RESEARCH PROTOCOL
PROTOCOL TITLE: THE INCIDENCE OF ANTERIOR CRUCIATE LIGAMENT
INJURIES IN FILIPINOS OF DIFFERENT AGE GROUPS IN RELATION TO
CAUSE IN THE UST HOSPITAL: A RETROSPECTIVE STUDY
Author:
Norraine Anne T. Marquez, M.D.
Co-Author:
Stephanie J.H. Pe, M.D.
University of Santo Tomas Hospital, Espana, Manila
Department of Radiological Sciences
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TITILE OF RESEARCH PROPOSAL
The Incidence of Anterior Cruciate Ligament Injuries in Filipinos of Different Age
Groups in Relation to Cause in the UST Hospital: A Retrospective Study.
INTRODUCTION
The anterior cruciate ligament (ACL) is the primary stabilizing structure of the
knee. It stabilizes the knee by preventing anterior translation and internal rotation of
the tibia with respect to the femur. The anterior cruciate ligament originates from the
posterior aspect of the femur coursing medially and inserting on the anterior aspect
of the tibia. Loss of these restraints leads to substantial morbidity and can result to
dysfunction of the other structures in the knee.
Injuries to the anterior cruciate ligament are one of the most common knee
injuries that are encountered today. These types of injury are most common to
athletes. However, sports-related events are not the only possible cause of the
injuries to the ACL. They may also be acquired through trauma secondary to fall or
motor vehicular collisions as well as idiopathic causes.
The overall incidence of anterior cruciate ligament injuries and their causes in
the general Philippine population is not known. In the review of the related literature,
only few materials referred to the causes and incidence of anterior cruciate ligament
injuries in different age groups. The identification of the most common causes of the
injuries to the ACL may lead to prevention.
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BACKGROUND AND REVIEW OF RELATED LITERATURE
The anterior cruciate ligament is a band of dense connective tissue that
connects the femur and tibia20. It is enveloped into the synovial membrane of the
human knee joint, which by definition places the ligament intra-articular but extrasynovial1,18. It extends from a broad area anterior to and between the intercondylar
eminences of the tibia to a semicircular area on the posteromedial portion of the
lateral femoral condyle10. The ligament originates at the medial side of the lateral
femoral condyle and runs an oblique course through the intercondylar fossa distaanterior-medial to the insertion at the medial tibial eminence 20. The anterior cruciate
ligament is composed of two (2) bundles that are named based on their relative
attachments on the femur and tibia: an anteromedial bundle (AMB), which is tight in
flexion, and a posterolateral bundle (PLB), which is more convex and tight in
extension10. The AMB inserts at a more medial and superior aspect of the lateral
femoral condyle while the PLB inserts at a more lateral and distal aspect of the
lateral femoral condyle13. Occasionally, a third intermediate bundle is appreciated 10,
13.
The whole ACL measures approximately 31-38 mm in length and 10-12 mm
in width10,
13.
The anteromedial bundle is 36.9
± 2.9 mm in length, while the
posterolateral bundle is 20.5 ± 2.5 mm in length. Both bundles are similar in size,
with an average width of 5.0 ± 0.7 mm and 5.3 ± 0.7 mm in the mid-substance13.
The proximal part of the ACL is supplied by vessels from the middle genicular
artery.
Distally, the ligament is supplied by branches of the lateral and medial
inferior geniculate artery. Proximal and distal vessels support a synovial plexus from
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which small vessels run into the ligament and align longitudinally parallel to the
collagen bundles24.
The main purpose of all joints is to allow for motion of the osseous segments
surrounding the joint while being able to withstand the loads against gravitational
force imposed by these movements. The knee joint must provide a normal amount
of motion without sacrificing stability during static activities to more dynamic
functions. These goals are achieved by the interaction of the osseous anatomy,
articular surface, ligaments, menisci and surrounding musculature about the knee 10.
The anterior cruciate ligament is an important stabilizer of the knee. Due to
the orientation of the anterior cruciate ligament, it has been shown to be the primary
restraint to anterior tibial translation20.
It also serves as secondary restraint to
internal rotation of the tibia and valgus angulation of the knee. In full extension, the
ACL absorbs 75% of the anterior translation load and 85% between 30 and 90° of
flexion10. Loss of the ACL leads to a decreased magnitude of this coupled rotation
during flexion and an unstable knee.
