the basion and
the posterior arch to the axis. (19) In 90% of cases, details of the
fused atlas posterior arch can be discerned at the occiput on a plain
film. (1) The space between the posterior arch of C1 and the base
of the occiput will be absent or greatly reduced. (Fig. 3-3, A and B)
Often the site where the vertebral artery, accompanying veins, and
the first occipital nerve pass over the atlas posterior arch will become more apparent as a circular bony foramen. (20) (Fig 3-3C )
Basilar impression is a common tandem finding and should be
considered in the assessment. Up to 70% of occipitalizations will
have an accompanying block vertebra of C2 – C3. (1,4)
Accompanying anomalies of the dens are common and include
agenesis, hypoplasia, os odontoideum, ossiculum terminale, and
abnormal tilt, which may predispose the patient to instability.
Thin-section CT with multiplanar and three-dimensional (3-D)
reconstructions is the technique of choice for defining bony
abnormalities. (17,21). MRI is vital for identifying soft tissue
abnormalities, such as infarction, cerebellar tonsil herniation
(Chiari malformation), syrinx formation, and hydrocephalus,
and for isolating the source of cranio-cervical cord compres-
3
Figure 3-3 OCCIPITALIZATION OF THE ATLAS. A. Lateral
Cervical Spine. The posterior arch of the atlas is fused to the
base of the occiput (arrow). The anterior arch is not discernible because it is fused to the anterior foramen magnum
(basion). B. AP Open Mouth. Fusion of the atlanto-occipital
joint can be seen. Note the absence of the joint space
(arrows) and observe that the plane of the atlantoaxial joints
is asymmetrical and more horizontal than normal. C. Lateral
Cervical Spine. In a different case the occipitalization is more
readily defined, and the passage of the vertebral artery over
the atlas posterior arch is marked by the well-defined foramen. Careful evaluation of the anterior arch confirms union
sion. (18,21) (Fig. 3-2) MRA is quickly replacing plain film angiography for demonstrating vertebrobasilar anomalies, which
are present in up to 25% of cases. Anomalies include hypoplasia,
abnormal posterior inferior cerebellar artery terminations, and
occlusions. (11,15,21)
Medicolegal Implications
OCCIPITALIZATION OF THE ATLAS
•
•
•
•
• Non-recognition is common owing to the
wide variation in fusion types, subtle findings, and obscuration when views are not
taken in true anatomic position—especially the lateral
view or in the presence of torticollis.
Identification of known associations usually requires imaging of the entire spine, vertebral arteries, abdomen, and
spinal cord and is best accomplished with MRI. (18,21)
Awareness and monitoring for complications, especially
of the cerebellum, brainstem, cervical cord, and transverse ligament of the atlas, need to be instituted. Appropriate counseling on management of known risk factors,
including therapeutic options that can precipitate complications, should be encouraged.
Therapy options need to be evaluated as to effectiveness
and risk before being performed. (10)
Extension and rotational maneuvers may place the spinal
cord and vertebral arteries at risk. (10,11,12,19)
Congenital Anomalies and Normal Skeletal Variants I
261
with the basion. COMMENT: Fusion of the atlas to the occiput can be mimicked by a lateral projection obtained with
head tilt at the time of exposure. Flexion–extension studies
should be obtained to evaluate the atlantodental interspace
because the transverse ligament of the atlas may be compromised and responsible for dynamic compression of the brainstem and vertebrobasilar complications. Co-existing basilar
impression, platybasia, Chiari malformation, syrinx, odontoid
anomalies, vertebrobasilar perfusion abnormalities, and
C2–C3 block vertebra are common and should be searched
for; this may require MRI studies. (Panels A and B courtesy of
Kip LaShoto, DC, Waltham, Massachusetts.)
OCCIPITAL VERTEBRAE
The occipital bone is formed from the union of four to five somites,
which normally fuse together to encircle the foramen magnum.
The last occipital somite, or pro- atlas somite, may fail to fully
incorporate into the occiput, resulting in occipital or pro-atlas
vertebrae. Manifestations of occipital vertebrae include the third
condyle, paramastoid process, epitransverse process, and various
occipital ossicles. (1,2) Additional anomalies sometimes encompassed in this group are duplication of the atlas and ponticles of
the atlas. (2–5)
Third Condyle
Synonyms. Condylus tertius.
Description. First described by Hadley in 1948, third condyle is
the most common form of an occipital vertebra. (1,2) An anterior
midline bony process located between the two occipital condyles
and continuous with the anterior foramen magnum extends a variable distance caudally. It occasionally forms an articulation with
the apex of the odontoid process or anterior arch of the atlas.
Clinical Features. Clinically significant symptoms are rare but,
if the anomaly is large, reduced atlanto-occipital movements or
possible brainstem complications are clinical considerations. (6)
There is an increased incidence of associated os odontoideum. (7)
Radiologic Features. Small third condyles may be impossible to visualize on lateral plain film radiographs because of the
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Figure 3-4 THIRD CONDYLE. Lateral Upper Cervical. An
anomalous bony bar descends from the basion to form a
pseudo-joint with the deformed atlas anterior arch (arrow).
In a common variation the bony process forms an articulation
with the tip of the dens; this often requires a CT scan for depiction. (Courtesy of Gary M. Guebert, DC, DACBR, St. Louis,
Missouri.)
superimposed mastoid processes and the petrous portion of the
temporal bone. Larger third condyles may be seen on true lateral
radiographs of the upper cervical spine as oval or round bone densities equal in size or smaller than the anterior arch of the atlas.
Some are sufficiently large and caudally placed to articulate with
the superior aspect of the anterior arch of the atlas or tip of the
dens. (3,8) (Fig. 3- 4) A third condyle will not be evident on
open mouth radiographs, but fine-section CT evaluation is ideally
suited for imaging this anomaly. MRI may be used when there is a
clinical suspicion for brainstem symptoms.
irritation, initiating localized pain, and could irritate the closely
approximated first cervical nerve. There has been no proven link
with vertebrobasilar disease. A paramastoid process occurs in at
least 20% of occipitalizations. (2,12) Large processes may be
palpable in asthenic individuals and may inhibit atlanto-occipital
movements.
Epitransverse Process. An epitransverse process is far less common than a paramastoid process, and its clinical significance is
rarely described. (10) A single case has been linked with posttraumatic basal subarachnoid hemorrhage. (13)
Radiologic Features. These anomalies are frequently overlooked on both AP and lateral radiographs because of the superimposed anatomy. (Fig. 3-5) A slightly rotated open-mouth view
will shift the molars on the side opposite the direction of head
rotation away from the area of interest so that the bony connection between the occiput and the transverse process may be clearly
seen. The process is typically cone-shaped, broader at its occipital base, and narrower distally; it often curves medially. Internal
pneumatization with air cells extending from the adjacent mastoid process may sometimes be seen within the connecting bone
strut. (2) An accessory joint may be present between the anomalous process and the superior aspect of the C1 transverse process, or a solid bony union may be present. (Figs. 3-6 and 3-7)
Occasionally, this process acts as a shim, causing a lateral tilt of
the head.
Fine-section CT with reconstructed coronal images will show
the anomalous connections to advantage, clarifying the exact
Paracondylar, Paramastoid,
and Epitransverse Processes
Synonyms. Paramastoid or paracondyloid process.
Description. Paracondylar, paramastoid, and epitransverse processes are variations of congenital bone bars that extend between
the occiput and transverse processes of the atlas. They may be unilateral or bilateral. The paramastoid process is a bony protuberance that originates from the jugular process of the occiput and
projects inferiorly toward the atlas transverse process. A paracondylar process arises slightly more medial and anterior in the
paracondylar area of the occiput. (2) In both forms the bony
strut projects inferiorly to either end blindly above the atlas transverse process and may form a joint or be completely fused. (2,9)
The terms are often used synonymously and for the purposes of
this discussion they are treated as one entity. An epitransverse
process is attached to the atlas transverse process and directed
superiorly toward the adjacent occiput. (10)
Clinical Features
Paracondylar (Paramastoid) Process. Symptoms attributable to
the paracondylar process are unusual but may be found in conjunction with muscle contracture and pain. (11) It is feasible,
though it has never been shown, that the neo-arthrosis between
the bone bar and the atlas transverse process has the potential to
produce localized synovitis, adventitious bursae, and periosteal
Figure 3-5 PARACONDYLAR PROCESS. A. AP Open Mouth.
Observe the bony protuberance projecting from the paracondylar area and directed toward the transverse process of
the atlas (arrow). This should not be confused with the
slender styloid process of the temporal bone (arrowhead ).
B. AP Tomogram. Tomography clearly shows the paracondylar
process (arrow) forming an accessory articulation with the
transverse process of C1.
3
Congenital Anomalies and Normal Skeletal Variants I
Figure 3-6 EPITRANSVERSE AND PARACONDYLAR PROCESSES. A. AP
Open Mouth. An epitransverse process (arrow) and an accessory articulation are present at the atlas. The clarity of the open-mouth radiograph is
the result of two factors: The patient is edentulous, and the patient’s jaw
was moving intentionally during the exposure. B. AP Open Mouth. Note
the osseous bar between the paracondylar area and the transverse process
of the atlas, to which it is fully fused (arrow ). C. Epitransverse Process.
A
Figure 3-7 PARACONDYLAR PROCESS. A. AP Open Mouth.
Note the bony protuberance projecting from the paracondylar area of the skull base and directed toward the transverse
process of the atlas (arrow ). B. CT Occipital-Cervical
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C
B
Junction. CT shows the paracondylar process projecting from
the occiput and forming an accessory articulation with the
transverse process of C1 (arrow). (Courtesy of Alan A. Hiatt,
DC, Pueblo, Colorado.)
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cess of Kerckring. (8,15) The terminale ossicle (of Bergmann) at
the apex of the dens should not be included as an occipital ossicle.
Clinical Features. No physical or neurological disturbance has
been linked with these pro-atlas ossicles. (2) It is important not
to mistake these anomalies for fracture fragments.
Radiologic Features. The bone segments take the appearance
of a sesamoid bone with smooth margins and distinct bony cortices. They are variable in shape, being round, oval, semilunar,
or triangular. Accessory ossicles can be confused with fractures
of the foramen magnum or atlas but usually are smooth and corticated. When anterior they can on occasion be seen to form articular surfaces, which they share with the adjacent deformed atlas
anterior arch. Differential diagnosis includes the third condyle
anomaly.
Vertebralization of the Atlas
Figure 3-8 EPITRANSVERSE PROCESS. A. Axial CT. The CT
bone window demonstrates the osseous bar (arrow) that
unites the C1 right transverse process with the occiput. B.
Axial MRI. The MRI scan shows normal marrow signal from
within the epitransverse process (arrow). (Courtesy of
G. Matt Howard III, DC, Muncie, Indiana.)
location and extent of the anomalous process and ruling out neoplasm or other causes for this appearance. (Fig. 3-8) Calcification
within the stylohyoid ligament can mimic the anomaly but is
typically a thinner, medially angulated structure. Given the association with occipitalization there is an increased potential for
brainstem anomaly. An MRI examination may be warranted
when the clinical picture is unclear.
Accessory Atlanto-Occipital Ossicles
Synonyms. Pro-atlas ossicles, basilar ossicles, atlanto-occipital
ossicles, process of Kerckring.
Description. A variety of small bone fragments may develop
in the atlanto-occipital interspace. These ossicles usually occur
in a solitary fashion but occasionally are multiple. These can occur
at the atlanto-occipital interspace anteriorly, laterally, or posteriorly and occasionally as an arcade surrounding the dens embedded in ligamentous tissue. (2,4) Anterior occipital ossicles
(basilar processes) occur around or between the anterior border
of the foramen magnum and the anterior arch of the atlas, may
be paired across the midline, and may form articulations with the
adjacent atlas anterior arch. (2,14) A pro-atlas ossicle in the midline between the occiput and atlas posterior arch is called the pro-
Synonyms. Regressive occipital vertebra, double atlas.
Description. Vertebralization is an embryologic tendency for a
part of the pro-atlas to not incorporate into the occiput; it is rare.
(4) This results in duplication of all or part of the atlas vertebra
at the C0–C1 interspace. A complete double atlas is exceedingly
rare (3–5). There may be an extra posterior arch, anterior arch,
transverse processes, or lateral masses.
Clinical Features. Combined fusion of the anterior atlas arch
with the basion (occipitalization) and the posterior arch with the
axis (vertebralization) has been recorded. The condition may
precipitate atlantoaxial instability with insufficiency of the transverse ligament. (4)
Radiologic Features. Routine radiographs show various degrees of supernumerary atlas development that is best examined
with thin-section CT and multiplanar reconstructions. (5) The
odontoid process is often elongated and may be malformed.
Various degrees of bony fusion of the upper joint surfaces with
the occiput is the rule. (Fig. 3-9).
Agenesis of the Atlas Posterior Arch
Synonyms. Aplasia or congenital absence of the posterior arch.
Description. Lack of ossification of the posterior arch of the
atlas may be complete and bilateral, may be purely unilateral, or
may manifest as small clefts (i.e., spina bifida). (16–18) Dense
fibrous connective tissue remains at the site devoid of ossification. (16,19) Ossification of the posterior arch of the atlas is normally present at birth, with union visible by 6 years of age. (18)
Clinical Features. Pain or neurological complications are rare.
Atlantoaxial instability has been described. (20) There is occasional association with C2–C4 block vertebrae and Klippel-Feil
syndrome. (16,19) Spinal stenosis may also occur (see “Radiologic
Features”). Absence of the posterior arch needs to be differentiated from occipitalization, osteolytic metastases, aneurysmal bone
cyst, and osteoblastoma. (21) Differentiation from fractures, aggressive bone destruction, and occipitalization must be made with
confidence, which may require CT or even MRI investigations.
Radiologic Features. The lateral view is the best projection
for identifying the various forms of aplasia. Oblique views are
also of assistance in determining unilateral aplasias and clefts.
(22) Thin-section CT is the technique of choice for determining
the extent of aplasia and providing accurate differential diagnosis.
MRI is indicated if a neurological deficit is present.
3
Congenital Anomalies and Normal Skeletal Variants I
265
C1
A
B
Figure 3-9 VERTEBRALIZATION OF THE ATLAS. A. Lateral
Cervical Spine. Observe the duplication of the atlas with a
posterior and anterior arch (arrows). The inferior normal
atlas is well formed with all elements present. The odontoid
process is elongated and forms a normal atlantodental articulation at both levels (arrowheads). B. AP Open Mouth. The
normal atlas (C1) is completely formed. The superior duplicated atlas has lateral masses (arrows) with non-union of the
posterior arch (crossed arrow). Extending superiorly, the
elongated dens articulates with both atlas vertebrae (arrowheads). COMMENT: A double atlas is a rare anomaly and in
this case was an asymptomatic finding. A follow-up MRI
examination showed a normal upper cervical cord and posterior fossa but a significant disc herniation at C5, which,
when removed, relieved lower neck symptoms. (Courtesy of
Raymond Fracheboud DC, Monthey, Switzerland.)
Bilateral Posterior Arch Agenesis. The characteristic triad of
findings with bilateral posterior arch agenesis is absence of the
atlas posterior arch, union of the posterior tubercle to the axis
spinous process (axis megaspinous sign), and compensatory enlargement and sclerosis of the anterior arch. (21,23) (Fig. 3-10)
Occasionally the posterior tubercle will remain visible in normal
position (Keller type aplasia). (16,7) Hypertrophy of the posterior
atlantoaxial ligaments may produce spinal canal stenosis and be
a factor for cord injury after trauma. (24)
Unilateral Posterior Arch Agenesis (Hemi-Atlas). With unilateral posterior arch agenesis, absence of half of the posterior arch
is uncommon. The condition is best determined on the AP open
mouth view and CT. (18,25,26)
Isolated Clefts of the Posterior Arch. Isolated clefts of the posterior arch are most common in the midline posteriorly (posterior rachischisis, spina bifida occulta), accounting for 97% of
arch clefts, with only 3% occurring elsewhere. (18) The second
most common site is at the junction zone of the posterior arch
with the lateral mass, where the vertebral artery passes over the
arch (vertebral artery sulcus cleft). (18) (Fig. 3-11) These clefts
range in size from 1 to 5 mm; have smooth, corticated opposing
margins; and are best seen on oblique and slightly off-lateral
projections. (18,22,25,26)
Hypoplasia of the Posterior Arch. Two forms of hypoplasia of
the posterior arch are described: thin and short.
• Thin posterior arch. The width of the posterior arch is thin
and attenuated maximally at the vertebral artery sulcus. An
association with Turner’s syndrome and gonadal dysgenesis has been suggested. (16) It may be a factor for fracture
at this site after trauma.
• Short posterior arch. The atlas posterior arch is thick
and bulky, and the diameter of the spinal canal is diminished. (27,28) A described tandem finding is a thick, bulky
dens that may contribute to symptomatic spinal stenosis.
(29) The incidence of symptoms increases with age or may
be triggered by minor trauma. An association with patients
of Asian origin has been implicated. (28,29)
Accessory Atlantoaxial Joint (Cervical Baastrup’s Disease).
Enlargement of the posterior arch occasionally forms an accessory joint space with the adjacent axis spinous. (4,8) (Fig. 3-12)
The radiologic hallmarks are enlargement of the posterior tubercle, flat corticated opposing surfaces, and a smooth joint space.
Occasionally, signs of degeneration—including osteophytes,
sclerosis, and a narrowed joint space—are seen. Whether this is an
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Figure 3-10 ATLAS, COMPLETE AGENESIS OF THE POSTERIOR
ARCH (AXIS MEGASPINOUS SIGN). A and B. Lateral Upper
Cervical Spine. Observe the complete agenesis of the posterior
arch of the atlas up to the junction with the lateral masses.
Note the commonly associated large axis spinous process (axis
megaspinous sign), representing fusion of the rudimentary
posterior arch and posterior tubercle of the atlas (arrows).
Careful examination of the axis spinous process will often
demonstrate the incorporated corticated tubercle. (Panel B
courtesy of John C. Slizeski, DC, Denver, Colorado.)
Figure 3-11 ATLAS, PARTIAL AGENESIS OF THE POSTERIOR
ARCH. A. Lateral Upper Cervical Spine. Observe the agenesis
of the posterior arch of the atlas; the posterior tubercle is present. Stress hypertrophy of the anterior tubercle of the atlas
can be seen (arrow). B. Lateral Upper Cervical Spine. Failure
of development of the middle portion of the posterior arch
of the atlas is noted, along with stress enlargement of the an-
terior tubercle of the atlas. C. Lateral Upper Cervical Spine.
A focal agenesis of the middle portion of the posterior arch
of the atlas is present, as is hypertrophy of the anterior arch
(arrow). COMMENT: Observe the stress hypertrophy of the
anterior tubercle of the atlas in all three instances; this important sign allows differentiation from acute fracture or a
destructive process.
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Congenital Anomalies and Normal Skeletal Variants I
267
Posterior Spina Bifida Occulta of the Atlas
Synonyms. Posterior spondyloschisis of the atlas; cleft atlas;
bifid, cleft, non-union, cleavage, or dehiscence of the posterior
arch; congenital absence of the posterior tubercle.
Description. Spina bifida occulta (SBO) is an embryologic failure in midline ossification of the vertebral neural arch. It occurs primarily at the spinal transitional regions, although no segment is immune. The gap is filled with fibrous tissue or fibrocartilage. (30,31)
Clinical Features. SBO affects the posterior arch of the atlas in
1–5% of the population, and this site is the second most common
region to be affected, after the lumbosacral region. (32–35) The
axis is occasionally involved with SBO simultaneously. (8) Posterior arch SBO sometimes occurs simultaneously with occipitalization
(25) and anterior arch spina bifida (bipartite atlas). (33–35) A described association with brain tumors of the posterior fossa of the
skull and atlas SBO has been recorded. (36) Axial compression
trauma may result in fracture through the site of non-union (37,38)
Figure 3-12 C1–C2, ACCESSORY JOINT. A and B. Lateral
Upper Cervical Spine. Shown are two examples of accessory
joints between the inferior aspect of the posterior tubercle/
posterior arch of the atlas and the superior surface of the
lamina of the axis. COMMENT: This anomaly may limit flexion
and extension at C1–C2 and may be a source of suboccipital
pain. (Courtesy of John C. Slizeski, DC, Denver, Colorado.)
acquired or congenital joint is uncertain, but there are similarities
with lumbar spinous process impaction syndrome (Baastrup’s disease). This may be a site for upper cervical pain or inhibited
atlantoaxial motion and possibly for degenerative spinal canal
stenosis. Manual therapies and trauma have the potential to exacerbate pain emanating from this accessory joint.
Medicolegal Implications
AGENESIS OF THE C1 POSTERIOR ARCH
• The integrity of the transverse ligament
is rarely compromised, although cervical
flexion–extension radiographs should be
performed to evaluate the atlantodental interspace.
• Associated hypertrophy of the posterior atlantoaxial ligaments may be a factor for cord injury after trauma. (12)
Figure 3-13 ATLAS, POSTERIOR ARCH NON-UNION (SPONDYLOSCHISIS). A. AP Open Mouth. Observe the radiolucent cleft
in the posterior arch of the atlas (arrow) owing to failure of
fusion of its lateral ossification centers. B. Lateral Upper
Cervical Spine. The spinolaminar junction lines of C2, C3, and
C4 have been marked (lines); each forms a smooth continuous
line. No spinolaminar line is visible at the atlas as a marker of
non-union. COMMENT: The atlas anterior arch is sclerotic and
has a thickened cortex. It is enlarged, a characteristic of secondary stress hypertrophy caused by posterior arch non-union,
which is a useful sign not found in cases of tumor destruction,
such as metastases, aneurysmal bone cyst, and osteoblastoma.
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Figure 3-15 C1, POSTERIOR SPONDYLOSCHISIS. AP Open
Mouth. Note the posterior cleft of the C1 posterior arch
(arrow). (Courtesy of Paul Van Wyk, DC, Denver, Colorado.)
or predispose the patient to a hemi-Jefferson fracture with only one
site of ring disruption, usually of the anterior arch. (33) Myelomeningoceles of the craniocervical junction have an associated
atlas SBO in 70% of cases. (39) The diagnosis of atlas SBO cannot
be made with confidence in patients > 6 years of age because ossi-
fication may not be complete until after this age. (30) Anterior arch
ossification is absent at birth but complete by 2 years of age.
Radiologic Features. The size of the non-union zone runs a
spectrum from a minute cleft to the complete absence of arch ossification. (16) On the lateral view there is absence of the spinolaminar junction line and the posterior arch is thin and attenuated, with
club-shaped, tapered, or beaked ends, best shown on CT. (32,34)
(Figs. 3-13 and 3-14) Differentiation from fracture is based on
location and the clubbed smoothly corticated opposing ends. (Fig.
3-15) (8,26,31,33) If a lateral film is obtained with 10° of lateral
flexion, the un-united posterior arch will be more effectively
demonstrated. Occasionally the atlas posterior tubercle can be identified fused to the axis spinous (axis megaspinous sign). The anterior tubercle is often sclerotic and enlarged and is a useful sign for
a congenital absence of posterior continuity. (40,41) Frontal open
Figure 3-16 AXIS, SPINA BIFIDA OCCULTA. A. AP Open
Mouth. The midline radiolucent cleft of the spinous process
of C2 can be seen (arrow). B. Lateral Upper Cervical. The cortical white line created by the junction of the lamina and
spinous process is clearly noted at C1 and C3 (arrows) but absent at C2 (arrowhead ). The lack of a spinolaminar junction
line at C2 signifies spina bifida occulta. (Courtesy of Kenneth
E. Yochum, DC, St. Louis, Missouri.)
Figure 3-14 ATLAS AND AXIS, SPINA BIFIDA OCCULTA.
Lateral Cervical Spine. Observe the absence of a C1 posterior
cervical line (arrow), which indicates the presence of spondyloschisis at C1. Also note the hypoplastic appearance of the
posterior arch of the axis. (Courtesy of John C. Slizeski, DC,
Denver, Colorado.)
3
mouth and base vertex skull views show the midline hiatus. (8) In
the presence of combined anterior and posterior arch non-union (bipartite atlas), overhang of the lateral mass with the axis may simulate a Jefferson’s fracture. (34) The combined total overhang of the
atlas is usually < 2 mm (18,35,42), although offset up to 4 mm has
been recorded. (42) CT is the best way to differentiate fractures;
however, MRI may assist in difficult cases. (33,43) Occasionally,
spina bifida of C2 is also identified, with loss of the spinolaminar
junction line. (Fig. 3-16)
Ponticles of the Atlas
Calcification or ossification along the margins of normally occurring foramina in the atlanto-occipital ligament is referred to
as ponticles (Latin for “bridges”). Atlas ponticles are considered
by some to be an expression of an occipital vertebra. There are
two types of atlas ponticles: posterior and lateral.
Congenital Anomalies and Normal Skeletal Variants I
269
Radiologic Features. A posterior ponticle is best seen on a
lateral radiograph of the cervical spine; it forms a partial or complete foramen at the ventral and superior aspect of the vertebral
arch. (44) (Figs. 3-17 and 3-18) Ossification rather than calcification is usually discernible, with cortical bone, and even trabeculae are often visible. (46) It is usually only 1–2 mm in thickness.
Expressions of the posterior ponticle are myriad, including a complete arcual foramen, a limited hook-like and tapered spur from
either the posterior lateral mass or the posterior arch, and occasionally a curvilinear free-floating ossicle. The superior surface
of the atlas arch is grooved to a variable degree as the vertebral
sulcus. The posterior ponticle must be differentiated from an overlying pneumatized mastoid air cell and occipitalization. Sometimes
this curvilinear calcification is erroneously attributed to atheromatous calcification of the vertebral artery, which is extremely rare at
any level throughout the artery.
Lateral Ponticle
Posterior Ponticle
Synonyms. Pons posticus, ponticulus posticus, Kimerle’s
anomaly, arcual or arcuate foramen, foramen arcual, retroarticular vertebral artery ring.
Description. A posterior ponticle of the atlas is ossification or
calcification of the oblique portion of the atlanto-occipital membrane that bridges the posterior lateral mass and the posterior
arch. It forms the peripheral border of the arcuate foramen, which
transmits the vertebral artery and veins, the first cervical nerve,
and the perivascular sympathetic nerves. It is usually bilateral and
asymmetrical and exhibits no gender dominance. Partial ossification is found in up to 35% of the population, and the complete
ring-like form has been found in up to 15% of the white population. (44–46) It is not present at birth and generally first appears
during puberty as a secondary ossification center; it increases in
prevalence with age. (46) In humans it is probably a vestigial trait
because most other primates express this ossification. (47)
Clinical Features. The clinical significance of a posterior ponticle remains controversial. There is no additional significance to
heavily ossified bridges. Given the high levels of prevalence in the
general population it is clear that the majority are asymptomatic
and are not predisposed to clinical manifestations. There have been
no reports since the 1990s describing invasive treatment of a ponticle, either by excision or therapeutic anesthetic injection. Three
clinical associations have been made: vertebrobasilar insufficiency,
Barre-Lieou syndrome, and chronic upper cervical syndrome. (45)
Vertebrobasilar Insufficiency. The suspected pathomechanics of
vertebrobasilar insufficiency have been extensively reviewed
elsewhere. (45) Briefly, the adventitia of the vertebral artery is
contiguous with the periosteum of the ponticle, and atlantoaxial
movements may create traction or compression of the artery. The
smaller the caliber of the foramen, the greater the potential for
vascular impingement (48) Intimal dissection may result through
transmission of shear forces.
Barre-Lieou Syndrome. Headaches; retro-orbital pain; facial
vasomotor disturbance; and visual, phonation, and swallowing
difficulties from involvement of the perivascular vertebral artery
plexus have been potentially linked to posterior ponticles. Symptoms improve after excision of the bony ring. (48,49)
Chronic Upper Cervical Syndrome. The symptom complex of
neck pain, occipital headaches, vertigo, and other disturbances
have been linked to various forms of posterior ponticles. (47)
Synonyms. Ponticulus lateralis, pons lateralis.
Description. A lateral ponticle is ossification in the oblique
occipital membrane as it passes laterally from the superolateral
aspect of the atlas lateral mass to the transverse process. (45)
Clinical Features. The anomaly appears to have no clinical
relevance and is incidentally seen in 3% of cervical radiographs. (45)
Radiologic Features. The lateral ponticle is seen only on the
AP open mouth view and is manifest as a curvilinear ossification
between the transverse process and the lateral mass of the atlas,
often forming a distinct foramen. (Fig. 3-19)
Medicolegal Implications
POSTERIOR PONTICLE
• The clinical significance to practitioners of
spinal manipulative therapy relates to possible vertebrobasilar insufficiency during rotary manipulations of the cervical spine. (45,50) It would
appear that the ponticle may compress or restrict the
vertebral artery, which may temporarily diminish blood
flow to the base of the brain. This does not occur in the
majority of patients with a posterior ponticle. However,
proper testing for vertebrobasilar insufficiency must be
performed before forceful manipulations of the cervical
spine are conducted when a posterior ponticle is found
on plain film to avoid the potentially catastrophic effects caused by postmanipulative vasospasm or vertebral
artery dissection.
• Patients with a posterior ponticle may be at risk for
post-traumatic basal subarachnoid hemorrhage. (13)
• The finding of a posterior ponticle has been found in
patients with vertebrobasilar insufficiency, Barre-Lieou
syndrome (headache; retro-orbital pain; vasomotor disturbance of the face; and recurrent disturbances of vision, swallowing, and phonation caused by alteration of
the blood flow in the vertebral arteries and an associated disturbance of the periarterial nerve plexus), and
chronic upper cervical syndrome. (47,48)
Figure 3-17 POSTERIOR PONTICLE. A and B. Lateral Upper
Cervical Spine. A thin, complete posterior ponticle of the atlas
forms an arcuate foramen (arrows). This contains the vertebral artery, vertebral veins, and the first cervical nerve.
Ossification in the marginal fibers of the oblique occipital
membrane forms the ponticle (arrowhead). C and D. Lateral
Upper Cervical Spine. Note the different thicknesses and density of ossification of the ponticle (arrows). COMMENT: Partial
ossification is found in up to 35% of the population, and the
complete ring-like form has been found in up to 15% of the
population; its clinical significance remains controversial.
There is no additional significance to heavily ossified bridges.
Given the high levels of prevalence in the general population
it is clear that the majority are asymptomatic and are not predisposed to clinical manifestations. (Panel D courtesy of
Eugene A. Ver Meer, DC, Denver, Colorado.)
Figure 3-18 POSTERIOR PONTICLE, PATHOLOGIC SPECIMEN.
A. Superior Macroscopic View. A probe has been inserted
into the foramen beneath the unilateral ponticle to show
the course of the contained vertebral artery. B. Lateral
Macroscopic View. This perspective, which is seen on lateral
radiographs, demonstrates the position behind the lateral
mass of an incomplete posterior ponticle. (Courtesy of
J. P. Ellis, St. Louis, Missouri, and Marc S. Gottlieb, DC,
Raleigh, North Carolina.)
3
Figure 3-19 ATLAS, LATERAL PONTICLE. AP Open Mouth.
The curved bony bridge of the lateral ponticle (ponticulus
lateralis, pons lateralis) can be seen arcing superiorly from
the atlas lateral mass toward the transverse process (arrow).
This should not be confused with the atlas transverse foramen, paramastoid process, or epitransverse process.
COMMENT: This asymptomatic variant of the atlas is found
on 3% of cervical radiographs and marks the course of the
vertebral artery. (Courtesy of Michael P. Buna BS, DC,
Victoria, British Columbia, Canada.)
Congenital Anomalies and Normal Skeletal Variants I
271
dental incisors over the dens. The posterior arch defect lies caudad
to the anterior arch cleft on the AP open mouth view. (35,57) (Fig.
3-20) In the presence of combined anterior and posterior clefts
(bipartite atlas or split atlas), combined right and left overhang of
the lateral masses beyond the axis facet margins is usually < 2 mm
(18,35), occasionally up to 4 mm (42), and rarely > 6 mm. (58)
This finding may be confused with a Jefferson’s fracture, in
which the combined sum of right and left overhang is usually >
2 mm. Axial and submentovertex views of the skull can show the
cleft to advantage. (35)
The lateral projection may show no abnormality of the normally
half-moon-shaped anterior tubercle, but it may be enlarged, appear homogeneously sclerotic, or exhibit absence or duplication
of the anterior cortex. ( 7,18,40,58) There is often absence of the
normally well-defined posterior cortex, and the atlantodental
interspace seems to be obliterated. ( 7) A bipartite atlas will also
have absence of the posterior arch spinolaminar junction line.
Thin-section CT clearly shows the anterior midline cleft, which
has sclerotic margins that are often mildly irregular. The opposing ends of the non-union are typically beaked anteriorly. (34,35)
MRI is seldom indicated, unless neurological symptoms are present; it can assist in differentiating fracture with the presence of
hematoma and bone marrow edema. (43)
Agenesis of the Atlas Anterior Arch
Synonyms. Aplasia of the atlas anterior arch.
Description. Isolated congenital absence of the anterior arch
of the atlas is rare. The first account was in 1886, and there have
been only a few subsequent reports. (36,51,52)
Clinical Features. Acquired destruction of the anterior arch may
occur secondary to inflammatory arthropathy, especially rheumatoid arthritis, tumor, and infection. (53) Delayed ossification in
infants may simulate agenesis up until 2 years of age. (54) The
anomaly has been reported in association with median cleft face
syndrome and Pierre-Robin syndrome. (55,56)
Radiologic Features. Lateral radiographs demonstrate absence of the D-shaped, corticated anterior arch of the first cervical
vertebra. CT or MRI better defines the extent of osseous agenesis. Flexion and extension views may be necessary to determine
if hypermobility exists between C1 and C2. Retrosubluxation of
C1 on C2 may be present.
Non-Union of the Atlas Anterior Arch
Synonyms. Anterior spina bifida, anterior spondyloschisis.
Description. Non-union of the atlas anterior arch may occur as
an isolated anomaly or in tandem with a cleft of the posterior arch
(bipartite atlas) or a lateral cleft through the vertebral artery sulcus.
(18,53,55,56)
Clinical Features. No clinical pain syndrome, neurological disorder, or biomechanical change has been documented. The major
importance of the anomaly is to differentiate it from fracture seen
on imaging. (34,43)
Radiologic Features. The cleft through the anterior arch is vertically orientated and usually in the midline. On AP open mouth
views the defect may be visible superimposed over the dens and
may resemble a bipartite dens. The defect can be simulated by
superimposition of the midline diastema between the upper first
Figure 3-20 ATLAS, COMBINED ANTERIOR AND POSTERIOR
NON-UNION (BIPARTITE ATLAS). A. AP Open Mouth. The
cleft in the anterior arch is seen superimposed over the apex
of the odontoid process (superior arrow), and the posterior
arch cleft is projected inferiorly (inferior arrow). B. Lateral
Upper Cervical Spine. The cleft anterior arch appears enlarged and dysplastic on this view. The lack of the spinolaminar junction line posteriorly at the atlas confirms non-union.
The combined posterior and anterior clefts (bipartite or split
atlas) may allow for lateral spread of the lateral masses, mimicking a Jefferson’s fracture, but it is clearly distinguished on
CT by the corticated, club-shaped ends bordering the bony
defects. (Courtesy of Harry R. Shepard, DC, Marion, Indiana.)
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Fusion of the Atlas Anterior Arch
with the Dens
Synonyms. Atlantoaxial block vertebra.
Description. Fusion of the atlas anterior arch with the dens is
usually discovered incidentally on radiographic examination. (59)
Clinical Features. Unless associated with os odontoideum no
symptoms have been ascribed to this rare anomaly. (59,60) Decreased head rotation may be present. (59) Associations include os
odontoideum, ossiculum terminale, block vertebrae, and hypoplasia of the atlas with canal stenosis. (59) The diagnosis cannot
be made in the presence of known inflammatory conditions, such
as rheumatoid arthritis and ankylosing spondylitis, which can
produce acquired fusion.
Radiologic Features. On the lateral projection the anterior arch
is contiguous with the dens but no intervening atlantodental
interspace is visible. (59) Flexion–extension studies should not
show any anterior atlas translation. (61,62) CT scan can confirm
bony fusion. MRI may help evaluate any complications associated with block vertebrae.
Differential considerations include os odontoideum, in which
the zone of separation is much lower, and the infrequent type I
fracture of the odontoid tip. Flexion–extension studies are important for ruling out atlantoaxial instability and ensuring stability of
the ossicle relative to the dens. (5) Demonstrated displacement,
especially in extension, may be associated with brainstem myelopathy. MRI examination may be required to exclude this involvement in Down’s syndrome and when the neurological status is in
ANOMALIES OF THE AXIS
The most common congenital anomalies of the axis vertebra involve the odontoid process and are generally discovered when
radiographs are taken of the cervical spine for other clinical reasons, most commonly trauma. Known associations for odontoid
anomalies include Down’s syndrome (trisomy 21), occipitalization,
Klippel-Feil syndrome, chondrodysplasia punctata, Morquio’s
disease, and spondyloepiphyseal dysplasia and other dwarfisms.
The most common anomalies of C2 are ossiculum terminale, os
odontoideum, agenesis, and hypoplasia. Other anomalies of the
axis include block vertebra and defects of the posterior arch
(spondylolysis).
Figure 3-21 OSSICULUM TERMINALE OF BERGMANN.
Lateral Upper Cervical. A single corticated ossicle lies adjacent to the tip of the odontoid process (arrow). Note that
the ossicle does not align anatomically with the dens tip
(arrowhead ) and, in fact, is slightly posteriorly displaced.
COMMENT: This patient had trisomy 21 (Down’s syndrome),
which is known to be associated not only with ossiculum terminale but also with other variations of the odontoid (agenesis, os odontoideum) and transverse ligament (agenesis,
hypoplasia). An unstable ossiculum terminale, as in this case,
may be a factor in brainstem compression, which requires
MRI for evaluation. (Courtesy of Eric C. Ho, MBBS, FRCS,
Newcastle, New South Wales, Australia.)
OSSICULUM TERMINALE PERSISTENS
(OF BERGMANN)
Synonyms. Terminal ossicle, ununited summit epiphysis, Bergmann ossicle.
Description. The secondary apical ossification center at the
tip of the dens (summit epiphysis) normally appears at 2 years of
age and unites to the dens by age 12–13 years. (1,2) Failure of
union to the dens produces an isolated ossicle at the tip that is
not typically linked to neck pain syndromes. (3)
Clinical Features. Rarely, it has been associated with brainstem
symptoms when the transverse ligament dislocates into the cleft to
allow atlantoaxial instability. (4,5) There is an increased incidence
of a terminal ossicle in Down’s syndrome, which may also be
a factor in atlantoaxial instability. (6–8)
Radiologic Features. The secondary ossification center at the
tip of the dens can be seen in only 25% of children < 12–13 years
of age. On conventional radiographs the ossicle appears as a
3- to 5-mm, discrete, ovoid, or diamond-shaped ossicle visible at
the most cephalic portion (odontoid summit) of the dens. (Fig.
3-21) The tapered inferior margin may be mildly invaginated into
a V-shaped cleft in the subadjacent dens. (9) (Fig. 3-22) Failure
of this ossification center to fuse produces a persisting ossicle
referred to as the ossiculum terminale (of Bergmann).
Figure 3-22 ODONTOID PROCESS, SUMMIT OSSIFICATION.
AP Atlantoaxial Tomogram. Observe the normal dense
secondary ossification center for the odontoid process tip,
which exhibits a characteristic symmetrical V-shaped lucent
zone of separation from the body of the dens. COMMENT:
This is a normal finding of the odontoid seen in 25% of
patients < 12 years of age; but it is usually not seen after
this age, at which time it constitutes non-union (ossiculum
terminale of Bergmann).
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273
Synonyms. Un-united odontoid process.
Description. Os odontoideum is defined as non-union of the
dens with the axis body. A transverse, radiolucent cleft separates
an ossicle of variable size from the axis body. The transverse ligament is usually intact, although it has been documented to sublux
into the cleft. Os odontoideum was first described in 1886. (1) It is
important to remember that the normal development of the dens
includes a synchondrosis separating the base of the dens from the
C2 vertebral body. It is a transverse band that lies below the level
of the superior zygapophyseal joints of C2. It normally ossifies to
connect the odontoid to the C2 body by age 5–7 years. (2–5)
Clinical Features. Familial incidence has been reported, and
associated conditions include twins, Down’s syndrome, occipitalization, atlas hypoplasia, block vertebrae, Klippel-Feil syndrome, and skeletal dysplasias. (3,4) The cause remains controversial, and there are congenital and post-traumatic theories.
The congenital hypothesis proposes developmental failure of
ossification across the dental synchondrosis. (6) The majority
opinion supports the idea of a previous occult fracture with subsequent non-union because the transverse cleft of os odontoideum
is typically above the level of the normal dental synchondrosis.
