TIPS FOR
INTERPRETING XRAYS IN TRAUMA
KENG SHENG CHEW, MD, MMED (Emerg Med)
Senior Lecturer/Emergency Medicine Physician,
School Of Medical Sciences, Universiti Sains Malaysia
CERVICAL SPINE
• In patients with major trauma
– 5% have an unstable cervical spine
– 2/3rd of this 5 percent present without initial neurologic
deficit.
• Chiles III BW, Cooper PR. Acute Spinal Injury. New England Journal of
Medicine 1996; 334 (8):514-20.
• Site of Injuries: Cervical spine (60%),
Thoracolumbar junction (20%), Thoracic (15%),
Lumbosacral Spine (5%)
• Savitsky E, Votey S. Emergency Department Approach To Acute
Thoracolumbar Spine Injury. The Journal of Emergency Medicine 1997;
15 (1):49-60.
CERVICAL SPINE
• Ensure visualization of ALL cervical
vertebrae as well as the atlanto-occipital and
C7-T1 articulations
• Cervical region – most commonly injured part
due to
– its flexibility (most mobile) and
– its exposure
• Savitsky E, Votey S. Emergency Department Approach To
Acute Thoracolumbar Spine Injury. The Journal of
Emergency Medicine 1997; 15 (1):49-60.
INTERPRETING CERVICAL X-RAY
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•
Look at:
Mnemonic:
A = Alignment
„ABCs‟
B = Bones
C = Cartilaginous and
S = soft-tissues
• A = smooth, unbroken alignment
of three lines
ALIGNMENT
CASE STUDY
A 41-year-old man was
brought to the ED
following a motor vehicle
collision in which he was
an unrestrained driver
whose vehicle hit a
roadway median divider.
The automobile driver‘s
air bag deployed.
HANGMAN FRACTURE
The usual site of fracture
is because it is the
weakest part of the C2
neural arch.
THE „TRUE‟ HANGMAN FRACTURE VS
ASPHYXIATION DUE TO HANGING
HANGMAN FRACTURE
HANGMAN FRACTURE
The typical mechanism of injury causing hangman‘s fractures.
Hyperextension and axial compression occur when the head impacts
on the windshield. This fractures the posterior skeletal elements of
the cervical spine.
PSEUDOSUBLUXATION
• Malalignment of the
posterior vertebral
bodies is more
significant than that
anteriorly
• Two most common
causes of C2-C3
malalignment are
pseudosubluxation and
hangman's fracture.
PSEUDOSUBLUXATION
*
*
*
• To distinguish these
two, draw a Swischuk
line from the base of
spinous process of C1
to the base of the
spinous process of C3.
• The base of C2 should
normally not be more
than 2 mm from the
Swischuk line
HANGMAN FRACTURE
DISTANCE >3 CM
BONES
• Vertebral bodies below
C2 have a uniform,
square (cuboidal)
shape.
• An increase in density
may indicate a
compression fracture.
CARTILAGINOUS STRUCTURES
• The intervertebral spaces
should be uniform.
• Widening of these or the
interspinous distance may
indicate an unstable
dislocation.
• An increase in
interspinous distance of
50% suggests ligamentous
disruption.
SOFT TISSUES
• Prevertebral soft
tissue
• C1 – C4: 50% of the
AP width of a vertebral
body
• C5 – C7:  the AP width
of one vertebral body
‗2 – 6‘ Rule
C2 = 6 mm
C6 = up to 2 cm
PRE-DENTAL SPACE
PRE-DENTAL SPACE
• Predental Space < 3
mm in adult
• < 5 mm in children
• Widening of predental
space – suspect
Jefferson‘s fracture of
C1
JEFFERSON FRACTURE
A 37-year-old man lost his
balance while standing on a
subway platform and fell five
feet, head first onto the tracks.
He had consumed an alcoholic
beverage prior to his fall.
Fortunately, train was not
entering the station at the time.
He was extricated from the
tracks, immobilized, and brought
to the ED.