The overall incidence of ACL injury in the general Philippine population is not
known.
Rupture of the ACL, unfortunately, is a common sports injury, with a
reported incidence of 0.38 per 100,000 individuals23. This generally begins to occur
in late adolescence. Younger athletes usually sustain growth plate injuries rather
than ligamentous injuries because of the relative weakness of the cartilage at the
epiphyseal plate compared with the anterior cruciate ligament 4. Studies have shown
a 1.4 to 9.5 times increased of ACL tear in women4.
Patients who sustain ACL injuries classically describe a popping sound,
followed by immediate pain and selling of the knee. Contact injuries account for 30%
of all ACL injuries while noncontact injuries account for the remaining 70% 4. ACL
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injuries caused by contact require a fixed lower leg and torque with enough force to
cause a tear. Non-contact injuries, on the hand occur primarily during deceleration
of the lower extremity, with the quadriceps maximally contracted and the knee at or
near full extension.
ACL tears may be partial or complete. Partial tears can range from a minor
tear involving just a few fibers to a high grade near-complete tear involving almost all
of the ACL fibers. A partial tear can involve both or only a single bundle to varying
degree. Sometimes plastic deformity of the ACL without fiber discontinuity can occur
causing ACL insufficiency22. Most ACL tears (approximately 80%) are complete,
occurring around the middle one-third of the ACL (90%) or less frequently close to
the femoral (7%) or tibial (3%) attachments. Less frequently (approximately 20%),
ACL tears are incomplete with partial disruption of the ACL fibres22. Partial tears
may involve only one or both bundles to a varying degree though the anteromedial
band does tend to be the more commonly affected. Imaging, and in particular MRI, is
very helpful in the assessment of suspected ACL injury13.
Radiographs have limited value in the diagnosis of acute anterior cruciate
ligament injury.
Findings are indirect and limited to bony abnormalities.
On
radiography, several indirect signs raising the suspicion of ACL injury may be seen
which includes avulsion fracture at the tibial insertion or femoral origin lr at the lateral
tibial rim (Segond fracture), lateral femoral notch sign, sulcus deeper than 1.5 mm
and
increased
opacity
in
the
suprapatellar
pouch
with
fat
fluid
level
(lipohemarthrosis)23.
The anterior cruciate ligament can also be visualized by CT scan imaging
however, its demonstration is impaired in the presence of hemarthrosis. However,
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ACL avulsion injury by is seen by radiography, CT may be helpful in determining the
size and comminution of the avulsion bone fragment.
MRI is highly accurate at diagnosing ACL tears with accuracy, sensitivity and
specificity of more than 90%. MRI sequences applied for optimal visualization of the
ACL are 2D fast spin echo sequences either with or without fat suppression.
Different planes are used for anatomical correlation. In most institutions, the
sequences used to visualize ACL include Turbo spin echo (TSE) sagittal
intermediate weighted sequence either with fat suppression and non-fat suppression,
TSE coronal T2 weighted fat suppression sequence and TSE axial intermediate
weighted with fat-suppression sequence. The normal ACL should have a taut, low to
intermediate signal intensity with continuous fibres in all planes and sequences. It
courses parallel or steeper than the intercondylar line. The PLB usually has higher
signal intensity than the AM bundle13. Primary sign of an ACL tear is discontinuity
which was defined as a focal gap in the ligament or depiction of more than one
ligament piece11, 13. Partial tears are more difficult to diagnose and are characterized
by increased signal intensity and fiber laxity with increased concavity or bowing of
the ACL13. Secondary signs of an anterior cruciate ligament injury include bone
contusions or bruises, deep lateral femoral notch sign, Bosch-bock bump, anterior
tibial translation, femorotibial translation and rotation resulting to buckling of the
patellar tendon, buckling of the posterior cruciate ligament (PCL), a posterior PCL
line, and uncovered posterior horn of the medial or lateral meniscus4, 11-13.
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OBJECTIVES
GENERAL OBJECTIVE:
The main purpose of this paper is to retrospectively compile data regarding
the injuries to the anterior cruciate ligament in patients of different age groups who
underwent MRI of the knee in the UST Hospital and establish the most common
causes.
SPECIFIC OBJECTIVE (S):
-
This research will focus in patients diagnosed with ACL sprain, partial tear
and complete tears.
-
Etiologies or mechanism of injury will be correlated to the injury acquired.