(7,8) The precarious nature of the blood supply to the dens may
play a role in impaired healing. (9) Abnormal motion in the
developing child may also be a factor. (2)
There is a broad spectrum of presentation. The majority of patients are asymptomatic, and the anomaly is found incidentally
on radiographs taken for unrelated conditions. The average age of
discovery is between 19 and 30 years, and there are no definite
gender differences. (6,7) Postural changes of the cervical spine
may be present. Recurrent and persistent torticollis may develop
as an indication of atlantoaxial subluxation. The so-called cock
robin position, with the head rotated and the chin retracted and
elevated, may occur in atlantoaxial subluxation from any cause.
Suboccipital pain and neuralgia, audible crepitus, and jerky motion on sagittal flexion-extension may be present. Palpable anterior gliding of the atlas may be detected during cervical flexion
(Sharp-Purser test). In the presence of instability, the ossicle may
occlude or damage the basilar or ventral spinal arteries, or atlas
translation may cause occlusion of the vertebral arteries at the
atlas–axis region. (10 –14) Vertebrobasilar artery, cerebellar, and
ventral cord syndromes may result.
Manipulation is contraindicated in the presence of atlantoaxial
instability. High-velocity injury can produce central cord syndrome or even fatal injury. (15,16) Instability of C1 on C2 secondary to os odontoideum carries the risk of damage to the spinal
cord or vertebral arteries with or without trauma. (10,11)
Compression syndromes of the upper cervical cord and brainstem are encountered. As with any atlantoaxial instability the
degree of motion does not correlate with symptoms, owing to
the space surrounding the cord (Steele’s law of thirds), and in
os odontoideum is even better tolerated because mobility of the
dens prevents cord compression between the dens and the atlas
posterior arch (guillotine mechanism). The transverse ligament is
usually intact, although it has been documented to relocate into the
cleft. In the presence of neurological symptoms treatment options
are limited to various types of posterior fusion techniques. (12,17)
In asymptomatic cases, prophylactic intervention is controversial because the risk for morbidity and even death remains significant. (14,18)
Radiologic Features. The ossicle is readily overlooked or obscured and requires scrupulous attention to detail in obtaining
an adequate cervical spine radiographic series. The open mouth
view is particularly important for depicting the upper cervical
complex. On this view the ossicle is round to oval in shape and
is usually about one half the size of the normal odontoid. There is
typically a distinct circumferential cortex. The separating cleft lies
above the level of the superior articular facets of the axis, and a
residual smooth-surfaced rounded stump of the odontoid is usually discernible. (Fig. 3-23A) The ossicle may be aligned with
the stump (orthoptic) or subluxed laterally (dystopic). (17) When
Figure 3-23 OS ODONTOIDEUM WITH INSTABILITY. A. AP
Open Mouth. The wide radiolucent defect lies above the
base (arrow) and the separated ossicle remains in normal
position (orthoptic). B. Flexion, Lateral Cervical Spine. The
atlas, along with the separated ossicle, has subluxed anteriorly as evidenced by the position of the anterior arch and
loss of continuity in the spinolaminar alignment with C2
(posterior spinal line). C. Extension, Lateral Cervical Spine.
The atlas has now moved posteriorly, signifying instability.
There is a stress enlargement of the anterior tubercle of the
atlas as a result of this underlying instability (arrow).
COMMENT: The presence of a horizontal radiolucent band
at the base of the odontoid process may represent Mach
lines—an odontoid fracture—of the cleft of an os odontoideum and must always be differentiated. (Courtesy of
Robert J. Longenecker, DC, DACBR, Dallas, Texas.)
question. Thin-section CT with reconstructions will also be of
assistance when a congenital basis for the ossicle is unclear.
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Yochum & Rowe’s Essentials of Skeletal Radiology
the ossicle is subluxed, the atlas moves in unison with offset at the
lateral margins of the atlantoaxial joint. (19)
On the lateral film the ossicle and separating cleft are often
not visible. The altered appearance of the anterior arch of the
atlas may be the only marker to the anomaly’s presence; the atlas
can take a number of forms, including enlargement, sclerosis,
and an angular posterior surface where it invaginates into the
cleft. (12,20,21) (Figs. 3-23B and 3-24) In the adult patient,
hypertrophy of the atlas anterior arch is often present as an indication of chronic biomechanical stress and is useful in ruling out
an acute dens fracture. It is not a reliable sign in the pediatric patient, however. (21) The transverse ligament is usually intact,
and the atlantodental interspace (ADI) is typically unaffected.
A rare case has been recorded with associated anterior arch –
ossicle fusion. (22) Concomitant developmental anomaly of the
posterior C1 arch has also been reported. Many cases of os odontoideum are misdiagnosed as odontoid agenesis or hypoplasia
because the separated ossicle may be obscured on conventional
radiography and confirmed only with subsequent CT or MRI
studies.
Assessment of instability can be performed with flexion–
extension plain films, fluoroscopy, CT, or MRI. Anterior to posterior translation can be assessed by the combined excursion
offset between the spinolaminar junction lines of the atlas and
axis. (Fig. 3-23, B and C ) Alternatively, this can be determined
by lines drawn on the posterior surface of the axis and atlas anterior arch. With both methods, instability is deemed present
when the combined translation is > 3 mm. The average amount of
instability found in symptomatic cases is 10 mm. (7)
Anterior displacement of the atlas vertebra may also be indicated by deflection of the retropharyngeal soft tissues, producing
a sigmoid curve in the normally straight to minimally convex
soft tissue contour. In children < 5 years of age the normally
unfused dens will not show mobility on flexion–extension. The
radiographic diagnosis of os odontoideum in a child younger
Figure 3-24 OS ODONTOIDEUM. Lateral Cervical Spine.
Observe the failure of union of the odontoid process to the
base of the body of the axis, as demonstrated by a radiolucent band (arrow). Cortical thickening of the anterior
tubercle of the atlas, as well as an angular deformity of the
posterior surface of the anterior tubercle, suggests a
congenital origin.
than 5 years can be made if there is demonstration of mobility
of the odontoid process on the body of C2 during flexion and/or
extension. Fluoroscopy may show two types of motion: pure anterior translation and atlantoaxial S-shaped motion superior to
inferior. (19) Thin-section CT with reconstructions will also be
of assistance in the diagnosis and can be performed with flexion–
extension to assess instability.
MRI will elucidate pathologic changes of the craniocervical
cord in asymptomatic, acute, and chronic symptomatic presentations. (23) (Fig. 3-25) The nature of the tissue occupying the
dens defect can be identified on MRI and may reflect stability
of the condition. Homogenous low signal in both T1- and T2weighted images is compatible with fibrous tissue, which is often
stable. Instability is more likely to be associated with the presence of fluid, seen as high signal intensity on T2-weighted images. Cicatricial overgrowth of fibrocartilage at the defect may
also be identified as an offending compression site on the ventral
cord. (24) The separated ossicle often will have fatty marrow,
which has a high internal signal on T1-weighted images. On
sagittal studies the nuchal ligament between C1 and C2 may
show an increase in the central signal and may be disrupted or
avulsed from the spinous processes. (25) MRA studies are useful in detecting the presence of any associated vertebrobasilar
vascular abnormalities.
Figure 3-25 OS ODONTOIDEUM. T1-Weighted MRI, Sagittal.
Observe the abrupt change in signal intensity where the failure of fusion occurred, causing an os odontoideum (arrow).
The secondary ossification center (tip of the dens) can be
seen as an area of brighter signal intensity superior to the
stump of the dens (arrowhead ). This has permitted posterior
subluxation of C1 on C2 and a posterior deformity of the
upper cervical spinal cord. Other high-signal structures in
the C1–C2 complex include fat, posterior to the ossification
center. COMMENT: The normal odontoid process also displays a decrease in signal intensity at its more cephalad end,
reflecting the decrease in marrow in its tip. (Courtesy of
Steven R. Nokes, MD, Baptist MRI, Little Rock, Arkansas.)
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Congenital Anomalies and Normal Skeletal Variants I
275
Medicolegal Implications
OS ODONTOIDEUM
• Adequate radiological technique is imperative for accurate depiction of the anomaly. Assessment for atlantoaxial instability
(flexion–extension) and neurological complications (MRI,
MRA) should be made.
• Instability of C1 on C2 secondary to os odontoideum
carries the risk of damage to the spinal cord or vertebral
arteries with or without trauma. (10,11)
• High-velocity, spinal manipulative techniques are contraindicated in patients with these conditions. Anesthetic
risk during intubation with neck extension needs to be
considered. Surgical consultation must be considered
for patients with progressive instability or neurological
symptoms.
HYPOPLASTIC AND AGENETIC
ODONTOID PROCESS
Synonyms. Odontoid agenesis or aplasia, vestigial or attenuated dens.
Description. A failure of the dens to form and ossify is an uncommon anomaly. (1) This malformation was first described
by Bevan in 1863. (2) Total absence of the dens is referred to
as agenesis, whereas partial formation is hypoplasia. True agenesis is exceedingly rare and most cases show a vestigial odontoid
stump on close scrutiny.
Clinical Features. Hypoplasia of the dens is present when
it measures < 12 mm in vertical height. (3) Known associations include Down’s syndrome, occipitalization, Klippel-Feil
syndrome, and skeletal dysplasias. (4,5) Acquired causes for
destruction of the dens include tumor, infection, rheumatoid
and other less common inflammatory arthropathies, and posttraumatic dissolution. (6)
The majority of cases are discovered incidentally on radiographs, often following trauma. The lesion can be found at any age,
even at birth when the dens is usually present, though occasional
delay until 2 years of age does occur. (7) Torticollis, suboccipital
pain, and neuralgia; upper cervical crepitus; and vertebrobasilar
symptoms may be present. (8) Occasionally with atlantoaxial
instability, neurological symptoms from dysfunction of the cerebellum, brainstem, and cervical cord may occur. The onset of
symptoms may be triggered by activities of daily living and minor
or major trauma. (8) Prolonged hyperextension in the prone
position may initiate neurological complications. (9) With absence of the odontoid, atlantoaxial instability of up to 10 mm may
remain asymptomatic because the cord is not compressed readily between the atlas and the axis.
In the presence of neurological symptoms, treatment options
are limited to various types of posterior fusion techniques. (1)
(Fig. 3-26) In asymptomatic cases, prophylactic intervention
is controversial because the risk for morbidity and even death
remains significant. (10)
Radiologic Features. Scrupulous attention to detail in obtaining an adequate cervical spine radiographic series is required for
diagnosis. The AP open mouth projection is particularly important for depicting the upper cervical complex. In true agenesis
Figure 3-26 SURGICAL ARTHRODESIS (GALLIE FUSION),
AGENESIS OF THE ODONTOID PROCESS. Lateral Upper
Cervical Spine. Posterior interspinous wiring of C1, C2, and C3
has been performed with anatomic alignment of the atlantoaxial segments. In this child the underlying cause of the
atlantoaxial instability was agenesis of the odontoid process.
Figure 3-27 ODONTOID PROCESS, HYPOPLASIA. AP Open
Mouth. Here the odontoid process exists as an abbreviated
remnant stump; therefore, it is not true agenesis. The lateral
shift of the atlas relative to the axis, C1 on C2, indicates
instability. (Courtesy of Klaus W. Weber, MD, Fort Wayne,
Indiana.)
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there is no evidence of a dens on any projection. If hypoplastic,
the odontoid process is seen as an abbreviated stump of bone projecting slightly above the C1–C2 articulations on the AP open
mouth film. (Fig. 3-27) There may be lateral or rotary subluxation
of the atlas with an offset at the lateral margins of the atlanto-axial
joint or marked asymmetry in the width of the atlas lateral
masses. On the lateral film no dens will be visible and there are
no dental landmarks to assess the atlantodental interval. The anterior arch of the atlas may take a number of altered forms, including enlargement, sclerosis, and a rounded posterior surface.
In the neutral position the atlas may lie in a distinct flexed position relative to the plane of the axis. If there is anterior subluxation, the spinolaminar lines between the atlas and the axis will be
noticeably misaligned. The posterior arch of the atlas may be
hypoplastic, is occasionally sclerotic, and may exhibit a claw-like
spur from the posterior tubercle curving superiorly. (11)
Assessment of instability can be performed with flexion–
extension plain films, fluoroscopy, CT, or MRI. (Fig. 3-28)
Anterior to posterior translation can be assessed by the combined
excursion offset between the spinolaminar junction lines of the
atlas and axis. Deflection of the retropharyngeal soft tissues by
the anteriorly displaced atlas anterior arch produces a sigmoid
curve in the normally straight to minimally convex soft tissue
plane. In children younger than 2 years the normally unfused
dens will not show mobility on flexion–extension. The radiographic diagnosis of agenesis in children can be made with confidence if the dens is absent by age 2 and suspected if not present
at birth. (7)
Thin-section CT with reconstructions will also be of assistance in the diagnosis and can be performed with flexion–
extension to assess instability. Many cases of os odontoideum
are misdiagnosed as odontoid agenesis or hypoplasia because
the separated ossicle may be obscured on conventional radiography and only confirmed with subsequent CT or MRI
studies. MRI will elucidate pathologic changes of the craniocervical cord in asymptomatic, acute, and chronic symptomatic
presentations.
DOWN’S SYNDROME
Figure 3-28 ODONTOID PROCESS, AGENESIS WITH INSTABILITY. A. AP Upper Cervical Tomogram. Note the complete
lack of an osseous odontoid process; no stump is evident.
B. Flexion, Lateral Cervical Spine. C. Extension, Lateral
Cervical Spine. Observe that there is no odontoid process,
allowing significant translation of the atlas in flexion and
extension. COMMENT: Patients with this degree of instability
and who manifest neurological symptoms are destined for
surgical arthrodesis. (Courtesy of Bryan Hartley, MD,
Melbourne, Australia.)
Synonyms. Trisomy 21, mongolism, mongoloidism.
Description. Down’s syndrome is the result of trisomy of
chromosome 21 and is the most common autosomal syndrome,
occurring in 1 of every 600 births.
Clinical Features. Assessment of nuchal translucency during
antenatal ultrasound examination between weeks 11 and 12 is
used as a tool for early diagnosis. Patients affected with Down’s
syndrome are recognizable at birth, with a decreased AP diameter
of the skull, a small nose with a flat bridge, slanting eyes (epicanthal folds), simian creases of the palms, and a protruding
tongue. Mental retardation is a constant feature, although severity varies considerably. Leukemia is significantly more common
in patients with Down’s syndrome than in otherwise normal individuals. Ligamentous laxity with spontaneous dislocation of various joints has been reported, including the hip and patellar and
atlantoaxial articulations. (1)
3
The involvement of the cervical spine, specifically the
craniocervical junction, is highlighted because of its important
and often unexpected clinical implications. Documented associations include atlanto-occipital and atlantoaxial instability, abnormalities of the transverse ligament, and atlas and odontoid
anomalies. These may occur singularly or as a cluster of abnormalities, which may precipitate a gradually progressive anterior
atlantoaxial subluxation in 10 –30% of cases. (2,3) The mean
age for developing neurological symptoms (e.g., hemiplegia,
quadriplegia, and even death) as a consequence of these conditions is around 10 years of age, although no age is immune. (4)
Torticollis is a common indicator for underlying atlantoaxial instability and rotatory dislocation. (5,6) Trauma, often relatively
trivial, may be the initiating event for neurological deterioration; however, sometimes no direct cause may be found. (7)
Trisomy 21 patients who are contemplating or who are already
participating in athletic pursuits should be examined, and cervical radiographs in flexion and extension should be obtained
when indicated. ( 7,8)
Treatment by manipulative therapists remains empirical and
needs great care in appropriate technique selection and application. (9–11) When instability and /or myelopathic signs are
present, manual therapies to this region are contraindicated. Controversy exists regarding surgical versus conservative treatment
options for patients in whom the ADI exceeds 5 mm. (5) In the
presence of severe pain, persistent torticollis, and neurological
symptoms in which the spinal cord is at risk, surgical stabilization is the treatment of choice. (7) Attempts to reduce the degree
of displacement before fixation should be avoided, owing to the
high risk for precipitating cord trauma because the dislocated
position is often the most stable.
Radiologic Features. Plain film examination is the initial study
of choice and must include flexion– extension studies. Supplemental MRI studies in symptomatic cases can assist with cervical
cord and brainstem assessments.
Atlas Anomalies. At least 25% of Down’s syndrome children
have a hypoplastic atlas with a significantly reduced AP diameter
of the C1 bony ring, which increases the risk for cord compression, and lesser degrees of atlantoaxial instability. (12) Non-union
of the posterior arch of the atlas has been recorded. (3) Anteriorly
orientated atlantoaxial joint surfaces are usually present in cases
of anterior atlas subluxation. (7)
Axis Anomalies. At least 6% of Down’s syndrome patients have
been found to have odontoid anomalies, such as agenesis, hypoplasia, os odontoideum, and ossiculum terminale. (7,13) Additional
anomalies include third condyle, occipital vertebrae, and accessory
ossicles. (5,14) When osseous anomalies of the odontoid process
exist, the probability for instability with neurological complications
greatly increases. (7,13)
Atlanto-Occipital Instability. AP translation of the occiput on
the atlas > 1 mm from flexion to extension is found in up to 70%
of Down’s syndrome patients, although this is rarely of clinical
significance. (15,16) Posterior subluxation of the occiput on C1
is the most common finding. (17,18)
Atlantoaxial Instability. Hypoplasia of the transverse ligament
precipitating anterior atlantoaxial subluxation and even dislocation occurs in 10–20% percent of cases. (15,19) The ligament can
be involved in various ways, including agenesis (19); malformation (19); and laxity, which is part of the generalized ligamentous
laxity of the condition. (13,20) On flexion radiographs the ADI is
Congenital Anomalies and Normal Skeletal Variants I
277
Figure 3-29 DOWN’S SYNDROME, UPPER CERVICAL
INVOLVEMENT. Lateral Upper Cervical Spine. The atlantodental interspace (lines) is 5 mm, secondary to laxity
or agenesis of the transverse ligament of the atlas.
COMMENT: Up to 20% of patients with Down’s syndrome
will have laxity or agenesis of the transverse ligament of
the atlas. A flexion radiograph of the upper cervical spine
is necessary to demonstrate this instability; if present,
instability may contraindicate spinal manipulative therapy
of the upper cervical complex.
the most critical measurement to assess. (Fig 3-29) Intervals of
< 6 mm are invariably asymptomatic, whereas with those > 7 mm
compressive myelopathy manifestations become more likely and
are usually present by 9 mm of displacement. (5,20) Rotatory
atlantoaxial dislocation, while less common, does occur and
correlates with persistent torticollis. (6)
Lower Cervical Spine. There appears to be a higher incidence
of degenerative change at the C2–C3 and C3–C4 levels in
adults, usually older than 37 years of age. (21) Other findings may include subaxial subluxations and congenital block
vertebrae. (2)
Thoracic and Lumbar Spines. The vertebral body heights are
increased secondary to poor muscle tone and delay in walking (cuboid vertebral bodies). (22) The sagittal diameter of
the vertebral bodies, especially in the lumbar spine, is reduced
and has accentuated anterior and posterior concavities. (23)
Widening of the spinal canal with elongated pedicles can be
seen. Narrowing of the thoracic intervertebral disc spaces can
be observed. (19)
Extra-Spinal Sites. Other radiographic findings include a decreased iliac index, hypoplasia of the middle phalanx of the
fifth finger with clinodactyly, multiple ossification centers for
the manubrium, under-pneumatization of the paranasal sinuses,
11 or 13 pairs of ribs, and a prominent conoid process of both
clavicles. (24)
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Medicolegal Implications
ANOMALIES OF C3–C7
DOWN’S SYNDROME
•
•
•
•
•
• In light of the frequency of atlantoaxial subluxation the National Special Olympics Committee has a policy that all participants with
Down’s syndrome be screened for atlantoaxial instability
with flexion–extension radiography. (8)
Participation in recreational or competitive sports has
been highlighted as an indication for screening for
atlantoaxial instability.
If the ADI is > 4.5 mm, there is sufficient reason to restrict
the sporting activities of patients who may incur head or
neck trauma. (16)
Non-operative management of Down’s syndrome patients with asymptomatic atlantoaxial instability has
been recommended because of the high rate of postsurgical complications. (25)
Adult patients with Down’s syndrome are prone to
develop cervical myelopathy secondary to cervical
spondylosis. (21)
Physical treatment modalities, including manipulation
to the cervical spine, would appear to have an empirical
increased risk for precipitating atlantoaxial instability.
(9–11) If instability is present, manipulation to the upper
cervical spine is contraindicated.
Figure 3-30 C2–C3, BLOCK VERTEBRAE. A. Flexion, Lateral
Cervical Spine. B. Lateral Cervical Spine. Observe the block
vertebra present between C2 and C3, with fusion of the
apophyseal joints. C. Specimen Radiograph C2–C3. Observe
BLOCK VERTEBRAE
Synonyms. Congenital synostosis, blocked vertebrae, congenital
vertebral fusion, failure of vertebral segmentation, intercorporeal
fusion.
Description. Embryological failure of normal spinal segmentation resulting in fusion of one or more contiguous vertebral segments is described as congenital block vertebrae. This most likely
is the result of locally decreased blood supply during the 3rd–
8th week of fetal development. Unless otherwise specified, use
of the term block vertebrae typically implies a congenital cause;
the term acquired block vertebrae is sometimes used to describe
vertebrae joined by some other pathologic process.
Clinical Features. The cervical spine is most commonly involved, followed by the lumbar and thoracic areas, respectively.
The most common individual motion segments involved are reported as C5–C6, C2–C3, T12–L1, and L4–L5, (1,2) although
other investigators have concluded that C2–C3 is the most common site involved. (Figs. 3-30 and 3-31) (3,4) Isolated fusions of
two segments are 50 times more frequent than fusions involving
more than two segments. (5) General population incidence estimates range from 0.4% to 0.7% (6,7) with no sex predilection. (3)
Most vertebral fusions are rarely symptomatic and are usually
found incidentally on radiographs. (8) Increasing age and injury
may precipitate clinical manifestations. Physical examination is
typically unremarkable. Head tilt, neck deformity, or loss of
intersegmental mobility may be identified, particularly when multiple motion segments are involved. Neurological changes may be
identified from nerve compression or myelopathy secondary to
the rudimentary calcified disc at C2 in this blocked specimen.
COMMENT: Block vertebrae are most commonly found at
C5–C6, C2–C3, T12–L1, and L4–L5, in decreasing order of
incidence.
3
Figure 3-31 C2–C3, BLOCK VERTEBRA. Lateral Cervical
Spine. Observe the unusual C2–C3 block with a deformed
posterior arch of C2 and C3. This abnormality resulted in
increased biomechanical stress, which increased the size of
the anterior arch of C1. (Courtesy of James D. Abel, DC,
Columbus, Nebraska.)
degenerative changes. (4,9) Vertebrobasilar perfusion should be
explored with appropriate history and examination. (10)
A spectrum of clinical syndromes can emanate from at least
six possible anatomic sources: posterior joint changes, degenerative disc disease, spinal stenosis, fractures, and alteration and
anomaly of vertebrobasilar blood flow. (6,10,11) Most notably it
is the immediately adjacent segments that are placed under greater
biomechanical stress and become the focus for the majority of
clinical manifestations.
Facet Arthrosis. Premature degenerative change at adjoining
motion segments is common. Subsequent remodeling of the zygapophyseal joints may precipitate spondylolisthesis, and surgical fusion may be required if instability ensues. Osteophytic
overgrowth of the posterior joints may also narrow the exit foramina posteriorly and produce nerve root compression. Before
degenerative changes become radiologically evident, capsular
strain, synovitis, cartilage fibrillation, or meniscal entrapment may
contribute to posterior joint pain syndromes.
Degenerative Disc Disease. Discs immediately adjoining the
block vertebra are prone to annular tear, herniation, and fibrillation with subsequent discogenic pain syndromes. Associated
spondylosis may develop, as discussed below.
Spinal Stenosis. Notably, it is rare to develop bony stenosis of the
central or lateral canals at the level of the fusion. The site of canal
stenosis is characteristically immediately below or above the fusion
secondary to spondylosis of the vertebral endplate, osteophytic
overgrowth of the zygapophyseal articulations, and degenerative
hypertrophy and thickening of the ligamentum flavum. Central
canal stenosis can produce cord compression, myelopathy, myelomalacia, and even syrinx formation. Neck trauma in the presence
of block vertebrae can produce acute cord injury, including edema,
contusion, hemorrhage, and even transection. (6,8)
Congenital Anomalies and Normal Skeletal Variants I
279
Fractures and Trauma-Induced Instability. Block vertebra at
C2–C3 can precipitate laxity or frank rupture of the transverse ligament, producing either acute or chronic atlantoaxial instability and
leading to cord compression. (12–14) The triggering mechanism
may be trivial but usually involves more significant hyperextension
from motor vehicle collision, industrial or sports injury, or physical assault. (6,8,9,15) In the presence of trauma, block vertebra at
C2–C3 has been associated with odontoid fracture (16). A compression fracture of a blocked segment has been reported (17);
however, fracture of an adjacent vertebral body is more likely if
sufficient force is encountered (6,8,15,18).
Vertebrobasilar Perfusion Abnormalities. The vertebral artery
may be singularly or bilaterally abnormal. Changes include congenital hypoplasia, abnormal course, and compression from degenerative osteophytes or anomalous scalene muscle attachments.
(4,9) Occlusion of the vertebral artery has been recorded. (10)
Soft Tissue Abnormalities. Ligamentous instability from chronic
or acute trauma may occur at adjacent levels, including the capsular, interspinous, and atlas transverse ligaments. The degenerative
ligamentum flavum thickening often occurs at adjacent levels.
Muscle fatigue syndromes are common.
Other Associations. Other segmentation anomalies may occur, such as hemivertebrae and butterfly vertebrae. Scoliosis and
kyphosis are common. At least 70% of occipitalizations have
a block vertebra at C2–C3 (13). Sprengel’s deformity and
omovertebral and costovertebral bones may occur. Block vertebrae occur in Klippel-Feil, fetal alcohol, Goldenhar’s, Turner’s,
Apert’s, and VATER syndromes. Anomalies of other organ systems are more common when there are multiple block vertebrae
present. Zenker’s diverticulum of the upper esophagus and cysts
(duplication, bronchogenic, neurenteric) of the gastrointestinal
and tracheobronchial tracts may occasionally be found. (3,4,19)
They generally appear as isolated entities, though occurrence in
families has been documented. (5,20)
Radiologic Features. Plain film studies are the usual method
for detecting and assessing intersegmental instability and degenerative changes. In the presence of neurological changes, MRI is
the technique of choice for investigation.
Radiographs in the frontal, lateral, and oblique planes should be
supplemented with flexion–extension views. The lateral view
shows the characteristic triad of vertebral body hypoplasia, small
disc, and variable posterior arch fusion. The involved vertebral
bodies are maximally hypoplastic in their sagittal dimension near
the intervening vestigial disc space, such that the combined anterior contour is distinctively concave (wasp-waist deformity, hourglass deformity, C concavity [for congenital]). (7,21) (Figs. 3-32
and 3-33) The involved disc space is thin and variably ossified.
The nucleus pulposus is often visible as a dense central calcification. The overall vertical dimension of a congenital block vertebra
is roughly equal to the height of two normal vertebrae plus an
intervertebral disc (law of blocks). (6,7)
There is variable fusion of the posterior arches in up to 50%
of cases at the level of body union, reflected as a single large spinous, laminae, or articular pillar. Complete or partial fusion of the
posterior elements may be seen in blocked vertebrae (2,15). Other
changes include isolated element agenesis, hypoplasia, and nonunion, especially spina bifida. The intervening intervertebral foramina (IVFs) of blocked segments are typically small and rounded
with smooth anterior margins (5). All of these features assist
in differentiating congenital fusions from acquired causes, such
as surgical arthrodesis, infection, or inflammatory spondyloarthropathy (e.g., ankylosing spondylitis). (Figs. 3-34–3-37)
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Figure 3-32 CONGENITAL BLOCK VERTEBRAE. A. Lateral
Cervical Spine. Observe the classic signs of block vertebra at
C5–C6, including wasp-waist vertebra, C-shaped anterior margin, rudimentary disc, and fusion of the posterior elements.
B. T1-Weighted MRI, Sagittal. This image is of the same patient
shown in panel A. Recall that, with T1-weighting, cortical bone
has a low signal intensity. Note the characteristic C shape to the
anterior bodies of C5–C6 (arrow). The low signal intensity band
that crosses represents the endplates of the vertebrae that
failed to separate. C. T1-Weighted MRI, Sagittal. This image is
of a different patient. The congenital block is at C3–C4, which
have the typical anterior C shape. COMMENT: In both MRI
studies the spinal cord is of normal signal intensity. (Panel C
courtesy of Robert D. Thompson, DC, Buena Park, California.)
Figure 3-33 CONGENITAL BLOCK VERTEBRAE. A–C. Lateral
Cervical Spine. Observe the congenital block vertebrae with
the characteristic C-shaped (wasp-waist) deformity, signifying the congenital origin of this fusion. COMMENT: Note the
coronal orientation of the intervertebral foramina within
the blocked segment. This foraminal orientation occurs with
an increased incidence in blocked vertebrae. (Panel A courtesy of Geoffrey G. Rymer, DC, Katoomba, New South Wales,
Australia; panel B courtesy of Jon P. Carmichael, DC, Denver,
Colorado; panel C courtesy of J. Todd Knudsen, DC, DACBR,
Los Angeles, California.)
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Congenital Anomalies and Normal Skeletal Variants I
Figure 3-34 SURGICALLY FUSED VERTEBRAE (ARTHRODESIS). A–D. Lateral Cervical Spine. The lack of anterior
concavity, rudimentary discs, and fusion of the apophyseal joints suggest a surgical rather than a congenital
origin for these fused segments. Another clue to the
surgical origin in panel B is the lack of lamina and spinous processes (C3–C6), which were removed during
laminectomy. (Panel D courtesy of Richard N. Garian,
DC, Holliston, Massachusetts.)
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Figure 3-35 CONGENITAL BLOCK AND SURGICALLY FUSED
VERTEBRA. Lateral Cervical Spine. Note the rudimentary disc
and posterior joint fusion at the congenitally blocked C2–C3
segment. These features are not present at the surgically
fused C5–C7 complex. (Courtesy of Paul Van Wyk, DC,
Denver, Colorado.)
27˚
Figure 3-37 POST-TRAUMATIC FUSED VERTEBRA. Lateral
Cervical Spine. Note the acute angulation of C5 on C6 (> 11º),
the varying interspinous distance at this level (> 3-mm difference from the adjacent segments), and uncovering of the
facet joints. This is a grade 3 sprain that was unstable; the
vertebrae were ultimately fused in this position. (Reprinted
with permission from White AA, Johnson RM, Panjabi MM,
et al.: Biomechanical analysis of clinical instability in the
cervical spine. Clin Orthop 109:85, 1975.)
Figure 3-36 DEGENERATIVE FUSED VERTEBRA. Lateral
Cervical Spine. Block vertebra caused by a degenerative
process is demonstrated at C4-C5. Note the opacified disc at
C2–C3 (arrow), the C3–C4 facet joint sclerosis (arrowhead ), and
osteophytosis at C3–C4 through C6–C7, all radiographic indicators of the degenerative process. The discogenic narrowing in
intervertebral disc height (C4–C5) has allowed C4 to fuse to
C5. (Courtesy of Richard L. Green, DC, Boston, Massachusetts.)
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Congenital Anomalies and Normal Skeletal Variants I
283
Figure 3-38 CERVICAL BLOCK VERTEBRAE. A. Single Block
Vertebra, Lateral Cervical Spine. Observe the block vertebra
present at the C5–C6 level. The arrested growth of the vertebral bodies resulted in the typical anterior concavity, or
wasp-waist appearance (arrow). The facet structures at C5–C6
are also fused. B. Multiple Block Vertebrae, Lateral Cervical
Spine. There are block vertebrae present at C5–C6 and C7–T1.
Facet joint fusion is noted at the C5–C6 level. Premature de-
generative discopathy with spondylosis is present at the
C6 disc level. Posterior osteophyte formation affecting the
C6–C7 vertebrae (arrow) may result in spinal canal stenosis.
COMMENT: Of patients with block vertebrae, 50% have
associated apophyseal joint fusion, as is present in both
of these cases. (Courtesy of John Nolan, DC, Wanganui,
New Zealand.)
Immediately adjacent to the fusion site the first mobile vertebral body is often flattened and widened. Signs of instability in
these segments and the atlantoaxial joint may be demonstrated
on flexion–extension views. (22) Immediately adjoining intervertebral disc spaces may develop premature degenerative joint
disease as early as the 2nd or 3rd decade of life. (4,5) (Fig. 3-38)
MRI is employed to assess for secondary soft tissue complications, including disc disease, stenosis, and any other associated
neurovascular abnormality. (4)
tual model for characterizing the broad spectrum of presentations (5) : KFS I, extensive cervical segmental fusion anomalies;
KFS II, one or two cervical block vertebrae; and KFS III, combined cervical, lower thoracic, and lumbar fusions.
The true incidence of KFS is not known, but the presence of
at least one cervical block vertebra has been documented in 0.5%
of live births. (6–8). The simultaneous occurrence of more than
two fused vertebrae is 50 times less common than is an isolated
cervical block vertebra. (9) Familial clustering and some increased
incidence in twins has been reported, but is unusual (7,8,10,11).
There is no gender predilection. The fundamental mechanism is
most likely a hypoxic intrauterine event that targets the somites
of the cervical spine, scapula, and genitourinary system during
fetal weeks 3–8.
Myriad clinical manifestations are known. The inability of
the infant to rotate the head without moving the shoulders during
parturition may lead to trauma. The deformity may be recognizable at birth or during infancy, although many cases escape
detection into adulthood, when secondary degenerative and biomechanical changes precipitate pain and subsequent radiologic
discovery. (7,12,13) Although the anomaly is generally well tolerated, activity modification throughout life can minimize the
risk of significant complications. (10) Known KFS associations
include VATER syndrome, iniencephaly, occipitalization, basilar
invagination, odontoid anomalies, atlantoaxial instability, scoliosis, and Sprengel’s deformity. The classic Klippel-Feil triad
of short webbed neck, low posterior hairline, and reduced cervical motion is present in approximately 50% percent of cases.
(7,13) Facial asymmetry, torticollis, and webbing of the neck
are seen in only 20% of patients. (7,13,14) The most consistent
finding is limitation of neck motion. (13)
KLIPPEL-FEIL SYNDROME
Synonyms. Congenital brevicollis, cervical assimilation, cervical
thoracic cage, cervico-oculo-acoustic syndrome.
Description. In 1912 Klippel and Feil described a 46-year-old
man with a triad of signs: a short webbed neck (pterygium colli),
low hairline, and reduced range of cervical motion. (1–3). They
provided the first correlative autopsy, demonstrating the underlying
vertebral fusion anomalies. The original report described almost
complete non-segmentation throughout the entire cervical spine.
Clinical Features. Klippel-Feil syndrome (KFS) is currently
a loosely applied eponym used to describe congenital segmentation defects of the cervical spine. (4) Because isolated block
vertebrae of two segments is more common and is usually not associated with the other non-vertebral anomalies, the term KlippelFeil syndrome should be reserved for congenital fusions involving
more than one motion segment (i.e., more than two vertebrae),
although this convention is often not followed. Klippel and Feil’s
original classification (KFS types I–III) provides a useful concep-
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Biomechanical. Sagittal movements are often frequently preserved, whereas rotation and lateral flexion may be severely restricted. (11,13) KFS patients are predisposed to increased motion
of the upper cervical segments, which may produce atlas transverse ligament weakening with atlantoaxial instability requiring
surgical fusion. (11,15)
Musculoskeletal. The classic triad of neck webbing, low hairline, and limited neck movements is expressed in only approximately 50% of patients. (13) There may be the illusion of no
neck, with the head seeming to be continuous with the shoulders.
Torticollis is common. Scoliosis is present in almost 80% of
cases. (11) Iniencephaly may be present where there is massive
enlargement of the foramen magnum, basilar impression, hyperextension of the neck, and cervical spina bifida. Other spinerelated defects include spina bifida (45%), hemivertebrae (75%),
butterfly vertebrae (2%), Sprengel’s deformity (25–50%), cervical ribs (15%), odontoid anomalies, and occipitalization,
(7,15). Additional skeletal changes include rib and digit anomalies, ulnar agenesis, cleft palate, and cranial and facial asymmetry. Associated anomalies of other organ systems are common
(Table 3-1). KFS epitomizes the following well-recognized clinical
adage: “Where there is one anomaly, look for another.”
Respiratory. Thoracic deformities may precipitate reduced ventilation and cor pulmonale and may present an increased anesthetic risk.
Cardiovascular. Congenital heart disease—most commonly ventricular septal defect (VSD) and patent ductus—occurs in 5–14%
of patients. (14) Situs inversus and vertebrobasilar anomalies
have been reported. (16,17)
Gastrointestinal. Duplication and neurenteric cysts as well as
aganglionosis have been reported.
Genitourinary. Renal anomalies have been recorded in up to 35%
of KFS patients, including agenesis, horseshoe, ectopia, and duplex
collecting systems. (14,18) Cryptorchism and uterine anomalies
also occur (18).
Neurological. A broad spectrum of neurological manifestations
can occur. Deafness can be found in up to 30% of cases. (14)
Mirror movements of the hands (synkinesia) and ocular disturbances are sometimes seen. Upper and lower motor neuron
changes can all be seen. Cord and radicular compressive symptoms from degenerative osteophytes with stenosis are common.
(19,20) The vertebrobasilar system appears vulnerable to both
acquired and congenital lesions, which can precipitate neurological changes such as cerebral and cerebellar infarction. (16,21,22)
Imaging features associated with higher risk for neurological
complications include extensive fusion with craniocervical anomalies, occipitalization with C2–C3 block vertebra, multiple fusions
with only a single mobile level, intersegmental hypermobility and
translation, basilar impression, and iniencephaly. (11,15,23,24)
There is a higher risk of odontoid fracture when there are fusions
of C2–C3. (24,25)
Differential diagnosis of neck webbing includes Turner’s
and Goldenhar’s syndromes. Multiple block vertebrae may be
seen in myositis ossificans progressiva, juvenile rheumatoid
arthritis, ankylosing spondylitis, multilevel discovertebral postinfections (e.g., tuberculosis), and fetal alcohol syndrome (4,26)
Radiologic Features. Plain films are typically the first step in
investigation of patients with known or suspected Klippel-Feil
syndrome. Multiple block vertebrae produce vertebrae that are
hypoplastic with anterior concavity (wasp-waist sign). (4) The
intervertebral disc spaces are small and may have calcification
of the nucleus pulposus. Hemivertebrae may be visible on the
frontal study. Variable anomalies of the posterior elements are
common, including fusion, spina bifida, and other dysplasias. In
addition to identifying all the motion segments involved, care-
Table 3-1
Klippel-Feil Syndrome Associations
System
Musculoskeletal
Spine
Hemivertebrae
Diminished neck mobility
Scoliosis
Spina bifida occulta
Butterfly vertebrae
Os odontoideum
Degenerative stenosis
Generalized platyspondyly
Extraspinal
Rib anomalies
Facial anomalies
Sprengel’s deformity
Basilar impression
Cervical ribs
Thoracic asymmetry
Platybasia
Limb anomalies
Omovertebral bone
Costovertebral process
Soft tissue
Ear anomalies
Eye disturbances
Torticollis
Webbed neck
Cardiovascular
Vertebral artery anomalies
Congenital heart defects
Respiratory
Deformed thorax
Accessory lobes
Neurological
Deafness
Pyramidal tract disease (myelopathy)
Synkinesia
Vertebrobasilar ischemia
Syringomyelia
Genitourinary
Renal anomalies (agenesis, collecting systems)
Genital anomalies (cryptorchidism, uterus)
Turner’s syndrome
Gastrointestinal
Cysts, duplication, malrotation
Dermatological
von Recklinghausen’s disease
Nevoid basal cell carcinoma
Incidence
75%
65%
60%
45%
3%
N/A
N/A
N/A
33%
25%
25%
25%
12%
10%
6%
1%
N/A
N/A
25%
24%
20%
6%
25%
5%
N/A
N/A
30%
30%
20%
N/A
N/A
35%
N/A
N/A
N/A
N/A
N/A
Data from Gray SW, Romaine CB, Skandalaikis JE: Congenital fusion of the cervical
vertebrae. Surg Gynecol Obstet 118:373, 1964; Hensinger RN, Lang JE, MacEwen
GD: Klippel-Feil syndrome. A constellation of associated anomalies. J Bone Joint Surg
56A:1246, 1974; and Hensinger RN: Congenital anomalies of the cervical spine. Clin
Orthop Rel Res 264:16, 1991.