JEFFERSON FRACTURE
JEFFERSON FRACTURE
Increased
Predental
space 
Normal Predental space
THE OPEN MOUTH VIEW
OPEN MOUTH VIEW
• The distance between the odontoid and the lateral
masses of C1 should be equal.
• Inequality may be due to head rotation.
It A + B >7 mm, this
suggests a disruption
of the transverse
ligament
PREDENTAL SPACE ABNORMALITIES
Predental space
distance
3 – 6 mm
6–10 mm
> 10 mm
Significance
Partial disruption of the
transverse ligament
Disruption of the
transverse ligament, but
intact alar and
Accessory ligaments
Complete
ligamentous instability
CHEST X-RAY
CHECKLIST FOR A CXR
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Name, ID particulars, etc
Check for the ‗L‘ or ‗R‘ marker.
To prevent missing dextrocardia
Quality of the film
Is the film well-centered?
Is the patient‘s position rotated?
Is the exposure and X-ray penetration adequate?
IS IT AP or PA VIEW?
CRITERIA
Spinous process
lamina
Scapula
Clavicle direction
Heart size
PA VIEW
Prominent
inverted ‗V‘
shape
Out of the chest
wall
Medial end is
lower
Not enlarged
AP VIEW
Straight
Inside
Straight
Appears enlarged
CHECKLIST
• Penetration – the spine should be ‗just seen‘
through the mediastinum
• Well-centeredness – the medial ends of the
clavicicle should be equa-distant from
midline
• Exposure - scapular end should be outside of the
lung fields
• In full inspiration, 6th anterior or 10th posterior rib
should touch the hemidiaphgram
DISTORTIONS ON A PORTABLE AP X-RAY
• Rotated positioning of the patient—apparent shift of
trachea and mediastinum
• Poor inspiration—crowded lung markings at the
bases
• Suboptimal exposure—over or under-penetrated
• Cardiac enlargement
• Widened and indistinct mediastinum
• Superimposed extrathoracic objects—spine
immobilization boards, tubes, monitoring wires, and
clips
A WELL-CENTERED X-RAY FILM
A
ROTATED
FILM
The patient
is rotated to
which side?
THREE ZONES LEVEL OF THE LUNG FIELD
ZONE
Upper zone/apices
Mid-zone
Lower zone
LEVEL
Apical region to 4th
posterior rib
4th to 8th posterior rib
From 8th posterior rib
downward
HILA
• The hila is formed by
the pulmonary veins
with the lower lobe
arteries superimposed.
• Left hila is higher than
right hila by 1 cm
• Left hila has a ‗square‘
shape, right a V-shape
MEDIASTINUM STRUCTURES
PARA-TRACHEAL
STRIPE
• The right paratracheal stripe
is a thin layer of connective
tissue that lies along the
right tracheal wall adjacent
to the right lung.
• It is normally no more than 5
mm thick.
• Widening >1 cm is a sign of
pulmonary venous
hypertension (e.g., CCF)
HEMIDIAPHRAGM
• The highest point of the right diaphragm is usually
1–1.5 cm higher than that of the left. Each
costophrenic angle should be sharply outlined.
ASSESSING FOR FLATTENING OF
HEMIDIAPHRAGM
• The highest point of a hemidiaphragm should be at
least 1.5 cm above a line drawn from the
cardiophrenic to the costophrenic angle.
Remember: Tension pneumothorax is a clinical
diagnosis, NOT a radiological diagnosis
Deep sulcus sign:
abnormal deepening
and lucency of the
left lateral
costophrenic angle
When the patient is supine, a pneumothorax collects anteriorly and
may be impossible to detect. A large pneumothorax may widen the
costophrenic sulcus—the ―deep sulcus‖ sign
QUANTITATIVE MEASUREMENT OF
PNEUMOTHORAX SIZE
Rhea (1981): Ptx % = 5 + 9* AID (after
Choi 1998)
Collins (1995): Ptx % = 4 + 14 * AID
Light formula: Ptx % = (1 - x3/y3)*100
ACCP (2001): ―small‖ a < 3 cm; ―large‖
a 3 cm
BTS (2003): ―small‖ m < 2 cm; ―large‖ m
2 cm
where Average interpleural
distance (AID) = (a+b+c)/3
QUALITTATIVE CLASSIFICATION
• More recent guidelines have proposed using single
measurements to determine patient care.
