ACL Tear: Management in Skeletally Immature Athletes

By admin On Dec 18, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Holly J. Benjamin

Michael Ladewski

Basics

Description

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
Considerable controversy exists regarding treatment in the skeletally immature population.

Epidemiology

Higher incidence in female basketball and soccer players than in their male counterparts
The higher incidence in females is thought to be due to differences in biomechanics, joint laxity, hormonal influences, intercondylar notch dimensions, and ligament size.
Other sports associated with anterior cruciate ligament (ACL) injury are skiing and football.

Incidence

16/1,000 high school athletes annually
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

Midsubstance tear most common
Tibial spine avulsion fracture more frequent in the skeletally immature athletes
Femoral ACL avulsion fractures are rare causes of ACL injury.
Mechanisms of injury:
- Hyperextension, sudden deceleration, or a valgus and rotator force with a planted foot
- External rotation of the femur on a fixed tibia combined with a valgus load often the result of a noncontact pivoting injury

Commonly Associated Conditions

Bone bruise: Lateral compartment more than medial compartment
Meniscus tears: Lateral more commonly in acute knee injury; medial more common in athlete with chronic ACL deficiency
Associated medial meniscus tears and medial collateral ligament injury in patient with valgus stress mechanism

Diagnosis

History

May be a “pop” sensation at the time of injury
Effusion usually develops acutely.
Athlete unable to continue play
Instability of knee after injury

Physical Exam

It can be difficult to perform an accurate physical exam after significant hemarthrosis develops.
Ecchymosis and loss of normal knee contour secondary to effusion are often present.
The Lachman test is the most sensitive physical examination test and is the “gold standard” for diagnosis.
Anterior drawer and pivot-shift tests are positive but are less sensitive tests.
Palpate the distal femur and proximal tibia physes for tenderness.
Tenderness at the ends of long bones is a fracture until proven otherwise in skeletally immature patients.

Diagnostic Tests & Interpretation

Imaging

Knee radiographs to rule out tibial spine avulsion fracture, physeal fractures, Segond fracture, and osteochondral fractures
MRI to evaluate ACL and concomitant meniscal, posterior cruciate ligament, collateral ligament, and chondral injuries:
- 95% sensitivity and 88% specificity when correlated with arthroscopic findings
- Tear imaging shows increased signal intensity with a disrupted pattern.
- May have a higher false-positive rate in adolescents
Consider wrist x-rays to assess bone age, which may influence surgical approach.

Diagnostic Procedures/Surgery

Diagnostic arthroscopy is sometimes required when physical exam and imaging studies are equivocal.
KT-1000 device may be helpful in quantifying relative ACL laxity.

Differential Diagnosis

Tibial spine avulsion fractures
Physeal fractures of the distal femur or proximal tibia
Meniscal injury
Patellar subluxation
Other ligamentous injury of the knee

P.13

Treatment

Compression
Ice
Pain management
Weight bearing as tolerated unless physeal fracture is suspected
Therapeutic aspiration is rarely performed on the hemarthrosis.
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.

Not a definitive treatment choice owing to risk of recurrent instability and further meniscal damage
Bracing with derotational ACL-stabilizing brace does not restore stability when athlete returns to high-demand sport.
Restoration of range of motion
Strengthening quadriceps and hamstrings
Activity modification
May be recommended if ACL reconstruction delayed owing to skeletal immaturity

Surgery/Other Procedures

Controversy related to approach and risk for early physeal closure:

Related to skeletal maturity
Undertaken only after restoration of range of motion (ROM)
Acute repair not proven to be successful
Considered with unsuccessful nonoperative treatment, high-level adolescent athlete
Associated meniscal tear an indication for surgical treatment
Options include physeal sparing and partial or complete transphyseal reconstructions.

Ongoing Care

Follow-Up Recommendations

Patients with suspected ACL injuries should be referred to an orthopedic or sports medicine specialist.
Preference would include specialist with experience in surgical approaches in the skeletally immature athlete.

Prognosis

Typical postoperative recovery and rehabilitation period is usually 9–12 mos.
Up to 78% risk of radiographic evident osteoarthritis within 14 yrs of injury ± surgery.
Natural history of the ACL-deficient knee is chronic instability, chondral injury, subsequent meniscal pathology, pain, and joint arthrosis.

Complications

Associated medial collateral ligament (MCL) and meniscal injuries
Surgical complications:
- Graft failure
- Premature physeal closure
- Slow recovery in ROM
- Usual risks of infection and anesthesia

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.

Codes

ICD9

844.2 Sprain of cruciate ligament of knee