N/A, not available.
ful attention must be given to assessing the integrity of the dens
and stability of the upper cervical complex. (Fig. 3-39) Flexion–
extension studies should be obtained to identify increased translation at non-fused levels. (11). Complete radiographic assessment
of the spine and thorax should be performed to identify any other
osseous anomalies. (Figs. 3-40 and 3-41)
MRI is extremely useful in the presence of neurological changes
to assess the brainstem, spinal cord, nerve roots, and the effects of
disc disease and osteophytes. (24,27) In acute trauma, high sig-
3
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Figure 3-39 KLIPPEL-FEIL SYNDROME WITH OMOVERTEBRAL BONE. A. AP Lower Cervical Spine. Observe the omovertebral bone projecting from the lamina of C7 toward the
superior angle of the scapula (arrows). There is associated
congenital failure of descent of the scapula (Sprengel’s de-
formity) (arrowhead ). B. Lateral Cervical Spine. Note the
multiple congenital block vertebrae. COMMENT: Sprengel’s
deformity is found in 25% of patients with Klippel-Feil syndrome. (Panel B courtesy of James R. Brandt, DC, DABCO,
Coon Rapids, Minnesota.)
Figure 3-40 KLIPPEL-FEIL SYNDROME. A. AP Lower Cervical
Spine. Observe the multiple block vertebrae noted throughout the lower cervical and upper thoracic spine, as evidenced
by the lack of disc spacing. Anomalous rib development is
also seen. B. Lateral Cervical Spine. There are multiple block
vertebrae throughout the cervical spine. The zygapophyseal
joints are also fused. Of incidental notation are posterior
spina bifida of the atlas and multiple lower cervical and
upper thoracic segments.
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SPRENGEL’S DEFORMITY
Figure 3-41 KLIPPEL-FEIL SYNDROME. Neutral, Lateral
Cervical Spine. Note the block vertebrae at C2–C3 and C5–C6
(arrows). COMMENT: There is also significant disc degeneration at the C4–C5 and, to a lesser extent, C6–C7 segments
(arrowheads). This is a result of the additional stresses that
these segments must withstand because of the hypomobility
of the block segments. (Courtesy of Dennis V. Salisbury, DC,
Chadron, Nebraska.)
nal within the cord may be present on T2-weighted studies as a
sign of cord edema or contusion. Syrinx formation is not an uncommon finding after significant trauma. (24) If MRI is unavailable, contrast-enhanced CT with reconstructions can be employed. MRA should be part of the examination for assessing the
extracranial and intracranial circulation, especially for anomalies
of the vertebrobasilar system. (24)
Synonyms. None.
Description. Congenital elevation of the scapula, described
by Sprengel in 1891, was actually first mentioned in 1863 by
Eulenberg. (1) Sprengel’s original report describes four children
with similar scapular deformities. (2) In all four of these patients,
the left scapula was elevated. Although various postulates have
been advanced, the reason for this deformity remains a mystery.
Clinical Features. At the 3rd fetal week the scapula develops
in the neck, at the C4–C5 level. Under ordinary conditions the
scapula migrates to its normal position by the 15th day of gestation. Therefore, failure to descend, rather than elevation of the
scapula, is a more accurate description of the pathology. It seems
likely that the problem evolves before the 3rd month of skeletal
development. A 2:1 female predominance has been noted. (3)
The deformity can be detected at birth and is usually unilateral,
but may be seen bilaterally. (3)
Examination of a patient with Sprengel’s deformity shows
elevation of the scapula and limited humeral abduction. Torticollis, with or without muscle spasm, may be present. The degree
of fixation and the quantity of malrotation and maldevelopment
should be determined. (3)
Sprengel’s deformity may present as an isolated anomaly, but
it also occurs in 20–25% of Klippel-Feil syndrome cases.
Omovertebral Bone. Another frequent concomitant is the omovertebral bone, present in 30–40% of Sprengel’s deformity cases.
(4) (Figs. 3-39 and 3-42) It is not always bone, as the term implies; it may also be composed of cartilage or fibrous tissue. The
omovertebral bone usually runs from the C5 or C6 spinous process, lamina, or transverse process to the superior angle of the
scapula. The earliest description of the omovertebral bone is
attributed to Willett and Walsham in 1880. (5)
Concerning Sprengel’s deformity, Lovell and Winter state:
“The treatment of choice is surgery. The deformity does not progress, but it does not spontaneously improve without surgery.
Medicolegal Implications
KLIPPEL-FEIL SYNDROME
• KFS patients at highest risk for neurological
complications are those with atlantoaxial
anomalies (occipitalization, os odontoideum,
odontoid agenesis), more than one block vertebra, and
degenerative changes at the adjacent mobile levels, especially if between two levels of fusions. (11,15,19,20,24)
• The presence of intersegmental instability on flexion–
extension radiographs may be associated with neurological symptoms. (23)
• The vertebral artery is prone to anomalous development,
and vertebrobasilar ischemia and infarction have been
recorded. (16,21,22)
• Identification of spinal cord, nerve, and vertebral artery abnormalities may require MRI and MRA examinations. Visceral anomalies, especially of the abdomen,
can be evaluated with ultrasound or CT. Additional
spinal segmentation defects need to be identified with
spinal radiographs.
Figure 3-42 SPRENGEL’S DEFORMITY WITH OMOVERTEBRAL BONE. AP Cervicodorsal. Observe the congenital failure of descent of the scapula (arrow), denoting a Sprengel’s
deformity. There is a large, bony bar projecting from the
lamina and spinous process of C7 to the vertebral border of
the scapula, representing an omovertebral bone (arrowead).
COMMENT: Of Sprengel’s deformity cases, 30–40% will have
an associated omovertebral bone.
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Synonyms. None.
Description. Since the original description by Perlman and
Hawes in 1951 more than 100 case reports of C6 spondylolisthesis have occurred in the literature. (7,8) The majority involve only
a single level and rarely two or three. (9) Usually the defect is bilateral, although unilateral forms are found. (10,11) Males are more
commonly affected, in a ratio as high as 3:1. (10,11) It has been
found in twins, families, and in basal nevus and Rubinstein-Taybi
syndromes. (12–15)
Clinical Features. There is a wide spectrum of clinical presentations encountered, although most patients are asymptomatic and
lack neurological abnormalities. Cases have been found in conjunction with neck and radicular pain, neck stiffness, headache, and
torticollis, but the link to the defects is unclear. (1,2,15,16) A palpable step defect, caused by the relative offset of the spinouses at
the C5–C6 levels (2,7) Conservative treatment is the mainstay of
management. (2,6) Occasionally instability or neural compression is associated with displacement, and surgical intervention may
be required (8,16–18). Because the defect mimics fracture with
anterolisthesis and is frequently found incidentally on trauma radiographs, the lesion may be misinterpreted and treated inadvertently
with fusion. (8)
Radiologic Features. A complete seven-view cervical spine
series (Davis series) should be performed. (1,2) Pillar views are
optional but can be helpful in the absence of CT availability. (2)
The key plain film findings are anterolisthesis, defect in the posterior neural arch, and—almost invariably—spina bifida occulta of
the affected segment. On the lateral film the vertebral body is displaced anteriorly 1–3 mm but usually remains stable on flexion–
extension. (Fig. 3-43) The defect in the posterior neural arch may
not be visible but the articular pillar appears dysplastic and the
posterior separated segment is often dorsally displaced. The adjacent contiguous pillars are often enlarged. (19) The spinolaminar
line is absent, owing to spina bifida, and the spinous process is
often dysplastic. (2) On the frontal film the midline vertical defect
of the spina bifida is usually broad enough to identify readily. (Fig.
3-44) The pillar separation is not typically depicted on the routine
AP view but may be shown on pillar views. The oblique film reveals a smooth, corticated cleft lying obliquely or perpendicular to
the facet joint plane. The separated posterior part of the pillar is
usually triangular and lies dorsally subluxed. The foraminal shape
Figure 3-43 C6, SPONDYLOLISTHESIS. A. AP Lower Cervical
Spine. Observe the spina bifida occulta at C6 (arrow). Considerable joint of von Luschka’s arthrosis is present bilaterally at the C4–C5 levels (arrowheads). B. Lateral Cervical
Spine. Note the marked dysplasia of the pedicles and articu-
lar pillars of C6. There is anterior translation of the vertebral
body of C6 on C7. COMMENT: The spinolaminar line, which
is usually the most reliable indicator of translation of a vertebral segment, cannot be used in this case because of the
spina bifida occulta.
Conservative treatment does not result in any improvement.
Physical therapy also is not helpful.” (3) Surgery is best considered
between the ages of 4 and 7 years.
Radiologic Features. The scapula is hypoplastic, shortened
vertically, and is broad on radiographic examination. It is rotated
so that the glenoid process is directed inferiorly. The inferior
angle rests above the normal T7 level. The amount of elevation
may be from 2 to 10 cm. Two thirds of patients presenting with
these features demonstrate associated scoliosis, hemivertebrae,
block vertebrae, spina bifida occulta, or cervical ribs. (6)
CERVICAL SPONDYLOLISTHESIS
Cervical spondylolisthesis is the result of a congenital cleft
(spondylolysis) through the posterior neural arch, most commonly involving the C6 vertebra. Other segmental levels are recorded, including C2 and C4 (1–5); however, it has not been
recorded at the atlas or C7. (6)
C6 Spondylolisthesis
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Figure 3-44 C5–C6, Spondylolisthesis. A. AP Lower Cervical
Spine. Note the oblique lucency in the midline of both C5
and C6, representing spina bifida occulta at both segments
(arrow). Incidentally and unrelated is elongation of the C7
transverse processes (arrowhead). B. Lateral Cervical Spine.
There is a break in the posterior vertebral line (George’s
line) with an anterolisthesis of C6 on C7. There are also
abnormally shaped articular pillars at C6 (arrow). C and
D. Oblique Cervical Spine. The oblique views demonstrate
defects in the pedicles of C6 and dysplasia of the C6 articular
processes. (Courtesy of Marc Moramarco, DC, Woburn,
Massachusetts.)
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Congenital Anomalies and Normal Skeletal Variants I
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Figure 3-45 C6, SPONDYLOLISTHESIS. A. Cervical CT Bone
Window. The bilateral defects in the C6 posterior arch
(arrow) are clearly demonstrated. Note that the osseous
margins of the defects are smoothly corticated. B. Cervical
Sagittal T1-Weighted MRI. The MRI study of the same
patient shows no evidence of disc herniation, bulge, or
spinal cord defect. (Courtesy of Jeffrey J. Pfeifer, DC, Alton,
Illinois.)
is altered and usually appears enlarged. The combination of location (C6), spina bifida, and smooth corticated cleft margins is the
key to excluding acute fracture. (20) (Fig. 3-45A)
CT is useful for demonstrating the bilateral defects with their
smooth cortical margins. MRI often does not show the defect in the
posterior neural arch. (8,10) When a history of trauma is involved,
neurological abnormalities are present, or there is difficulty in
excluding fracture, MRI is useful for assessing the integrity of the
neurovascular structures. (Fig. 3-45B)
vical spine, associated spina bifida is uncommon. (26) Flexion–
extension radiographs are recommended to ensure stability. CT
examination may more clearly demonstrate features that are useful in excluding fracture (bilateral symmetry, smooth sclerotic
margins, and spina bifida) (5,26,27).
C2 Spondylolisthesis
Synonyms. Congenital hangman fracture, pseudo-hangman
fracture, spondylolisthesis of the axis.
Description. C2 spondylolisthesis is a congenital defect that
has been variously described as being through the pedicle or pars
interarticularis of the axis vertebra. As there is uncertainty about
where the actual pars is located radiographically most reports
locate the defect in the pedicle.
Clinical Features. This is an uncommon disorder that is often
asymptomatic; patients tend to present during infancy and childhood. (21) The few patients who are symptomatic tend to have
neck pain or audible crepitus. (4,5,22) Known associations include familial transmission, occipitalization, block vertebrae, C6
and L5 spondylolysis, Crouzon’s disease, and pyknodysostosis.
(3,23–25) The majority of cases do not require surgical intervention, and an 8-week or more regimen of bracing has been reported
as a means to induce ossification (24).
Radiologic Features. On the lateral view a wide defect is seen
through the pedicle with forward flexion and anterolisthesis of
the axis body. (Fig. 3-46) In adults the defect is much narrower
and more difficult to see, often visible only on oblique views or
CT scans. Unlike congenital spondylolysis elsewhere in the cer-
Figure 3-46 C2 SPONDYLOLISTHESIS. Lateral Upper Cervical
Spine. Note that the articular pillars of the axis are absent,
with a residual radiolucent defect (arrow). There remain
small attenuated tapered pedicles. The body of C2 has subluxed anteriorly (arrowhead). The spinous process and part
of the laminae of the axis is fused to C3, as evidenced by the
megaspinous sign (crossed arrow). COMMENT: This is an uncommon congenital anomaly, and the variably sized defect
can be found anywhere from the pedicle through to the
articular pillars. The majority of patients are asymptomatic;
few require surgical fixation. (Courtesy of Colin Clarey,
BAppSc (Chiro), Eleanora, Queensland, Australia.)
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ABSENT PEDICLE OF
THE CERVICAL SPINE
Synonyms. Congenital agenesis of the pedicle, absent pedicle
syndrome, pedicle aplasia.
Description. Congenital agenesis of the pedicle is a complete
failure of embryonic chondrification and ossification of the pedicle. A less complete form (pedicle hypoplasia) results in a thin,
attenuated pedicle.
Clinical Features. The first report of this anomaly is credited
to Hadley in 1946. (1) The cervical spine is most commonly involved, followed by the lumbar and thoracic areas. Within the
cervical spine C6 is the most frequent level of occurrence (45%)
followed by C5 (30%), C4 (12%), and C7 (12%). (2) The condition is consistently unilateral and right–left distribution is equal.
(3) There is no gender dominance, and age at discovery varies
widely from childhood to old age. (4)
Its discovery is often incidental after trauma or in the initial
investigation of cervicogenic pain syndromes when radiographs
are taken. The relationship to these clinical disorders is unclear,
and usually no specific intervention is required. (3,5,6) In the
presence of altered nerve root function, the presence of herniated
disc, nerve tumor, or syrinx needs to be excluded. (4,6) The majority of cases occur in isolation, although close inspection, especially
on CT, may show additional anatomic variations in up to 50% of
cases, including spina bifida, pillar dysplasia, block or butterfly
vertebrae, and Klippel-Feil syndrome. (6)
Histologically, the site of the absent (aplastic) pedicle demonstrates loose connective tissue, fibrocartilage, or no remnant tissue.
Two nerve roots contained within a single dural sleeve usually
exit in tandem through the now confluent foramen (3,6). There
appears to be no predisposition to intersegmental instability, or degenerative disc or facet disease. (6) There are numerous differ-
Figure 3-47 ABSENT PEDICLE OF THE CERVICAL SPINE.
A. Lateral Cervical Spine. Observe the altered appearance of
the articular pillar of C6. B. Oblique Cervical Spine. Note that
there is no pedicle shadow present on C6 (arrow). Observe the
ential diagnostic considerations for absence of a cervical pedicle.
(Table 3-2) (3,4,7–9)
Radiologic Features. Plain films usually suffice for diagnosis,
but additional imaging may be required to confirm the congenital origin, exclude other differential diagnostic considerations,
and identify co-existing pathologies that may be the cause for any
clinical findings.
Routine frontal and lateral radiographs are insufficient for diagnosis because cervical pedicles are not well demonstrated on
these views. (6) On the AP film, absence of the pedicle may be appreciated by a lack of the pedicle outline, but this is often a subtle
finding. Oblique films provide clear depiction of an enlarged
intervertebral foramen and, on the contralateral oblique, absence
of the usual pedicle silhouette over the vertebral body (10). (Fig.
3-47) Occasionally there is compensatory contralateral pedicle
sclerosis. Other commonly associated findings include a dysplastic and dorsally placed articular pillar and a dysplastic transverse process. (6,8,10) The superior facet may be hypoplastic or
absent. (11)
Table 3-2
Differential Diagnostic Considerations
for Absence of a Cervical Pedicle
Osteolytic metastases
Aneurysmal bone cyst
Osteoblastoma
Intraforaminal tumors
Neurofibroma
Dural ectasia of neurofibromatosis
Meningocele
Vertebral artery tortuosity
Vertebral artery aneurysm
normal pedicle shadow on C4, C5 (arrowheads). C. Oblique
Cervical Spine. The failure of pedicle development has resulted in an abnormally large intervertebral foramen (arrow).
(Courtesy of Gary M. Guebert, DC, DACBR, St. Louis, Missouri.)
3
Thin-section CT with reconstructions is extremely useful for
identifying the abnormal anatomy and excluding other pathologic
causes. (11) MRI confirms the absence of other neural and bony
diseases and may identify other clinically important pathologies,
such as disc herniation or syrinx. Scrutiny of T2-weighted images
may isolate two exiting nerves in an enlarged dural pouch, and
on T1-weighted images an increased amount of foraminal fat is
often seen. (8)
Exclusion criteria for other causes of pedicle loss can be used.
(3,4,7–9) Changes in the vertebral body are uncommon in pedicle
agenesis and are useful for excluding other pathologies. Osteolytic metastases often involve the adjacent posterior vertebral
body and neural arch components, with loss of cortex and “motheaten” destruction. Aneurysmal bone cysts and osteoblastoma
are expansile, often with a thin peripheral cortex and internal
septations. Nuclear bone scan is normal in congenital agenesis
and hot in metastases, aneurysmal bone cyst, and osteoblastoma.
Intraforaminal masses, such as neurofibroma, meningocele, and
dural ectasia, cause pressure erosion bordered by a cortical margin
of the posterior vertebral body and adjacent pedicles. Vertebral
artery tortuosity or aneurysm causes similar changes. (9)
CERVICAL RIB
Synonyms. Dorsalization of the cervical spine.
Description. A costal bony process that originates from the C7
vertebra and forms true articulations with the transverse process
and vertebral body constitutes a cervical rib. Less complete examples are often described in common usage as cervical ribs as
well, however.
Clinical Features. Most cervical ribs are asymptomatic and are
discovered incidentally. When present, symptoms are commonly
related to compression of neural or vascular structures in the thoracic outlet (thoracic outlet syndrome). The first reported case—
in which compression of the subclavian vessels caused upper limb
ischemia, which was relieved when the cervical rib was removed—
was reported by Coote in 1861. (1) The documentation of associated vascular abnormalities and the role of non-radiographically
demonstrable fibrous bands was first alluded to by Halsted in
1916. (2) Cervical ribs are present in 0.5% of the population; of
these, 66% are bilateral. It is twice as common in females as in
males. (3) Up to 15% of Klippel-Feil syndrome patients have
cervical ribs. (4)
At least 95% of cervical ribs occur at C7, but they have been
recorded as high as C4. (5) They vary greatly in size, shape, and
anatomic course and exhibit variation in their termination. Clinical
symptoms bear little relation to the radiographic abnormality because the long fibrous bands that may be associated with the short
ribs may create symptomatic compression, not the bony components. The incidence of symptomatic cervical ribs is probably
< 5%. (6) Cervical ribs are one of many causes for neurovascular
compression syndromes of the upper limb, including nerve root entrapment, cervical disc disease, clavicle fractures, anterior scalene
muscle lesions, poor shoulder girdle muscular tone, and lung apical pathologies such as Pancoast’s tumor. If these ribs cause
symptoms, it is usually after middle age, when the shoulders
begin to droop. The dominant arm is involved more commonly.
Of the symptomatic cases, at least 97% exhibit neurological complaints, 2% venous disturbances, and 1% arterial manifestations.
Palpation of the supraclavicular fossa may disclose an associated
Congenital Anomalies and Normal Skeletal Variants I
291
fibrous band as a taut, firm structure that may reproduce neurological symptoms upon compression.
Hand muscle wasting, pain, and paresthesia are the most common expressions of nerve involvement. Swelling of the upper
limb may indicate obstruction of the subclavian vein, either
from mechanical deformity or venous thrombosis. Arterial compression may result in a Raynaud-like presentation, with hand
ischemia, coldness, pallor, cyanosis, claudication, and reduced
pulses. Dynamic vascular testing, such as elevating the arm
(Wright’s test), deep inspiration with neck hyperextension,
and contralateral neck rotation while palpating for obliteration
of peripheral pulses (Adson’s test) may help confirm thoracic
outlet compression.
Typically, the subclavian vessels and brachial plexus pass superior to a cervical rib. Pathologic abnormalities associated with
cervical ribs include poststenotic subclavian artery dilation (aneurysm) and kinking or thrombosis of either the subclavian artery or
vein. The anterior scalene muscle is often more fibrous and contracted and may contribute to compression syndromes. (7) The
brachial plexus may be divided by a cervical rib. (8)
Radiologic Features. The diagnosis is usually made on plain
film examination of the cervical spine or chest. The AP lower
cervical spine with tube tilt and the oblique studies are the most
useful views. An osseous rib-like structure closely adjoining but
not fused to the distal end of the C7 transverse process is typically
seen projecting anteriorly and inferiorly over a course of variable
distance. Articulation with the C7 vertebral body is seen in the
classic presentation; however, many patients do not display this.
To avoid mistaking a cervical rib for an atypical first thoracic rib,
it is useful to remember that the C7 transverse processes are typically either horizontal or inferiorly angulated. If the orientation is
equivocal, it may be necessary to count all thoracic ribs. A costotransverse joint must be visible to make the diagnosis. The length
of the cervical rib is quite variable, from a rudimentary stump to a
fully developed rib that may also articulate with the sternoclavicular junction. (Fig. 3-48) Fusion to the first rib is common, but it
may remain unattached. A pseudo-arthrosis within the cervical rib
is not uncommon and may be associated with pain and cause a
palpable mass in the supraclavicular fossa. (9)
Coronal oblique MRI sequences depict details of the thoracic
outlet to advantage. In addition to the details of the cervical rib
and the thoracic outlet, the cervical spine, exiting nerve roots,
and spinal cord can all be examined. Signs of compression
include deviation of roots, cords, or branches, vascular deviations and kinks, focal vessel dilatations, and collateral circulation. Compression may result from bony elements or fibrous
bands that sometimes originate from the distal ends of cervical
ribs. These abnormal connective tissue structures are not exclusive
to cervical ribs and can also be seen extending from atypically
elongated cervical transverse processes or in the absence of
any bony abnormality. (10) CT is slightly inferior to MRI, but
in the axial images it can show similar abnormalities. A duplex
ultrasound is useful for detecting flow variations, thrombus,
and static and dynamic obstruction. Angiography may help identify stenoses, thromboses, and occlusions and simultaneously
provide the opportunity for percutaneous thrombolysis, angioplasty, or stent deployment. (Fig. 3-49)
Elongation of the C7 Transverse Process. Also called false
cervical rib, droopy transverse process syndrome, apophysomegaly, and mega-apophysis, elongation of the C7 transverse
process is a congenital anomaly. The transverse processes curve
and taper distally, lack costotransverse and costovertebral joints,
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Figure 3-48 CERVICAL RIBS. A. AP Lower Cervical Spine.
Observe the complete cervical rib at C7 on the right side.
An attenuated cervical rib is present at the same level on the
left side. B. AP Lower Cervical Spine. Note the cervical rib
A
with an accessory articulation (arrow). A small cervical rib is
also noted on the opposite side. (Courtesy of Donald E.
Freuden, DC, DABCO, Denver, Colorado.)
B
C
Figure 3-49 CERVICAL RIB, SUBCLAVIAN ARTERY COMPRESSION. A. AP, Preinjection. Observe the cervical rib
(arrow). An arterial catheter has been advanced to lie proximal within the subclavian artery (arrowhead). B. Neutral
Shoulder Position, Postinjection. The subclavian, axillary,
brachial, and branch arteries are opacified. There is irregularity of the inferior margin of the subclavian artery as it
passes over the first rib (arrow) and slight dilatation of the
lumen just distal, a sign of long-standing stenosis (arrow-
head ). C. Abducted Shoulder Position, Postinjection. With
the arm abducted, dynamic compression of the subclavian
artery by the cervical rib is demonstrated (arrow). The
distal vessels are reconstituted by collateral anastomoses.
COMMENT: Arterial involvement is uncommon with cervical
ribs but may include stenosis or poststenotic dilatation,
which may become aneurysmal, possibly propagating ipsilateral upper limb embolism. (Courtesy of Arjith de Silva MBBS,
FRANZCR, Newcastle, New South Wales, Australia.)
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are usually < 2 cm, and do not fuse with the first rib. (5,11) (Fig.
3-50) Although symptoms associated with this frequent variation are uncommon, they can have co-existing fibrous bands
and may directly impinge into the scalene triangle and middle
scalene. (10,12)
Elongation of the C5 and C6 Transverse Processes. The anterior tubercle of the transverse process is the costal element
homologue. It may be elongated, especially at C5 and C6, and is
occasionally encountered on cervical spine radiographs. (13,14) It
is usually asymptomatic but may rarely be associated with brachial
plexus pain syndromes, although the pathoanatomy remains unclear. There is no association with vertebrobasilar insufficiency.
The bony prominence may be palpable in the anterolateral neck.
When concurrent involvement of C5 and C6 occurs, lateral and
oblique radiographs show approximation of bony outgrowths from
the adjoining transverse processes, up to 1 cm in length. (Fig 3-51)
Complete or incomplete bony union may occur, and there may be
a planar or curvilinear line of separation between the opposing
bony elements. (14–16) Hypoplasia of the involved vertebral segments and intervening intervertebral disc (IVD) space may also be
seen. Flexion– extension radiographs show reduced mobility at
C5–C6 and increased mobility at C4–C5. (16) Mimics of the
condition include osteophytes, fracture, and expansile neoplasm.
(14,16) Axial CT with reconstructions are extremely helpful for
making the definitive diagnosis. (14,16)
Non-Union of the T1 Transverse Process Apophysis. Developmental non-union of the secondary ossification center at
the tip of the transverse process is occasionally seen on frontal
cervicothoracic radiographs and should not be misconstrued
for acute fracture or previous trauma. The margins remain
smooth with corticated surfaces and an intervening lucent junction zone. (Fig. 3-52)
Droopy Shoulder Syndrome. A long gracile neck with low-set
shoulders may be associated with thoracic outlet syndrome and
fatigue syndromes of the shoulder girdle. Exacerbation of the
symptoms may occur if loads are carried on the shoulders. (17)
Women are more commonly affected. Radiographically, the thoracic spine may be visualized down to the T2 vertebra on a routine
lateral cervical projection (Fig. 3-53)
Medicolegal Implications
CERVICAL RIB
• Although the majority of cervical ribs remain asymptomatic, vigilant awareness of
serious complications, including thrombosis
and aneurysm, needs to be considered. (18,19)
• The size of the radiographically identified cervical rib
bears no relationship to the compressive effects on the
neurovascular structures in the thoracic outlet. Symptomatic cases often have fibrous bands as the causative element, which require MRI for accurate assessment. (10,18)
• Cervical ribs are one of many causes for neurovascular
compression syndromes of the upper limb, and other
causes need to be excluded, such as nerve root entrapment, cervical disc disease, clavicle fractures, anterior scalene muscle lesions, poor shoulder girdle muscular tone,
and apical lung pathologies (Pancoast’s tumor).
Figure 3-50 C7, ELONGATED TRANSVERSE PROCESSES.
A. AP Lower Cervical Spine. Observe the bilateral elongation
of the transverse processes of C7 in this 22-year-old (arrows).
Also note the open physeal lines in the medial aspects of the
clavicles (arrowheads). These growth centers appear around
the age of 17 years and close at approximately age 25. B. AP
Lower Cervical Spine. Note the bilateral elongation of the
C7 transverse processes. The transverse process of T1 is outlined as a reference point, and the elongated transverse
process of C7 is beyond its distal tip. C. AP Lower Cervical
Spine. The elongated transverse processes are evident even
in this 8-year-old. COMMENT: This finding may mimic a
cervical rib with potential for thoracic outlet syndrome.
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Figure 3-51 C5–C6, ELONGATED ANTERIOR TUBERCLE.
A. Neutral, Lateral Cervical Spine. Note that anterior to the
C5–C6 vertebral bodies, two bony processes are directed
toward each other with an intervening joint space (arrows).
B. Oblique, Posterior Cervical Spine. These changes are more
clearly demonstrated on this view, confirming that the bony
processes originate from the anterior transverse processes
(arrows). C. Flexion, Lateral Cervical Spine. Note the transverse process elongation and anomalous articulation (arrow)
in a different patient. Motion is present at the C5–C6 level,
with widening of the interspinous space. Note also the hypoplasia of the involved vertebral bodies, which is a common
associated finding. D. Oblique, Posterior Cervical Spine. The
anomalous articulation (arrow) is also demonstrated on this
view. (Panels A and B courtesy of Gary M. Guebert, DC,
DACBR, St. Louis, Missouri; panels C and D courtesy of William
E. Litterer, DC, DACBR, Fellow, ACCR, Elizabeth, New Jersey.
Reference from Applebaum Y, Gerald P, Bryk D: Elongation
of the anterior tubercle of a cervical vertebral transverse
process: An unusual variant. Skeletal Radiol 10:265, 1983.)
3
Figure 3-52 T1, NON-UNION OF THE SECONDARY GROWTH
CENTER OF THE TRANSVERSE PROCESSES. A. Unilateral
Form, AP Lower Cervical Spine. Observe the unilateral nonunion of the secondary growth center of the T1 transverse
process (arrow). B. Bilateral Form, AP Lower Cervical Spine.
Here, the non-union is present bilaterally (arrows).
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COMMENT: These non-unions must be differentiated from a
fracture by identifying smooth sclerotic margins. The T1
transverse processes are identified by their cephalad orientation, which assists in the accurate identification of
cervical ribs.
ANOMALIES OF THE THORACIC
AND LUMBAR SPINES
VERTEBRAL BODY ANOMALIES
Block Vertebra
T2
Figure 3-53 DROOPY SHOULDER SYNDROME. Lateral
Cervical Spine. The spinal segments are visible down to the
T2 vertebra, which is characteristic of droopy shoulder syndrome. The long, gracile neck with low-set shoulders allows
this visualization as well as a clear depiction of the lung
apex (arrow). COMMENT: This neck configuration, especially
in women, may be associated with thoracic outlet syndrome
and fatigue syndromes of the shoulder girdle; exacerbation
of the shoulder symptoms may be noted when carrying
heavy bags.
Synonyms. Congenital synostosis, intercorporeal fusion, failure
of segmentation.
Description. A congenital block vertebra is fusion of two or
more vertebrae secondary to embryonic failure of somite segmentation. It is an uncommon anomaly of the thoracolumbar spine.
Clinical Features. Block vertebrae can occur at any level; and
there is no regional predilection. Block vertebra accounts for at
least 20% of segmentation anomalies in the thoracolumbar spine.
(1) Most are found incidentally when radiographs are obtained
for back pain or trauma. (2) Localized scoliosis, kyphosis, or reduced mobility may be detected clinically, especially when the
block occurs at the thoracolumbar junction. (1,3) Pain near the
fused level may be associated with adjacent degenerative disc or
facet syndromes, muscle fatigue from postural disturbance, and
spondylolysis. Occasionally there may be simultaneous anomalies of the cervical spine (Klippel-Feil syndrome) (4), thoracic
spine (5), kidneys and genitalia. (3,6)
Radiologic Features. The cardinal plain film findings of a lumbar or thoracic block vertebra are small vertebral bodies; variable
degrees of bony fusion; small hypoplastic disc, which is often calcified; and associated anomalies of the posterior arch. (Fig. 3-54)
The number of segments involved ranges from 2 to > 11. (1)
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T11
Figure 3-55 LUMBAR BLOCK VERTEBRA. Lateral Lumbar
Spine. There is > 80% fusion across the hypoplastic disc and
indistinct endplates at the L4–L5 level. The characteristic
wasp-waist abnormality is lacking, which is often the case
when there is a broad zone of fusion across the disc.
(Courtesy of Gordon A. Kuether, DC, Blair, Nebraska.)
C
Figure 3-54 LUMBAR BLOCK VERTEBRA. A. Lateral Lumbar
Spine. Note the block vertebra at the T12–L1 vertebral bodies.
Observe the C-shaped deformity present at the anterior
surface of the blocked vertebra (wasp-waist appearance).
B. Specimen, Lumbar Radiograph. The classic features are
well demonstrated: small vertebral bodies and disc, fusion
across the disc confirmed with bony trabeculae bridging the
space, and fusion of the posterior elements. Note the large
spinous process (megaspinous). C. Schematic Diagram,
Anterior Concavity. The prominent anterior-shaped concavity has been highlighted (wasp-waist appearance), signifying the congenital nature of the vertebral fusion. (Panel A
reprinted by permission from Yochum TR, Hartley B,
Thomas DP, et al.: A radiographic anthology of vertebral
names. J Manip Physiol Ther 8:87, 1985.)
Two radiographic forms occur, depending on the extent of
interbody fusion. If > 80% of the discovertebral articulation is
fused, the vertebral bodies are less hypoplastic and often lack the
classic finding of the anterior wasp-waist concavity. (Fig 3-55) If
the process involves < 80% of the discovertebral joint, the term
unsegmented bar (1) is used to describe the bony union across
the involved portion of the disc space. The bar is identified at the
site of union by the bony trabeculae contiguous across the disc,
focal absence of the endplate, and lack of disc space. These occur
most commonly anteriorly, occasionally anterolaterally, and rarely
as an isolated posterior union.
Anterior unsegmented bars produce marked inhibition of anterior vertebral body growth, leading to prominent anterior vertebral body concavity (wasp-waist deformity) and an increasing
kyphotic angle. Anterolateral unsegmented bars cause anterior
and lateral vertebral body hypoplasia, producing kyphoscoliosis.
The degree of angular deformity (kyphotic angle) and its progression are assessed by a modified Cobb’s angle measurement
on the lateral projection, using the superior endplate of the upper
fused vertebral body and the inferior endplate of the lower most
contributing fused segment and drawing intersecting perpendicular lines. (1,7)
Associated findings are numerous. The posterior elements of
the involved vertebrae may show fusion of the spinous processes
(megaspinous), laminae, facet joints, transverse processes, and
ribs. (Fig 3-56) Absence or hypoplasia of the pedicle, laminae,
or spinous process (spina bifida) can occur. Other segmentation
anomalies, including hemivertebrae and butterfly vertebrae, may
occur in close proximity. Careful scrutiny in children for widening of the interpediculate space and a midline intracanal bony
spicule may reveal diastematomyelia.
Acquired complications do occur with some regularity. Spondylolysis and spondylolisthesis can occur at adjacent segments,
especially at L5 in association with a block vertebra of L4–L5.
Disc degeneration and herniation, facet syndromes, and osteoarthritis are more common at adjacent mobile segments (transitional syndrome). (Fig. 3-57) Low lumbar blocks often reduce
the lordosis while upper lumbar and thoracic fusions may cause
increased kyphosis and even gibbus. (3) Scoliosis in the develop-
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Figure 3-56 LUMBAR BLOCK VERTEBRA, MEGASPINOUS.
A. AP Lumbar Spine. Observe the single, large, common
spinous process (megaspinous) at the L4–L5 level. B. Lateral
Lumbar Spine. There is a remnant disc present between the
L4 and the L5 block vertebra. Underdevelopment of the
anterior surface of the vertebral bodies of L4–L5 has created
the wasp-waist appearance. Note the single common spinous
process for L4–L5 (arrows). A radiolucent band (arrowheads)
represents a fat-fold artifact at the patient’s waist. (Courtesy
of Douglas B. Hart, DC, Carina, Queensland, Australia.)
Figure 3-57 MULTIPLE LUMBAR BLOCK VERTEBRAE. A. AP
Lumbar Spine. B. Lateral Lumbar Spine. Multiple block vertebrae are present at L1–L2 and L3–L4. At the interposed unfused
levels, advanced discopathic changes are evident with loss of
disc height, endplate sclerosis, and prominent osteophytes.
(Courtesy of James F. Winterstein, DC, DACBR, Chicago, Illinois.)
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ing spine, especially if sharply angled and over only a few segments, may be rapidly progressive and surgery may be required.
The main differential considerations for interbody fusion are
previous infection, trauma, and surgery. CT is useful to define
complicated anatomy, degenerative stenosis of adjacent levels, and
diastematomyelia. MRI is especially suited to these anomalies,
allowing visualization of osseous and soft tissue abnormalities
over long sections of spine segments.
Butterfly Vertebra
Synonyms. Anterior spina bifida, sagittal cleft vertebra, anterior
cleavage vertebra.
Description. The term butterfly vertebra was first coined by
van Rokitansky in 1844 based on the macroscopic appearance.
The sagittal cleft (the insect body) separates the vertebral body
into two symmetrical halves (the insect wings). (8) Most contemporary descriptions based on x-ray findings ascribe the butterfly
“body” to the superimposed spinous process. There is also associated co-existing deficiency of ossification of the anterior and
central portions of the vertebral body. (6) There is no consensus on
pathogenesis; suggested mechanisms include persistence of the
perichordal sheath, failure of the notochord to regress, and embryologic failure of fusion of lateral ossification centers. (9,10)
Clinical Features. There is no gender dominance and no definite familial clustering. This anomaly most commonly occurs in
the lumbar and thoracic spines and is rare in the cervical spine.
(9,11–14) The single most common site is at the thoracolumbar
junction, and there is often an associated progressive kyphosis.
(6) Asymmetry in the size of the vertebral body halves produces
kyphoscoliosis in approximately one third of cases. The average
angular kyphosis by skeletal maturity is approximately 45°, and
the butterfly vertebra is typically situated at the apex. Concurrent
spinal segmentation defects are common, including hemivertebrae
and block vertebrae, diastematomyelia, and Klippel-Feil and
VATER syndromes. (9,11–15) Co-existing visceral anomalies are
recorded, such as renal and cardiac anomalies and congenital cysts,
including bronchogenic, neurenteric, and intestinal types. (9,15) In
neonates, a chest radiograph for a respiratory infection may lead
to its discovery.
Figure 3-58 L3, BUTTERFLY VERTEBRA. A and B. AP Lumbar
Spine. The wedged-shaped lateral halves are clearly visible,
with smooth convex opposing margins at the site of the
Most patients are asymptomatic, and the condition is usually
found in adults serendipitously, often on radiographs obtained
after trauma. As the child grows through to 10 years of age the
onset of an increasing scoliosis, kyphosis, and even gibbus may
result in radiographic identification.
Radiologic Features. Plain film frontal radiographs show a
characteristic triad of two lateral wedged shaped halves, a midline hour glass–shaped sagittal cleft, and widened interpediculate
distance. (9,14) (Fig. 3-58) The pedicles may be larger than normal. (Fig. 3-59) Superimposition of the spinous process as an
ovoid structure over the cleft simulates the body of the butterfly,
with each wedged lateral body half representing a wing. (16,17)
Vertebral bodies immediately above and below are also deformed;
their endplates invaginate toward the sagittal cleft. Accompanying
scoliosis or kyphosis is common, and the anomaly is usually at
the apex of the curves. Degenerative changes in the adjacent
disc will often be visible. (Fig. 3-59) Other segmentation defects
may be visible in adjacent vertebrae, including hemivertebrae,
blocked vertebrae, and other butterfly deformities (scrambled
spine). (16,17)
CT may be used to confirm the diagnosis and demonstrate
the sagittal cleft demarcated by smooth, sclerotic margins. Disc
material is usually visible in the cleft. Rarely, there may be an
additional coronal cleft, which produces a four quadrant vertebral body. (9) On MRI disc material within the cleft is contiguous with and isointense to the adjacent discs (18). MRI may also
be used to detect spinal cord defects, including syrinx, disc disease, and spinal stenosis.
Hemivertebrae
Synonyms. Half vertebrae, demivertebrae, hemimetameric
segmentation anomaly, congenital wedged vertebra.
Description. Failure of ossification of part of a vertebral body
produces a hemivertebra. Three types are recognized on the
basis of location: lateral, dorsal, and ventral. Lateral hemivertebrae are the most common form. The thoracic spine has the highest incidence of hemivertebrae, followed by the lumbar and cervical spines. There is no hereditary risk for offspring to develop
hemivertebrae. (19)
sagittal cleft. Ancillary findings are the lateral spread of the
vertebral body and invaginating adjacent endplates into the
cleft.
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Lateral Hemivertebra. Various configurations of lateral hemivertebrae are described based on the radiographic appearance, best
seen on the AP view.
Figure 3-59 L4, BUTTERFLY VERTEBRA. AP Lumbar Spine.
Observe the wedged-shaped lateral halves of the L4 vertebral
body and converging endplates toward the midline. Note the
widened interpediculate distance and that the entire vertebral body is wider than the adjacent segments. The adjacent
endplates of L3 and L5 invaginate into the midline cleft and
are parallel to the butterfly segment. (Reprinted with permission from Yochum TR, Hartley B, Thomas DP, et al.: A radiographic anthology of vertebral names. J Manip Physiol Ther
8:87, 1985. Courtesy of Robert J. Hooke, BAppSc (Chiro),
Cootamundra, New South Wales, Australia.)