• Only two sizes of pneumothorax are distinguished:
small and large.
• Small pneumothoraces can be managed by
observation, as long as the patient is stable, has
only mild symptoms, and has no underlying lung
disease.
• Large pneumothoraces need chest tube or catheter
aspiration to reexpand the lung.
DIFFERENCES BETWEEN ACCP VS BTS
GUIDELINES
• The American College of Chest Physicians
(ACCP) proposed using an apex to cupola
distance of 3 cm to distinguish small from
large pneumothoraces
• The British Thoracic Society (BTS) uses an
average pneumothorax width of 2 cm to
distinguish large from small
pneumothoraces, although the exact method
of measurement is not specified.
RADIOLOGIC FEATURES DUE TO
MEDIASTINAL HEMATOMA
• Wide mediastinum
• Indistinct or distorted aortic knob or proximal
descending aorta
• Opacification of the aorticopulmonary
window
• Wide right paratracheal stripe
• Left paraspinal line displaced and extending
superior to aortic knob
RADIOLOGIC FEATURES DUE TO
MEDIASTINAL HEMATOMA
• Left apical pleural cap
• Right paraspinal line displaced
• Mass effect due to periaortic blood at the
aortic arch
• Trachea or nasogastric tube displaced to the
right
• Depressed left mainstem bronchus
AORTIC DISSECTION
AORTIC DISSECTION
MECHANISMS OF AORTIC INJURY
MECHANISMS OF AORTIC INJURY
PELVIC X-RAY
2 – 4 mm
< 5 mm in adults
< 10 mm in
adolescents
CHECKLIST FOR PELVIC X-RAY
• Look for symmetry of the hemipelvis
• Scrutinize the three ‗rings‘ for fractures
– Main pelvic inlet
– Obturator foramen
• Sacroiliac joints
– Normal width 2 – 4 mm
• Symphysis pubis
– < 5 mm in adults
– Up to 10 mm in children
– Superior surfaces should align or offset < 2 mm
CHECKLIST FOR PELVIC X-RAY
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Look for special radiographic landmarks
Iliopubic line
Ilioischial line
‗U‘ curve and teardrop sign
Shenton line
RADIOGRAPHIC LANDMARKS OF PELVIC
X-RAY
RADIOGRAPHIC LANDMARKS OF PELVIC
X-RAY
RADIOGRAPHIC LANDMARKS OF PELVIC
X-RAY
Radiographic “U” is the
inferior lip of the anterior
articular surface of
acetabulum.
Radiographic teardrop
is composed of the
ilioischial line, the
acetabular articular
surface, and the
radiographic ―U.‖
THE SHENTON LINE
• It is an imaginary
line drawn along
the inferior border
of the superior
pubic rami
(superior border of
obturator foramen)
and along the
inferiomedial
border of the neck
of femur. The line
should be smooth
and continuous
MAXILLO-FACIAL X-RAY
THE WATERS VIEW
• Also known as
Occipito-mental view
(O-M view)
• The Waters view is the
most important view
and by itself is probably
a sufficient screening
radiograph for patients
with facial injuries.
Occipito-frontal view
To visualize frontal sinuses, superior
orbital rim, and ethmoid air cells
DOLAN‟S LINES
WATERS VIEW (OM VIEW)
LE FORT
FRACTURES
McGrigors Lines
WRIST AND HAND X-RAY
WRIST ARCS (PA VIEW)
Three arcuate lines can be
drawn along the carpal
articular surfaces
Approximately equal distance (usually 1
to 2 mm) between each of the carpal
bones
1. Disruption of these curves or
2. Widening of the carpal spaces
implies carpal ligament disruption
and carpal instability
THE TERRY THOMAS SIGN
Scapholunate dissociation
SCAPHOID FRACTURE
• Most common carpal fracture (more than 60% of all
carpal fractures)
– Highest incidence of avascular necrosis of carpal bone –
Lunate Fracture (Keinbock‘s disease)
– (Note: Most common wrist fracture - Distal radius)
• Commonly seen in young adults age 15 to 30 and
occurs after a fall on the outstretched hand
• Rare in skeletally immatured individuals because of
the relative weakness of distal radius compared to
scaphoid
COLLES‟ FRACTURE
A - showing Posteroanterior
view shows fracture and
shortening of radius
B - Lateral view shows typical
dorsal displacement and
angulation of radial fracture.