-
Establish the most common causes of injuries in the anterior cruciate ligament
occurring in Filipinos of different age groups.
STUDY DESIGN
DESIGN: Retrospective Study
SETTING: University of Santo Tomas Hospital
STUDY POPULATION: Patient from the period of January 2009 to December 2013
who underwent MRI of the knee and diagnosed with anterior cruciate ligament injury
SUMMARY
This will be a retrospective study of patients who were diagnosed with anterior
cruciate ligament injury, which includes partial tear, sprain of complete tears, after
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undergoing MRI of the knee from the period of January 2009 to December 2013 in
the Department of Radiological Sciences at the University of Santo Tomas Hospital.
The age of the patients as well as their respective pertinent medical histories
as to the causes of their respective injuries as seen in the MRI database will be
reviewed for completeness of the patient’s entries.
All data for the study will be acquired from the digital files of the MRI section
of the University of Santo Tomas Hospital. Likewise, the approval from concerned
authorities with attention to confidentiality (patient data-identification process) will be
practiced.
DATA MANAGEMENT AND STATISTICAL ANALYSIS
The stratified sampling method will be used in selecting the included subjects
in this study.
The data acquired will be analyzed by descriptive statistics and
frequency distribution, while the measure of association between the data will be
assessed using the Pearson correlation coefficient.
INCLUSION CRITERIA
1. Patients who underwent MRI of the knee from the period of January 2009 to
December 2013 in the MRI section of the University of Santo Tomas Hospital.
2. Interpretation or official MRI result revealed a definite injury to the anterior
cruciate ligament, whether it is a sprain, partial tear or complete tear.
3. Patients with no previous diagnosis of ACL injury.
4. Patients aged 13 years old and above.
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5. Data of the patient as recorded in the MRI database includes the history of the
patient, i.e. chief complaint, activity prior to symptoms.
EXCLUSION CRITERIA
1. Interpretation or official result of the knee MRI revealed inconclusive findings.
2. Incomplete information in the MRI database and/or records.
3. Patients on follow-up with previous diagnosis of anterior cruciate ligament
injury and those who received therapeutic intervention.
After careful evaluation and screening of each patient, the final study population of
this study will only be composed of the patients that have met all the criteria, as
specified above.
ETHICAL CONSIDERATIONS
DUTY OF CONFIDENTIALITY
The research, being retrospective in nature, will only deal with pre-collected
data in the form of the subjects’ individual medical histories as well as the MRI digital
images and results of the eligible patients. The patient’s privacy will be protected as
their identities will not be revealed nor any personal information be disclosed when
the study is published or presented.
The anonymity and confidentiality of the
subjects will be maintained before, during and after the completion of this study. All
data collected will only be used for research purposes. Breach of confidentiality may
occur if the information of the patients included in this study will be used in any other
way.
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INFORMED CONSENT
Authorization to access the medical information of all included patients is
approved by the chairman of the department. As this study will only be a review of
the records kept by the department, no informed consent from each participant will
be undertaken.
DECLARATION OF INTEREST
The authors of this retrospective study declare that there is no conflict of
interest that could be perceived as prejudicing the impartiality of this scientific study.
FUNDING
This study will not receive any grant for its completion from any funding
agency from the public, commercial or not-for-profit sectors and any expenses will be
paid for by the investigators.
BUDGET
ITEMS
AMOUNT
Office Supplies and Material
500.00 Php
Photocopying/Printung Expenses
500.00 Php
Statistician
2,300 Php
TOTAL
3,300 Php
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REFERENCES
1. Amockzy, S..
Anatomy of the Anterior Cruciate Ligament.
Clinical
Orthopedics 1983; 172: 19-25.
2. Arendt, M.D., E., Agel, J. & Dick, R.. Anterior Cruciate Ligament Injury
Patterns Among Collegiate Men and Women. Journal of Athletic Training
1999; 34 (2): 86-92.
3. Besette, M.D. and Hunter, M.D., R.. The Anterior Cruciate Ligament.
Orthopedics 1990; 13: 551-562.
4. Cimino, M.D., F., Volk, M.D., & Setter, D.. Anterior Cruciate Ligament Injury:
Diagnosis, Management and Prevention. American Academy of Family
Physicians. 2010. www.aafp.org/afp.