Clinical Features. The clinical implications vary according to
type but usually relate to altered spinal curvatures, secondary
degenerative changes, and differential diagnosis from other causes
of vertebral body collapse (e.g., trauma, malignancy, and causes
of osteoporosis). A common clinical concern related to lateral
hemivertebrae is the formation of a scoliosis, which is often progressive. Treatment in progressive scoliosis includes fusion and
excision. (20) Different forms of lateral hemivertebra occur and
frequently present widely divergent prognoses. (5) Hemivertebrae
may precipitate the sudden onset of severe neurological deficits;
may co-exist with unrecognized visceral anomalies; and may occur
in tandem with other vertebral anomalies such as block vertebrae,
diastematomyelia, Klippel-Feil syndrome, meningocele, multiple enchondromatosis (Ollier’s disease), and spondylothoracic
dysplasia. (14,22) Known visceral associations include VATER
syndrome and cardiovascular, spinal cord, gastrointestinal, and
genitourinary anomalies. (20)
Radiologic Features. Plain films outline the bony anomaly, scoliosis, and kyphosis and provide a baseline for on-going assessment
of curve progression. MRI is often performed soon after discovery
to evaluate the spinal cord. Progression of deformity is more likely
when the hemivertebra is not fused to an adjacent segment (nonsegmented) (23) and the adjacent vertebral bodies maintain their
normal shape (non-incarcerated). (24) Multiple hemivertebrae in
conjunction with other segmentation anomalies, including block
and butterfly vertebrae, produces long spinal distortions referred
to as a scrambled spine. (16,17)
• Incarcerated hemivertebra. Hemivertebra are designated
incarcerated when the adjoining endplates of adjacent
segments are configured to accommodate the shape of
the hemivertebra. Incarcerated hemivertebrae are triangular in shape and have a disc space. Scoliotic deformity is
limited with little tendency to produce progressive deformity. This is the most common form of hemivertebra.
(Fig. 3-60)
• Non-incarcerated or free hemivertebra; wedge vertebra.
The hemivertebra is trapezoidal in shape and reaches the
contralateral side of the spine. The endplates of the adjacent vertebral bodies are of normal shape, and there is a
greater tendency for a progressive scoliotic deformity to
develop than with the non-incarcerated type. (24)
• Multiple non-incarcerated hemivertebrae. Contiguous
hemivertebrae on the same side of a curve are at greater
risk for curve progression. When two hemivertebrae are
present on opposite sides of the curve and there are several
normal segments interposed, the curve is less and usually
stable (hemimetameric shift).
• Non-segmented hemivertebrae. The half segment is fused
to an adjacent segment with no separating intervertebral
disc. (Fig. 3-61) Scoliosis is variable and, if present, is
Figure 3-60 INCARCERATED LATERAL HEMIVERTEBRAE.
AP Lower Cervical Spine. Two lateral hemivertebrae are
present, which are triangular in shape and separated from
the adjacent segments by an intervertebral disc (arrows ).
The endplates of the adjacent vertebral bodies are deformed to accommodate the hemivertebrae (incarcerated).
The two hemivertebrae are present on opposite sides of the
curve, and the intervening segments are fused, which has reduced the degree of scoliosis (hemimetameric shift) (arrowheads). COMMENT: This is the most common form of hemivertebra. The spine remains relatively straight, with little
tendency to produce progressive deformity. (Courtesy of Joe
Y. Ghabriel, MBBS, FRACS (Orthoped), Newcastle, New South
Wales, Australia.)
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Figure 3-61 L1, NON-SEGMENTED LATERAL HEMIVERTEBRA. AP Thoracolumbar Spine. A half segment is fused to
the L1 vertebral body, producing two pedicles on one side.
Note that there is no separating intervertebral disc. A structural scoliosis has occurred secondary to the trapezoidalshaped fused segment. (Courtesy of Russell Banks, B.App.Sc.
(Chiro), Melbourne, Australia.)
Figure 3-62 L2, NON-SEGMENTED LATERAL HEMIVERTEBRA.
AP Lumbar Spine. Observe the fused hemivertebra at L2,
with no separating intervertebral disc. There are only four
lumbar-type vertebrae. The wedging of the hemivertebra
has created a significant structural scoliosis and is being
complicated by secondary advanced degenerative disc disease with spondylophyte formation and substantial disc
space narrowing, most dramatic on the concave margins
of the curvature. (Courtesy of Donald E. Freuden, DC,
DABCO, Denver, Colorado.)
usually not progressive during skeletal growth; but secondary degenerative disc and facet disease in later adult
life may precipitate a collapsing and progressive degenerative scoliosis. (Fig. 3-62)
Dorsal Hemivertebra. Lack of formation of the anterior portion
of the vertebral body results in a dorsal hemivertebra. (26) These
most commonly are seen in the lower thoracic spine and can occur
at a single level or at two adjacent segments. (6) The characteristic deformity is an acute kyphotic gibbus, which can be rapidly
progressive at > 10° increase per year in those under the age of
10 years. (6).
The hemivertebra typically lies at the apex of the kyphosis.
The posterior vertebral body is wedge shaped, the anterior apex
often does not reach the anterior vertebral body margins of the
adjacent vertebrae, and the posterior arch may be deficient and
possibly subluxed or even dislocated. (Fig. 3-63) Acute onset of
spastic paraparesis is most common in this type and usually occurs
by 20 years of age. MRI provides the best evaluation for patients
with signs of cord compression. (6) Secondary degenerative disc
disease may lead to increasing kyphosis. Dorsal hemivertebrae
may be seen with achondroplasia, cretinism, chondrodystrophy,
and Morquio’s and Hurler’s diseases. (22)
Ventral Hemivertebra. Absence of the posterior half of the vertebral body with the formation of only the anterior half constitutes the least common form of hemivertebra. (Fig. 3-64) The
most commonly affected areas of the spine are the thoracolumbar vertebrae. The adjacent vertebral bodies will show
Figure 3-63 DORSAL HEMIVERTEBRA. Lateral Mid-Dorsal
Thoracic Spine. Observe the triangular posteriorly positioned
vertebral body (arrow) remnant separated by a disc space.
Note that a slight gibbus is present, with the apex corresponding to the site of dorsal hemivertebra. Secondary degenerative disc disease is present at this level, with anterior
osteophytes and loss of disc height.
3
Figure 3-64 L4, VENTRAL HEMIVERTEBRA. Lateral
L5–S1 Spine. A wedge-shaped anterior hemivertebra is
present at the L4 lumbar level. Note that the segment has
smooth endplates, which are symmetrically parallel with
the adjacent vertebrae, and a disc space is present.
(Courtesy of Frank and Daniel Grayson, DC, Rochester,
New York.)
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301
Figure 3-65 CORONAL CLEFT VERTEBRA. Lateral Thoracolumbar Spine. Observe the coronal cleft through the L3 vertebral body in this normal newborn (arrow). There is coexisting calcification within the nucleus (arrowhead), which
is an uncommon finding and of no significance. COMMENT:
Coronal cleft vertebra can be observed in up to 2–5% of
newborns, with no clinical significance. (Courtesy of Anne E.
Baxter MB.MCh., FRANZCP (Pediatr), Newcastle, New South
Wales, Australia.)
Schmorl’s Nodes
deformed endplates, reflecting the absence of the posterior half
of the involved segment, and may even fuse. In the lumbar
spine the lordosis may show angular accentuation with the ventral hemivertebra at the apex. In the thoracic spine the kyphosis
may be lost.
Coronal Cleft Vertebra
Synonyms. Vertebral cleavage in the frontal plane.
Description. Delayed union of the anterior and posterior halves
of the vertebral body creates a vertical cleft in the coronal plane.
(Fig. 3-65) It is a normal finding in all fetuses but regresses after
the 16th week.
Clinical Features. Coronal cleft vertebra has been reported in
up to 2–5% of newborns, rarely persisting into adulthood. (25)
There is a higher incidence in premature births and chondrodysplasia punctata. It is most common in males and in the lumbar spine. (25,26)
Radiologic Features. On the lateral radiograph the cleft
occurs at the junction of the anterior third with the posterior
two thirds of the vertebral body. Usually the cleft margins are
indistinct but can be smooth. The posterior vertebral body
is smaller than the anterior segment in children, a finding that
reverses in adulthood. With skeletal growth the coronal cleft
is usually obliterated by the end of the 1st year of life without
sequelae.
Synonyms. Cartilaginous nodes, intravertebral disc herniation,
intraosseous nodes, intraspongy nuclear herniations.
Description. Herniation of disc material into the vertebral body
was first described independently in 1927 by Schmorl and Putchar.
(27,28) (Fig. 3-66) Schmorl’s nodes have been recorded in 2–76%
of patients, depending on the method of assessment and age of the
subjects. They have been documented in 7–38% of cadavers
(9,29–32), in 15% of plain radiographs, and in up to 38% of MRI
studies. (33)
Clinical Features. The age of initial occurrence is often indeterminate but is most likely during adolescence. Later onset is usually
associated with significant trauma or bone pathology. Schmorl’s
nodes are not found in the 1st decade of life, but may occur in up
Figure 3-66 DEVELOPMENT OF SCHMORL’S NODES.
A. Normal Disc. Observe the normal location of the nucleus
pulposus relative to the cartilaginous endplate. B. Schmorl’s
Node. The nucleus pulposus has breached the cartilaginous
endplate and occupies an intraosseous location.
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to 20% of individuals during the 2nd decade. (34) Males are affected slightly more often. The most common location is the thoracolumbar junction (T8–L2), followed by the midthoracic, lumbar,
and cervical spines. (29,30,35,36) The clinical significance of
Schmorl’s nodes is controversial. Most appear to be asymptomatic
(37,38), although some reports show an increase in back pain in the
presence of these nodes. (36,39–42) Acute intrabody disc herniations in young patients are occasionally painful.
The pathogenesis remains controversial, although the main theory relates to a weakened cartilaginous endplate and subchondral bone at the site of the embryologic notochord regression
or the involuted discal nutrient vessels. (27,34,43) Bone softening diseases—including Paget’s disease, osteomalacia, hyperparathyroidism, infection, and neoplasm (29)—may precipitate
these nodes, particularly those of later onset (9,35). Acute trauma,
chronic low-level trauma as in athletes, and Scheuermann’s disease are also known precipitants of Schmorl’s nodes. (42,44–47)
Osteoporosis may also be a factor in adult node formation. (31,48)
The nodes occur more commonly in straight endplates rather
than curved ones, such as in the presence of nuclear impressions.
(29) Marked sclerosis within the vertebral body in a hemispherical
distribution with a broad, convex contour is occasionally encountered adjacent to a Schmorl’s node (hemispherical spondylosclerosis). The most common level of involvement for this pattern
is L4. (49)
Numerous types and variations of Schmorl’s nodes have
been described.
• Central Schmorl’s nodes. These typically occur at multiple, contiguous levels and are vertically aligned in the
same slightly posterior location centrally within the vertebral bodies. (Fig. 3-67) These occur at the site of the previous notochord and are the most common form. The node
is usually < 6 mm. (9,29) The vertebral body size and gen-
Figure 3-67 SCHMORL’S NODE. A. Lateral Lumbar Spine.
The short, sharply defined defects involving the vertebral
endplates on multiple lumbar levels represent central
Schmorl’s nodes. These occur at multiple, contiguous levels
and are vertically aligned in the same slightly posterior
eral morphology are typically normal, with no sign of
developmental growth anomaly
• Peripheral Schmorl’s nodes. Often found at only a single
level, these tend to be peripherally located in the anterior
portion of the vertebral body and are more common in the
superior endplate. Athletes, manual workers, and patients
with a history of significant trauma are more commonly affected. (Fig. 3-68) These most likely occur through residual
zones of decreased resistance where vascular channels have
regressed. This type may isolate a portion of the peripheral
(ring) endplate apophysis, resulting in a persistent separate
ossicle adjacent to the corner of the vertebral body, known
as a limbus bone (see below). The vertebral body may also
be mildly deformed to a wedged or elongated configuration.
• Anterior limbus bone. Herniation of nuclear material
through the cartilaginous junction zone of the ring apophysis sometime during childhood through to skeletal maturity
(late teens) may isolate a variable portion (1–5 mm) of this
ossification center from the vertebral body margin. (Fig.
3-69) Up to 5% of cadavers have an anterior limbus bone.
(9,30) This anomaly is most common in the midlumbar
spine (L2–L4) but can occur at any vertebral level, including the cervical spine. (51) It is generally an asymptomatic
lesion of the discovertebral junction. Synonyms include
limbus vertebra, corner vertebra, and ununited ring
apophysis, although the limbus bone is typically displaced
farther from the margin of the vertebral body than an
apophysis that has simply failed to completely ossify.
• Posterior limbus bone. Herniation into the posterior vertebral body may displace a fragment of the posterior endplate. This has been variously termed posterior marginal
intraosseous node, paradiscal defect, dislocated ring epiphysis, discovertebral rim lesion, and apophyseal ring
fracture. (52,53) Significant clinical findings may result if
location centrally. B. CT, L5 Lumbar Vertebra. In a different
patient the central Schmorl’s node is surrounded by a characteristic sclerotic halo (arrow). Co-existing bilateral pars defects are present (arrowheads).
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L2
A
B
Figure 3-68 SCHMORL’S NODE PHENOMENON. A. Lateral
Lumbar Spine. Note the peripheral Schmorl’s node present on
the anterosuperior corner of the L3 vertebra with associated
disc space narrowing at the L2–L3 level. Observe the increase
in the AP diameter of the L3 vertebral body. This constellation
of changes represents the Schmorl’s node phenomenon.
A
B
Figure 3-69 LIMBUS BONE. A. Lateral Lumbar Spine. Observe
the smoothly corticated triangular fragment at the anterosuperior corner of the L3 vertebral body (arrow). B. Lateral
Lumbar Spine. The separated and ununited ring epiphysis can
be seen (arrow), which lies within a distinct peripherally
B. Specimen Radiograph, Lateral Lumbar Spine. A peripheral
type of node is displayed, with a sclerotic margin and calcification (arrows). Note the associated increased sagittal length
of the involved vertebral body. (Panel B courtesy of Donald
Resnick, MD, San Diego, California.)
C
placed anterior Schmorl’s node. The adjacent disc space is narrowed secondary to the node. C. Pathophysiology. During
spinal growth, before skeletal maturity, there is herniation of
disc material beneath the ring epiphysis (arrow), which
inhibits its osseous fusion to the vertebral body.
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the fragment displaces sufficiently to create nerve root or
spinal cord compression (54–56), although these lesions
may also be symptomatic and discovered incidentally.
They most commonly occur in adolescents and young
adults, affecting males in a ratio of at least 4:1. The most
common site is the posterior inferior aspect of L4.
Calcified Schmorl’s nodes. Calcification within the endplate pit is occasionally seen, especially on CT. This is
degenerative hydroxyapatite crystal deposition and is not
linked to clinical pain.
Pneumatocysts. Occasionally the intravertebral herniation
pit may wall off and create an enclosed cavity or remain
in communication with the disc and acquire nitrogen gas
by diffusion from the adjacent marrow. (57) These may
extend deeply into the vertebral body but usually at least
one margin will abut closely to the vertebral endplate.
Tunneling Schmorl’s node. Occasionally a herniation is
seen on CT or MRI to extend from a superior endplate
through the vertebral body into the inferior endplate, leaving a bony tunnel. (58) These may contain disc material,
fibrous tissue, or sometimes calcification.
Pathologic Schmorl’s nodes. Adjacent bone disease beneath
the endplate may allow for an intrabody disc herniation.
When associated with metastasis or other malignancy these
have been referred to as malignant Schmorl’s nodes. (35)
Giant Schmorl’s node. A large anterior endplate defect that
occupies a larger than expected area, often > 6 mm, has been
referred to as a giant node. (59,60) These are commonly
painful. Lumbar plexopathy has been reported; however, the
majority are devoid of neurological implications (60) owing
to the typically anterior location. Vertebral wedging with
sagittal elongation, disc height loss, and a gibbus deformity
may result (41). The increase in the AP diameter of the
vertebral body with a giant Schmorl’s node has been
referred to as the Schmorl’s node phenomenon. (41)
Acute traumatic Schmorl’s node. Flexion trauma can produce acute protrusion of the nucleus through the endplate,
a finding seen in 15% of fatal motor traffic accident
victims. (42,47)
Nuclear trail. In only the thoracic spine CT may sometimes reveal a linear channel instead of the characteristic
endplate pit. The trail extends centrally and then posteriorly through the vertebral body. In up to 50% of these
cases a posterior thoracic disc herniation is present, and
the channel appears to correlate with the migration path of
the displaced disc material. (61).
Radiologic Features. Conventional radiography depicts fewer
nodes than CT, MRI, or cadaver specimen inspections. (29) Imaging predictors for symptomatic nodes include acute loss of disc
height with a flattened endplate at the thoracolumbar junction
(46), provocation of pain on discography (42), increased uptake
(hot spot) on bone scan, and marrow changes and peripheral
gadolinium enhancement on MRI. (33)
Acute Schmorl’s nodes may be radiologically occult until peripheral reactive sclerosis occurs, which may take months. (59)
The most sensitive examinations for discovery of these occult
injuries are the radionuclide bone scan (shows increased radioisotope uptake) and MRI (shows high signal on fat-suppressed T2weighted sequences) (33,40,42,47,59). The only reliable plain film
findings related to painful Schmorl’s nodes are in an adolescent or
young adult patient, including a single-level decreased disc height,
slight flexion of the upper segment, and mild flattening of the anterior portion of the involved endplate (36,40–42).
The plain film hallmarks of a typical node are the presence of a
short based endplate depression, ranging in size from 1 to 10 mm,
surrounded by a thin sclerotic rim. (Fig. 3-67) Within the pit
may be a focal gaseous collection (vacuum phenomenon) or calcification. The border zone sclerosis may be more extensive,
at times involving up to 50% of the vertebral body and demonstrating a characteristic convex external contour (hemispherical
spondylosclerosis). (49) The contiguous disc space may be narrowed, with degenerative features. The relationship to degenerative disc changes is not consistent, and central types usually have
a normal disc height and MRI signal. (29) In the presence of a
peripherally sited node the vertebral body is often elongated as a
manifestation of altered growth and is a marker of preadulthood
occurrence (Schmorl’s node phenomenon). (Figs. 3-68 and 3-70)
These nodes also occur in tandem with limbus bones. These
separate ossicles develop from displaced fragments of the ring
apophysis and are typically triangular in shape with sclerotic margins. There is a reciprocating defect of the involved vertebral body
and reactive sclerosis along the adjoining margin. A vacuum phenomenon at this site may occur. (Fig. 3-71) Giant Schmorl’s nodes
are characteristically located at the AP vertebral endplate and
are associated with reduced adjacent disc space and increased AP
vertebral body diameter (Schmorl’s node phenomenon). (40,41)
(Figs. 3-68 and 3-70–3-72)
Figure 3-70 GIANT SCHMORL’S NODE. Lateral Thoracolumbar
Spine. Note the large, anteriorly placed, giant Schmorl’s node
present on the superior endplate of L1. Significant disc space
narrowing is present at the T12–L1 level, associated with the
node formation. The increased sagittal dimension of the involved vertebral body is readily apparent and greatly aids in
excluding infection as a cause for this appearance. Smaller
Schmorl’s node formations are present at the anteroinferior
corner of T11 and at the vertebral endplates of L2 and L3.
COMMENT: Multiple Schmorl’s nodes at contiguous levels are
commonly misdiagnosed as representing Scheuermann’s disease because all criteria—including more than three contiguous segments, irregular endplates, loss of disc height, and
more than 5º of vertebral body wedging—need to be present
before the diagnosis of Scheuermann’s is made.
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Figure 3-71 SCHMORL’S NODES. A. Lateral Thoracic Spine.
Observe the multiple Schmorl’s nodes in the thoracic spine
(arrow) in a champion swimmer present. These vertebrae
show the Schmorl’s node phenomenon, with increased sagittal dimensions of these same vertebral bodies. B. Lateral
Lumbar Spine. In the same patient additional peripheral
nodes are present with associated limbus bones at the
anterosuperior vertebral body margins. (Courtesy of Jeanne
M. DesRoche, DC, Englewood, Colorado.)
Figure 3-72 GIANT SCHMORL’S NODE. A. AP Lumbar Spine.
The superior cortical endplate of the L4 vertebral body
shows a broad, deep indentation > 6 mm (arrow). There is
coincidental facet asymmetry at L4–L5, with a sagittal facet
on the left side of the figure. B. Lateral Lumbar Spine. At
the anterosuperior margin of L4 the broad-based indentation from the giant Schmorl’s node is partially filled with
reciprocal adjacent overgrowth from the L3 endplate.
(Courtesy of Carr Chiropractic Clinic, Huron, South Dakota.)
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Synonyms. Persistent notochord, notochord remnant, cupid’s
bow endplate, double-hump endplate, balloon disc.
Description. Nuclear impressions are a common variation in vertebral endplate contour characterized by bilateral, parasagittal endplate depressions separated by a centrally placed osseous mound.
Histopathology demonstrates lack of hyaline cartilage over the
endplate depression and a thickened bony plate. (27,63) The
annulus inserts in these thickened plates directly, with no intervening cartilage zone (63). The pathogenesis of the deformity
has remained in dispute. The absence of growth cartilage in the
floors of the parasagittal concavities may result in growth retar-
dation at these sites and may produce these depressions. (63) Alternatively, it is hypothesized that as the notochord regresses embryologically, it simply leaves a residual mound in the posterior third of
the vertebral endplate. The volume of the disc is greater than in
straight endplates.
Clinical Features. Nuclear impression has been reported in up to
50% of cadavers and > 60% of thoracolumbar radiographs. (63,64)
They may be slightly more frequent in males. (65) No definite familial occurrence has been demonstrated. (66) With progressive
spinal ossification they become recognizable by the 3rd decade of
life. They most commonly occur in the lumbar spine and become
increasingly less common in the cephalad direction. The most common level is the L4 segment followed by L5 and L3. (63) Rarely,
all spinal regions will show simultaneous involvement. Nuclear
impressions are both more prominent and more common in the
inferior endplates. (63,64).
There has been no correlation with pain, disc degeneration,
herniation, spina bifida, transitional segment, spondylolysis, facet
tropism, or instability. (65) There is no relationship with osteoporosis, body height, or weight. (63) A loose connection with a
predisposition to the development of Scheuermann’s disease has
been made but remains unsubstantiated (27). In chronic scoliosis
the depth of the concavity is greatest on the convex side of the
curve, possibly from long-standing eccentric placement of the
nucleus pulposus. (66)
Radiologic Features. Plain films are sufficient for diagnosis.
On the frontal projection smooth parasagittal endplate concavities with thickened cortices are present. These are separated in
the midline by a smooth convex hump. This configuration is referred to as the Cupid’s bow sign. (64) Other terms are doublehump, seagull, and bird’s wings sign. The superimposition of the
spinous process over the bow is often referred to as the arrow.
(Fig. 3-73 and Fig. 3-74, A–E )
Figure 3-73 LUMBAR NUCLEAR IMPRESSION. A. Lateral
Upper Lumbar Spine. Observe that the lowest two vertebrae
show the characteristic broad-based sweep of the posterior
two thirds of the endplates as a result of nuclear impressions.
The upper vertebral endplates are planar and not involved.
B. Lateral Lumbosacral Spine. The sweeping concavity is
clearly visible at the inferior endplate of the L5 vertebra.
C. Schematic Diagram, Nuclear Impression. The anomaly
affects the posterior two thirds of the vertebral body with a
broad-based sweeping concavity.
On CT the endplate defect shows a characteristic halo sign of
reactive sclerosis surrounding the central radiolucent pit, which
may contain nitrogen gas. (Fig. 3-67B) Small nodes are difficult
to detect on plain radiographs and may be visible only on CT.
(36) CT is also useful in defining limbus bones and differentiating them from acute fracture. MRI will reveal interposed disc
material between the limbus bone and the vertebral body. (62)
Defects and irregularity of the endplates may present a diagnostic dilemma, with the main exclusion being infection. Key
signs seen in Schmorl’s nodes but not in infection include preservation of the endplate cortex, vacuum phenomena, and altered
vertebral body length. (Fig. 3-70) MRI findings also show decreased disc signal as a useful differential finding against infection.
Marrow edema associated with acute Schmorl’s node endplate
infraction may show confusing MRI signal changes on nonenhanced studies and can also result in marrow enhancement on
gadolinium contrast MRI studies (59).
Nuclear Impression
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Figure 3-74 CUPID’S BOW CONTOUR, LUMBAR SPINE.
A and B. AP Lumbar Spine. The paired parasagittal concavities affecting the inferior endplate of the L4 vertebra
(arrows) in two different patients represent depressions in
the endplate with a relatively elevated centrally placed
mound. C. Lateral Lumbar Spine. In the lateral view of the
same patient as panel B the posterior sweeping endplate
concavities are visible. D. Tomogram, AP L5 Vertebra. With
the overlying posterior arches removed from the primary
imaging plane the Cupid’s bow contour affecting the inferior endplate of the L5 vertebra is clearly depicted (arrows).
E. Cupid’s Bow Contour. The “bow” is the endplate defor-
mities and the arrow is the overlying spinous process. F. CT,
Owl’s Eyes Appearance. The CT axial image through the
endplate shows the Cupid’s bow contour as paired, wellcorticated, round areas of intervertebral disc density within
the vertebral bodies (arrows). COMMENT: The Cupid’s bow
contour and owl’s eyes appearance are characteristic of
nuclear impression vertebral endplate deformities. They
commonly affect the L4 and L5 vertebrae. The bilateral
smooth indentations help differentiate this from a
vertebral endplate fracture and osteoporotic deformities
(fish vertebrae).
On the lateral view the concavities are superimposed as a
broad sweeping curvature apexing toward the posterior third of
the vertebral body. Careful scrutiny of the concavity reveals the
convex shape of the midline hump. The visual effect of the end
plate sweep deformity is that of increased disc space. On axial
CT images the floor of the depressions are often dense owing to
the thicker cortical bone, whereas at the endplate these are radiolucent and have been referred to as the owl’s eyes appearance.
(37) (Fig. 3-74F )
Because nuclear impressions are extremely common, differentiation from other pathologic processes is important.
Schmorl’s nodes are more focal, more short based, and often
more anterior. Endplate fracture typically shows acute angular
deformity and lacks the Cupid’s bow. Similarly the so-called
fish vertebrae of osteoporosis show a generalized endplate
concavity from the vertebral margins and lack the Cupid’s bow.
(37, 64) In sickle cell anemia, infarction of the central nutrient
artery produces a central depression with more abrupt margins
(step deformity) that is quite different from the smoothly curved
cupid’s bow.
ANOMALIES OF THE POSTERIOR ARCH
There are numerous anomalies of the posterior vertebral arch in
the thoracolumbar spine. These may involve the pedicle, transverse
process, articular process, lamina, and spinous process. Examples
of isolated involvement are agenesis (total absence), hypoplasia
(underdevelopment), and dysplasia (abnormal development). More
widespread multisegmental anomalies are often manifestations of
a multisystem process. The term spinal dysraphism embraces the
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numerous spinal anomalies characterized by abnormal neural tube
closure, including spina bifida occulta, spina bifida vera, diastematomyelia, and tethered cord.
Agenesis of a Lumbar Pedicle
Synonyms. Congenital absence of the pedicle, absent pedicle
syndrome, pedicle aplasia or hypoplasia, deficient lumbar pedicle.
Description. Absence of a lumbar pedicle is a failure of ossification within the neural arch. Total agenesis is relatively rare, and
hypoplasia (underdevelopment) is found in the majority of cases
on careful scrutiny. (1)
Clinical Features. The first reported pedicle hypoplasia case
was by Bardsley in 1971 (2) and agenesis by Norman in 1973. (3)
These anomalies are generally rare and may involve any lumbar
segment, although L4 is by far the most commonly reported site.
(4) The condition has been reported in the upper sacrum (5) and
rarely in the thoracic spine, usually at T11 or T12. (6,7) There
occasionally will be an associated segmentation defect, especially
block vertebra. The clinical importance of the anomaly is purely
in regard to establishing the correct diagnosis and excluding other
more significant causes. Differential considerations for an absent
pedicle include osteolytic metastasis, neurofibroma, aneurysmal
bone cyst, osteoblastoma, and, rarely, aortic aneurysm. Pedicle
agenesis or hypoplasia is not an established cause of pain or segmental instability.
Radiologic Features. Plain film features usually allow for a
correct diagnosis; however, CT or MRI may be required for
confirmation. (Fig. 3-75)
• Altered pedicle outline. The most obvious sign is an
absent cortical outline of the pedicle on the AP projection.
When hypoplastic, the pedicle is small, laterally displaced
on the vertebral body, and often orientated inferiorly. An
apparent agenetic pedicle on the frontal projection is often
subsequently proven on the oblique radiograph or CT
study to, in fact, be hypoplastic. (1)
• Malformed transverse process. The ipsilateral transverse
process is usually small and directed inferiorly. Occasionally a small joint-like space separates the transverse
process from the pedicle or vertebral body (accessory
transverse process sign). (8)
• Spinous process deviation. The spinous process is usually
deviated at the level of involvement, usually away from
the affected side (spinous tilt or spinous deviation sign).
(9–11) (9,10) The spinous process above the level may
be tilted toward the altered pedicle side. (10,11)
(Fig. 3-76)
• Facet joint anomalies. The ipsilateral inferior articular process may be absent, small, fused, or malorientated. (1,3,4)
• Lamina anomalies. Associated ipsilateral agenesis or
hypoplasia is common and best identified by the enlarged
interlaminar space.
• Contralateral pedicle sclerosis. Stress hypertrophy
(enlargement, cortical thickening, and sclerosis) of the
contralateral pedicle is a common radiologic finding with
agenetic pedicle and unilateral pars defect (Wilkinson’s
syndrome). (12) These changes can extend into the adjacent lamina and transverse process. Other defects in the
posterior arch, including spondylolysis, deficient lamina,
and pedicle, can produce the same findings.
Figure 3-75 CONGENITAL AGENESIS OF A LUMBAR PEDICLE.
A. AP Lumbar Spine. Agenesis of the L2 pedicle is present
(arrow). The increased stress is transmitted through the
contralateral pedicle, producing significant compensatory
reactive stress sclerosis (arrowhead ). B. Bone Scan, Lumbar
Spine. Observe the area of increased radionuclide uptake in
the area of stress hypertrophy opposite the agenetic pedicle
(arrow). C. CT. The CT study clearly demonstrates the agenesis of the pedicle and a small transverse process, which has a
small joint present (accessory transverse process sign)
(arrow). COMMENT: The presence of contralateral stress sclerosis is useful in cases of a one-eyed pedicle sign to exclude
tumor destruction. In addition, tilt of the spinous process
and an accessory transverse process are further criteria.
(Panels A–C reprinted with permission from Albers VL: Congenital absence of the lumbar pedicle, with sclerosis and
hypertrophy of the contralateral pedicle [Radiology Case
Report]. ACA J Chiro 6:27, 1984.)
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Spina Bifida Occulta
Figure 3-76 CONGENITAL ABSENCE OF LUMBAR PEDICLE.
AP Lumbar Spine. Observe the agenesis of the pedicle of L4
(arrow) with contralateral reactive sclerosis and hypertrophy
of the opposite pedicle (arrowhead). The spinous process
above the level is tilted toward the altered pedicle side,
which is a common finding. COMMENT: The absence of a
vertebral pedicle should be considered the result of osteolytic metastatic carcinoma unless the contralateral pedicle
demonstrates hypertrophy and reactive sclerosis, indicating
a long-standing congenital lesion with stress response.
Vertebral Body Changes. Affected vertebrae commonly display decreased height on the same side as the pedicle anomaly,
producing lateral wedging. Congenital segmentation anomalies,
especially block vertebrae, are sometimes found at the same
segment. (10)
CT is especially useful for defining the pedicle malformation,
associated variations of the neural arch, and the distortion of the
spinal canal. Lack of soft tissue mass helps exclude neoplastic
pedicle destruction from metastases, aneurysmal bone cyst, osteoblastoma, and neurofibroma. MRI provides similar information
and may also demonstrate a collection of fat and absence of the
nerve root in the exit foramen, with a thick, conjoined nerve root
exiting from the foramen below. (13) Nuclear bone scan often
shows the contralateral pedicle to have increased uptake as a
result of increased physiological activity. (Fig. 3-75)
Other pedicle anomalies can be encountered.
• Thinned pedicles. At the thoracolumbar junction the pedicles are often thinned and should not be confused with an
expanding intraspinal neoplasm. (14)
• Pedicle clefts. Transverse clefts are occasionally seen and
can be impossible to differentiate from stress fracture.
• Pedicle vertical foramen. On CT, a corticated tunnel
through the pedicle may occasionally be seen passing
between the mamillary process and base of the transverse
process to allow transmission of the medial branch nerve
of the dorsal ramus and associated blood vessels (15).
Synonyms. Cleft spinous process, cleavage of the spinous process, spinous process agenesis, posterior (neural) arch non-union,
lumbosacral fontanelle.
Description. Spina bifida occulta (SBO) is a developmental
failure of osseous union between the two halves of the posterior
arch, typically resulting in a sagittal midline cleft of variable size
without posterior herniation of the thecal sac or its contents.
Clinical Features. In the thoracic and lumbar spine SBO most
commonly affects S1, L5, and T12–L1, in decreasing order of
incidence. (16) Occurrence at other thoracic or lumbar levels is
uncommon and should provoke a search for other dysraphic syndromes, including diastematomyelia, vertebral segmentation defects, VATER syndrome, and spina bifida vera. Two neural arch
defects that are not classified as manifestations of SBO are those involving the lamina (retroisthmic defect) or the pars interarticularis
(spondylolysis).
The overall incidence of SBO has been variously estimated
at 5–50% (16–21) but most likely lies in the range of 10 –22%.
(16,22,23). S1 SBO is the single most common site of occurrence, found in 15–17% of patients. (24,25) L5 SBO is estimated
to be present in 1–6% of spines, making it three to four times less
common than S1 SBO. (16,25,26) At T12–L1 the incidence
of SBO is unrecorded but is probably < 5%. SBO of the entire
sacrum occurs in 2–4% of the population. (25,27,28) The pathogenesis of the defect has also been debated. It is apparent that
there is an intrauterine failure of either mesodermal migration
at week 4, a failure to form cartilage, or a lack of ossification.
The diagnosis of SBO cannot be made radiologically until after
12 years of age because normal spinolaminar ossification is
not complete until this time and L5 and S1 are the last spinal segments to do so.
SBO of the thoracolumbar junction most commonly involves
T12, less commonly L1, and occasionally T11 either in isolation
or as simultaneous multisegmental involvement. In this location pure hypoplasia or complete agenesis of the spinous process
can occur without a radiographically visible laminar cleft. (28) The
defect is invariably clinically silent without pain or neurological
complication. It is often noticed serendipitously when the patient
or physician detects a noticeable step defect at the site of spinous
agenesis, which can become tender with repeated palpation.
SBO is a radiologic diagnosis and the only physical clues are a
palpable depression or occasionally a sacral dimple. Palpation of
the depression may mimic the step defect sign of spondylolisthesis. The clinical significance of SBO has been a topic of debate and
conflicting evidence, complicated by its common occurrence.
Known associations with SBO are many, but notably in contrast
to spina bifida vera, the clinical complications begin to manifest
some time after birth. (23) (Table 3-3)
• Back pain. This is the most controversial of possible associated findings. Some studies have concluded that the incidence of back pain in the presence of SBO is no higher
than in the population without SBO. (16,17,21,29–31)
There has been a documented higher incidence of disc
herniation at L5–S1 in patients > 41 years of age in the
presence of an S1 SBO. (24) A slight increase in low
lumbar disc degeneration has also been recorded. (32)
• Lumbosacral anomalies. Lumbosacral transitional vertebra, facet hypoplasia, and clasp knife syndrome can be
seen as tandem lesions. (28,33,34)
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Table 3-3
Associations with Lumbosacral
Spina Bifida Occulta
Cutaneous
Hypertrichosis
Nevi, scar
Sacral dimple
Telangiectasia
Gastrointestinal
Constipation
Genitourinary
Enuresis
Kidney anomalies
Musculoskeletal
Back pain
Clasp knife syndrome
Facet hypoplasia
L5–S1 disc herniation
Lumbar disc degeneration
Lumbosacral transitional vertebra
Scoliosis
Spondylolysis
Spondylolisthesis
Vertebral segmentation defects
Neurological
Conjoined nerve roots
Diastematomyelia
Epilepsy
Intraspinal lipoma
Pes cavus
Syringomyelia
Tethered cord syndrome
• Spondylolysis, spondylolisthesis. In the presence of L5
SBO there is a 13 times greater incidence of L5 spondylolysis. (35,36) In up to 50% of L5 spondylolistheses
there will be SBO of S1. (17) The combination of SBO
with facet hypoplasia contributes to a dysplastic
spondylolisthesis.
• Scoliosis. There is an increased incidence in SBO with
both idiopathic and congenital forms.
• Neurological abnormalities. Abnormalities of the lower
cord and thecal structures are reported, including low termination of the conus medullaris (tethered cord syndrome), syrinx formation, lipoma, fibrolipoma, nerve root
adhesions, and conjoined nerve roots. (23,33,37,38)
Inclusion of intraspinal fat cells into the conus or
meninges during embryologic development can produce a
slowly expanding lipoma, often found in conjunction with
a tethered cord. Pes cavus often co-exists with tethered
cord or lipoma. Epilepsy has also been associated with a
higher incidence of SBO. (39)
• Cutaneous variations. These variations include hypertrichosis, telangiectasia, sacral dimple, nevi and pilonidal
sinus, and cyst.
• Genitourinary abnormalities. SBO is commonly associated with segmentation anomaly of the spine, which in
turn is linked to the presence of developmental renal
anomaly, including horseshoe kidney. Incontinence, often
a sign of tethered cord, is another secondary condition
linked to segmentation anomaly of the spine.
• Gastrointestinal abnormalities. Slower intestinal transit
times and constipation have been demonstrated in the
presence of lumbosacral SBO. (40)
Radiologic Features. The key bony signs of SBO are best
appreciated on AP radiographs and CT of the spine. (Fig. 3-77)
MRI can be used in the presence of scoliosis, widening of the
interpediculate space, or neurological dysfunction or to rule out
the presence of tethered cord, lipoma, nerve root anomaly, or
disc herniation.
L5 SBO. In the most common form of L5 SBO, the lamina converge to form a vertical or oblique radiolucent cleft with smooth,
thinly corticated margins. Occasionally a variably sized spinous
process may be visible, either wholly on one side or equally divided bilaterally, rendering the laminar ends as club-shaped terminations. (Fig. 3-77, C and D) Innumerable variations can be
encountered, including asymmetrical length or density of the lamina and a variety of width and orientation of the cleft. Occasionally
one lamina may be directed inferiorly to form a cleft with the
S1 lamina or superiorly with L4. Sclerosis of the lamina raises
the suspicion for an associated unilateral spondylolysis. Similarly,
sclerosis of the pedicle can occur as a result of contralateral
spondylolysis or even just from the SBO. (41)
Upper Sacral SBO. In upper sacral SBO the laminae converge
toward the midline without a visible tubercle, leaving a cleft of
variable width. Usually only the S1 segment is involved, although
simultaneous cleft formation at additional levels is sometimes encountered and may extend to involve the entire sacrum. Careful
scrutiny of the midline often reveals the ununited sacral tubercles.
(Fig. 3-77E) Attachment of these tubercles to the L5 spinous process elongates it to invaginate into the sacral defect (clasp knife
syndrome). (34)
Thoracolumbar SBO. Absence of the spinous process in thoracolumbar SBO is identified on the frontal film by lack of the
teardrop-shaped outline; it is confirmed on the lateral projection
or CT study. The cleft separating the two opposing laminae is
vertical, with smooth corticated margins. (28) (Fig. 3-77B) The
defect is often not reported or identified because of subtle findings and its peripheral location on lateral radiographs. (42)
Spina Bifida Vera
Synonyms. Spina bifida cystica, spina bifida aperta, spina bifida
manifesta.
Description. In spina bifida vera there is a wide bony defect
in the posterior arch of the lumbar vertebrae, usually over more
than one segment, with a protrusion of the spinal cord contents
(meninges, cerebrospinal fluid, nerve roots) beyond the confines
of the spinal canal. Herniation of a CSF-filled sac covered with
meninges is called a meningocele. A sac containing CSF and neural
elements is called a myelomeningocele, and if neural elements
project through the bony defect without thecal covering, then a
myelocele is present. Myeloschisis refers to the presence of completely uncovered neural elements exposed through a sagittal midline defect that involves the bone, thecal sac, and all other posterior
soft tissues. Acquired meningoceles may occur after extensive surgical laminectomy when the meningeal tissues distend into the
paravertebral muscles.