(From Propp DA, Chin H: Forearm and
wrist radiology
SMITH‟S FRACTURE
Open reduction usually
necessary.
Closed reduction often
unsuccessful due to
flexor muscle pull.
BARTON FRACTURE
Volar Barton‘s Fracture
Barton‘s fracture is an oblique intraarticular
fracture of the rim of the distal radius, with
displacement of the carpus along with the
fracture fragment.
COLLES‟ VS BARTON‟S
Colles or Smith – Extraarticular
Barton‘s – Intra-articular
In Barton‘s Fracture,
surgical fixation is usually
necessary when over 50%
articular surface is involved
or fragment not adequately
reduced
Barton’s Fracture
Colles’ Fracture
ROLANDO VS BENNETT‟S FRACTURE
Rolando fracture (comminuted;
worse prognosis)
Bennett fracture
RADIUS AND ULNA SHAFT FRACTURES
• Because of protection by surrounding
muscles, most radial shaft fractures require
significant force and most have concurrent
ulna fractures
• Also, non-displaced fractures are rare
• In ulna shaft fractures, solitary fracture of
ulna may occur, often called nightstick
fracture since it can be caused when stuck
with a blunt object while self-defencing.
MONTEGGIA‟S
FRACTURE
Is a fracture at the junction
of the proximal and middle
thirds of the ulna
associated with anterior
dislocation of the proximal
radial head
GALEAZZI'S FRACTURE
Involves the
junction of the
middle and distal
thirds of the
radius, with an
associated
dislocation or
subluxation of the
DRUJ.
Mnemonics: MU-GR
Monteggia = ULNA
Galeazzi = RADIUS
ELBOW X-RAY
ANATOMY OF THE ELBOW
Secondary growth centers of the elbow
Mnemonic: “CRITOE”
OSSIFICATION CENTERS
Ossification Center
C = Capitellum
R = Radial Head
Age appearing
radiologically
1 year old
3 years old
I = Internal epicondyle
5 – 7 years old
T = Trochlear
9 – 10 years old
O = Olecranon
9 – 10 years old
E = External epicondyle
9 – 10 years old
Scaletta & Schaider, 2001
ANTERIOR HUMERAL LINE
This line passes
through the
middle one third
of the capitellum
in bones that
are not injured
RADIOCAPITELLAR LINE
If radiocapitellar
line does not
pass through
capitellum, a
dislocated radial
head is
suspected
ANTERIOR AND POSTERIOR FAT PADS
Anterior fat pad with
sail sign appearance
(due to joint effusion)
Normally anterior fat pad is seen
only as an anterior narrow strip of
lucency but the posterior fat pad is
not seen as it is hidden in the
olecranon fossa.
Posterior fat pad
ANTERIOR AND
POSTERIOR FAT PADS
Anterior fat pad displacement in the
lateral view suggests effusion, but if the
posterior fat pad is visible at all, an elbow
fracture is likely.
In the absence of trauma, the presence
of a fat pad suggests other causes of
effusion (e.g., gout, infection, bursitis)
Search hard for occult fractures,
which are:
1. Radial head fracture (in adults)
2. Supracondylar fracture (in children)
Discuss the abnormalities seen
Lateral view
AP View
Diagnosis?
SUPRACONDYLAR FRACTURES
• Most frequent elbow fracture in children, accounting
for 50-60% of cases
– Most occur in children aged 3-10 years, with a peak
incidence in those aged 5-8 years
• 10% have radial pulse loss temporarily, most often
as a result of swelling and not direct brachial artery
injury.
• Reducing the fracture, avoiding flexing the elbow
more than 90 degrees, and elevating the arm help
prevent secondary obstruction to arterial flow.
