ACL Tear: Management in Skeletally Immature Athletes
ACL Tear: Management in Skeletally Immature Athletes
Holly J. Benjamin
Michael Ladewski
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Description
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Injury sustained by known mechanism that leads to instability with significant effect on the athlete's ability to perform at the highest levels of sport
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Considerable controversy exists regarding treatment in the skeletally immature population.
Epidemiology
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Higher incidence in female basketball and soccer players than in their male counterparts
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The higher incidence in females is thought to be due to differences in biomechanics, joint laxity, hormonal influences, intercondylar notch dimensions, and ligament size.
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Other sports associated with anterior cruciate ligament (ACL) injury are skiing and football.
Incidence
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16/1,000 high school athletes annually
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38,000 high school students yearly
General Prevention
Neuromuscular balance training and core strengthening have been shown to decrease the incidence in female athletes.
Etiology
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Midsubstance tear most common
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Tibial spine avulsion fracture more frequent in the skeletally immature athletes
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Femoral ACL avulsion fractures are rare causes of ACL injury.
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Mechanisms of injury:
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Hyperextension, sudden deceleration, or a valgus and rotator force with a planted foot
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External rotation of the femur on a fixed tibia combined with a valgus load often the result of a noncontact pivoting injury
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Commonly Associated Conditions
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Bone bruise: Lateral compartment more than medial compartment
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Meniscus tears: Lateral more commonly in acute knee injury; medial more common in athlete with chronic ACL deficiency
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Associated medial meniscus tears and medial collateral ligament injury in patient with valgus stress mechanism
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History
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May be a “pop” sensation at the time of injury
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Effusion usually develops acutely.
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Athlete unable to continue play
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Instability of knee after injury
Physical Exam
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It can be difficult to perform an accurate physical exam after significant hemarthrosis develops.
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Ecchymosis and loss of normal knee contour secondary to effusion are often present.
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The Lachman test is the most sensitive physical examination test and is the “gold standard” for diagnosis.
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Anterior drawer and pivot-shift tests are positive but are less sensitive tests.
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Palpate the distal femur and proximal tibia physes for tenderness.
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Tenderness at the ends of long bones is a fracture until proven otherwise in skeletally immature patients.
Diagnostic Tests & Interpretation
Imaging
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Knee radiographs to rule out tibial spine avulsion fracture, physeal fractures, Segond fracture, and osteochondral fractures
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MRI to evaluate ACL and concomitant meniscal, posterior cruciate ligament, collateral ligament, and chondral injuries:
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95% sensitivity and 88% specificity when correlated with arthroscopic findings
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Tear imaging shows increased signal intensity with a disrupted pattern.
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May have a higher false-positive rate in adolescents
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Consider wrist x-rays to assess bone age, which may influence surgical approach.
Diagnostic Procedures/Surgery
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Diagnostic arthroscopy is sometimes required when physical exam and imaging studies are equivocal.
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KT-1000 device may be helpful in quantifying relative ACL laxity.
Differential Diagnosis
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Tibial spine avulsion fractures
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Physeal fractures of the distal femur or proximal tibia
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Meniscal injury
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Patellar subluxation
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Other ligamentous injury of the knee
P.13
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Compression
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Ice
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Pain management
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Weight bearing as tolerated unless physeal fracture is suspected
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Therapeutic aspiration is rarely performed on the hemarthrosis.
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If fat is noted in the hemarthrosis, then a fracture is present.
Additional Treatment
Additional Therapies
Nonoperative therapy may be considered depending on physical demands and age of athlete.
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Not a definitive treatment choice owing to risk of recurrent instability and further meniscal damage
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Bracing with derotational ACL-stabilizing brace does not restore stability when athlete returns to high-demand sport.
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Restoration of range of motion
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Strengthening quadriceps and hamstrings
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Activity modification
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May be recommended if ACL reconstruction delayed owing to skeletal immaturity
Surgery/Other Procedures
Controversy related to approach and risk for early physeal closure:
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Related to skeletal maturity
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Undertaken only after restoration of range of motion (ROM)
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Acute repair not proven to be successful
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Considered with unsuccessful nonoperative treatment, high-level adolescent athlete
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Associated meniscal tear an indication for surgical treatment
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Options include physeal sparing and partial or complete transphyseal reconstructions.
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Follow-Up Recommendations
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Patients with suspected ACL injuries should be referred to an orthopedic or sports medicine specialist.
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Preference would include specialist with experience in surgical approaches in the skeletally immature athlete.
Prognosis
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Typical postoperative recovery and rehabilitation period is usually 9–12 mos.
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Up to 78% risk of radiographic evident osteoarthritis within 14 yrs of injury ± surgery.
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Natural history of the ACL-deficient knee is chronic instability, chondral injury, subsequent meniscal pathology, pain, and joint arthrosis.
Complications
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Associated medial collateral ligament (MCL) and meniscal injuries
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Surgical complications:
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Graft failure
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Premature physeal closure
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Slow recovery in ROM
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Usual risks of infection and anesthesia
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Additional Reading
Fehnel DJ, Johnson R. Anterior cruciate injuries in the skeletally immature athlete: a review of treatment outcomes. Sports Med. 2000;29:51–63.
Murray MM. Current status and potential of primary ACL repair. Clin Sports Med. 2009;28:51–61.
Schachter AK, Rokito AS. ACL injuries in the skeletally immature patient. Orthopedics. 2007;30:365–370; quiz 371–372.
Siow HM, Cameron DB, Ganley TJ. Acute knee injuries in skeletally immature athletes. Phys Med Rehabil Clin N Am. 2008;19:319–345, ix.
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ICD9
844.2 Sprain of cruciate ligament of knee
Clinical Pearls
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Injury that is increasing in incidence in the adolescent population
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Surgical therapies vary in their approach and timing.
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Type of ACL reconstruction and timing of surgery in the skeletally immature athletic population are extremely controversial, and cases should be decided on an individual basis.