Clinical Features. Antenatal diagnosis is often made on ultrasound as early as 12 weeks of gestation and most commonly at
the 18- to 20-week routine morphology ultrasound study. Elevated
3
Figure 3-77 MULTIPLE LOCATIONS OF SPINA BIFIDA
OCCULTA. A. AP Cervicothoracic Spine. There are multiple
spina bifida affecting C6–T2. B. AP Thoracolumbar Spine.
Failure of formation of the spinous processes of the T11 and
T12 vertebrae has left a clearly defined midline radiolucent
Congenital Anomalies and Normal Skeletal Variants I
311
cleft (arrows). C and D. AP Lumbosacral Spine. Spina bifida
occulta is present at the L5 vertebrae, where the spinous
process shows a distinct cleft. E. AP Lumbosacral Spine.
Spina bifida occulta is present at the S1 tubercle, where the
cleft can be seen.
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tional disturbances such as constipation, incontinence, dysmenorrhea, or dystocia. (44)
Radiologic Features. Meningoceles are visible on the antenatal ultrasound as an overlying cystic mass posterior to the
spine. Plain film findings include absence of the lamina and
spinous processes, widening of the interpediculate space, thinning of the pedicles, and scalloping of the posterior vertebral
body. Segmentation anomalies such as block vertebra, hemivertebra, and butterfly vertebra are common. The meningocele
is occasionally visible as a well-defined soft tissue mass. (Fig.
3-78) The lumbosacral area is most commonly affected. Sacral
meningoceles are usually directed anteriorly and laterally with
a resultant sickle-shaped deformity of the remaining sacrum
on AP radiographs, which simulates a Turkish sword (scimitar
sacrum). (44,45) (Fig. 3-79) Ultrasound and especially MRI are
most helpful for investigating possible involvement of neural
elements (myelomeningocele), lipoma of the conus, syrinx, tethered cord, and Chiari malformation. (46)
Figure 3-78 SPINA BIFIDA VERA WITH MYELOMENINGOCELE.
Lateral Lumbar Spine. Note the large myelomeningocele posterior to the lower lumbar spine and upper sacral area (arrows).
These are usually diagnosed antenatally by ultrasound.
Figure 3-79 MENINGOCELE (SCIMITAR SACRUM). AP
Sacrum. The lower sacrum appears bifid with a curved inner
surface (arrows). The actual long-standing meningocele is
not visible. COMMENT: The curved medial contour with the
remaining blade-like extension of the lower sacrum simulates the shape of a Turkish sword (scimitar) from which the
common name is derived (arrowheads).
serum and amniotic fluid α-fetoprotein has high positive predictive value for spina bifida vera. (43) Known associations include
Chiari malformation, hydrocephalus, tethered cord, lower limb
neuropathies, pelvic dysfunction (including incontinence), and
other dysraphic syndromes (including diastematomyelia). Most
meningoceles protrude posteriorly and are visible at birth, usually
at the lumbosacral junction and occasionally at the remaining
spinal transitional regions. Lateral meningoceles through intervertebral foramina are uncommon but may be seen with neurofibromatosis. Anterior meningoceles usually are encountered at
the sacrum in children and adults in association with pelvic dermoids; anal stenosis; kidney anomalies; bicornuate uterus; or func-
Diastematomyelia
Synonyms. Split cord syndrome, diplomyelia with bony spur.
Description. The term diastematomyelia was first coined by
Ollivier in 1837. (47) It represents a rare form of spinal dysraphism,
in which an osseous, cartilaginous, or fibrous bar partially or completely divides the spinal cord or cauda equina and fixes it in the
midline, effectively tethering the cord. (48) The thoracolumbar area
is most commonly affected; less commonly affected is the cervical
spine. (49) It may rarely occur at more than one level. (50)
Clinical Features. Symptom onset in early childhood usually
leads to the diagnosis; however, diagnosis may be delayed until
adulthood. (51–53) Prenatal diagnosis is also possible. (54). Physical findings in patients with diastematomyelia include anal dimple, hairy lumbar patch ( fawn’s beard ), asymmetrical size of the
lower extremities, and lipoma. (48) Progressive kyphosis and scoliosis may occur later in adolescence if associated segmentation
anomalies are present.
Radiologic Features. If an osseous bar is present it may be
demonstrable on plain film radiographs; a fibrous or cartilaginous
septum will not be seen. The spur is 1–20 mm in size and often
larger caudally, making it club shaped. There is usually a fusiform
widening of the interpediculate distance, not necessarily maximal
at the level of the midline spur. Other vertebral deformities, such
as spina bifida occulta, hemivertebrae, congenital bar, and scoliosis, are present in at least 50% of cases. (55) (Fig. 3-80) MRI
is essential for identifying ossified and unossified bony spurs,
assessing cord integrity, and especially identifying tethering of
the cord. Full-spine MRI is advocated, particularly if scoliosis is
present, to exclude syrinx and herniation of the cerebellar tonsils
through the foramen magnum (Chiari malformation).
Lumbosacral Transitional Vertebra
Synonyms. Lumbosacral transitional segment, lumbarization,
sacralization, lumbosacral transanomaly, borderline vertebra.
Description. Lumbosacral transitional vertebra (LSTV) is the
term preferred to describe the condition in which the lowest lumbar or upper-most sacral vertebra has characteristics of both spinal
areas. A lumbar segment with enlarged transverse elements and an
upper sacral segment with lumbar-type posterior elements are the
two most common presentations.
3
Figure 3-80 DIASTEMATOMYELIA. A. AP Lumbar Spine.
Observe the widened interpediculate spaces present throughout the lumbar spine. The bony spicule is not visible on the
plain film in this case. A drainage tube has been sited in the
subarachnoid space (arrow). B. CT. The osseous bar dividing
the spinal canal is clearly depicted (arrow).
Terminology related to the condition is confusing and often inaccurate. A normally segmented spine has 24 presacral vertebrae.
(56) Traditionally, by definition, lumbarization refers to the condition in which the S1 segment develops partial or complete lumbartype morphology. Complete lumbarization results in the presence
of six lumbar-type vertebrae. Sacralization refers to complete or
partial failure of developmental segmentation of the L5 vertebra
from the S1 segment. Although not completely reliable, in practice
these terms are often applied on the basis of the number of typical
lumbar vertebrae seen on a lumbar spine radiographic study. The
most accurate assessment is to count the number of vertebra in
the entire spine. Although an accurate accounting of the number
of segments in each spinal area may be accomplished with a fullspine radiographic examination or MRI, it is unlikely to be of sufficient importance to warrant the investigation. The terms partial
sacralization and partial lumbarization are sometimes used to
describe the incomplete forms of these anomalies.
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When a lumbar-type segment is present with enlarged transverse element(s) abutting the adjacent sacral ala, a true synoviallined articulation or a pseudoarticulation may be present between
the adjoining bone surfaces. The term lumbosacral transitional
vertebra is preferred as a descriptor for those segments that demonstrate features of both lumbar and sacral segments because it
is not the direction of the anomaly but the morphology that is the
important clinical feature. (56–58)
Clinical Features. The population incidence of LSTV is estimated at 4–10%. (17,28,59,60,61,62) There is no gender predominance. LSTV in families has been reported. (61) Sacralization is
reported more commonly than lumbarization, although this may
reflect the investigators’ lack of discrimination between the two
entities. Different types of LSTV are described. (58) A complete
lumbarization is when there are six vertebrae with typical lumbar
morphology and no “transitional” appearing segment. A complete
sacralization is represented by four lumbar and six sacral segments, with total incorporation into the sacrum. Incomplete forms
are by far more common and display varying degrees of enlargement of the transverse process; they are often asymmetrical. In
the preoperative and intraoperative setting it is vital to identify
each spinal segment, including the LSTV, to avoid errors in surgical exposure. (56,59)
The relationship of LSTV to back and leg pain has long been
a subject of debate. The association of back pain with antalgic
scoliosis was first described by Bertolotti in 1917 (sacralization
douleureuse, Bertolotti’s syndrome). (63) Conflicting studies exist
on whether the LSTV is a significant factor in the genesis of
clinical symptoms, particularly because it is frequently found in
asymptomatic populations. (17,60,61,64–66) Despite these conflicting studies there is a distinct cluster of structural problems
that occur at the segment above, including altered biomechanics,
disc bulging, annular tears, herniation, central and lateral stenosis,
facet arthritis, and spondylolysis. (61,67,68) Up to 30% of cases
may develop herniation at the segment above the LSTV. (58,62)
There is the perception that unilateral forms are more likely to be
linked to pain syndromes, although they do not correlate with
the side of pain. (58,62,69) Disc herniation at the LSTV interspace itself has been recorded but is uncommon. Facet arthrosis
can be seen, though rarely enough to cause stenosis; spondylolysis has sometimes been seen. (33,58,61,62) If an anomalous
articulation exists between adjoining transverse and alar elements
of the transitional segment and the sacrum, inflammation and /or
degenerative joint disease may result in pain on palpation or movement. (28,69). Selective percutaneous injection of anesthetic
agents into the pseudo-joint provides putative evidence for the
site of pain in selected patients. (69)
The L4 nerve root may be affected as it passes anteriorly over
the pseudo-joint. (61) The relative segmental exits of the lumbar
and upper sacral nerve roots can also be anomalous. In at least
75% of cases, the L5 nerve root exits at the last mobile vertebra
above the LSTV (59) Conjoined nerve roots may also occur at
the LSTV level. (33) Resection of the transverse process remains controversial, even when anesthetic agents are successful in proving their pain-producing role. (69,70)
Radiologic Features. LSTV is characterized by enlargement
of the transverse process(es). (58) Frontal and lateral views
should be performed and preferably supplemented with an angulated view of the lumbosacral junction (Ferguson-Hibb view).
(Fig. 3-81) Given that spondylolysis can occur above the LSTV,
oblique films should be considered. Obliques also provide a
tangential view of the pseudo-joint to assess for degenerative
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Castellvi Type II LSTV. Larger expansions of the transverse
process result in accessory articulations with the sacral ala, iliac
surface, or both in Castellvi type II LSTV. (Fig. 3-82) Injection
of contrast into the pseudo-joint often shows communication
with the adjacent sacroiliac joint. This joint is usually referred to
as a pseudo-articulation and is marked radiologically by corticated
opposing bony surfaces with a 1- to 2-mm joint space. Sclerosis
and osteophytes can be seen as signs of degenerative change,
though these may not be reliable symptomatic signs. (60). On CT
the sacral ala is broadened anteriorly. The vertebral body is often
small and wedged laterally with narrowing on the side of attempted
union, often precipitating a scoliosis. On the lateral view, a transitional vertebral body will be wedged posteriorly and the inferior
endplate length will typically be less than the superior endplate
length by a ratio of 1.37 or less (squaring sign). (56) The intervening disc and facet joints are usually hypoplastic. (71) Accompanying spina bifida occulta is a common associated structural
anomaly. (33)
Castellvi Type III LSTV. Castellvi type III LSTV is characterized
by complete bony fusion between the sacral ala and transverse
process with no visible joint. (Figs. 3-81 and 3-83)
Castellvi Type IV LSTV. Castellvi type IV LSTV is a combination of a unilateral pseudo-joint (type II) and contralateral fusion
(type III).
Nuclear bone scan does not appear to discriminate between
symptomatic and asymptomatic joints. (69) MRI can be used to
count the number of vertebrae, and both CT and MRI can identify disc herniations and assess stenosis. MRI may assist in depicting nerve root relationships to the enlarged transverse process
and pseudo-joint as well as in identifying bone marrow edema as
a sign of bony impingement syndrome.
Figure 3-81 TRANSITIONAL SEGMENT, LUMBOSACRAL
JUNCTION. A. Erect, AP Lumbopelvic Spine. Lumbosacral
abnormalities in general, including lumbosacral transitional
vertebra, are not clearly shown on frontal studies, especially
when weight bearing because of the anterior tilt of the
sacral base angle and lumbar lordosis. Also, exposure difficulties can arise owing to patient size. Note how all of these
factors lead to lack of visualization of the lumbosacral junction. B. Tilt-Up, AP L5–S1. This specific view angled with the
central ray parallel to the lumbosacral disc shows to advantage the presence of a unilateral fused lumbosacral transitional vertebra (arrow). (Courtesy of Paul Van Wyk, DC,
Denver, Colorado.)
change and its relationship to the sacroiliac joint. (33) To assist
in the semantical division of lumbarization versus sacralization
it is helpful to recall that the L3 transverse processes are typically the longest, whereas the L4 transverses are usually shorter
and thinner and have a pointed tip. Counting the number of
sacral segments may also be useful. (33,56) The anomaly may
be unilateral or bilateral. Another classification for LSTV has
been described by Castellvi (see below).
Castellvi Type I LSTV. In Castellvi type I LSTV the transverse
process is expanded toward its tip as a spatulated bony process
that is < 19 mm with no obvious connection to the sacral ala.
This anomaly has a dubious role in back pain syndromes.
Facet Tropism
Synonyms. Asymmetrical facets, facet joint asymmetry.
Description. The term tropism is derived from the Greek word
trope, meaning literally “a turning.” It is used to describe left-toright variations in the plane of the zygapophyseal joints of more
than 5°. (72,73)
Clinical Features. Tropism is found in 20–35% (1 in 5) of
lumbar spines, most commonly at L5–S1 followed by L4 –L5.
(16,72–75) It is not a congenital anomaly but an acquired condition because all lumbar facet planes are orientated in the coronal
plane at birth and remodel throughout infancy and childhood to
attain their adult orientation by about 11 years old. (76–78) The
multifidus muscle appears to play an important biomechanical role
in joint plane orientation. (79) The clinical implications of facet
tropism have been long debated and remain largely unresolved.
Increased incidence of pain, instability annular tears (80–83), and
disc herniation (84,85) have all been recorded, usually on the side
of the more coronal articulation. Degenerative facet disease has
been shown predominantly in the sagittal facet (72,86), although
this has been disputed. (87) Sclerosis of the pedicle on the side of
coronal facet is a marker of increased biomechanical bone stress
from the neural arch to the vertebral body. (88,89)
Radiologic Features. Facet tropism is a radiologic diagnosis
best identified on CT or MRI axial images but is often visible on
frontal lumbar radiographs. (89)
3
Figure 3-82 TRANSITIONAL SEGMENT, LUMBOSACRAL
JUNCTION. A. AP Specimen Radiograph. The large, spatulated transverse process of the L5 vertebra is visible. Observe
the lateral osteophyte from the pseudo-joint. Of incidental
notation is a benign bone island within the spatulated transverse process of L5 (arrow). B. Axial Specimen Radiograph.
This projection of the specimen demonstrates the large,
spatulated transverse process of the transitional segment.
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315
The benign bone island is noted (arrow). C. AP Lumbosacral
Junction. A unilateral transitional segment is present, with an
accessory articulation (arrow). Of incidental note is a Cupid’s
bow contour on the inferior endplate of L5 (arrowheads), resulting from nuclear impression. D. AP Lumbosacral Junction,
Type IIb. Bilateral enlargement of the transverse processes
with pseudo-joints is clearly depicted (arrows).
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B
Figure 3-83 TRANSITIONAL SEGMENT, LUMBOSACRAL JUNCTION. A. AP Lumbosacral Junction. Note the bilateral completely fused transitional segment; the site of fusion is
marked by a faint sclerotic line (arrows) B. Lateral
Lumbosacral Spine. The hypoplastic disc (D) between the
transitional segment and the sacral base is a common marker
of a transitional lumbosacral segment because it actually represents a form of block vertebra.
On the AP projection of the lumbar spine, the joint space normally seen is the posterolateral joint cavity of a more sagittally
facing joint plane. In tropism, a joint space will be visible on the
more sagittal joint but not on the coronally oriented side. (Fig.
3-84) Increased sclerosis of a pedicle on the side of the coronal
facet is occasionally seen. (88) Accurate assessment cannot be
made on oblique views or on weight-bearing studies because
of the acute lumbosacral angle. The presence of scoliosis or
osteoarthritis of the sagittal joint will also obscure assessment of
tropism. Lateral projections are non-contributory. Lateral bending studies may show inhibition of intersegmental rotation on the
side of the sagittal joint.
If plane lines are drawn on axial CT or MRI studies along the
surfaces of the facets and the angle relative to the midsagittal
plane is measured, it is possible to quantify the orientation and degree of asymmetry. (72,89) The sagittal facet tends to have a flat
surface, whereas the coronal facet is typically curved. Frequently
the coronal facets appear more bulbous and enlarged with narrowing of the adjacent exit foramen. On cross-sectional CT or
MRI studies the additional benefit is the assessment for disc herniation and canal stenosis.
C
Figure 3-84 FACET TROPISM, LUMBOSACRAL JUNCTION.
A. AP Lumbosacral Spine. Note the bilateral sagittal facet facings at the lumbosacral junction (arrowheads). Asymmetric
facet facings (tropism) are present at the L4–L5 level, and a
sagittal facet is seen on the right side of the image. A Cupid’s
bow deformity is incidentally present, affecting the inferior
endplate of L5 (arrows). B. AP Lumbosacral Spine. The more
sagittal facet joint space is visible (arrow), but the coronal facet
joint space is not (arrowhead). C. CT, Bone Window, Axial
L5–S1. The posterior facet joint space is more sagittally orientated and represents the part of the joint seen on the plain
film study (arrow). The coronal facet joint lies perpendicular to
the sagittal plane and is not depicted on the plain film (arrowhead). COMMENT: The CT study demonstrates that for most
cases of tropism only the posterior joint cavity is depicted on
plain film and that, in fact, most lumbar facet joints are usually curved and not commonly planar in nature. Despite this, a
difference in joint orientation can be detected (Panels B and C
courtesy of Donald E. Freuden, DC, DABCO, Denver, Colorado.)
3
Agenesis of the Articular Process
Synonyms. Facet joint agenesis, facet joint aplasia, absent
facet syndrome.
Description. Absence of a lumbar articular process is a rare
anomaly, which most commonly involves the inferior articular
process of the L4 or L5 vertebrae. (90–94) The less extensive
form in which the articular process is small (hypoplasia) is more
common.
Clinical Features. The opposing superior articular process is
usually present but may exhibit varying degrees of dysplasia, except at L5–S1, in which case there is a tandem agenesis of both the
L5 inferior articular process and the S1 superior articular process.
(92,94) The lesion exists as an isolated agenesis or as part of a
combined anomaly, including ipsilateral pedicle agenesis, spina
bifida, and block vertebra. (2,11,95) The majority are clinically
benign lesions not linked to instability (92,93,95), though occasional instances have been linked with back pain. (96) Bilateral
Figure 3-85 UN-UNITED SECONDARY OSSIFICATION
CENTERS, ARTICULAR PROCESSES. A. AP Lumbar Spine. At
the tip of the inferior articulating process of L4 an ununited
ossicle is visible (arrow). B. Oblique Lumbar Spine. The nonunion of the secondary ossification center is depicted
(arrow). COMMENT: Exclusion of fracture is based on the
smooth sclerotic margins and location. The plane of attachment is planar or concave–convex.
Congenital Anomalies and Normal Skeletal Variants I
317
facet joint hypoplasia at L5–S1 predisposes the patient to a dysplastic spondylolisthesis (Wiltse type I). Accurate diagnosis is
necessary to exclude a destructive pathologic process. (92,93)
Non-union at the tip of the articular process is a more common variation, found in 1–7% of lumbar spines. (28,74,97) Its
origins are obscure, but most researchers implicate it as a nonunion of the secondary growth center. (28,98,99) It has attracted
the eponym Oppenheimer’s ossicle. (99) (Figs. 3-85 and 3-86)
The inferior articular process is involved in 95% of cases; 80% are
unilateral and single-level ossicles predominate, though multiple
levels can be observed. (98,100) The most common segments affected are L2 (45%), L3 (45%), L1, and L4. (28,98–100) The L5
segment is rarely involved. Males are affected six times more
commonly. (100) There is no clinical significance except to
exclude acute fracture, accomplished by the radiologic features
of exhibiting a smooth, sclerotic margin. (74,101,102)
Figure 3-86 UN-UNITED SECONDARY OSSIFICATION CENTERS, OPPENHEIMER’S OSSICLES. A. AP Lumbar Spine.
Observe the bilateral failure of union of the ossification
centers for the inferior articulating processes of L5 (arrows).
B. Oblique Lumbar Spine. The triangular nature and typical
non-union features at the site of apposition are well shown.
COMMENT: The size of the non-unions in this example are
atypically large but still fulfill the characteristic criteria. The
most common sites are at L2 and L3, and they can occur at
multiple simultaneous levels. They are not linked to any pain
syndrome.
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Figure 3-87 AGENESIS OF A LUMBAR ARTICULAR PROCESS.
AP Lumbosacral Spine. The lumbosacral facet joint is absent,
as evidenced by a lack of osseous tissue and short, attenuated articular processes (arrow). COMMENT: These anomalies
are rare and do not usually induce intersegmental instability. They are readily overlooked and are best confirmed with
oblique projections and CT. (Courtesy of James R. Brandt,
DC, DABCO, Coon Rapids, Minnesota.)
Radiologic Features. Agenesis of the articular process is readily overlooked unless there is careful scrutiny of the normal
anatomic details of each articulation. On a frontal projection, absence of the articular process will result in a widened interlaminar space, tilting, and dysplasia of the segmental spinous process
(spinous process tilt sign); stress hypertrophy of the contralateral
pedicle is also frequently seen. (11,95,103) (Fig. 3-87) The oblique
projection is useful in determining the amount of agenesis and
the effect on the joint and in confirming the contralateral pedicle
sclerosis. These findings are also noted on CT axial images. (95)
Ununited ossicles of the articular process tips (Oppenheimer’s
ossicles) range in size from 1 to 10 mm; are round, oval, or triangular; and have a smooth corticated margin at the site of
separation. They can often be seen on AP, oblique, and lateral
radiographs. The separating cleft often communicates with the
joint surface, which may be demonstrated on arthrography. CT
and MRI confirm these findings and may be useful for excluding fracture and identifying any lateral canal stenosis. (101,102)
Clinical Features. The majority of cases identified radiographically are not related to clinical symptoms. When symptoms
are present, two presentations are recognized: low back pain and
compression of the sacral nerve roots. (34,108) When the patient is
hyperextended in the standing position symptoms are reproduced.
(34,105) Low back pain is thought to be the result of mechanical impingement of the elongated L5 spinous process into the
sacral laminar stumps or covering membrane. (34) The less frequent sacral nerve root compression may produce radiating pain,
paresthesia, and loss of the Achilles reflex. (34,105) Known associations with symptomatic cases include loss of disc height, instability, horizontally orientated sacrum, and increased lumbosacral
angle. (34) There is no known association with increased incidence
of disc herniation, spondylolysis, or spondylolisthesis. (34,104)
Treatment in symptomatic cases remains problematic. Conservative measures aimed at reducing the lordosis and sacral base
angle, flexion exercises, flexion–distraction manipulation, and appropriate bracing may be helpful. (34,105,107) Surgical excision
of osseous or fibrocartilaginous elements and/or division of dural
adhesions may be required in recalcitrant cases. (34,106,107)
Radiologic Features. Three variations have been described. (34)
Type I. Type I is characterized by wide spina bifida occulta
with a long L5 spinous process. This is the classic form, and on
frontal radiographs the long L5 spinous process (spina magna)
is seen invaginating into the space. (109) (Fig. 3-88) As with any
abnormality of the spinous process, many cases are not recognized and not reported on radiographs. (42) The AP tilt-up view
(30° cephalic angulation; Hibb’s view) through the lumbosacral
disc may improve visualization of the clasp knife deformity. (20)
The lateral film may have to be purposely underexposed for complete depiction of the distal enlargement of the L5 spinous process
Clasp Knife Syndrome
Synonyms. Knife clasp deformity (syndrome), spina bifida engagement syndrome, spina magna, long spinous process syndrome.
Description. The tandem bony findings of elongation of the L5
spinous process that invaginates into a spina bifida occulta of at
least the S1 segment was first described by Ferguson in 1934.
(20) Tissue that would normally construct the posterior tubercle(s) of the upper sacrum is joined to the L5 spinous process,
resulting in the elongated appearance of this structure. The term
clasp knife deformity was coined by Henry in 1958 as an analogy
to the blade of a pocket (clasp) knife folding into its handle. (104)
Sacral spina bifida typically is limited to the S1 level but may
involve more of the sacrum. The anomaly has been reported in
up to 2% of lumbar spine radiographs and cadavers. (38,105)
Anatomically, the long spinous process abuts or, more often,
is continuous with fibrocartilaginous tissue in the sacral defect.
(20,28,106,107) The dura of the sacral thecal sac may be adherent
to the fibrocartilaginous membrane. (34)
Figure 3-88 TYPE I CLASP KNIFE SYNDROME. AP Lumbosacral Spine. The wide spina bifida present in the first sacral
segment allows the elongated spinous process of L5 to enter
the defect without bony impingement or pseudo-joint
formation.
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Congenital Anomalies and Normal Skeletal Variants I
319
B
Figure 3-89 TYPES II AND III CLASP KNIFE SYNDROME.
A. Lateral Lumbosacral Spine. The large and elongated spinous process of L5 (spina magna) (arrow) projects caudally
into the S1 cleft. B. AP Lumbosacral Spine. The large elongated spinous process of L5 projects into a narrow spina
bifida affecting the S1 segment and forms smooth faceted
pseudo-articulations (type II). In addition, there is an isolated
ossicle at its tip (type III). (Courtesy of James R. Brandt, DC,
DABCO, Coon Rapids, Minnesota.)
caudally into the sacral defect. The spinous is enlarged, expanded,
and hook-like at its anteroinferior margin.
Type II. Type II is characterized by narrow spina bifida with a
long L5 spinous process. The space between the spinous process
and the laminar stumps is narrow, and on close inspection signs
of bony impingement with sclerosis, flat surfaces, and a narrow
lucent joint-like cavity may be appreciated. (Fig. 3-89A) Erect
studies with flexion– extension have the greatest probability of
demonstrating bony impaction. (104)
Type III. In type III there is spina bifida with a long spinous process
and isolated sacral ossicle. A midline round to oval ossicle lies
close to but separate from the L5 spinous process. (Fig. 3-89B)
Additional imaging is infrequently required, though the investigation of leg pain may prompt either CT or MRI studies. Myelography is rarely performed but, with the patient in extension, may
demonstrate a complete block of the flow of subarachnoid contrast.
(106) MRI is extremely useful in showing any mechanical deformation of the sacral thecal sac from the spinous process. Axial CT
soft tissue windows performed with and without supportive measures to increase the lumbar lordosis may be useful in showing any
mobility of the spinous process within the cleft or dynamic deformation of the sacral thecal sac or specific nerve roots. (105) CT
bone windows clearly demonstrate the intrusion of the long spinous process through the S1 spina bifida. (105)
(1) Recognition of rib anomalies may provide key clues to related
generalized conditions, including skeletal dysplasias and endocrine
and neoplastic processes.
Pseudo-Arthrosis of the First Rib. In about the midcourse of the
first (less commonly the second) rib, an irregular, joint-like cavity
with opposing bulbous rib ends can be encountered, known as a
pseudo-arthrosis. (Fig. 3-90) This has been documented in 0.1%
of the population. (2) The anomaly usually occurs unilaterally,
but bilateral forms have been documented. (3) The origins of the
defect have been debated as being congenital, the result of nonunion of an acute fracture, or from a chronic unhealed stress fracture; case demonstrations of each have been published. (4) The majority do not cause pain or thoracic outlet compression but can be
a confusing cause for a palpable hard mass in the supraclavicular
fossa.
Luschka’s Bifurcated Rib (Forked Rib). In Luschka’s bifurcated
rib, the anterior end of an upper rib, most commonly the fourth,
may be forked. (2) It is the most common rib anomaly, being
found in at least 0.6% of the chest radiographs. No clinical significance is ascribed to the anomaly, but it may simulate a lung
cavity. (4) (Fig. 3-91)
Rib Foramen. In a posterior lower rib, an oval-shaped corticated “foramen” can be encountered and is of no clinical significance. It does, however, need to be differentiated from a
benign bone tumor, such as aneurysmal bone cyst or enchondroma. (Fig. 3-92)
Rib Fusion. Synostosis (bony bridging) over long segment fusions can be observed in both the anterior and the posterior ribs.
(3,4) (Figs. 3-93 and 3-94) Associated block vertebrae or hemivertebrae can be seen at the same level as a manifestation of fused
mesodermal costal processes. (1)
Srb’s anomaly. Srb’s anomaly describes partial or complete
fusion of the first and second ribs, forming a solid bony plate
with variable sternal articular patterns. (4) Radiographic views
taken for the chest or ribs will demonstrate this anomaly. The
ANOMALIES OF THE THORAX
ANOMALIES OF THE RIBS
A variety of normal variants, congenital anomalies, and pathological conditions involve the ribs and are frequently overlooked.
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Figure 3-90 PSEUDO-ARTHROSIS OF THE FIRST RIB. Oblique
Upper Ribs. The first rib in its midportion shows an angular
radiolucent line of non-union (arrow), which has sclerotic
margins with bulbous expansion of the opposing rib ends.
Whether this represents a congenital defect, non-union of
an acute fracture, or stress fracture in most cases is not clear.
The majority do not cause pain or thoracic outlet compression but can be a confusing cause for a palpable hard mass
in the supraclavicular fossa.
Figure 3-91 VON LUSCHKA’S BIFURCATED RIB. PA Ribs.
A focal bifurcation of the anterior end of the right fourth
rib produces a forked appearance. The overlying nipple
shadow is present as a circular, radiopaque density (arrow).
COMMENT: von Luschka’s bifurcated rib is clinically insignificant but can mimic a cavity within the lung.
Figure 3-92 RIB FORAMEN. PA Chest. Observe the wellcircumscribed oval-shaped radiolucent foramen (arrow) within
the posterior eighth rib. (Courtesy of Kenneth E. Yochum, DC,
St. Louis, Missouri.)
Figure 3-93 FUSED POSTERIOR RIBS. A. PA Upper Ribs.
Observe the congenital fusion of the posterolateral surface
of the third and fourth ribs (arrow). Each costal element is
hypoplastic. In such cases the reciprocal vertebrae should be
scrutinized for evidence of a segmentation anomaly, which
is not present in this case. B. PA Lower Ribs. Note the congenital synostosis of the posterior surface of the eleventh
and twelfth ribs close to their medial ends (arrow). Also
seen is a thoracolumbar scoliosis, with the apex adjacent to
the site of costal fusion but no segmentation defect.
3
Figure 3-94 RIB SYNOSTOSIS. AP Thoracic Spine. Note the
congenital fusion of the eleventh and twelfth ribs on the
left, just lateral to T11–T12, without scoliosis or vertebral
segmentation defect. (Courtesy of Ron D. Myhra,
DC, Denver, Colorado.)
normal rib interspace between the first and second ribs is absent. (Fig. 3-95) A pseudo-arthrosis may be seen in the midportion of the fused rib.
Intrathoracic Rib. An anomalous costal process can arise from
a lateral vertebral body or posterior rib, most commonly in the
midthoracic spine, descending vertically within the thorax in a
curvilinear course and tapering gradually at its terminal end. (5–7)
(Fig. 3-96) Cortex and medullary cavity of mature bone are present. These most commonly occur on the right side and usually do
not co-exist with other skeletal or visceral anomalies. They are
usually insignificant, though a fibrous attachment to the hemidiaphragm has been recorded, with a related restrictive ventilatory
effect. (7)
Postsurgical Rib Regrowth. Years after rib resection during
thoracotomy, variable degrees of regrowth are common. Usually
Figure 3-95 SRB’S ANOMALY. A. PA Chest. The first and
second ribs are fused posteriorly, with division of the anterior end into a forked appearance (arrow). B. AP Upper Ribs.
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the regrown rib is smaller and often serpiginous in its course,
with areas of incomplete ossification. (Fig. 3-97)
Cervical Ribs. Most cervical ribs are asymptomatic and are
discovered incidentally, as discussed earlier. The key is to distinguish a cervical rib from congenital elongation of the C7 transverse process by recognizing that the T1 transverse process is
directed superiorly, whereas the C7 transverse process is orientated inferiorly.
Lumbar Ribs. Ribs at the L1 vertebra are referred to as gorilla ribs
and occur in about 8% of the population. (8) Rarely an additional
rib may be found at other vertebral segments. (Fig. 3-98) (3)
Acquired fusion owing to post-traumatic heterotopic bone formation (myositis ossificans) may bridge two or more transverse processes, known as lumbar ossified bridge syndrome (LOBS) (see
Chapter 9) and should be differentiated from rare lumbar ribs. (9)
Sacral Ribs. Rarely, ribs can form from the sacrum or coccyx; they
typically extend laterally in the pelvic inlet. (10) They can be
spatulated or tapered in shape with smooth corticated margins.
Differentiation from more common sacrotuberous or sacrospinous
ligament calcification or myositis ossificans can usually be made.
Pelvic Ribs. Though not probably true congenital ribs, segmented
ossifications extending off the iliac crest or acetabulum simulate
pelvic ribs. (Fig. 3-99) It is most likely these finger-like ossifications represent myositis ossificans, and given the radiographic
similarities to finger phalanges these have been also referred to as
pelvic digits. (Fig. 3-100) (11)
Costochondral Junction Calcification. Calcification within the
anterior rib cartilages is a common, often striking, finding on thoracic images. First costochondral calcification is often bulbous,
irregular, and may demonstrate a joint-like linear lucency, which
can simulate an upper lung or mediastinal mass. (Fig. 3-101)
Generally, costochondral calcification is uncommon under 35 years
of age. (12) Males tend to show peripheral perichondral calcification as two parallel lines (railroad track appearance), whereas females display a central linear calcification (wagging tongue-like appearance). (12) (Fig. 3-102) At least 12% of males will demonstrate
In a similar case, the posterior first and second ribs are fused,
with anterior bifurcation (arrow).
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Figure 3-96 INTRATHORACIC RIB. PA Chest. Originating from
the posteromedial fifth left rib, an intrathoracic rib with cortex and medullary cavity courses inferiorly in a curvilinear configuration toward the left hemidiaphragm (arrows). (Courtesy
of Bryan Hartley, MD, Melbourne, Australia.)
Figure 3-98 LUMBAR RIB. AP Lumbar. A rare lumbar rib is
present, projecting from the inferior aspect of the L3 transverse process (arrow). (Courtesy of Gary M. Guebert, DC,
DACBR, St. Louis, Missouri.)
Figure 3-97 POSTSURGICAL RIB REGROWTH. PA Chest.
Reformation and growth of a previously resected rib is
seen (arrows). This is a common occurrence after rib resection if residual periosteum is left behind. COMMENT: The
patient’s history of previous surgery is helpful because the
radiographic appearance may simulate a destructive rib
lesion.
Figure 3-99 PELVIC RIB. AP Pelvis. A smoothly corticated and
spatulated piece of bone extends from the lateral sacral
margin toward the posterior ischium (arrow). At its distal expanded end there is an accessory joint. COMMENT: These accessory ribs are rare and present clinical problems only in pregnancy, when they may obstruct parturition. These should not
be confused with ossification of the sacrospinous ligament.
(Courtesy of Lloyd Morris MBBS, FRANZCR, Adelaide, South
Australia. Data from Sullivan D, Cornwall WS: Pelvic rib.
Report of a case. Radiology 110:355, 1974.)
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Figure 3-100 PELVIC DIGIT. AP Pelvis. Arising from the iliac
crest is a segmented finger-like ossification (arrow). This was
an incidental finding discovered in the radiographic assessment for back pain. COMMENT: These are not true congenital ribs and represent post-traumatic myositis ossificans. The
appearance of intervening clefts in the ossification simulates
finger phalanges, from which the term pelvic digit is derived. They are most commonly found around the acetabulum. (Courtesy of Graham Jones, DC, Belmont, New South
Wales, Australia.)
Figure 3-101 FIRST COSTOCHONDRAL JOINT IRREGULARITY
AND CALCIFICATION. A. AP Cervicothoracic. There is florid
calcification with irregular margins in the first costochondral
junctions bilaterally (arrows). Note also that there is a visible
linear zone at both sites where there is no calcification; this
most likely represents the zone of residual mobility. B. AP
Apical Lordotic. Similar but less prolific calcification is present bilaterally, which is more granular and again shows the
typical residual uncalcified linear zone, which should not be
confused with fracture (arrows).
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Figure 3-102 IDIOPATHIC COSTOCHONDRAL CARTILAGE
CALCIFICATION. A–E. AP Lower Ribs. Observe the varying
amounts of costochondral calcification involving the lower
ribs, ranging from small at the anterior rib ends (arrow) to
extensive. These may appear very dense, symmetric, and
homogeneous, but usually they have no pathologic significance. Costochondral calcification may occur in children as
well as in adults and is a variation of normal. COMMENT: An
increased incidence of costal cartilage calcification in chil-
dren with hyperthyroidism has been reported. Some loss of
thoracic cage compliance may occur and fractures can be
identified in trauma. (Panel A courtesy of Daniel L. Perkins,
DC, Denver, Colorado. Comment data from Senac MO, Lee
FA, Gilsnaz V: Early costochondral calcification in adolescent
hyperthyroidism. Radiology 156:375, 1985; and Ontell FK,
Moore EH, Shepard JO, Shelton DK: The costal cartilages in
health and disease. RadioGraphics 17:571, 1997.)
3
female-type calcifications. Postmenopausal women display more
globular types of calcification. Heavy premature costal cartilage
calcification before 40 years of age may be a normal finding.
ANOMALIES OF THE STERNUM
Pectus Excavatum. Pectus excavatum is the most common deformity of the chest wall and consists of an exaggerated anterior concavity of the sternum, sometimes described as funnel
chest. A lateral radiograph of the chest will confirm the physical
examination finding of a posteriorly displaced sternum and a
decreased retrosternal clear space. (Fig. 3-103) On the frontal
study, the posterior ribs lie horizontally and the anterior ribs
appear steeply downsloping. The right heart border is often obscured and displaced to lie over the spine. The right middle lobe
may show increased opacity from compression, and there may
be splaying of the pulmonary vessels.
Pectus Carinatum. In pectus carinatum the sternum is bowed anteriorly creating a pigeon breast chest. This deformity is produced
Figure 3-103 PECTUS EXCAVATUM. A. PA
Chest. The depressed sternum displaces the
heart to the left so the right atrial heart
border cannot be seen. In addition, the
anterior ribs are angled inferiorly (black
arrow ) and the posterior ribs are quite
horizontal (white arrow). The radioopaque density to the right of the spine
represents the compressed middle lobe of
the right lung, which is also a characteristic
finding. B. Lateral Chest. The sternal
depression is clearly visible (arrow).
Figure 3-104 STRAIGHT BACK SYNDROME. A. PA Chest. Findings are often
the same as in pectus excavatum with
inferior angulation of the anterior ribs,
horizontal posterior ribs, lack of a right
heart border, and increased opacity of
the right middle lobe. B. Lateral Chest.
The sternum is minimally depressed, as
in pectus excavatum, but the thoracic
kyphosis is markedly reduced, thus compressing the heart, which can produce
flow murmurs. (Courtesy of Jay D.
Fullinwider, DC, Littleton, Colorado.)
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by an anterior displacement of the sternum. It has been found
in association with Morquio’s syndrome. A lateral chest film
will demonstrate a prominent sternum and an increased retrosternal clear space.
Straight Back Syndrome (Cobbler’s Heart). Any significant reduction in the dimensions of the chest, especially in the sagittal
plane, may alter the cardiac hemodynamics and create murmurs.
(1) In straight back syndrome there is a marked reduction of the
normal kyphotic contour of the thoracic spine with an associated
reduction in the AP diameter of the thorax. As the heart and mediastinal structures are compressed between the thoracic spine and the
sternum, the heart “pancakes” and shifts to the left. An ejection
murmur results that typically decreases when the patient sits up or
inspires. (2) There is an increased incidence of mitral valve prolapse in patients with straight back syndrome. (3) It may be inherited as an autosomal dominant trait with the genetic determinants
located on chromosome 6. (3) The PA chest view demonstrates an
unusual downward angulation of the anterior rib ends; the heart is
displaced toward the left with no right heart border visualized. The
lateral chest view demonstrates a diminished kyphosis or straight
thoracic spine. (4) (Fig. 3-104) A pectus excavatum is variably
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present. Measurement for straight back syndrome is performed by
dividing the AP diameter of the chest by the transthoracic ratio. (4)
Another measurement method, performed on the lateral chest
radiograph, determines the distance from T8 to the sternum. A
positive finding is a measurement < 12 cm. (3)
ANOMALIES OF THE HIP AND PELVIS
DEVELOPMENTAL DYSPLASIA
OF THE HIP
Synonyms. Congenital hip dysplasia, congenital hip dislocation (CHD).