Relative ligamentous
laxity in childhood
allows the elbow to
hyperextend, and with
hyperextension, the
olecranon transmits
the load into a
bending force on the
distal humerus in the
supracondylar region.
10-POINT CHECKLIST IN INTERPRETING
ELBOW X-RAY
• 1. Examine the anterior fat pad
• The presence of an anterior fat pad is normal. It
should be small and appear to be flat against the
anterior surface of the humerus.
• If it is large or it appears to be triangular in shape
(sail shape) as if its lower tip is being displaced
upwards, this indicates the presence of an elbow
joint effusion
10-POINT CHECKLIST IN INTERPRETING
ELBOW X-RAY
• 2. Look for the presence of a posterior fat pad.
• A posterior fat pad is always an abnormal sign and
indicates the presence of an elbow joint effusion
• 3. Examine the anterior humeral line.
• If this line fails to bisect the capitellum, this
indicates the presence of a fracture in the
supracondylar region displacing the capitellum
(usually posteriorly) or a Salter-Harris Type I
fracture between the capitellum and the distal
humerus.
10-POINT CHECKLIST IN INTERPRETING
ELBOW X-RAY
• 4. Examine the radial head
• The shape of the radial head should show a
smooth metaphysis. Any angles in the metaphysis
may indicate a radial head fracture.
• 5. Examine the radiocapitellar line
• The radius should point directly at the capitellum in
all views. If the radius does not point directly at the
capitellum, this indicates a dislocation of the radial
head.
10-POINT CHECKLIST IN INTERPRETING
ELBOW X-RAY
• 6. Count the number of ossification centers
• CRITOE sequence
• 7. Check for the Hourglass sign OR Figure-of-8
shape at the distal humerus to indicate that the Xray is a true lateral view
• An oblique view of the elbow may obscure some
radiographic findings
10-POINT CHECKLIST IN INTERPRETING
ELBOW X-RAY
• 8. Look carefully at the distal humerus
• Any lucencies indicating a supracondylar fracture
• 9. Examine the olecranon and the remainder of the
ulna for irregularities in the cortex.
• An ossification center over the olecranon may
resemble a fracture. The presence or absence of
tenderness over the olecranon may help to
establish a diagnosis
• 10. Correlate X-ray with clinical picture
10 THINGS TO LOOK FOR IN ELBOW XRAY
1. Anterior fat pad
2. Posterior fat pad
3. Anterior humeral line.
4. Radial head contour.
5. Radiocapitellar line
6. Ossification centers - CRITOE
7. Hourglass sign
8. Distal humerus
9. Ulna/Olecranon
10. Clinical correlation
Checklist:
1. Anterior fat pad.
2. Posterior fat pad.
3. Anterior humeral
line.
4. Radial head
contour.
5. Radiocapitellar line.
6. Ossification
centers. CRITOE
7. Hourglass sign.
8. Distal humerus.
9. Ulna/Olecranon.
10. Clinical
correlation.
ANKLE AND FOOT X-RAY
ANKLE MORTISE VIEW
Check joint space around talus
for symmetry/disruption
Search for fractures of distal
tibia and fibula
The lines formed between the
articular surfaces should be
parallel throughout the
tibiotalar and talofibular
components of the joint
MALLEOLAR FRACTURES
• The stability of an isolated lateral malleolar
fracture depends on the location of the fracture in
relation to the level of the tibiotalar joint.
• Medial malleolar fractures are commonly
associated other fractures/disruption
• Therefore, the identification of a medial malleolar
fracture demands a careful examination of the
entire length of the fibula for tenderness
(Maisonneuve fracture)
MAISONNEUVE FRACTURE
LISFRANC‟S JOINT
Lisfranc‘s Joint - Bases
of the first three
metatarsals with their
respective cuneiforms
and the fourth and fifth
metatarsals with the
cuboid
CALCANEAL INJURIES
An angle of less than 20 degrees suggests a
compression fracture of calcaneum
Boehler‘s angle of 20 to
40 degrees gives the
best balance of
sensitivity and
specificity for fracture
detection