5. Crema, M.D., Roemer, M.D., F., et al..
Articular Cartilage in the Knee:
Current MR Imaging Techniques and Applications in Clinical Practice and
Research. Radiographics 2011; 31: 37-62.
6. Dalinka, M.D., M., Gohel, M.D., V., and Rancier, M.D., L.. Tomography in the
Evaluation of the Anterior Cruciate Ligament. Radiology 1973; 108: 31-33.
7. Duin, J.. Anterior Cruciate Ligament Injury: Pre- and Post-operative
Rehabiltation. Dubin Chiropractic.
8. Hayes, M.D., C., Brigido, M.D., M., et al..
Mechanism-based Pattern
Approach to Classification of Complex Injuries of the Knee Depicted at MR
Imaging. Radiographics 2000; 20: S121-S134.
9. Kim, M.D., K., Laor, M.D., T., et al..
Anterior and Posterior Cruciate
Ligaments at Different Ages: MR Imaging Findings. Radiology June 2008;
247: 826-835.
Page 11 of 13
Protocol Version 1 dated October 2013
10. Kweon, C., Lederma, E., and Chhabra, A.. The Multiple Ligament Injured
Knee: A Practical Guide to Management.
Chapter 2 - Anatomy and
Biomechanics of the Cruciate Ligaments and Their Surgical Implications.
Springer Science 2013 http://www.springer.com/978-0-387-49287-2.
11. Lee, M.D., K., Siegel, M.D., M., et al.. Anterior Cruciate Ligament Tears: MR
Imaging-Based Diagnosis in a Pediatric Population. Radiology 1999; 213:
697-704.
12. Mesgarzadeh M.D., M., Schneck, M.D., and Banakdarpour, A..
Magnetic
Resonance Imaging of the Knee and Correlation with Normal Anatomy.
RadioGraphics July 1988; 8 (4): 707-733.
13. Ng, W., Griffith, J., et al.. Imaging of the Anterior Cruciate Ligament. World
Journal of Orthopedics 2011; 2 (8): 75-84.
14. Oie, M.Sc, E., Nikken, M.D., J., et al..
MR Imaging of the Menisci and
Cruciate Ligaments: A systematic Review. Radiology 2003; 226: 837-848.
15. Petersen, W. and Tillmann, B..
Anatomy and Function of the Anterior
Cruciate Ligament. Orthopedic 2002; 31:710-718.
16. Prince, J., Laor, T., and Bean, J.. MRI of Anterior Cruciate Ligament Injuries
and Associated Findings in the Pediatric Knee: Changes with Skeletal
Maturation. American Journal of Radiology 2005; 185: 756-762.
17. Recondo, M.D., J., Salvador, M.D. E., et al.. Lateral Stabilizing Structures of
the Knee: Functional Anatomy and Injuries Assessed with MR Imaging.
Radiographics 2000; 20:S91-s102.
18. Reiman, P. and Jackson, D.. Anatomy of the Anterior Cruciate Ligament, in
Jackson, D., Drez, D. (eds): The Anterior Cruciate Deficient Knee. St. Louis,
CV Mashy & Co. 1987: 17-26.
Page 12 of 13
Protocol Version 1 dated October 2013
19. Remer, M.D., R., Fitzgerald, M.D., S., et al..
Anterior Cruciate Ligament
Injury: MR Imaging Diagnosis and Patterns of Injury. Radiographics 1992; 12:
901-915.
20. Robertson, P., Schweitzer M.D., M., and Bartolozzi M.D., A..
Anterior
Cruciate Ligament Tears: Evaluation of Multiple Signs with MR Imaging.
Radiology 1994; 193: 829-834.
21. Tung M.D., G., Davis M.D., L., et al.. Tears of the Anterior Cruciate Ligament:
Primary and Secondary Signs at MR Imaging. Radiology 1993: 188: 661-667.
22. Vahey, T., Broome, D., et al.. Acute and chronic tears of the anterior cruciate
ligament: differential features at MR imaging. Radiology 1991; 181: 251-253.
23. Wong, J., Khan, T., et al..
Anterior Cruciate Ligament Rupture and
Osteoarthritis Progression. The Open Orthopedics Journal 2012; 6, (Suppl 2:
M6): 295-300.
24. Zantop, T., M.D., Petersen, W., M.D., et al.. Anatomy of the Anterior Cruciate
Ligament. Operative Techniques in Orthopedics 2005; 15:20-28.
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