Description. Developmental dysplasia of the hip (DDH) is
the current preferred term used to describe a spectrum of conditions that range from irreducible dislocation of the hip at
birth to neonatal hip instability. (1) The condition has been previously described as congenital hip dislocation and congenital
hip dysplasia.
Clinical Features. Fixed dislocation at birth is estimated at
1:1000 births and late dislocation, subluxation, and dysplasia at
0.4 – 0.6:1000 births. There is a definite female predominance,
which is as high as 6:1. If one of the parents has had DDH, then
the risk for the first child is 12%. (2). Bilateral but asymmetrical
dysplasia can occur in up to 25% of cases. Known risk factors for
DDH include breech fetal presentation, oligohydramnios, and
firstborn status. Known associated abnormalities include neuromuscular disorders, congenital torticollis, and skull and foot
deformities.
Over the last decade there has been an increased awareness for
the early postnatal diagnosis of DDH on the premise that simple
conservative measures may reverse hip instability and reduce the
incidence of secondary osteoarthritis of the hip later in life. (3) On
physical examination of the newborn, a palpable hip “click” can
be elicited when combined external rotation–abduction and internal rotation–adduction are alternately applied to the flexed hip
(Ortolani’s test and Barlow’s test). Diagnostic ultrasound is the
first choice for imaging investigation, and the presence of positive physical examination findings or history of significant risk
factors are sufficient to order an evaluation. (4,5)
The pathophysiology of DDH is multifactorial, including
shallow bony margin; delayed ossification of the acetabulum
or femoral head; ligamentous laxity; and neuromuscular disease with shortening, weakness, or contractures. (6). Hip flexion
associated with breech presentation induces DDH by causing
shortening of the psoas and decentering of the femoral head, a
mechanism that also results from other deformities and neuromuscular disorders.
Acetabular growth is dynamic during the first 2 postnatal
months, and a dysplastic hip can often be effectively treated
by simple flexion–abduction bracing techniques, such as the
Pavlik harness device. (6) Spontaneous improvement after
2 months following birth is unusual but can be influenced with
treatment. (7) Spica casting may be done when there is failure of the Pavlik harness to maintain reduction, usually after
4 months of age. (6)
Radiologic Features. The postnatal diagnosis within the
1st year is best assessed with ultrasound. (3,6,8) Plain films can
show bony changes in this period but do not depict cartilaginous
abnormalities of the unossified femoral head or cartilaginous
labrum.
Plain films may appear normal in the first 2–3 months but subtle signs can be evident at 6 weeks. Plain films are most useful
from 2 to 8 months (4,5) and reliable depiction of DDH can
often be made after 4–6 months. The classic findings are an absent
or small proximal femoral capital epiphysis, lateral displacement of
the femur, and a shallow acetabulum with an increased inclination
of the acetabular roof, usually > 30° (Putti’s triad). (9) (Fig. 3-105)
Disruption of Shenton’s line and/or the iliofemoral line may show
interruption of the expected smooth arcuate contour if there is sufficient superior and lateral subluxation of the femur. Accessory
findings may include shortened varus femoral neck with varus
angulation, delayed closure of the ischiopubic synchondrosis, and
triradiate cartilages.
In adolescents and adults, long-standing dislocation manifests
as a shallow acetabulum and a large, flattened femoral head with
superior and lateral displacement. The head is at risk for complicating avascular necrosis. On occasions a neo- or pseudoacetabulum is formed on the posterosuperior surface of the iliac
wing. (Figs. 3-106 and 3-107) The degree of secondary osteoarthritis is often surprisingly low grade or even absent.
Ultrasound allows visualization of the bony and cartilaginous acetabular margins, the cartilaginous femoral head, the
amount of femoral head coverage by the acetabulum, and with
stress testing assessment of hip stability. (3–5,7) The hip is
scanned in the coronal plane, and the bony (α) and cartilaginous (β) roof angles are measured. The critical measurement is
the cartilaginous (α) angle and is the basis for classifying the
degree of dysplasia. (3) (Table 3-4) Dynamic hip ultrasound
may show no movement, slight movement, true subluxation,
and frank dislocation. (7) Following the application of the harness sonographic reassessment at 4- to 6-week intervals over
2–3 months are performed to monitor and document the therapeutic response. (4)
CT arthrography with intra-articular contrast is often performed
with severe dysplasia when a hip spica is applied to assess the attempted concentric positioning of the head within the acetabu-
Figure 3-105 DEVELOPMENTAL DYSPLASIA OF THE HIP,
PUTTI’S TRIAD. AP Pelvis. Observe the three classic findings
of DDH: small hypoplastic femoral capital epiphysis (arrow),
lateral and superior subluxation of the femoral head, and a
shallow acetabulum. The contralateral hip is normal in alignment and bony development.
3
Figure 3-106 DEVELOPMENTAL DYSPLASIA OF THE HIP,
ADULT PRESENTATION. A. AP Hip. Observe the deformity
and flattening of the femoral head. The acetabulum is shallow. B. AP Pelvis. Observe the shallowness of the original
Congenital Anomalies and Normal Skeletal Variants I
327
acetabulum (arrow) compared with the accessory acetabulum, which has formed on the lateral edge of the ilium.
C. AP Pelvis. There is complete bilateral dislocation of the
femoral heads from the acetabuli, both of which are shallow.
Figure 3-107 DEVELOPMENTAL DYSPLASIA OF THE HIP, PSEUDO-JOINT FORMATION. CT Three-Dimensional Reconstruction. The femoral head is dislocated posteriorly and superiorly, forming a pseudo-articulation with the iliac wing (arrow). The
acetabulum is shallow as a result of the dysplasia (arrowhead). COMMENT: Ultrasound is the optimum method of examination in the neonate up to 1 year of age
who is suspected of having developmental dysplasia of the hip (DDH). In the first
3 months of life, response to conservative treatment can be followed. Indications for
examination include family history of DDH, breech birth, neuromuscular disorders,
and eliciting a hip click on examination (Ortolani’s test). (Courtesy of Kenneth B.
Heithoff, MD, Minneapolis, Minnesota.)
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Table 3-4
Type
1A
1B
2A
2B
2C
2D
3
4
Morphologic Hip Classification
by Ultrasound
Description
Normal hip
Normal hip, transitional form
Physiologically immature
(< 3 months old)
Delayed ossification
(> 3 months old)
Deficient bony acetabulum;
femoral head concentrically
located
Deficient bony acetabulum;
femoral head subluxed
Dislocated
Severe dysplasia with
inverted labrum
Bony
Angle
(α) (°)
Cartilaginous
Angle
(β) (°)
> 60
> 60
50–59
< 55
> 55
> 55
50–59
> 55
43–49
70–77
43–49
> 77
< 43
> 77
Reprinted with permission from Graf R: Classification of hip joint dysplasia by means
of sonography. Arch Orthop Trauma Surg 102:248, 1984.
lum. Three-dimensional CT is especially useful for more subtle
adult dysplasias and presurgical planning. (5,10) MRI is increasingly employed in adult DDH to assess for avascular necrosis
and for presurgical planning. (6)
COXA VARA AND COXA VALGA
The normal femoral angle of incidence (Mikulicz’s angle, neckshaft angle) between the femoral neck and shaft ranges between
120° and 130°. An angle < 120° is designated as coxa vara, and
one > 130° coxa valga. (See Chapter 2.) Either of these deformities can be unilateral or bilateral, occur as an isolated finding as
a result of local causes, or be found in association with systemic
metabolic disease or skeletal dysplasia. The proximal femoral
physeal plate has a unique “bifid” growth pattern that contributes
to producing the deformities—the medial portion grows twice as
rapidly as the lateral portion. (1)
Coxa Vara
Synonyms. Infantile coxa vara, developmental coxa vara, congenital coxa vara.
Description. Failure of medial growth of the physeal plate
produces the femoral deformity of coxa vara.
Clinical Features. In apparently idiopathic cases (developmental coxa vara) a painless limp occurs at around 2 years of
age, affecting both sexes equally with bilateral presentation in
about one third of cases. (2) Known associations include proximal femoral focal deficiency, osteogenesis imperfecta, rickets,
fibrous dysplasia, cleidocranial dysplasia, fracture, postreduction
of congenital hip dislocation, slipped epiphysis, and Legg-CalvéPerthes disease. (3)
Radiologic Features. The femoral neck is short and broad with
a relatively large greater trochanter. The femoral angle is < 120°.
Frequently there is evidence of disturbed growth at the medial
metaphysis, where there may be a characteristic triangular frag-
Figure 3-108 COXA VARA. A. AP Pelvis. In this pubescent
female patient with open growth plates there is a decreased femoral angle with an inverted radiolucent “V ” in
the proximal metaphysis of the femur (arrow ). This is a
characteristic appearance for infantile coxa vara. An associated widening of the metaphysis is related to the deformity. There is no evidence of degenerative joint changes at
this time. B. AP Hip. Later into adolescence the triangular
fragment is incorporated into the femoral neck, with reduction of the femoral angle and broadening of the neck
(metaphysis). The greater trochanter is enlarged and
elevated secondary to the deformity, which produces a
Trendelenburg-type gait. (Panel A courtesy of C. H. Quay,
MD, Melbourne, Australia.)
ment, cortical irregularity, radiolucency, and a growth arrest line
that is closely apposed to the physis. The physis is more steeply
orientated and often wider than normal. The acetabulum may
be slightly deformed. (Fig. 3-108) Secondary degenerative joint
changes may be superimposed in adults.
Coxa Valga
Synonyms. Congenital coxa valga.
Description. Generally coxa valga is far less common than
coxa vara.
Clinical Features. The most common causes are from neuromuscular disease, especially cerebral palsy, with a lack of mechanical stimulation to the growth plate and muscle imbalance. Skeletal
dysplasias, including Turner’s syndrome, mucopolysaccharidosis,
and Pyle’s disease, can produce bilateral coxa valga. Arrest of
growth at the physeal vertex can produce the deformity. (1)
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Figure 3-110 CAUDAL REGRESSION SYNDROME. AP Lumbosacral Spine. Failure of formation of the sacrum creates close
proximity of the posterior iliac surfaces. Observe the degenerative reactive sclerosis on approximated iliac surfaces.
(Courtesy of Appa L. Anderson, DC, DACBR, Fellow, ACCR,
Portland, Oregon.)
Figure 3-109 COXA VALGA. AP Hip. The femoral neck is
elongated, slender, and more vertical. The femoral angle is
> 130º (arrow). (Courtesy of Eric C. Ho, MBBS, FRCS (Ortho),
Newcastle, New South Wales, Australia.)
Radiologic Features. The femoral neck is elongated and slender, and the femoral angle exceeds 130°. (Fig. 3-109) The proximal
femoral growth plate is close to horizontal, and the acetabulum is
usually shallow, with the femoral head laterally subluxed.
SACRAL AGENESIS
Synonyms. Caudal regression syndrome, sacrococcygeal
agenesis.
Description. Sacral agenesis is part of a spectrum of conditions
labeled caudal regression syndrome, in which there is congenital
absence of one or more segments of the sacrum. More extensive cases also demonstrate absence of lumbar and thoracic
segments. (1)
Clinical Features. The anomaly was first reported by Hohl
in 1850. (2) Up to 20% of cases have diabetic mothers. (3,4) At
birth, the sacral region is flat or depressed with deficient musculature of the lower extremities. Associated problems include intestinal and urinary anomalies, spinopelvic instability, scoliosis
(most common), myelomeningocele, hip dislocation or contracture, knee contracture, and foot deformity. A rare finding is the
sirenomelus deformity (mermaid syndrome), in which the legs
are fused and the feet are absent.
Radiologic Features. The sacrum and possibly some of the
caudal lumbar segments are absent. The two iliac bones are small
and closely apposed, often in contact with each other (bird-like
pelvis). If the patient were to assume a weight-bearing posture,
such as in a wheelchair, abnormal biomechanics would cause degenerative joint changes to occur where the two ilia articulate.
(Figs. 3-110 and 3-111) MRI is useful for evaluating the conus
and cauda equina. In 50% of cases, the conus is longer and characteristically wedge-shaped. (5)
Figure 3-111 CAUDAL REGRESSION SYNDROME. A. Lateral
Lumbar Spine. Note the absence of the sacrum and the L5
vertebra. The lowest lumbar vertebra present is L4, and it is
dysplastic. B. AP Pelvis. The sacrum is not present and the
approximation of the ilia can be noted. COMMENT: Caudal
regression syndrome occurs at a much higher rate in children
of mothers who have diabetes mellitus. (Courtesy of The
Children’s Hospital, Denver, Colorado.)
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HERNIATION PIT OF
THE FEMORAL NECK
Synonyms. Synovial herniation pit, Pitt’s pit, fibrocystic conversion defect, reactive area lesion, fossa of Allen.
Description. A relatively common radiographic finding found
in up to 5% of the population occurs in the anterosuperior femoral
neck as a ring-like, cystic lesion. (1,2)
Clinical Features. The majority of these lesions are asymptomatic, though larger lesions, especially in runners, have been
linked with hip symptoms that have resolved on surgical excision. (1) The cause remains speculative, although ingrowth of
fibrous and cartilaginous elements through cortical perforations with synovial fluid accumulation has been described. (2)
In addition, chronic mechanical erosive effects from the overlying iliopsoas, thickened capsule, and iliofemoral ligament
may be factors. There are two components of the defect—a superficial fossa (reactive area) and under its floor the variably
sized herniation pit. (1) The reactive area fossa may be present
in up to 75% of femoral neck specimens, but only 12% will have
co-existing pits. (1) Instances of progressive enlargement and
even regression have been recorded. (1,3)
Radiologic Features. On plain film views the pit is visible as
a discrete, sharply marginated geographic lesion at the antero-
Figure 3-112 FEMORAL HERNIATION PITS. A. AP Hip. A single corticated defect is evident at the upper outer aspect of
the femoral neck (arrow). An accessory ossicle is present at
the tip of the lesser trochanter (arrowhead). B. AP Hip. Two
side-by-side, well-corticated geographic areas of radiolucency
are present within the femoral neck (arrow). COMMENT:
This cyst-like lesion is found in at least 5% of the population; it has a speculative origin and contains fibrous and
cartilaginous elements and sometimes synovial fluid. The
lesion should not be confused with smaller circular defects
common in this area caused by penetrating nutrient vessels.
Historically the pits have been referred to as fibrocystic
conversion defects.
superior aspect of the femoral neck. The defect ranges in size from
1 to 30 mm; the majority are 5–10 mm. The cortex is usually intact,
no matrix is visible, and the sclerotic border is thin. (Fig. 3-112)
Bone scan is usually normal, though larger lesions may show avid
uptake owing to increased metabolic activity, enlargement, or fracture. (1,3,4) Thin-section CT confirms the benign appearance of a
subcortical cyst with a thin sclerotic border but may demonstrate
defects in the cortical surface, which may be focal or wide. Fracture
may be demonstrated only on this study. (1) Hounsfield values vary
from 30 to 50 HU with no significant contrast enhancement. MRI
shows features consistent with fluid (high signal on T2- and intermediate on T1-weighted images.)
ANOMALIES OF THE
LOWER EXTREMITY
BIPARTITE, TRIPARTITE,
AND MULTIPARTITE PATELLAE
Synonyms. Segmented patella.
Description. The patella is the largest sesamoid bone in the
body and normally develops a single ossification center in the
5th or 6th year of life. Failure of complete ossification can result
in isolated segments: a bipartite patella has two pieces, a tripartite patella has three pieces, and more than three pieces is called
a multipartite or segmented patella.
Clinical Features. The most common form is the bipartite
patella, characterized by an isolated smaller fragment located
at the superolateral quadrant of the patella. It occurs in 2–3% of
the population, with bilateral presentation in 40 –80% of cases.
Males are predominantly affected with male to female ratios as
high as 9:1. (1,2) The exact cause of the fragmentation is usually
unclear, although chronic trauma during ossification is thought
likely. (2) The superolateral location of the bipartite variant may
relate to insertional stress from the vastus lateralis. (3) The fragments are usually united by fibrous union, although in the uncommon symptomatic cases these may be disrupted and require
excision. (1,4,5)
Radiologic Features. Routine AP, lateral, and tangential radiographs are surprisingly unrewarding at times for visualization of
the separate ossicle(s). Radiographs taken in the PA position will
often show better definition of the patella and should be considered for any circumstance in which evaluation of the patella is a
priority. An externally rotated oblique view may also be useful for
accurate depiction. (Fig. 3-113)
A stress tangential view in the squatting position may show
separation of the fragments as a sign of fibrous attachment disruption. (6) The sclerotic, smooth bony margins and characteristic location of the separate ossicles usually allows for differentiation from acute fracture. (7) Nuclear bone scan can be
useful in symptomatic cases, demonstrating increased uptake at
the fragment junction zone as a manifestation of disruption. (2)
MRI can also depict signs of disruption, with localized bone and
soft tissue marrow edema, as well as fluid within the fibrous
disruption.
3
Figure 3-113 PATELLA, OSSIFICATION ABNORMALITIES.
A. Bipartite Patella, AP Knee. Observe the smoothly marginated separated segment at the upper outer pole of the
patella. B. Tripartite Patella, AP Knee. Note the two separated fragments in the same location. COMMENT: Bipartite
and tripartite patellae almost always occur on the supero-
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331
lateral margin of the patella. They should not be confused
with patellar fracture because fractures usually occur
through the waist of the patella and do not have smooth,
often sclerotic, margins. (Courtesy of Kenneth E. Yochum,
DC, St. Louis, Missouri.)
DORSAL DEFECT OF THE PATELLA
Synonyms. None.
Description. Dorsal defect of the patella (DDP) is a small osteolytic defect involving the superolateral dorsal surface of the patella
and is seen in about 1% of the population (1). Non-specific, noninflammatory fibrous tissue is present in the defect. (1,2)
Clinical Features. More than 80% of these anomalies will be
bilateral. (1) There is a male predominance. (3) The cause is unknown, but given the locational similarity to bipartite patella, a
chronic stress reaction to force from the vastus lateralis attachment may be involved. Related symptoms are rare, although if
the lesion extends to the retropatellar articular surface a coexisting cartilage defect may precipitate patellofemoral joint
pain. (2) Its presence has been used for forensic identification of
skeletal remains. (1)
Radiologic Features. The lesion is visible in the upper
outer quadrant of the patella and is best visualized on the PA,
AP, or oblique patella views. (Fig. 3-114) The lateral and
skyline projections confirm it to lie predominantly on the dorsal surface. The lesion is usually round with sharply demarcated margins, averaging 9 mm in diameter with a range of
4–26 mm. (4) Some lesions may show progressive healing
with obliteration of the lucency. (4,5) Uptake on bone scan occasionally occurs but does not correlate with a symptomatic
lesion. (3,6)
Figure 3-114 PATELLA, DORSAL DEFECT. Oblique Patella.
Observe the round lucent lesion surrounded by a sclerotic
margin in the upper outer quadrant of the patella (arrow).
COMMENT: These lucent defects are of no clinical significance but can present differential diagnostic confusion with
osteoid osteoma and Brodie’s abscess when patellar pain is
present. (Courtesy of Neil R. Manson, DC, Newcastle, New
South Wales, Australia.)
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FONG’S SYNDROME
Synonyms. Iliac horn syndrome.
Description. Possibly associated with the nail–patella syndrome
and hereditary onycho-osteo dysplasia, Fong’s syndrome is transmitted as an autosomal dominant. The patient demonstrates abnormalities of the nails of the hands and feet, renal dysplasia, and bone
deformities. (1,2)
Radiologic Features. The patellae are hypoplastic and laterally placed. Exostoses from the posterior aspect of the ilia are
noted (iliac horns). The articulations of the elbow are malformed.
(See Chapter 8.)
SESAMOID BONES AND OSSICLES
OF THE KNEE
Sesamoid bones and other ossicles at the knee are common, and
knowledge of their appearances and locations is important, especially in the differential diagnosis of intra-articular loose bodies.
Three of the most common include the fabella, cymella, and
meniscal ossicle.
Fabella. The fabella is the most commonly seen accessory sesamoid bone of the knee and is characteristically located within the
lateral head of the gastrocnemius muscle just above the tibiofemoral joint line. (1) (Fig 3-115) The population incidence is at
least 30% and 50 –80% are present bilaterally. (2) The shape
is typically triangular or semilunar in adulthood and more round
when first visible during the 15- to 25-year age period. The bone
is corticated, and internal trabeculae are visible. The flat or slightly
curved surface opposing the posterior aspect of the femoral condyle
is in direct contact with the knee joint and is covered by articular
cartilage. The fabella may show hypertrophy and marginal osteophytosis in osteoarthritis of the knee, whereas inflammatory ar-
Figure 3-116 MENISCAL OSSICLE. AP Knee. Observe the
focal triangular ossification complete with cortex within the
lateral margin of the medial meniscus (arrow). COMMENT:
Meniscal ossicles are found in about 1% of knees and are
usually of no significance, though they have sometimes been
found in tandem with meniscal tears. They are commonly
confused with osteochondral fragments. (Courtesy of
Kenneth B. Heithoff, MD, Minneapolis, Minnesota.)
thropathies may produce erosions and periostitis. (3) Fabellar fracture has been reported with knee hyperextension. (4) Developmental bipartite fabella does occur. (5) Avulsion of the lateral
head may be suspected if the fabella is below the joint line, overlapping the tibia. In joint effusions, the fabella is displaced away
from the femoral condyle. (6)
Cymella. A sesamoid bone within the tendon of the popliteus
tendon is seen on AP films within the femoral popliteal groove
and is often bilateral. (5) On the lateral study the ossicle lies close
to the joint space in the midline.
Meniscal Ossicle. Focal ossification within the meniscus most
commonly occurs in the posterior horn of the medial meniscus
and is seen in < 1% of knee examinations, most commonly in
young men. (7) On plain film examination the ossicle is often a
triangular radiopacity at the periphery of the meniscus, with a
distinct cortex and occasionally internal trabeculae. (Fig. 3-116).
Ultrasound, CT, or preferably MRI confirms the intrameniscal
location. The association with adjacent meniscal tear is inconsistent but has been implicated as a cause of the ossicle. In the
absence of meniscal tear there usually is no specific treatment
required.
TARSAL COALITION
Figure 3-115 FABELLA. Lateral Knee. The small corticated
spherical radiopacity present in the popliteal fossa (arrow)
represents a fabella. COMMENT: A fabella is a normal
sesamoid bone within the lateral gastrocnemius tendon. This
should not be confused with an intra-articular osteochondral
fragment from osteochondritis dissecans or a loose body
from synoviochondrometaplasia. On the AP projection the
fabella typically is seen overlying the lateral femoral
condyle, which assists in differentiating these conditions.
Synonyms. Tarsal bar, tarsal fusion.
Description. Tarsal coalition is a congenital condition of fibrous, cartilaginous, or bony union of two or more tarsal bones.
These can be congenital or acquired as a result of infection,
trauma, inflammatory arthritis, or surgery. (1)
Clinical Features. Congenital coalition affects 1–2% of the
population, and reports date from antiquity. (1,2) There is a failure of mesenchymal segmentation during early embryonic development. Up to 50% of coalitions are bilateral. (3) Almost 40%
of first-degree relatives of affected individuals will have the condition. (4) The most common site is at the calcaneonavicular
joint, which accounts for 50% of cases. The second most common
3
site (35%) is the talocalcaneal joint. Less common fusion patterns include talonavicular and calcaneocuboid and entire fusion
of the tarsus. Fusion of the medial cuneiform–first metatarsal
joint is rare. (5)
Many cases remain asymptomatic throughout life. Foot and
ankle pain from tarsal coalition usually begins in the 2nd and
3rd decades, often triggered by relatively minor trauma or athletic
activity. (6) Tarsal coalition can be a cause of chronic inversion injuries to the ankle and should be looked for in patients with such
histories. Reduced subtalar motion, pes planus, weight-bearing
pain, and persistent or intermittent spasm of the peroneal muscles
( peroneal spastic foot) are the most common associations suggesting the diagnosis. (7,8) Tarsal coalition is probably the most
commonly missed diagnosis clinically and radiologically in persistent pain syndromes of the foot and ankle. (6) Surgical resection
in recalcitrant pain of the coalition often is curative.
Radiologic Features. The findings on routine AP, medial
oblique, and lateral plain film studies are often subtle and may
require specific projections of the subtalar joints, including the
Harris-Beath axial projection of the calcaneus for adequate demonstration. (7) The diagnosis may be suspected when a nuclear bone
scan is performed that is hot over the tarsus in the subtalar joint,
dorsal talus, or talonavicular joint. (9) Thin-section CT or MRI
is confirmatory. (3)
Calcaneonavicular Coalition. The most common site for coalition is the calcaneonavicular joint and requires the medial oblique
view of the foot for optimum plain film demonstration. Osseous
fusions are marked by continuous bony trabeculae and will be
seen only after 8–12 years of age. Cartilaginous and fibrous connections may be inferred by elongation of the anterior process of
the calcaneus (anteater sign), with sclerosis and irregularity of the
opposing margins at the coalition site. (Fig. 3-117)
CT is more conclusive for the same findings, whereas MRI
will show the intermediate signal of the connecting tissue. Bone
marrow edema at the site of fusion is common and best seen on
fat-suppressed, short tau inversion recovery (STIR), or proton
density sequences. Accessory signs seen in calcaneonavicular
unions include hypoplasia of the head of the talus, osteoarthritis
of the talonavicular joint, and a prominent dorsal osteophyte of
the head of the talus (talar beak). (3) (Fig. 3-118) Fracture of the
bar has been reported. (10)
Figure 3-118 TALAR BEAK. A. Lateral Foot. Note the bony
excrescence on the dorsum of the talus (arrow). Observe
also the small os trigonum (arrowhead) and calcification of
the posterior tibial artery (crossed arrow) of the Mönckeberg
medial sclerosis variety as a marker of underlying diabetes.
Congenital Anomalies and Normal Skeletal Variants I
333
Figure 3-117 TARSAL COALITION. A. Lateral Foot.
Observe the large bony bar projecting from the anterior
process of the calcaneus (arrow ) (anteater sign).
B. Medial Oblique Foot. The site of fibrous union is
marked by sclerosis and frayed margins of the opposing
anterior calcaneal process and navicular (arrow). This is the
optimum view for plain film diagnosis. COMMENT: Tarsal
coalition often goes unrecognized and may be the underlying cause of chronic inversion injuries of the ankle or
non-responsive hindfoot pain.
B. Lateral Foot. A more prominent talar beak (arrow).
COMMENT: The talar beak is a developmental variant that
should not be confused with hypertrophic spurring seen
adjacent to the talonavicular joint. It may be associated with
tarsal coalition.
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Talocalcaneal Coalition. Fusion is most common at the middle
facet and less so at the anterior and posterior facet. Routine views
occasionally depict the union, but usually specific subtalar and
axial (7) views are required. Thin-section CT, especially in the
coronal plane, is the technique of choice for depiction. A bony
connection is recognizable by absence of the joint space and continuous trabeculae. Cartilaginous and fibrous unions show irregularity and sclerosis of the opposing spaces. MRI of the tissue
shows intermediate density without interposed synovial fluid. On
the lateral projection the C sign can be seen as a bony ridge curving between the talar dome and sustentaculum tali. (11) Secondary
signs include the talar beak, osteoarthritis of the posterior subtalar
joint, broad rounding of the lateral process of the talus, flattening
or increased concavity of the undersurface of the talar neck, balland-socket tibiotalar joint, and absence of the middle facet joint
on the lateral projection. (3)
VERTICAL TALUS
Synonyms. Congenital vertical talus, rocker bottom foot.
Description. Congenital vertical talus is an anomaly consisting
of vertical orientation of the talus in which the head is orientated
inferiorly and a dorsally dislocated navicular lies on the dorsal
surface of the talar neck (1).
Clinical Features. The vertical orientation of the talus appears to
be the result of a short Achilles tendon. (2) The characteristic physical deformity is known as the rocker bottom foot because of the
rounded prominence on the medial plantar surface. It is often associated with spina bifida manifesta, myelomeningocele, arthrogryposis, and Down’s syndrome. Males and females are equally
affected, and presentation is bilateral in 50% of patients (3).
Radiologic Features. The lateral film will show plantar flexion of the calcaneus and an increased plantar inclination of the
talus. (Fig. 3-119) The navicular then articulates with the dorsal
aspect of the talus. On the dorsoplantar film a calcaneus valgus
is present, along with metatarsus adductus. The altered plane of
articulations for the talus predisposes these patients to development of degenerative joint disease later in life, and various surgical procedures are performed. (1)
Figure 3-119 VERTICAL TALUS. A. Bilateral Lateral Ankles.
The talus (T ) has assumed a vertical position bilaterally.
B. Normal Axial Relationships, Lateral Foot. The enhanced
lines demonstrate the normal axial relationships of the talus
with the remainder of the forefoot and the calcaneus with
the talus. (Panel A courtesy of David M. Walker, DPM,
Melbourne, Australia.)
MORTON’S SYNDROME
SESAMOID BONES AND OSSICLES
OF THE FOOT AND ANKLE
Synonyms. Morton’s toe (foot), metatarsus atavicus, first ray
insufficiency syndrome.
Description. Morton’s syndrome, named after Dudley Morton,
occurs in the presence of an abnormally short first metatarsal and
a relatively long second metatarsal, which may appear broader. (1)
Clinical Features. Between 35% and 40% of the population may
have Morton’s syndrome. (2) Pain on activity at the plantar surface
of the foot, in the vicinity of the first and second cuneiform–
metatarsal joint is common. A skin callus may be present under
the second and third metatarsal heads. The relationship to predisposition for stress fractures of the second and third metatarsals
remains unclear. (2–4)
Radiologic Features. The dorsoplantar view shows the first
metatarsal to be significantly shorter than the second metatarsal.
There is a varus deformity of the first metatarsal. The second
metatarsal shaft and base will be increased in transverse diameter through periosteal bone deposition. The tibial and fibular
sesamoids are proximally displaced.
More than 40 recognized sesamoid bones and accessory ossicles
occur in the foot and ankle, some of which can produce pain syndromes and present diagnostic confusion with fractures. Knowledge of the locations and common radiologic features usually
allows accurate differentiation from traumatic and symptomatic lesions. Additional imaging, including bone scan, CT, and MRI, may
be needed in selected cases to confirm the diagnosis and investigate
possible association with regionally related pain syndromes.
Os Trigonum. Failure of union of the secondary ossification center at the posterior aspect of the talus results in a triangular bony ossicle best depicted on lateral radiographs of the foot and ankle. (Fig.
3-120) The ossicle remains united to the talus by a synchondrosis
and is usually present by 7–14 years of age. This variation occurs
in 7–14% of patients and is frequently bilateral. (1,2) Normally the
ossification center unites with the talus to form Stieda’s process.
The majority of cases remain asymptomatic, but os trigonum can
be a cause for posterior ankle tenderness and pain (os trigonum syndrome), often provoked with plantar flexion. Imaging findings in
3
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symptomatic cases include irregular margins of the ossicle and distortion of the adjacent pre-Achilles fat pad. Advanced imaging
findings include focal uptake on bone scan and signs of edema in
soft tissues, flexor hallux longus, and marrow of the os trigonum on
MRI. (2) (Fig. 3-121)
Os Tibiale Externum. A secondary ossification center located
medial to the navicular can be seen in 10 –15% of cases and
is best demonstrated on dorsoplantar views of the foot. (Fig
3-122) Synonyms include accessory navicular and naviculare
secundum. Three morphologic types occur, with different clinical implications. (3)
Figure 3-120 OS TRIGONUM. Lateral Ankle. Observe the
smoothly corticated separated ossicle (os trigonum) at the
posterior talar margin (arrow). COMMENT: The os trigonum
is caused by a failure of union of the secondary ossification
center at the posterior aspect of the talus. It usually is of no
clinical significance but in athletes can precipitate a painful
impingement syndrome (os trigonum syndrome).
A
Figure 3-121 OS TRIGONUM SYNDROME. A. T1Weighted MRI, Sagittal Foot. The os trigonum is
visible as a separated ossicle at the posterior aspect
of the talus (arrow). B. Inversion Recovery with Fat
Saturation MRI, Sagittal Foot. The water-sensitive
sequence shows bone marrow edema at the opposing contact subchondral surfaces of the os trigonum
and talus as localized high signal (white areas; arrowheads). COMMENT: This bone marrow edema is secondary to chronic motion across the site of separation and is frequently pain producing. MRI and
nuclear bone scan studies are the techniques of
choice to determine when an os trigonum is involved
in posterior impingement syndromes. (Courtesy of
James O’Sullivan, MBBS, FRCS (Ortho), Newcastle,
New South Wales, Australia.)
B
• Type I. Round to oval, has smooth margins, and is widely
separated from the navicular. It is a sesamoid bone in the
posterior tibial tendon and rarely has clinical significance.
• Type II. The most common variety. It is triangular
with a flat surface abutting the navicular and an intervening cleft of 1–2 mm filled with cartilage. This is the most
common symptomatic variant, owing to injury of the synchondrosis. It is best confirmed by increased uptake on
bone scan or local edema noted on MRI.
• Type III. Characterized by fusion of the ossicle to the navicular, producing an elongated, curved navicular (cornuate
navicular). These are rarely significant.
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Figure 3-122 OS TIBIALE EXTERNUM. A. Lateral Foot. Note
the well-defined bony density overlying the anterior process
of the calcaneus and navicular (arrow). A co-existing os
trigonum is also evident (arrowhead). B. Lateral Oblique
Foot. The smoothly corticated separated ossicle is shown to
advantage in this specific projection (arrow). COMMENT:
This variation can be seen in 10–15% of the population in
various forms. This free rounded ossicle form (type I) is rarely
associated with symptoms, though it may cause a palpable
bony bump. A more closely apposed triangular form (type II)
is more commonly symptomatic. (Reference data from
Lawson JP: Symptomatic radiographic variants in extremities.
Radiology 157:625, 1985.)
Os Intermetatarsum. An accessory ossicle located between the
proximal first and second metatarsals occurs in about 3% of the
population. (4) (Fig. 3-123) The majority are asymptomatic, but
the anomaly may push the first metatarsal into varus and produce hallux valgus or fracture, cause dorsal foot pain, or create
nerve compression. (5,6)
Hallux Sesamoids. The most common variation of the hallux
sesamoids is separation into two (bipartite) or more (multipartite) segments, which may occur in up to 33% of cases. Bilateral
presentation is seen in up to 85%. (7) (Fig. 3-124) Traumatic
separation of the partite cleft may be marked by a wider-thanexpected gap, positive bone scan, or edema and fluid in the
space on MRI.
Figure 3-123 OS INTERMETATARSEUM. Dorsoplantar Foot.
Observe the smoothly corticated supernumerary metatarsal
fused to the second metatarsal (arrow). This was bilateral
and associated with pain, which was relieved by removal.
COMMENT: The anomaly may manifest, as in this case, with
fusion of the ossicle to the metatarsal or as a separated
bony fragment. The majority are asymptomatic. (Courtesy of
Eric C. Ho, MBBS, FRCS (Ortho), Newcastle, New South
Wales, Australia.)
Figure 3-124 HALLUX SESAMOID BONES. A. Bipartite Single
Sesamoid (arrow). B. Bipartite Double Sesamoid (arrows).
C. Tripartite Single Sesamoid (arrow). COMMENT: The plantar
sesamoids are found in the flexor halluces brevis tendons.
These sesamoid bones have a wide spectrum of appearances,
as demonstrated, and care should be made to not identify the
partite variations as fracture lines.
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ANOMALIES OF
THE UPPER EXTREMITY
SUPRACONDYLAR PROCESS
OF THE HUMERUS
Synonyms. Supracondyloid process, supraepitrochlear process,
epicondylic process, supracondylar spur.
Description. Supracondylar process, a rudimentary exostosis
of bone present on the anteromedial aspect of the distal humeral
metaphysis 5–7 cm above the medial epicondyle, may be seen in
up to 3% of the population. (1,2)
Clinical Features. The majority of these anomalies remain clinically asymptomatic, but fracture or local neurovascular compression may result in symptoms. (3,4) The median nerve and
brachial artery are the most commonly compressed structures,
either beneath the bony spur or from an anomalous fibrous ligament traversing from the medial epicondyle to the supracondylar
process (Struther’s ligament). (5) Less commonly, the ulnar nerve
or both the ulnar and median nerves can be compressed, especially
if Struther’s ligament inserts more distally in the cubital fossa. (2)
There is an association with Cornelia de Lange syndrome. (6)
Radiologic Features. On lateral and oblique views of the elbow
or humerus a curved, beak-like corticated bony exostosis can be
seen originating from the distal humeral metaphysis, which is usually not > 2 cm in length. (Fig. 3-125) Characteristically, it is
Figure 3-126 RADIOULNAR SYNOSTOSIS. Lateral Elbow.
Observe the congenital fusion of the proximal interosseous
space between the radius and the ulna (arrow). This may be
appreciated only on views done in pronation and supination.
curved and tapered inferiorly, with its apex directed toward the
joint, differentiating it from the benign bone tumor osteochondroma, which typically is orientated away from an adjacent joint.
RADIOULNAR SYNOSTOSIS
Synonyms. None.
Description. A failure of longitudinal segmentation of the radius and ulna results in fusion of the two bones, most commonly
at the proximal end. This defect is transmitted as an autosomal
dominant, with an equal male to female incidence.
Clinical Features. The anomaly may be seen unilaterally, but
is bilateral in 80% of cases. (1) The length of the fusion may
extend from 3 to 6 cm and may be osseous or fibrous. From a clinical standpoint, pronation and supination may be limited to nonexistent. The defect may be diagnosed at birth, but diagnosis is
delayed in most instances until childhood. Surgery may result in
a more normal position for hand function. Associated conditions
include congenital dislocated hip, clubfoot, Madelung’s deformity, syndactyly, or polydactyly.
Radiologic Features. This diagnosis can be made on AP and lateral views of the elbow. These will demonstrate bony union of the
proximal radius and ulna, for a distance of up to 6 cm. (Fig. 3-126)
MADELUNG’S DEFORMITY
Figure 3-125 DISTAL HUMERUS, SUPRACONDYLAR PROCESS.
Lateral Elbow. Observe the curved, slender bony spur projecting from the anterior distal diaphyseal surface of the humerus
and orientated toward the joint (arrow). COMMENT: The
supracondylar process projects toward the joint, a helpful differential point from an osteochondroma, which projects away
from the joint. The supracondylar process is usually asymptomatic but sometimes creates a compression neuropathy of
the median nerve, especially if trauma is sustained.
Synonyms. None.
Description. Madelung’s deformity was first defined in 1878 by
a German surgeon, Madelung, who described a young woman with
a deformity of her wrist. (1)
Clinical Features. The deformity consists of a short bowed
radius, volar and ulnar tilt of the distal radial articular surface, and
dorsal dislocation of a relatively long ulna at the distal radioulnar
articulation. The basic defect appears to be premature fusion of the
medial aspect of the distal radial epiphysis. Females are affected
4:1 and at least 50% of cases are bilateral.
Four types are recognized according to cause: traumatic, dysplastic (e.g., dyschondrosteosis), genetic (e.g., Turner’s syndrome),
and idiopathic. The diagnosis is usually made when wrist pain develops in early adolescence, subsequently resolving on closure of
the growth plate (2,3). Carpal tunnel syndrome and, rarely, spontaneous rupture of the extensor tendons can occur. (4) The physical
appearance of the resulting wrist deformity has been called the
bayonet appearance. (5) The posteriorly dislocated ulna is mobile
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Figure 3-127 MADELUNG’S DEFORMITY. A. PA Wrist. Premature closure of the medial portion of the distal radial
physis has created an ulnar slant to the distal articulating
surface of the radius. A characteristic V-shaped deformity is
present on the ulnar side of the distal radius (arrow). There
is a widening of the radioulnar articulation, and the lunate
lies at the apex of the proximal carpal row. B. Lateral Wrist.
Note the characteristic posterior subluxation of the ulna,
which has been referred to as the bayonet deformity
(Madelung’s deformity).
and can be repositioned manually, although only temporarily. A
spectrum of variations can occur, ranging from less severe forms to
a reversed Madelung’s deformity, in which the distal radial articular surface is tilted dorsally and the ulna ventrally.
Radiologic Features. Frontal and lateral radiographs of the
entire forearm, including the wrist and elbow, should be obtained
bilaterally. On the frontal study the radius is short and bowed,
and the radial epiphysis is wedged, resulting in a V-shaped configuration of the carpus with the lunate at the apex. A lucent defect is often visible at the medial cortex of the radial metaphysis.
The distal ulna overlaps the triquetrum. Carpal coalition is sometimes observed. The distal radioulnar joint is widened, and frequently there is accompanying abnormality of the elbow involving the radius. The lateral projection shows dorsal subluxation
of the ulna and a volar tilt of the distal radial articular surface
greater than the normal 10–15°. (Fig. 3-127)
change in variance of 1 mm can alter the radioulnar mechanical
transfer characteristics by 25%, which has marked implications
for individuals who perform repetitive loaded rotational movements. (1,3–5) The triangular fibrocartilage complex at the distal ulna is thicker in patients with negative ulnar variance. Surgical
shortening of the radius by osteotomy is a common treatment in
the management of Kienböck’s disease, whereas ulnar osteotomy
may be undertaken for ulna compartment syndromes from positive ulnar variance. (3,6)
Negative Ulnar Variance. Shortening of the ulna has been implicated in avascular necrosis of the lunate (lunate malacia, Kienböck’s disease), although some reports have not supported this
contention. (7,8) Sports-related Kienböck’s disease is first seen at
a mean age of 18 years and tends to have a higher incidence of
negative ulnar variance. Patients with work-related Kienböck’s
disease present at a mean age of 34 years and exhibit less ulnar
variance. (9) Separation of the scaphoid from the lunate owing to
disruption of the scapholunate ligament (scapholunate disassociation) with rotation of the scaphoid can have a short ulna in up to
50% of cases. (10,11) When the ulna is very short (> 5 mm disparity), a painful pseudo-arthrosis can develop between the radius
and the ulna (radioulnar impaction syndrome). (12)
Positive Ulnar Variance. Elongation of the ulna, especially when
the ulnar styloid is enlarged, results in mechanical impingement
onto the lunate and triquetral bones (ulnar abutment syndrome,
ulnar impingement syndrome) (Fig. 3-128). The triangular fibrocartilage is developmentally thin. In addition, the extra stress
through the triangular fibrocartilage complex may lead to painful
perforations, tears, and degenerative disease. Premature closure of
the radial epiphysis from acute trauma or repetitive chronic trauma,
such as in gymnastics, is commonly the cause. (1,13)
Radiologic Features. Standard PA radiographs of the wrist
are diagnostic and can be supplemented with views in ulnar and
ULNAR VARIANCE
Synonyms. Radioulnar index, short ulna syndrome, ulnar abutment syndrome.
Description. If the radius and ulnar articular surfaces are in the
same plane, the configuration is termed neutral variance and is
normal. When the ulna is relatively short, the appearance is referred to as negative (minus) ulnar variance, and if the ulna is
longer it is a positive (plus) ulnar variance. (1)
Clinical Features. The relative lengths of the radius and ulna
are important factors in dispersing compressive forces across
the proximal carpal joint. Ulnar variance may occur as a developmental (idiopathic) variant or secondary to traumatic or inflammatory causes, including juvenile rheumatoid arthritis (2,3). A
A
B
C
Figure 3-128 ULNAR ABUTMENT SYNDROME. A. Positive
Ulnar Variance, PA Wrist. Note that the ulnar head (arrow )
lies distal to the articular surface of the radius (arrowhead ).
The adjacent articular surface of the lunate is slightly
angular as a manifestation of chronic ulnar head impaction.
B. Enlarged Ulnar Styloid Process, Oblique Wrist. Observe
that the ulnar styloid process is elongated and large (arrow)
despite the presence of negative ulnar variance. The styloid
tip is sclerotic along with the opposing dorsal planar surface
of the triquetrum, which has a smooth sclerotic surface
(arrowhead). C. Delayed Bone Scan, PA Wrist. Focal in-
creased uptake corresponding with the impaction sites between the elongated ulnar styloid and the opposing triquetrum confirms the chronic bony abutment syndrome of
the two structures. COMMENT: Two manifestations of ulnar
abutment syndrome have been demonstrated: positive ulnar
variance and elongated ulnar styloid process. Both of these
findings are frequently overlooked on plain film studies.
Bone scan and MRI studies often suggest the diagnosis because of focal isotope uptake or increased signal from edema
on T2-weighted studies. (Panel A courtesy of Jonathon
Powell, RT, Newcastle, New South Wales, Australia.)
Figure 3-129 NEGATIVE ULNAR VARIANCE. A. PA Wrist. The
head of the distal ulna lies proximal to the articular surface
of the radius. B. Complicating Kienböck’s Disease, PA Wrist.
In this case there is marked negative ulnar variance with
sclerosis and collapse of the lunate owing to avascular
necrosis (Kienböck’s disease). The long-standing collapsed
lunate has resulted in mild narrowing of the radiocarpal
joint with resultant degenerative subchondral cysts in the
subarticular bone of the distal radius.
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radial deviation to assess for impaction sites. (5) The length of
the ulna is compared to that of the radius by drawing a line perpendicular to the long axis of the radius from the most proximal
point of the radial articular surface. Normally the distal ulnar
articular surface should not project beyond this line. (1,14)
Negative Ulnar Variance. When the ulna is proximal to the perpendicular line the diagnosis is confirmed. Careful scrutiny of
the lunate for sclerosis, collapse, and fragmentation (Kienböck’s
disease) should be performed. (Fig. 3-129) Additional signs of
degenerative joint disease in the radiocarpal joint and a scapholunate space > 2 mm (scapholunate instability) should also be assessed. Additional imaging, including bone scan and MRI, may
help in identifying these tandem lesions.
Positive Ulnar Variance. When assessed as described above, positive ulnar variance is present when the ulnar articular surface lies
distal to the perpendicular line at the radial surface. A planar surface of the ulnar styloid process that, on ulnar flexion views, is in
close contact with the lunate or triquetral bone and sclerosis with
cyst formation are common features. The ulnocarpal joint space is
reduced. (Fig. 3-128) Bone scan is confirmatory for symptomatic
impingement with focal ulnar compartment uptake. MRI shows
compartmental bone marrow edema and allows the important assessments of the triangular fibrocartilage complex.
CARPAL COALITION
Figure 3-130 CARPAL COALITION. PA Wrist. Observe the
congenital synostosis of the lunate and triquetrum and the
site of fusion (arrow). There is post-traumatic non-union of
the ulnar styloid tip.
Synonyms. Carpal fusion.
Description. Carpal coalition is the fusion of two or more
carpal bones.
Clinical Features. Acquired fusions occur in infections, inflammatory arthritis, and trauma and following surgery. Congenital
unions may occur as an isolated anomaly or as part of a skeletal
dysplasia. Isolated congenital fusions typically affect the bones in
one row of the wrist (i.e., proximal or distal), whereas fusions that
cross from one row to the other tend to be associated with dysplasias. (1,2) Congenital carpal fusion is due to the result of a failure of embryonic cartilaginous segmentation and joint formation.
Carpal coalition is more common in males and has a higher incidence in blacks. (1,3) Up to 60% can be bilateral. (4)
Many combinations of coalition have been described, although
the most common fusion of the wrist is between the lunate and the
triquetral bones. (2) Others include capitate–hamate, trapezium–
trapezoid, and pisiform–hamate. The majority are asymptomatic,
although cystic change, degenerative joint disease, and increased
risk for fracture have all been described. (5,6) Lunate–triquetral fusions may be associated with scapholunate ligament disruption,
leading to instability. Skeletal dysplasias associated with carpal
coalition include Madelung’s deformity, Holt-Oram syndrome,
Turner’s syndrome, and Ellis-Van Creveld syndrome. (1,2)
Radiologic Features. Standard PA views show the coalitions
of the proximal carpal row the best, but oblique and lateral projections should be routinely employed in assessment. Loss of
joint space and continuity of cortical and trabecular bone between adjacent carpal bones is demonstrated. (Figs. 3-130 and
3-131) Diagnosis will be delayed until ossification is radio-
Figure 3-131 CARPAL COALITION. A and B. PA Bilateral
Wrists. Observe the union of the pisiform, capitate, and
hamate in this patient who also has only four fingers on each
hand. It appears the triquetra are agenetic. There is associated
Madelung’s deformity with angulation of the radial articular
surface. (Courtesy of James R. Brandt, DC, DABCO, Coon
Rapids, Minnesota.)
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graphically evident; it may be as late as 15 years of age before
diagnosis can be confirmed. In lunate–triquetral fusions, the
scapholunate space may be widened owing to disruption of the
scapholunate ligament. In the presence of wrist pain MRI examination may be useful to confirm the status of the intrinsic
carpal ligaments, the triangular fibrocartilage, and Kienböck’s
disease of the carpal lunate.
with avid localized uptake. (1,4) Thin-section CT, especially in
the coronal and axial planes, will show the bony exostosis and
whether or not there is a non-union of the accessory center. MRI
can help identify painful lesions, with the presence of bone or
soft tissue edema, fluid within a ganglion, and the relationship to
extensor tendons. Ultrasound can confirm the presence of ganglia
or tenosynovitis.
CARPAL BOSS
POLYDACTYLY
Synonyms. Carpae bossu, os styloideum, styloid process
syndrome.
Description. A palpable bony protuberance (boss) on the dorsum of the wrist caused by an accessory ossification center (os
styloideum) at the base of the second or third metacarpal constitutes a carpal boss. It may be joined to the adjacent metacarpal or
remain separated by a non-ossified synchondrosis.
Clinical Features. The anomaly was first described in 1725 by
Saltzman and redescribed in 1931 by Fiolle. (1) It may be seen in
1–3% of hand radiographs. (2) The majority remain asymptomatic, but occasionally there is limited wrist extension and pain
from a ganglion, bursitis, osteoarthritis, slippage of tendons, or
inflammation of the synchondrosis to the accessory center. (1,3)
Surgical removal may be required, or a stabilizing screw may be
inserted if a symptomatic synchondrosis is present. (3)
Radiologic Features. Routine views are often normal, although
the lateral study may show the bony exostosis. The optimum view
is in 30° supination, with ulnar flexion. (1) The bony protuberance
is recognized at the base of the second or third metacarpals on
the dorsal surface at the joint with the capitate and trapezoid.
Frequently the bone is sclerotic and contains cysts. In the presence of a synchondrosis, the junction zone is often irregular and
may show sclerosis. (Fig 3-132) Bone scan is useful to localize
the presence of the lesion and to identify its inflammatory nature
Synonyms. None.
Description. Polydactyly is an increased number of fingers
or toes.
Clinical Features. There is a predominance for polydactyly in
black patients. The significance of the condition depends on
whether the extra digit is on the radial (preaxial) or ulnar (postaxial) side of the hand. Preaxial polydactyly is seen in Apert’s
syndrome, Fanconi’s syndrome, and Holt-Oram syndrome. Postaxial polydactyly is associated with Ellis-Van Creveld syndrome
and Laurence-Moon-Biedl syndrome. (1) The diagnosis of polydactyly is evident clinically and can occur as an isolated entity
unassociated with any syndromes. (Fig. 3-133)
Radiologic Features. The role of radiographs is to determine the nature of osseous development within the extra finger
as well as any additional bony maldevelopment associated with
co-existing syndromes.
A
Figure 3-132 CARPAL BOSS. A. Lateral Wrist. Note the prominent bony protuberance at the base of the third metacarpal
with irregular opposing cortices (arrow). B. Coronal CT Scan,
Wrist. The separated ossicle is clearly demonstrated (arrow).
Note the irregular cortices at the site of non-union
(arrowhead ). C. Bone Scan, Wrist. Observe the increased uptake at the base of the third metacarpal (arrow). COMMENT:
The patient had trauma to the hand 2 days previously with
SYNDACTYLY
Synonyms. None.
Description. Syndactyly is the most common developmental
anomaly of the hand, but it may also affect the foot and is manifest
B
C
marked soft tissue swelling of the dorsum of the hand over
the third metacarpal base. Background occupational-induced
pain, over the dorsal wrist prominent bony protuberance, to
the base of the third metacarpal had been experienced for
3 years. This accounted for the features of chronic separation
with mobility at the carpal boss. (Courtesy of Roland Hicks,
MBBS, FRCS (Ortho), Newcastle, New South Wales, Australia.)
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Figure 3-133 POLYSYNDACTYLY. Dorsoplantar Foot. Note
the duplication and hypoplasia of the second ray with soft
tissue fusion to the great toe. (Courtesy of Bryan Hartley,
MD, Melbourne, Australia.)
Figure 3-134 SYNDACTYLY. PA Hand. Note that the third
metacarpal is bifurcated and there is fusion of the third and
fourth fingers. Also note that there remains a separate
fourth metacarpal. (Courtesy of John Chomyn, MD, University
Hospital, Denver, Colorado.)
in the form of fusion of the skin between the digits (syndactyly)
or fusion of the osseous phalanges of adjacent digits (synostosis). It is the result of a defect of mesenchymal organization during the 5th fetal week, resulting in failure of an interphalangeal
joint to develop. (1)
Clinical Features. The incidence is thought to be 1 in 2500
births (2), with a distinct male predominance. (3) It is more common in whites than blacks in a 10:1 ratio. (4) It may be considered
partial when the fusion involves only the proximal segments, or
complete if the fusion extends to the distal aspect. If the fusion
is distal, with the proximal segments free, the appropriate name
is acrosyndactyly.
Five types of syndactyly have been described: (a) zygodactyly (most common type), involving the third and fourth
fingers and / or the second and third toes; (b) synpolydactyly
of the third and fourth fingers, with partial or complete reduplication of fingers three and four in the web (or may be toes
four and five); (c) ring and little finger syndactyly, in which
the middle phalanx of the fifth finger is rudimentary or absent;
(d ) complete syndactyly, involving all fingers; and (e) syndactyly associated with metacarpal and /or metatarsal synostosis. (5) It more commonly affects the medial side of the
hand. (6)
Syndactyly may be associated with other syndromes, including Poland’s, Apert’s, Saethre-Chotzen, and Pfeiffer’s
syndromes. (5)
Radiologic Features. On plain film examination the affected
extremity will show soft tissue fusion between the fingers or toes
and any osseous anomalies of development. In some instances
fusion of the phalanges of the same finger or toe may be present;
in other cases fusion of the phalanges between adjacent digits
(symphalangism) can be seen. (Fig. 3-134)
DIGITAL CURVATURES
Kirner’s Deformity. Kirner’s deformity, a type of curvature of the
fifth finger, is also known as dystelephalangy. (1) It occurs sporadically or is transmitted as an autosomal dominant trait. This
abnormality usually affects the fifth fingers bilaterally. (2) Physical examination will show a palmar curvature of the distal phalanx in a patient beyond 5 years of age. Before this age, the deformity is usually unnoticeable. Soft tissue swelling may precede
the bone deformity. (3) On radiographic examination there is
volar curvature of the fifth digits, with separation (widening)
of the growth plate and deformity of the epiphysis. There is no
apparent clinical significance of this deformity.
Clinodactyly. Hypoplasia and tilting of the distal articular surface of the middle phalanx of the little finger results in either
radial or ulnar curvature of the finger. Although it has been reported in > 30 skeletal dysplasias and occurs with increased frequency in Down’s syndrome, it is also seen in 1% of normal
hand radiographs (2).
Camptodactyly. Camptodactyly is permanent dorsiflexion of
the digit, usually at the proximal interphalangeal joint and usually caused by a shortening of the sheath of the flexor digitorum
profundus.
Delta Phalanx. There is a triangular appearance of the phalanx
in delta phalanx; it most often involves the thumb, sometimes
affecting the metacarpal.
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ATLAS OF COMMON NORMAL
SKELETAL VARIANTS
Figure 3-135 FALX CALCIFICATION. PA Skull. There is midline dense calcification of the falx cerebri (arrow), which is
of no clinical significance.
Figure 3-136 CHOROID PLEXUS CALCIFICATION. A. AP
Towne’s Projection. B. Lateral Skull. There are calcifications
in the glomus of the choroid plexuses bilaterally (arrows),
which lie within the trigone of the lateral ventricle and are
of no clinical significance.
Figure 3-137 PINEAL GLAND CALCIFICATION. Lateral Skull.
There is granular calcification within the pineal gland
(arrow), which is of no clinical significance. COMMENT: This
is a common finding on skull and intracranial imaging,
occurring in up to 60% of the population by 40 years of age.
Displacement from the midline has been used as a marker
of intracranial shift. (Courtesy of Kenneth E. Yochum, DC,
St. Louis, Missouri.)
Figure 3-138 BASAL GANGLIA CALCIFICATION. A. Towne’s
Projection. B. Lateral Skull. There is linear calcification
within the basal ganglia bilaterally (arrows). COMMENT:
Calcification of the basal ganglia may occur as a normal variant or can be associated with pseudo-hypoparathyroidism
and pseudo-pseudo-hypoparathyroidism.
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Figure 3-139 PETROCLINOID LIGAMENT CALCIFICATION.
Lateral Skull. Calcification of the petroclinoid ligament is
present (arrow). COMMENT: This is not to be confused with
calcified atheroma of the basal or carotid artery.
Figure 3-140 BRIDGED SELLA TURCICA. A and B. Lateral
Skull. There is osseous bridging between the anterior and
the posterior clinoid processes across the diaphragm sellae,
creating a bridge. (Panel B courtesy of James M. Kolodziej,
DC, Denver, Colorado.)
Figure 3-141 HYPEROSTOSIS FRONTALIS INTERNA. A. PA
Skull. B. Lateral Skull. There is florid ossification adjacent to
the inner table of the frontal bone bilaterally (arrows). The
frontal bone itself is normal. COMMENT: Hyperostosis
frontalis can be a difficult condition to differentiate from
intracranial meningioma, except that meningoma is unilateral
and often creates sclerosis and thickening of the frontal
bone itself.
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Figure 3-142 PERSISTENT METOPIC SUTURE. A. PA Skull.
B. AP Towne’s Projection. There is persistence of the metopic
suture (arrows). COMMENT: The suture is always present at
birth in the midline of the frontal bone and is usually oblit-
erated by 8 years of age. Persistence into adulthood may
simulate fracture and can be associated with cleidocranial
dysplasia.
Figure 3-143 PARIETAL FORAMINA. A and B. Lateral Skull.
Near the vertex there are focal defects in the calvaria, which
extend through both the inner and the outer tables. These
parietal foramina serve as a conduit for the emissary veins of
Santorini (arrows).
Figure 3-144 WORMIAN BONES. Lateral Skull. There are
multiple wormian bones, seen as isolated bony fragments,
along the line of the lambdoidal suture. COMMENT:
Wormian bones represent isolated intrasutural bones occurring along the course of the cranial sutures, most commonly
the lambdoidal suture. They may be seen as a normal variant or can occur with cleidocranial dysplasia, osteogenesis
imperfecta, and other congenital anomalies. (Courtesy of
C. H. Quay, MD, Melbourne, Australia.)
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Figure 3-145 PROMINENT EXTERNAL OCCIPITAL PROTUBERANCE. A and B. Lateral Upper Cervical Spine. The external
occipital protuberance is enlarged, which is a congenital
variation of no clinical significance.
Figure 3-146 BILATERAL MANDIBULAR RADIOLUCENCIES
FROM WISDOM TOOTH EXTRACTIONS. AP Open Mouth.
Removal of the mandibular third molar (wisdom) teeth results in a well-circumscribed lucency of the alveolar socket
(arrows). COMMENT: The smooth margin and short zone of
transition should suggest a benign process and not an
aggressive infectious or neoplastic lesion. (Courtesy of Leslie
Pepper, DC, Denver, Colorado.)
Figure 3-147 ADENOIDAL TISSUE. There is a prominent indentation on the posterior surface of the nasopharyngeal air
space from slight enlargement of adenoidal tissue (arrows).
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Figure 3-148 NASAL CAVITY PSEUDO-TUMOR, NEUTRAL.
Lateral Cervical Spine. A rounded soft tissue density (arrow)
is superimposed on the dorsal wall of the maxillary sinus and
represents the normal inferior turbinates and the superimposed mandibular coronoid processes. COMMENT: This
finding should not be confused with an intranasal neoplasm
or maxillary polyp. (Courtesy of Ronald D. Myhra, DC,
Denver, Colorado. Reference data from Sistrom CL, Keats TE,
Johnson CM: The anatomic basis of the pseudotumor of the
nasal cavity. AJR 147:782, 1986.)
A
B
Figure 3-149 PSEUDO-TUMOR (C1–C2 LATERAL MASS).
A. Lateral Upper Cervical Spine. There is a peculiar radiopacity seen anterior to the C2 vertebral body (arrow), mimicking the appearance of a soft tissue neoplasm. B. AP Open
Mouth. On this view there is exuberant degenerative joint
disease affecting the C1–C2 articulation, explaining the
pseudo-tumor appearance seen in panel A. COMMENT: This
degree of degenerative joint disease affecting the C1–C2 lateral mass articulation is peculiar. (Courtesy of Kevin J.
LaLonde, DC, Duxbury, Massachusetts.)
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Figure 3-150 TONGUE SILHOUETTE. AP Open Mouth. The
radiopaque soft tissue density seen adjacent to the lateral
mass and articular pillars of C2 (arrows) represents the water
density of the tongue and not an ossific or calcific lesion.
Figure 3-151 TONGUE PSEUDO-MASS. AP Open Mouth
Cervical. There is a large radiopaque water density superimposed on the skull base and the odontoid process, which
represents the tongue and not some form of bony pathology. (Courtesy of Joel G. Green, DC, Salem, Massachusetts.)
Figure 3-152 MACH EFFECT. A. AP Open Mouth. The overlap density created from the posterior arch of the atlas
crossing the base of the dens simulates a type II odontoid
fracture or os odontoideum (arrows). B. AP Open Mouth.
Overlap of the frontal incisor teeth has produced a pseudofracture line at the odontoid base (arrow). Also observe the
bilateral paraodontoid notches lateral to the dens attachment to the axis body, which are a normal variant.
COMMENT: A Mach effect is created whenever two densities
overlie one another and produce a lucent line at their junction that is a physiologic optical illusion.
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Figure 3-153 PARAODONTOID NOTCHES. AP Open Mouth.
There are bilateral paraodontoid notches (arrows), which
should not be confused as areas of erosion. COMMENT:
These notches are a normal developmental variant of no
clinical significance.
Figure 3-155 VIKING HELMET SIGN. AP Open Mouth.
“Horns” (arrows) protrude from the sides of the dens, a rare
morphological variation of the dens. Also seen in the right
lower jaw is a lucent area left by a recent tooth extraction
(arrowhead). (Courtesy of William E. Litterer, DC, DACBR,
Fellow, ACCR, Elizabeth, New Jersey.)
Figure 3-154 PSEUDO-JEFFERSON’S FRACTURE. AP Open
Mouth. There are overhanging edges of the C1 lateral
masses (artist-enhanced lines) bilaterally in this 10-year-old
male. COMMENT: In an adult this finding would suggest a
Jefferson’s fracture; however, in a child, this represents the
differential growth rate between C1 and C2. (Courtesy of
Appa L. Anderson, DC, DACBR, Fellow, ACCR, Portland,
Oregon.)
Figure 3-156 C2, PSEUDO-FRACTURE. Lateral Cervical Spine.
There is a radiolucent cleft (arrow) seen in the upper inferior
aspect of the C2 vertebral body. COMMENT: This is a normal
developmental growth variant for the base of the odontoid
process. This should not be confused with a fracture. Note
the secondary ring apophyses at the anterior corners of the
C2–C4 vertebral endplates (arrowheads). (Courtesy of Charles
W. Cairns, DC, Reedley, California.)
Figure 3-157 CALCIFIED CERVICAL LYMPH NODES.
A. Lateral Cervical Spine. Superimposition of the calcified cervical lymph nodes over the C3 vertebral body
has caused an appearance that mimics a pathologic
ivory vertebra. B. AP Lower Cervical Spine. This view
emphasizes the fundamental importance of obtaining
two views at 90º to each other as a minimum radiologic
investigation. The calcified nodes are seen (arrows).
(Courtesy of Allan J. Warrener, DC, Melbourne,
Australia.)
Figure 3-159 SUBMANDIBULAR GLAND CALCIFICATION.
Flexion, Lateral Cervical Spine. Circular calcification is seen
below the mandible and above the hyoid bone, characteristic of submandibular gland calcification. This patient complained of dryness of the mouth. (Courtesy of Kevin J.
LaLonde, DC, Duxbury, Massachusetts.)
Figure 3-158 CALCIFIED CERVICAL LYMPH NODES. A. AP
Cervical Spine. B. Lateral Upper Cervical Spine. There is
unilateral calcification in the submandibular lymph nodes
(arrows). Note that they are incompletely calcified, with the
non-calcified area representing the nodal hilum. COMMENT:
Calcifications of this degree frequently follow prior inflammatory disease of the lymph nodes, sometimes tuberculosis,
but are otherwise of no clinical significance.
Figure 3-160 SUBLINGUAL THYROID. Lateral Cervical Spine.
The rounded, soft tissue mass at the base of the tongue
(arrow) represents ectopic thyroid tissue that failed to descend into its normal position. (Courtesy of Michael A. Fox,
MD, Memphis, Tennessee.)
C
Figure 3-161 CALCIFIED STYLOHYOID LIGAMENT. A. AP
Open Mouth. Linear ossification is present bilaterally, extending from the skull base inferomedially, which has pseudojoints (arrow). B. Lateral Cervical Spine. The ossifications can
be seen extending to the lesser cornu of the hyoid bone
(arrows). At the site of pseudo-joint formation the ossification becomes bulbous in appearance, a common finding not
related to symptoms. C. Coronal CT. The segmented nature
of the stylohyoid ligament calcification (arrow) is more apparent on CT. COMMENT: The calcification is commonly and
erroneously implied to be calcified atherosclerosis of the vertebral artery. Symptoms of anterior neck pain, odynophagia,
and ear pain are uncommon in this condition but when present have been referred to as Eagle’s syndrome. (Panel C
Courtesy of Michael Grayson RT, Newcastle, New South
Wales, Australia.)
Figure 3-162 THYROID CARTILAGE CALCIFICATION. A. AP
Lower Cervical Spine. Calcification of the superior wings of
the thyroid cartilage results in divergent densities overlying
C4–C5 (arrows). B. Lateral Cervical Spine. The calcification is
dense and irregular (arrow). There is a block vertebra at C6
and C7. COMMENT: The appearance on the frontal study is
easily misconstrued as being within the vertebral artery, but
its oblique lateral course is not anatomically compatible with
that of the artery. The calcification is within cartilage and
not the thyroid parenchyma. Calcification becomes more
dense with age and is found in > 80% of individuals
younger than 40 years of age. It has no clinical significance.
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Figure 3-163 THYROID CARTILAGE CALCIFICATION. A. AP
Lower Cervical Spine. There are bilateral calcifications
(arrows) of the superior wings of the thyroid cartilage at the
levels of C5–C7. B. AP Lower Cervical Spine. Note the bilaterally calcified thyroid cartilage (arrows) extending obliquely
from C6, cephalad. COMMENT: This calcification is commonly
mistaken for atherosclerosis in the vertebral artery. Recall
that the vertebral artery passes through the transversarium
foramen and would be vertically orientated.
Figure 3-164 THYROID CARTILAGE CALCIFICATION VERSUS
ATHEROSCLEROSIS OF THE EXTERNAL CAROTID ARTERY.
AP Lower Cervical Spine. The calcific thyroid cartilage has a
curvilinear appearance (arrows). This should not be confused
with artery calcification. COMMENT: The orientation and
oblique angle not running vertically through the transverse
foramina helps differentiate this from the vertebral arteries.
Observe the atherosclerosis present in the area of the external carotid artery (arrowhead). (Courtesy of Joel G. Green,
DC, Salem, Massachusetts.)
Figure 3-165 THYROID CARTILAGE CALCIFICATION. Lateral
Cervical Spine. Prominent calcification of the superior
cornua of the thyroid cartilage creates a ring-like density
(arrows).
3
Figure 3-166 LARYNGEAL CONSTRICTION. AP Lower
Cervical Spine. The thin area of radiolucency superimposed
on the C6 vertebral body represents the vocal cords constricting the tracheal air shadow (arrow). COMMENT: This
should not be confused with a spina bifida occulta or a
vertical fracture line.
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Figure 3-167 AEROPHAGIA. A. Lateral Cervical Spine. Air in
the upper esophagus has been fortuitously captured at the
time of exposure (arrow). The normal air density of the
pharynx and trachea is identified (arrowheads). B. AP Lower
Cervical Spine. There is air trapped in the pyriform sinus of
the larynx adjacent to C4–C5 (arrow). (Panel B courtesy of
Michael J. Nehring, DC, Boulder, Colorado.)
Figure 3-168 C1, POSTERIOR TUBERCLE DEFORMITY. Lateral
Cervical Spine. The posterior tubercle of the atlas is deformed into a peculiar knife-like configuration.
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Figure 3-169 ATLAS, POSTERIOR TUBERCLE NOTCH.
A–C. Lateral Cervical Spine. A small notch-like defect, which
is well corticated, is evident in the superior aspect of the
posterior tubercle of the atlas (arrows) in these three cases.
There is an adjacent spur in panels A and C, which is a commonly associated finding. Panels A and C also show various
forms of a posterior ponticle. COMMENT: These notches are
common developmental variants of no clinical significance.
Figure 3-170 C1, LARGE POSTERIOR TUBERCLE. Lateral
Cervical Spine. The posterior tubercle of the atlas is large
but maintains normal alignment with the spinolaminar junction. (Courtesy of Dennis P. Nikitow, DC, Denver, Colorado.)
Figure 3-171 C1, SHORT POSTERIOR ARCH. Lateral Cervical
Spine. The spinolaminar line (posterior cervical line) is disrupted at C1–C2, with the anteriorly placed C1 spinolaminar
line. This patient was asymptomatic; the variant represents
a decrease in the canal size. COMMENT: Cases have been
recorded as being symptomatic. The most common cause for
a break in the posterior cervical line at C1–C2 is atlantoaxial
instability secondary to insufficiency of the transverse ligament from inflammatory spondyloarthropathy (e.g., rheumatoid arthritis). (Courtesy of Ron D. Myhra, DC, Denver,
Colorado.)
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Figure 3-172 SCLEROTIC ANTERIOR TUBERCLE. Lateral Upper
Cervical Spine. The anterior tubercle is homogeneously sclerotic but of normal size (arrow). This is a common, normal
variant. COMMENT: An enlarged, sclerotic anterior tubercle of
the atlas is commonly seen as a marker of stress hypertrophy
from spina bifida occulta of the atlas posterior or anterior
arch, odontoid anomalies (os odontoideum, agenesis), and
long-standing insufficiency of the transverse ligament.
Figure 3-173 C1, SMALL ANTERIOR TUBERCLE. Lateral
Cervical Spine. The anterior tubercle of the atlas is smaller
than normal and is a developmental variant of normal
(arrow).
Figure 3-174 C1, SPONDYLOSCHISIS. A. Base Vertex Skull.
There is a cleft in the anterior arch of the atlas (arrow).
B. Axial CT, C1–C2. Failure of fusion of both the anterior
(arrow) and the posterior arch (arrowhead) of the atlas is
seen. Also identified in this study are the dens (D) and mastoid air cells (M). (Courtesy of William E. Litterer, DC, DACBR,
Fellow, ACCR, Elizabeth, New Jersey.)
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Figure 3-175 CENTRAL INCISOR GAP. A and B. AP Open
Mouth. A vertical radiolucent line that appears to split the
odontoid process (arrows) represents the interdental space
between the maxillary central incisors. COMMENT: This may
appear to simulate a vertical fracture of the odontoid
process.
Figure 3-177 ATLAS, NOTCHED SUPERIOR ARTICULATING
SURFACES. AP Open Mouth. At the superomedial surfaces of
the atlas lateral masses there are symmetric radiolucent
notch-like concavities (arrows). Observe also the normal
paraodontoid notches (arrowheads) near the base of the
odontoid process.
Figure 3-176 ODONTOID PROCESS CLEFT. AP Open Mouth.
A congenital horizontal cleft at the base of the odontoid
process at the odontoid synchondrosis creates a pseudofracture appearance (arrow). There is co-existing asymmetry
of the joint planes of the atlantoaxial joint. (Courtesy of
Bruce Kniegge, DC, Honduras.)
Figure 3-178 ATLANTOAXIAL BALL-AND-SOCKET ARTICULATION. AP Open Mouth. The normally planar atlantoaxial
joints instead are ball-and-socket in configuration. Also note
the paraodontoid notches and the Mach effect, creating a
lucent pseudo-lesion across the base of the dens. (Courtesy
of Tyrone Wei, DC, DACBR, Portland, Oregon.)
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Figure 3-179 PERSISTENT INFANTILE ODONTOID PROCESS.
A and B. AP Open Mouth. Two examples of anomalous development of the base of the odontoid process showing the
characteristic findings of an orthogonal angulation to the
atlantoaxial joint plane and a co-existing broadening of the
odontoid base. COMMENT: This configuration should not be
confused with a post-traumatic deformity. The atlantoaxial
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357
biomechanics will be altered with decreased rotation, especially on the affected side. There is no predisposition to instability or degenerative change documented. (Courtesy of
Donald E. Freuden, DC, DABCO, Denver, Colorado. Reference
data from McClellan R, El Gammal T, Willing S, et al.:
Persistent infantile odontoid process: A variant of abnormal
atlantoaxial segmentation. AJR; 158:1305, 1992.)
Figure 3-180 V-SHAPED ATLANTODENTAL INTERSPACE.
Lateral Cervical Spine. The normal atlantodental interspace
(ADI) in children (arrow) is sometimes shaped as the letter V
owing to physiological sagittal flexion of the atlas on the
axis. COMMENT: After neck trauma in this 10-year-old boy
there was initial concern for this appearance, which possibly
represented atlas transverse ligament injury. Note that the
ADI is normal at < 5 mm, measured halfway from the top to
the bottom of the articulation. (Reference data from Bohrer
SP, Klein A, Martin W: V-shaped predens space. Skeletal
Radiol 14:111, 1985.)
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Figure 3-181 C2, PSEUDO-SUBLUXATION. A. Lateral
Cervical Spine. This 10-year-old has a normal atlantodental
space of < 5 mm (arrows) and trapezoidal-shaped C3–C6 vertebral bodies. The C2 vertebra is flexed and lies anterior to
C3. COMMENT: The posterior cervical line formed by the
alignment of the spinolaminar junction lines from C2 to C3
remains congruent, which confirms there is no pathological
slippage (pseudo-subluxation). B. Flexion, Lateral Cervical
Spine. In another patient the C2–C3 anterior slippage is accentuated on flexion. The atlantodental interval shows a
normal V-shaped variation owing to atlantoaxial flexion.
COMMENT: This C2–C3 pseudo-subluxation with flexion and
anterolisthesis is a normal physiological variant found under
the age of 18. It appears to be caused by age-related ligamentous laxity, unossified and horizontally placed facet joint
planes, and a higher fulcrum of motion found in young
necks. (Panel B courtesy of Donald E. Freuden, DC, DABCO,
Denver, Colorado. Reference data from Swischuk LE:
Anterior displacement of C2 in children: Physiologic or
pathologic? Radiology 122:759, 1977.)
3
Figure 3-182 C2–C3, PSEUDO-FUSION FACET JOINTS.
Flexion, Lateral Cervical Spine. The facet joint space C2–C3
is not demonstrated and creates the appearance of being
fused (arrow). COMMENT: This is an extremely common
finding and is caused by the oblique lateral angulation of
the joint surfaces such that the radiographic beam does not
pass through the joint.
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Figure 3-183 C3, FACET NOTCH. Lateral Upper Cervical
Spine. A distinct notch-like defect is present on the posterior
aspect of the superior facet surface of C3 (arrow). There is
also a steeper angulation of the joint plane and relative
hypoplasia of the articular pillar, which are common tandem
findings. COMMENT: These changes should not be mistaken
for erosive arthritis or fracture.
Figure 3-184 C2, FORKED SPINOUS PROCESS. Lateral Upper
Cervical Spine. Although C2 is an atypical cervical vertebra,
the spinous process can bifurcate. This bifurcation is typically
in transverse orientation, whereas in this normal variant it is
a predominantly sagittal bifurcation. (Courtesy of George E.
Springer, DC, Clearwater, Florida.)
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Figure 3-185 C2, NON-UNION OF THE SPINOUS PROCESS. A–C. Lateral Upper Cervical
Spine. The non-union of the axis spinous
process has various configurations (arrows).
Note the evidence for a long-standing condition, with smooth sclerotic opposing bony
margins not found in acute fracture.
COMMENT: When a fracture occurs at the tip
of a spinous process, the fracture fragment
displaces caudally. This and the sclerotic margins help differentiate this anomaly from a
recent fracture. D. Lateral Upper Cervical
Spine. All the features of a long-standing
avulsion are present, with smooth sclerosis opposing bony margins (arrow). E. T2-Weighted
MRI, Axial. This pulse sequence enhances
water to appear white, as identified by the
cerebrospinal fluid in the spinal subarachnoid
space. At the site of non-union of the spinous
process, fluid can be seen in the separating
cleft, signifying the anomaly; a pseudo-joint is
also present (arrow). Note that the adjacent
bone is homogeneously dark, confirming the
lack of bone marrow edema, which is another
sign of a chronic condition and not the site
for any clinical pain syndrome. (Courtesy of
Ralph E. Brewer, DC, Denver, Colorado.)
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Figure 3-186 NUCHAL BONES. Lateral Cervical Spine.
Ossification is present posterior to the lower cervical spinous
processes. Nuchal bones exhibit a smooth bony cortex and
often are angular, as here, or ovoid. COMMENT: These represent long-standing degenerative ossification within the
funicular portion of the ligamentum nuchae and have no
relationship to previous trauma or to pain syndromes.
Figure 3-187 C7, SPINOUS NON-UNION OF THE SECONDARY GROWTH CENTER. Lateral Cervicodorsal. Nonunion of the secondary growth center for the spinous
process is present at C7 (arrow). Its margins are smooth,
sclerotic, and there is no displacement. COMMENT: This is a
common variant and must be differentiated from a clay
shoveler’s avulsion fracture, which has irregular margins and
is usually displaced inferiorly. (Reference data from Rowe LJ:
Clay shoveler’s fracture. Am Chiro Assoc J 21:83, 1987.)
Figure 3-188 C7, CONGENITAL BIFID SPINOUS PROCESS.
A. AP Lower Cervical Spine. This radiographic series was
undertaken on a background of significant trauma and cervicothoracic tenderness. At the C7 spinous process two circular
densities were identified, suggesting possible clay shoveler’s
fracture (double spinous process sign) (arrow). B. Lateral
Cervical Spine. The dual tips of the bifurcated spinous
process of the C7 vertebra are visible (arrows). With the soft
tissue overlap of the shoulder, a fracture of one of the spin-
ous processes could not be confidently excluded. Note the
normal age-related vertebral body ring apophyses (arrowheads). C. Oblique Posterior Cervical Spine. This view enables depiction of both tips adequately to exclude fracture.
COMMENT: The lowest cervical vertebra to have a bifid spinous is C6, which is why the frontal projection finding created
initial difficulty in excluding fracture. (Courtesy of Donald E.
Freuden, DC, DABCO, Denver, Colorado.)
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Figure 3-189 ELONGATED CERVICAL TRANSVERSE
PROCESSES. Lateral Cervical Spine. Bony densities lie superimposed on the intervertebral discs, representing elongated
transverse processes of the midcervical spine, with prominent anterior and posterior tubercles (arrows).
Figure 3-191 ROTATION FACET–INDUCED PSEUDOFRACTURE. Lateral Cervical Spine. Rotation in the cervical
spine at the time of exposure has moved the articular pillar
and facet surfaces anterior, to overlap the posterior vertebral body (arrow). There is also some degenerative facet
arthropathy present and an associated vacuum effect, with
intra-articular nitrogen gas that has relatively enhanced the
joint cavity. (Courtesy of Scott A. Sole, DC, Kearney,
Nebraska.)
Figure 3-190 PSEUDO-TUMOR OF TRANSVERSE PROCESSES.
Lateral Cervical Spine. The circular radiolucencies at C3, C4,
and especially C5 vertebral bodies are the result of overlap
of the transverse processes from being viewed on end (arrows). A posterior ponticle is present at the posterior arch of
the atlas (arrowhead). COMMENT: The sclerotic U-shaped
density is formed by a confluence of densities making up the
foramen intertransversarii, the normal trough within the
transverse process, and the anterior and posterior tubercles
of the transverse processes. (Courtesy of Carr Chiropractic
Clinic, Huron, South Dakota.)
Figure 3-192 C7, NOTCHED SUPERIOR FACET (NOTCHED
LAMINA). Lateral Cervical Spine. At the posterior aspect of
the C7 superior facet near the junction with the lamina there
is a smooth concave defect (arrow). Note that the posteroinferior corner of the C6 inferior facet invaginates into this
normal variant defect. COMMENT: This common variant
should not be confused with a depressed fracture or inflammatory erosive defect. It occurs secondary to chronic mechanical pressure erosion effects during extension. (Courtesy
of Geoffrey G. Rymer DC, Katoomba, New South Wales,
Australia. Reference data from Keats TE, Johnstone WH:
Notching of the lamina of C7: A proposed mechanism.
Skeletal Radiol 7:273, 1982.)
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Figure 3-193 CERVICAL FORAMINAL PSEUDO-LESIONS.
A. AP Lower Cervical Spine. At C4–C5 bilaterally there are
seemingly localized areas of decreased bone density overlying the articular pillars and lateral vertebral body margins
(arrows). B. AP Lower Cervical Spine. At the same C4–C5
level the same loss of bone density is displayed, except that
here it is more asymmetrical, with the left side projected
well over the vertebral body of C5 (arrows). COMMENT:
These are common phenomena on AP lower cervical studies
when performed with routine cephalic tube tilt and represent superimposition of the exiting intervertebral foramina.
These most commonly occur at C4–C5 but can be seen at virtually all cervical levels and may be enhanced in scoliosis or
torticollis. (Courtesy of Richard N. Garian, DC, Holliston,
Massachusetts.)
Figure 3-194 C5, PSEUDO-FRACTURE. A. Lateral Cervical
Spine. Convex linear radiolucency overlies the body of C5
(arrow). B. AP Lower Cervical Spine. The advanced degenerative hypertrophy of the uncovertebral joint is evident, with
the osteophytes orientated horizontally (arrow). COMMENT:
This pseudo-fracture with a trilaminar density (scleroticlucent-sclerotic) is caused by advanced degenerative joint
disease of the uncovertebral joint; there are osteophytes
(sclerosis) at the borders of the joint (lucent). (Reference
data from Rowe LJ: The split vertebral body: A pseudofracture. J Austral Chiro Assoc 29:5, 1990, and Daffner RH,
Deeb ZI, Rothfis WE: Pseudofractures of the cervical vertebral
body. Skeletal Radiol 15:295, 1986.)
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Figure 3-196 TRACHEAL CARTILAGE CALCIFICATION.
Oblique Cervicothoracic Spine. The uniformly interspaced
calcification within the tracheal rings is readily apparent
throughout its entire course (arrow). COMMENT: These usually become more prominent and extensive with advancing
age and are not related to any specific disorder, including
tracheomalacia. (Courtesy of Kenneth E. Yochum, DC,
St. Louis, Missouri.)
Figure 3-195 CERVICAL NUCLEAR IMPRESSIONS (NOTOCHORDAL PERSISTENCY). A. Lateral Cervical Spine. There
are multiple smooth indentations affecting the superior and
inferior endplates of all segments. It is most prominent in
the posterior two thirds of the vertebral bodies. B. Lateral
Cervical Spine. The same effect is evident but more focally
at the inferior endplate of C6 and both endplates of C7
(arrows). (Courtesy of Wendy Neale, DC, Portland, Maine.)
Figure 3-197 NORMAL THYMUS GLAND. PA Chest. The
radiopaque paraspinal density just above the heart (arrows)
represents the normal infant thymus gland. The right margin is slightly undulating, characteristic of the thymus, which
is indented by adjacent costochondral cartilages (thymic
wave sign).
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Figure 3-198 CALCIFIED RIGHT PARATRACHEAL LYMPH
NODE. PA Chest. A large, irregular calcification is present in
the right paratracheal lymph node (arrow) at the T5 level.
COMMENT: These usually are asymptomatic and most commonly are associated with tuberculosis in the right upper
lobe as part of the Ranke complex. (Courtesy of Douglas L.
Forsstrom, DC, Denver, Colorado.)
Figure 3-200 AZYGOS VEIN AND LOBE. PA Chest. The delicate radiopaque line present in the right upper lung apex
(arrow) represents the azygos fissure. The radiopaque density at the base of the azygos fissure represents the azygos
vein (arrowhead ). COMMENT: The azygos fissure represents
one of the accessory fissures of the lung, which is a normal
developmental variant. It is of no clinical significance to the
patient. The fissure creates an accessory lobe (azygos lobe)
of the lung. (Courtesy of Michael S. Barry, DC, DACBR,
Denver, Colorado.)
Figure 3-199 AZYGOS FISSURE, VEIN, AND LOBE. A. Apical
Lordotic Chest. A fine radiopaque line is present in the right
upper lung apex, representing the azygos fissure (arrow).
The radiopaque density at the base of this fissure represents
the azygos vein (arrowhead ). Extensive atherosclerotic
plaquing is present within the aortic arch (knob), demonstrating a thumbnail sign (crossed arrow). B. AP Thoracic
Spine. The same anomaly in a bone film with a grid (instead
of the chest technique shown in panel A) makes the finding
more subtle (arrow). COMMENT: The azygos fissure creates
an accessory lobe (the azygos lobe). This is of no clinical significance and is found in about 7% of the population.
Figure 3-201 PROMINENT AORTIC KNOB. AP Thoracic. The
large round radiopaque density represents the aortic arch
(knob) (arrows). COMMENT: Patients with systemic hypertension often will have significant prominence of the
aortic arch.
Figure 3-202 AORTIC ARCH, THUMBNAIL SIGN. AP Thoracic
Spine. There are fine radiopaque margins at the superior
edge of the aortic arch (arrow). This is calcific atherosclerotic
plaquing within the aortic arch (thumbnail sign). COMMENT:
This defines the intima and subintima of the aorta, and the
external surface of the aorta should normally be < 5 mm
outside of the calcification. Otherwise dissection may be present. Also note the patchy calcification and fibrosis in the
left lung apex, the result of prior tuberculosis. (Courtesy of
Scott A. Sole, DC, Kearney, Nebraska.)
Figure 3-203 HIATAL HERNIA. A. PA Chest. An air–fluid
level extends from near the right border of the heart (right
atrium) (arrow) across the midline to the left lateral wall of
the thoracic cage (arrowhead). These air–fluid levels represent gas in the fundus of the stomach after herniation
through the diaphragm. B. Lateral Chest. Note the air–fluid
level (arrow) above the diaphragm in the retrocardiac space.
Figure 3-204 FLUID IN FUNDUS OF STOMACH, PSEUDOTUMOR APPEARANCE. AP Lumbar Spine. On the reading left
a circular water density is present just under the left hemidiaphragm (arrow). This water density is caused by fluid in the
fundus of the stomach; a superimposed air density in the
body of the stomach extends inferiorly off the radiograph
(arrowheads).
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Figure 3-206 HAHN’S VENOUS CHANNELS. Lateral Thoracic
Spine. Midthoracic vertebral body horizontal linear lucencies
are visible (Hahn’s venous channels), marking the site of passage of the basivertebral vein (arrows). COMMENT: These
channels are most frequently seen in the lower thoracic
spine and should not be confused with any pathologic
process, including fracture.
Figure 3-205 TORTUOUS DESCENDING THORACIC AORTA.
A. AP Thoracic Spine. A convex density lies to the left of the
lower thoracic vertebrae (arrow). This represents tortuosity
of the descending thoracic aorta. The aorta becomes tortuous (elongates) in elderly and hypertensive patients.
B. Variations of the Thoracic Aorta. The normal descending
thoracic aorta maintains a uniform caliber and overlies the
left half of the thoracic spine. The tortuous aorta also has a
uniform caliber but buckles away from the spine. The medial
border is difficult to visualize on radiographs. The aneurysmal descending thoracic aorta also has a lateral margin that
buckles away from the spine; however, this section of the
aorta has lost its parallel walls. The caliber of the aneurysmal section becomes dilated. Unfortunately, the medial portion of the aneurysm overlies the spine and is difficult to
visualize on radiographs.
Figure 3-207 NIPPLE SHADOWS. PA Chest. Two circular
opacities are seen overlying the chest in the region where
the nipples are normally located (arrows). This finding is
sometimes confused with a true pulmonary nodule.
COMMENT: Differentiating a nipple shadow from a true pulmonary nodule can be difficult and may require an opaque
marker to be placed over the nipple before a second radiograph is performed. (Courtesy of George E. Springer, DC,
Clearwater, Florida.)
A
B
C
D
Figure 3-208 COIN LESION VERSUS NIPPLE SHADOW. A. PA
Chest. B. Close-up, PA Chest. There is a circular radiopacity in
the area of the left lower lung (arrow) that appears to be a
solitary pulmonary nodule. The possibility of a prominent nipple exists but cannot be seen on the opposite side. This poses
a diagnostic dilemma and repeat films must be performed.
C. Penny over the Nipples, PA Chest (Repeat). D. Penny over
the Nipples, Lateral Chest. These radiographs clearly demon-
strate the questionable solitary pulmonary nodule, which is
actually a prominent left nipple and not an intraparenchymal
lung mass. COMMENT: This case demonstrates a simple means
of identifying a prominent nipple when there is a questionable appearance of a solitary pulmonary coin lesion. The only
coin lesion in this patient is the penny that was placed on the
nipple to answer the clinical question. (Courtesy of Robert J.
Astroth, DC, Palos Hills, Illinois.)
Figure 3-209 CALCIFIED MESENTERIC LYMPH NODES.
AP Abdomen. There are multiple, scattered, irregular areas
of calcification present in the right lower abdomen, representing calcified mesenteric lymph nodes. These most commonly are caused by previous tuberculosis. Contrast media is
noted within the collecting system of the kidney (arrows).
(Courtesy of Kenneth E. Yochum, DC, St. Louis, Missouri.)
Figure 3-210 RESIDUAL LYMPHANGIOGRAPHIC CONTRAST
MEDIA. AP Abdomen. The radiopaque material present adjacent to the lumbar spine and extending into the pelvic basin
(arrows) represents residual contrast media from a previous
lymphangiogram; it is now sited within the iliac and paraaortic chain of lymph nodes. Note the ovarian shield superimposed on the pelvic inlet.
Figure 3-211 NORMAL LUMBAR VERTEBRAL OSSIFICATION.
Lateral Lumbar Spine. There are prominent step defects
(arrow) present on the anterior surface of this juvenile lumbar vertebra. COMMENT: This is a normal developmental
variation and will disappear with ossification of the ring
apophysis.
Figure 3-213 POSTERIOR VENOUS CLEFTS OF THE VERTEBRAL BODY. A. Lateral Lumbar Spine. There is a partial congenital block vertebra present at L3–L4, with a small disc
and bridging ossification anteriorly. A posterior venous cleft
is present at the L3 vertebra marked by the discontinuity in
the posterior vertebral body surface (arrow). There is a normal secondary ring epiphysis (arrowhead) evident at L4 in
this 18-year-old. B. Specimen Radiograph. The posterior vertebral body shows bilateral perforations at the site of exit of
the basivertebral vein (arrows), which corresponds to the appearance in panel A. The neural arch has been removed at
the pedicles.
L
Figure 3-212 HARRIS GROWTH-ARREST LINES. Lateral
Lumbar Spine. There are thin radiopaque lines just beneath
the vertebral endplates of all lumbar vertebrae (Harris lines)
(arrows). A defect in the pars interarticularis is noted at a
single lumbar vertebra (arrowhead). No evidence of spondylolisthesis is present. COMMENT: Harris growth arrest lines
are seldom seen within the spine and should not be interpreted as lead lines or associated with any other metabolic
abnormality or bone-sclerosing dysplasia. They are the same
residual lines more commonly seen in the extremities.
(see Fig. 3-248)
Figure 3-214 AGENETIC LUMBAR TRANSVERSE PROCESSES.
AP Lumbar Spine. There is agenesis of the transverse
processes of L1 bilaterally, which is an uncommon anomaly.
(Courtesy of Kenneth E. Yochum, DC, St. Louis, Missouri.)
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Figure 3-215 L1, UN-UNITED SECONDARY OSSIFICATION
CENTERS. A. Unilateral Non-Union, AP Lumbar Spine.
Unilateral non-union of the ossification center for the transverse process is present, signified by the smooth sclerotic
borders of both bony components (arrow). B. Bilateral NonUnion, AP Lumbar Spine. Both L1 transverse processes
exhibit characteristic features of non-union (arrows).
C. Secondary Ossification Centers. There are seven secondary
ossification centers of the posterior arch of a typical vertebral
segment: two at the tips of the transverse processes, one
at the spinous process, and four at the articular processes.
There are two additional centers at the superior and inferior
vertebral body ring epiphyses.
Figure 3-216 LATERAL LUMBOSACRAL SPINE. Non-union of
the first sacral tubercle is present without union to the
L5 spinous process (arrow). COMMENT: This is a common
variant and not to be confused with fracture. Union with
the L5 spinous process is often associated with a knife-clasp
syndrome.
3
Figure 3-217 PIG SNOUT VERTEBRA. A and B. Oblique
Lumbar Spine. An anomalous malformation of the transverse process (arrows) of a lumbar vertebra that is orientated superiorly, creating the pig snout appearance of the
Scotty dog. (Panel A reprinted with permission from Keats
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371
TE: Atlas of Normal Roentgen Variants That May Simulate
Disease, ed. 3. Chicago, Year Book Medical, 1984; panel B
courtesy of William E. Litterer, DC, DACBR, Fellow, ACCR,
Elizabeth, New Jersey.)
Figure 3-218 TRAPEZOID LUMBAR VERTEBRAL BODY.
Lateral Lumbosacral Spine. The trapezoidal shape of the L5
vertebral body is caused by a smaller posterior body height
compared with the anterior height (vertebral body height
index). COMMENT: This is a developmental variation of
normal and should not be confused with a compression fracture. More prominent forms are often found in conjunction
with grade 3 or 4 spondylolisthesis.
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Figure 3-219 PSEUDO-LYTIC LESION OF THE LUMBAR VERTEBRA. Lateral Lumbar Spine. The radiolucent area (arrow)
superimposed on the L1 pedicle represents the transverse
process seen en face (head on). COMMENT: This should not
be confused with a lytic destructive lesion of the neural arch,
such as an early osteoblastoma or aneurysmal bone cyst. This
area was asymptomatic in this patient. (Courtesy of Donald
E. Freuden, DC, DABCO, Denver, Colorado.)
Figure 3-220 L5, THIN PARS INTERARTICULARIS. Oblique
Lumbar Spine. The pars interarticularis of the L5 vertebra is
developmentally thin (arrow) compared with the normal
width present at the L4 vertebra (arrowhead). COMMENT:
Patients with a thin pars interarticularis may be predisposed
to spondylolysis.
Figure 3-221 ACCESSORY FACET OSSICLES. AP Lumbosacral
Spine. Observe the small accessory ossicles (arrows) seen at
the facet articulations of the lumbosacral junction.
COMMENT: These should not be confused with fracture and
are of no clinical significance. (Courtesy of Kevin J. LaLonde,
DC, Duxbury, Massachusetts.)
Figure 3-222 ILIOLUMBAR LIGAMENT OSSIFICATION. A. AP
Lumbar Spine. There is early ossification of the iliolumbar ligament (arrow). B–F. AP (Ferguson’s Tilt-Up View) L5–S1.
Ossification of the iliolumbar ligament is shown in a variety
of appearances from heavy ossification to incomplete calcification (arrows). The added benefit of this view is the
clarity of sacral and sacroiliac detail. Residual myelographic
contrast is present (arrowhead). (Panel B courtesy of William
E. Litterer, DC, DACBR, Fellow, ACCR, Elizabeth, New Jersey;
panel C courtesy of David J. Byrnes, DC, Coffs Harbor, New
South Wales, Australia; panels D and E courtesy of Max L.
Denton, DC, Marlon, Ohio.)
Figure 3-223 PEDIATRIC WIDENING OF THE SACROILIAC
JOINTS. A. AP Pelvis. The sacroiliac joints in pediatric patients
usually appear poorly defined, with joint widening (arrows).
Also note the spina bifida occulta of S1 (arrowhead). B. Tilt-Up
AP (Ferguson’s or Hibb’s View) L5–S1. These variant joint
changes are shown to advantage by eliminating the effects of
sacral angulation. COMMENT: This appearance of apparent
widening and loss of joint definition can be confused with
erosive sacroiliitis, such as in ankylosing spondylitis. It is a transitory phenomenon and will reverse to the adult form after
18 to 25 years of age as the secondary ossification centers
mature. (Courtesy of John C. Slizeski, DC, Denver, Colorado.)
Figure 3-224 PSEUDO-SACROILIITIS. A. Straight (No
Angulation) AP Lumbosacral Spine. The sacroiliac joints
appear somewhat indistinct and suggest the possibility of
underlying sacroiliitis. B. Tilt-Up (Sacral Base Projection with
20º Cephalic Tube Tilt) Lumbosacral Spine. On the tilt-up
projection, however, these joints are seen clearly and there
is no evidence of sacroiliitis. COMMENT: The tilt-up view
may be helpful for evaluating the sacroiliac joints and the
height of the lumbosacral discs. It is often beneficial to
determine whether there is a transitional segment present
and whether there is an accessory joint articulation (pseudoarthrosis). The target site for metastatic disease in the pelvis
is the sacral ala and posterior aspect of the ilium. The tilt-up
view provides an optimum means for imaging this area of
predilection for osteolytic metastatic carcinoma. It is strongly
recommended that this view be added to any radiologic
examination of the lumbar spine as a matter of routine.
(Courtesy of Jack T. Dolbin, DC, Pottsville, Pennsylvania.)
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B
Figure 3-225 ACCESSORY SACROILIAC JOINTS. A. AP
Lumbosacral Spine. There are bilateral accessory sacroiliac
joints evident between the posterior inferior iliac spine
and the posterior aspect of S2 (arrow) and S3 (arrowhead ).
B. CT Scan. The site of accessory joint formation is evident as
being dorsal between the posterior inferior iliac spine and
the posterior sacrum (arrow). COMMENT: Accessory sacroiliac
joints are present in 10–35% of patients; the incidence increases with age and the joints are rare before the 4th decade.
Their contribution to back pain syndromes is unknown, though
reported symptoms include back pain, sciatica, muscle spasm,
limitation of motion, or tenderness to deep pressure over the
accessory joint. They are infrequently reported on imaging
studies because of their unfamiliarity. (Panel A courtesy of
Simon Leyson, DC, MS, Swansea, Wales, United Kingdom;
panel B courtesy of J. David Cassidy, DC, PhD, Edmonton,
Alberta, Canada. Reference data from Hadley LA: Accessory
sacroiliac articulations. J Bone Joint Surg 34A:149, 1952, and
Ehara S, El-Khoury GY, Bergman RA: The accessory sacroiliac
joint: A common anatomic variant. AJR 150:857, 1988.)
Figure 3-226 ACCESSORY SACRAL FORAMINA. AP Sacrum.
There are bilateral geographic defects in the sacral alae representing accessory sacral foramina (arrowheads). Bilateral
paraglenoid sulci are present, confirming that this is a
female pelvis (arrows). B. AP Sacrum. Another example of
smaller bilateral accessory sacral foramina (arrows). (Panel B
courtesy of John H. Phillips, DC, Carbondale, Colorado.)
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Figure 3-227 SACROILIAC FOSSAE. A. AP Tilt-Up (Ferguson’s
or Hibb’s View) L5–S1. A pit-like defect is present in the upper
ilium (arrow), creating the appearance of a sacroiliac erosion.
It has been referred to as a superior paraglenoid sulcus. B and
C. AP Sacrum. In the midjoint cavity a prominent iliac defect is
present that corresponds to the retroarticular space just infe-
Figure 3-228 SACRAL OSSIFICATION DEFECT. A and
B. AP Sacrum. There is failure of ossification of the
lateral margin of the distal sacral foramina (arrows).
rior to the posterior inferior iliac spine (arrows). It is most
often seen on erect or non-angulated studies owing to the
tangential projection of this space with increased sacral angulation. (Panel C courtesy of Richard L. Green, DC, Boston,
Massachusetts.)
This is a growth variant that is of no clinical significance and should not be interpreted as a destructive
lesion.
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Figure 3-229 PARAGLENOID SULCI. A–C. AP Pelvis. Various
expressions of the paraglenoid (pre-auricular) sulcus are
displayed, ranging in depth, size, and symmetry (arrows).
COMMENT: This sulcus transmits the neurovascular bundle
of the superior gluteal artery and nerve as well as serving as
the insertion for the ventral sacroiliac ligaments. It is a characteristic of the female pelvis and is rare in males. It is occasionally unilateral but is most often found bilaterally.
Figure 3-230 SACRAL AND COCCYX VARIATIONS. A and B.
Lateral Sacrum. Angular variation at the sacrococcygeal region is common and often of indeterminate significance
(arrows). This angulation may represent healed trauma and/or
normal anatomic variation. COMMENT: Severely angulated
coccygeal segments can be problematic during parturition.
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Figure 3-231 GLUTEAL FASCIAL PLANES. AP Pelvis. The converging radiolucent shadows above the pubic rami (arrows)
represent the fascial planes within the gluteus maximus
muscles. The clear, sharply demarcated midline lucency is the
gluteal crease (arrowhead).
Figure 3-233 IDIOPATHIC CALCIFIED SACROTUBEROUS LIGAMENTS. AP Pelvis. Calcification of the sacrotuberous ligaments is present bilaterally (arrows). COMMENT: Calcification
of the sacrotuberous ligaments may be an isolated idiopathic
finding; may occur after trauma; or may be part of more
widespread ligamentous ossification, such as in diffuse idiopathic skeletal hyperostosis (DISH) and fluorosis.
Figure 3-232 CALCIFICATION OF COOPER’S LIGAMENT. AP
Pubis. Fine radiopaque lines paralleling the superior aspect
of the pubic bones represent age-related calcification in the
Cooper’s ligament (arrows). The metallic density is retained
barium in a rectal diverticulum (arrowhead). COMMENT:
This is reported to be an aging phenomenon of no significance and should not be confused with cortical thickening
of Paget’s disease (brim sign). (Courtesy of Harry R. Shepard,
DC, Marion, Indiana. Reference data from Steinfeld JR, et al.:
Calcification in Cooper’s ligament. AJR 121:107, 1974.)
Figure 3-234 PENILE SHADOW. A. AP Pelvis. A dense round
opaque shadow represents the penis seen en face (arrow).
B. AP Pelvis. The elongated radiopacity seen superimposed
on the sacrum represents the water density of the penis
(arrows).
Figure 3-235 PELVIC PHLEBOLITHS. AP Pelvis. Multiple
round radiopacities above the superior pubic rami represent
phleboliths within the perivesical plexus. COMMENT: The
radiolucent center (arrows) is typical of phleboliths and aids
in the differentiation from bladder or ureteric calculi. In this
location, they are of no clinical significance.
Figure 3-236 SCROTAL PHLEBOLITHS. AP Pelvis. The irregular calcifications seen below the pubic rami bilaterally at the
periphery of the scrotal sac represent phleboliths of the
pampiniform venous plexus. COMMENT: These are often of
no significance but can be seen with varicoceles.
Figure 3-237 GAS AND FECAL ARTIFACTS. A. AP Ilium. In
the cecum the fecal material is often semifluid and gives rise
to a speckled soft tissue mass interspersed with small gas
bubbles, simulating a moth-eaten pattern of aggressive bone
destruction. B. AP Pelvis. This underexposed study shows a
mass of solid segmented feces within the rectal ampulla surrounded by a characteristic radiolucent gas halo. C. AP Pelvis.
Well-defined round soft tissue densities lie within the pelvic
inlet, which represent fluid-containing bowel and simulate
pelvic masses. D. AP Pubis. Within the rectum there are
multiple solid segmented feces that exhibit a surrounding
radiolucent crescent of air and extend across bony margins
and the symphysis joint. COMMENT: Feces and colonic gas
can mimic bone destruction. Key differentiating features include identifying colonic haustra; surrounding crescent- or
halo-shaped air collections traversing across anatomic boundaries, such as across joints; and subsequent movement on
either successive films or tube angulation. (Panel C courtesy
of Scott H. Smith, DC, DABCO, Greeley, Colorado.)
Figure 3-238 PSEUDO-LESION FROM FECAL MATERIAL.
A. AP Pelvis. In the midline a speckled soft tissue mass is present, which is superimposed over the bladder. More discrete
gas-filled sigmoid colon can be seen superiorly overlying the
midsacrum. B. AP Pelvis. After defecation the speckled midline pelvic pseudo-mass is now absent. COMMENT: The
speckled appearance is caused by solid feces interspersed
with gas. When difficulty exists in differentiating fecal artifacts from true bony or soft tissue lesions, a follow-up film
at a later time or even the use of tube angulation can be
used to confirm the true nature of the lesion, without having to perform a CT study. (Courtesy of Wesley E. Wilvert,
DC, Parker, Colorado.)
Figure 3-239 ILIAC NUTRIENT CANAL. A. AP Ilium.
Entering and then coursing through the medullary
cavity of the iliac wing is a bifurcating V-shaped large
nutrient artery (arrow). B. Innominate Specimen. The
vascular channel displays smoothly corticated boundaries and has a Y-shaped configuration (arrow).
COMMENT: This nutrient canal is present on virtually
all pelvic radiographs if the trabecular pattern is scrutinized. It conforms to either a V- or a Y-shaped divergent structure and represents the division of the
penetrating nutrient artery, derived from the internal
iliac artery, as it follows its intraosseous course.
A
Figure 3-240 TRIRADIATE (Y) PELVIC CARTILAGE. A. AP
HIP. In this 10-year-old hemipelvis the radiolucent defect
present on the medial surface of the acetabulum represents the normal triradiate cartilage (arrow). B. Lateral
View. Viewed laterally, the innominate is composed of
three bones, and the junction at the acetabulum is separated by the aptly named triradiate cartilage (arrows).
COMMENT: The Y cartilage represents a growth plate
and is responsible for enchondral bone growth of the
pelvis. In young patients (< 18 years of age), motion can
be demonstrated across this site, with offset at the
medial acetabulum. Another growth plate is present at
the ischiopubic synchondrosis (arrowhead in panel B).
3
Figure 3-241 ISCHIOPUBIC SYNCHONDROSIS GROWTH VARIANTS. A. AP Pubic Bones. The junction zone of the developing
ischium and inferior pubic ramus (ischiopubic synchondrosis)
shows unilateral bulbous enlargement (arrow). The adjacent
round soft tissue density represents the penis (arrowheads),
and the lateral border of the scrotum is seen below the pubic
arch (crossed arrow). B. AP Pubic Bones. Bilateral bulbous
ischiopubic synchondroses are present (arrows). C. AP Pubic
Bones. One ischiopubic junction has closed, while the other
remains open and expanded. D. AP Pubic Bones. Bony frag-
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381
mentation is present (arrow), which is occasionally seen as a
normal variant. COMMENT: These examples demonstrate the
wide spectrum of normal appearances of growth irregularity
at the ischiopubic synchondrosis. Differentiation from neoplasm or post-traumatic deformity is extremely difficult in
symptomatic patients; MRI offers the most help by demonstrating a lack of bone marrow and adjacent soft tissue
edema. (Courtesy of The Children’s Hospital, Denver,
Colorado.)
Figure 3-242 ISCHIAL AGENESIS. AP Pelvis. This asymptomatic
24-year-old patient presented with bilateral failure of ossification of the ischium. COMMENT: This is an occasional variant,
occurring in isolation and of no significance. The fusion of the
ischium with the pubis should have occurred by 8 years of age.
(Courtesy of Mark T. Clark, DC, Denver, Colorado.)
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Figure 3-243 PUBIC EARS. A. AP Pubic Bones. A symmetrical
flange of corticated bone extends inferiorly into the obturator foramina (arrows). B. AP Pubic Bones. Here the flanges
of bone (arrows) appear to be more radiolucent, owing to
their thin nature, which appears to mimic either a periosteal
reaction or contained focus of destructive change. COMMENT:
These represent varying degrees of ossification within the
obturator membrane and are of no clinical significance.
A
Figure 3-245 BUTTOCKS CALCIFICATION. A. AP Pelvis.
B. Lateral Lumbosacral. Cystic calcification (arrows) can be
seen in the soft tissues of the buttocks. COMMENT: This can
occur as a result of trauma from a direct blow to the buttocks
Figure 3-244 NORMAL ISCHIAL GROWTH CENTER. AP Hip.
The curved secondary apophysis of the ischial tuberosity is
clearly visible (arrow). COMMENT: This growth center typically is seen between 12 and 16 years of age and parallels
the appearance of the iliac wing apophysis. During this
growth period, avulsive forces from the hamstring inserts
can detach this growth center and precipitate its overgrowth
and persistent non-union.
B
(as in this case) or can represent a multiple injection site.
These are of no clinical significance to the patient. (Courtesy
of Eugene R. Bedner, DC, Bridgeville, Pennsylvania.)
Figure 3-247 ACCESSORY ACETABULUM, THIRD LEG SYNDROME. AP Pelvis. This patient has a supernumerary and
rudimentary third leg, which articulates with the inferior
pubic ramus, creating an accessory acetabulum. In addition,
there is incomplete development of the ischium. (Courtesy
of Robert L. Lile, MD, University Hospital, Denver, Colorado.)
Figure 3-246 OS ACETABULAE. A. AP Hip. A small ossicle lies
adjacent to the superior acetabular margin (arrow). B. AP
Hip. A smoothly corticated and well-aligned ossicle is present
at the posterior acetabular margin (arrow). COMMENT: These
examples show the spectrum of size and configuration of this
commonly observed asymptomatic variant. There is no association with defects of the acetabular labrum. (Courtesy of
Kenneth E. Yochum, DC, St. Louis, Missouri.)
Figure 3-248 HARRIS GROWTH ARREST LINES. A. AP Knee. B.
AP Ankle. Thin transverse radiopaque lines within the long
metaphyses are depicted (arrows). COMMENT: These lines are
commonly observed findings in asymptomatic individuals.
Occasionally severe disease or chemotherapy during bone
growth can be responsible for these same changes, which represent a failure to convert calcified cartilage at the zone of
provisional calcification to bone in the metaphysis. Synonyms
include growth recovery lines and Park’s lines. These bands
should not be confused with heavy-metal intoxication, bone
sclerosing dysplasia, or metabolic bone disease.
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Figure 3-250 PATELLAR ACCESSORY OSSIFICATION CENTER.
Lateral Knee. There is an accessory ossification center for the
inferior pole of the patella. COMMENT: This should not be
confused with an avulsion fracture. (Courtesy of Tracy G.
Hoyt, DC, DACBR, Los Angeles, California.)
Figure 3-249 FEMUR BONE BARS. A. AP Specimen
Radiograph. Obliquely orientated thick linear sclerotic lines,
which do not contact the inner cortices, are present in the
metadiaphysis. B. Transverse-Cut Specimen. The thickened
bone bars are demonstrated. COMMENT: This specimen was
fortuitously radiographed as part of a forensic survey. Bone
bars (reinforcement lines) are different from growth arrest
lines: They are found in adults, are thicker and obliquely orientated, do not extend to the inner cortical margins, occur
in the diaphysis and metadiaphysis, and are usually unilateral. They do not cause pain, are an acquired phenomenon,
are often found in osteoporosis, and may represent attempts to selectively reinforce stress zones.
Figure 3-251 PSEUDO-CYST. Lateral Calcaneus. A wellcircumscribed radiolucency is present in the calcaneus (arrow).
COMMENT: This radiolucency is caused by the orientation of
the calcaneal trabeculae. Differentiation from simple bone
cyst, intra-osseous lipoma, and other benign tumors can be
difficult and may require MRI examination. Pseudo-cyst is
typically not identifiable on an axial view of the calcaneus,
whereas tumors will be seen. (Courtesy of James R. Brandt,
DC, DABCO, Coon Rapids, Minnesota.)
3
Figure 3-252 CALCANEAL APOPHYSIS. Lateral Calcaneus.
The secondary ossification center for the calcaneal apophysis
is densely sclerotic (arrows). COMMENT: This is a normal
manifestation of the growing calcaneus and often will be
multisegmented. The multiserrated margins (arrowheads) of
the junction zone with the calcaneal body are also common
normal findings. In young patients with pain in the calcaneus these normal features of sclerosis, fragmentation, and
junctional irregularity should not be confused with avascular
necrosis (Sever’s disease). The film should be bright lighted
to examine the soft tissue details of the Achilles insertion
and pre-Achilles fat for evidence of edema. Plain film studies
of the opposite asymptomatic calcaneus are often helpful.
Figure 3-253 OS SUPRANAVICULARE. Lateral Foot. A triangular, smoothly corticated accessory ossicle is present adjacent to the navicular (arrow). A large plantar calcaneal spur
is also seen (arrowhead ). COMMENT: The os supranaviculare
should not be mistaken for an avulsion fracture. The os
supranaviculare has been referred to as Pirie’s bone.
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385
Figure 3-254 OS PERONEUM. Lateral Foot. There is an
accessory ossicle present near the cuboid (arrow), which is
referred to as an os peroneum. There are large calcaneal
spurs projecting from the Achilles and plantar surfaces of
the calcaneus (arrowheads).
Figure 3-255 FIFTH TOE SESAMOID BONE. Medial Oblique.
A small round sesamoid bone is seen adjacent to the fifth
metatarsophalangeal articulation (arrow).
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Figure 3-256 PHALANGEAL SYNOSTOSIS. Dorsoplantar
Toes. There is congenital synostosis of the middle and distal
phalanges of the fifth toe (arrow). A small accessory ossicle
is seen adjacent to the distal interphalangeal articulation of
the great toe (arrowhead ). COMMENT: This fusion is a frequent congenital variation of normal and should not be
confused with any underlying pathology.
Figure 3-258 CONOID TUBERCLE. A. AP Clavicle. A small
bony process projecting from the inferior surface of the clavicle (arrow) represents the conoid tubercle and should not be
confused with any underlying pathology. B. AP Clavicle. There
is an enlarged conoid tubercle projecting as an exostosis and
forming an accessory articulation with the coracoid process of
the scapula (arrow). COMMENT: These conoid tubercle variations can be difficult to differentiate from post-traumatic
myositis ossificans of the coracoclavicular ligaments.
Figure 3-257 POLYDACTYLY. Dorsoplantar Foot. There is
duplication of the proximal phalanx of the fifth digit with
an associated additional accessory ossicle. There are two
distal ungual tufts. (Courtesy of Steven P. Brownstein, MD,
Springfield, New Jersey.)
Figure 3-259 MANUBRIUM, NON-UNION. PA Sternoclavicular.
There is non-union of the secondary growth centers for the
manubrium (arrows).
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Figure 3-260 RHOMBOID FOSSAE. A. AP Cervicothoracic
Spine. There are bilateral rhomboid fossae present on the
inferior surface of the medial aspect of the clavicles (arrows).
B. Anatomic Specimen. The specimen clearly defines the
indentation of the rhomboid fossae and deficient cortex,
which produces the corticated angular defect (arrowhead).
COMMENT: The rhomboid fossa represents a developmental
variation at the insertion of the rhomboid (costoclavicular)
ligament, which is of no clinical significance.
Figure 3-261 SUPRACLAVICULAR FORAMEN. A. AP Clavicle.
A pseudo-lesion is created by a foramen in the middle clavicle (arrow). B. PA Clavicle. A small circular radiolucency is
seen along the superior aspect of the medial one third of
the clavicle (arrow), which represents a foramen that transmits the supraclavicular nerve.
Figure 3-262 SUPRACLAVICULAR FORAMEN. A. PA Clavicle.
There is a small radiolucency seen in the midportion of the
superior aspect of the clavicle (arrow). COMMENT: This is a
normal foramen for transmitting the supraclavicular nerve
and should not be considered a lytic lesion.
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Figure 3-263 CLAVICLE, PROMINENT CONOID TUBERCLE.
AP Clavicle. The osseous density extending from the clavicle
inferiorly represents an enlarged conoid tubercle (arrow).
COMMENT: This must be differentiated from post-traumatic
ossification of the coracoclavicular ligaments. The lack of a
trauma history and the smooth, corticated margin point to
a congenital origin for this anomaly. (Courtesy of James J.
Holland, DC, DABCO, Carmichael, California.)
Figure 3-264 HUMERUS, PSEUDO-TUMOR. Internal Rotation,
AP Shoulder. Within the humeral head there is an apparent
well-circumscribed radiolucent lesion that extends into the
surgical neck. This pseudo-tumor appearance is from superimposition of thinly corticated tuberosities over the humeral
head. COMMENT: This confluence of densities has been referred to as the tennis racquet appearance and can be seen
in internal rotation views, PA chest radiographs, and posterior
dislocations of the humerus.
Figure 3-265 HUMERUS, PECTORALIS MAJOR INSERTION.
A. External Rotation, Humerus. A linear radiolucency is evident in the proximal diaphysis (arrow). B. Internal Rotation,
Humerus. The groove for the pectoralis major insertion
when seen in profile gives the appearance of cortical destruction (arrows). (Reference from Brower AC: Cortical defect of the humerus at the insertion of the pectoralis major.
AJR 128:677, 1977.)
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Figure 3-266 HUMERUS, PECTORALIS MAJOR AND DELTOID
INSERTION. A. Internal Rotation, Humerus. The radiolucent
linear groove for the pectoralis major is visible (arrow). At
the lateral humeral shaft the cortex appears to be thickened
and raised, simulating a periosteal response at the site of
the deltoid tuberosity (arrowhead). B. Anatomic Specimen,
Humerus, External Rotation. The radiolucent defect in the
area of the humeral cortex represents the area of insertion
of the pectoralis major muscle (arrows). The slight cortical
bump on the lateral surface of the humerus represents the
normal deltoid tuberosity, which comes into profile on external rotation (arrowhead).
Figure 3-267 CALCIFIED AXILLARY LYMPH NODES. AP
Shoulder. There is calcification in multiple axillary lymph
nodes (arrows). COMMENT: These should not be confused
with blastic bone lesions or pulmonary nodules when they
overlie these anatomic structures. (Courtesy of Kenneth E.
Yochum, DC, St. Louis, Missouri.)
Figure 3-268 DISTAL HUMERUS, CHEVRON SIGN. AP Elbow.
The prominent trabecular pattern in a V-shaped, or chevron,
configuration in the distal humerus is evident. There is often
more than one opaque line; they are most prominent distally and become thinner and less conspicuous proximally
(arrow). COMMENT: This is a common variant of the region
and not to be construed as a sign of bone destruction,
abnormal trabecular thickening (e.g., Paget’s disease,
hemangioma), stress response, or osteoporosis.
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Figure 3-269 RADIAL TUBEROSITY PSEUDO-TUMOR. A. AP
Elbow. There is a cystic radiolucency over the proximal radius
representing the radial tuberosity en face owing to the thinner cortex (arrows). B. Lateral Elbow. The expanded anterior
and thinned cortex is readily apparent (arrow).
COMMENT: The appearance is common and can simulate
tumor infiltration. (Courtesy of Gary M. Guebert, DC, DACBR,
St. Louis, Missouri.)
Figure 3-270 MULTIPLE UPPER LIMB ANOMALIES. A. AP
Forearm. The proximal ulna is absent. The lateral bowing of
the radius is caused by increased stress from the lack of an intact ulna. At the elbow there is dislocation. B. PA Left Hand.
There is absence of the thumb, little finger, and trapezium.
C. PA Right Hand. The thumb, trapezium, and fifth
metacarpal are absent. The phalanges of the fifth finger are
fused to the fourth finger. The carpal lunate is sclerotic from
co-existing avascular necrosis. COMMENT: The patient had
been exposed to thalidomide, which is a known teratogen
that often affects developing sclerotomes and accounts for
the ulnar–little finger and radius–thumb–trapezium distribution. (Courtesy of Richard Edmonds, BAppSc (Chiro), Port
Macquarie, New South Wales, Australia.)
3
Figure 3-271 OS CENTRALE. PA Wrist. A separated ossicle
lies adjacent to the distal scaphoid and is adjacent to the
capitate and trapezoid (arrow).
Congenital Anomalies and Normal Skeletal Variants I
391
Figure 3-272 UN-UNITED SECONDARY OSSIFICATION CENTER. PA Wrist. The non-union of the ulnar styloid process is
a common finding and represents post-traumatic non-union
(arrow). COMMENT: Differentiation from a developmental
non-union of the ulnar styloid process is based on the position of the ossicle; as in this case, most fractures occur near
its base and the resultant non-union occurs at the site of
fracture. Developmental ossicles tend to cap the styloid and
be away from its base.
Figure 3-273 POLYDACTYLY. AP Thumb. Twin distal phalanges on the thumb can be seen. Note that these phalanges
have an articulation between themselves (arrow), as well as
an articulation with the proximal phalanx.
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Figure 3-274 SESAMOID BONES. A. PA Hand. B. Lateral Hand. C. Dorsoplantar Foot. D. Lateral Foot. Sites of normally occurring
sesamoid bones are shown.
3
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OCCIPITALIZATION OF THE ATLAS
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OS ODONTOIDEUM
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DOWN’S SYNDROME
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ANOMALIES OF C3–C7
BLOCK VERTEBRAE
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KLIPPEL-FEIL SYNDROME
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SPRENGEL’S DEFORMITY
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