Acl Tear: Management in Skeletally Immature Athletes

Holly J. Benjamin, MD, FAAP, FACSM

Michael Ladewski, DO

BASICS

DESCRIPTION

Acute injury sustained by known mechanism that leads to knee instability with significant effect on the athlete’s ability to perform at the highest levels of sport
Considerable variation exists regarding specific treatment in the skeletally immature population with operative treatment becoming more favorable when compared to non- or delayed operative treatment (1,2,3)[B].

EPIDEMIOLOGY

Higher risk in female athletes than in male athletes participating in similar sports (4)
The higher incidence in females is thought to be due to differences in biomechanics, joint laxity, hormonal influences, intercondylar notch dimensions, and ligament size (4).
Sporting activity associated with anterior cruciate ligament (ACL) injury involves cutting, pivoting, and sudden deceleration (4).

Incidence

ETIOLOGY AND PATHOPHYSIOLOGY

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 (MCL) injury in patient with valgus stress mechanism

DIAGNOSIS

HISTORY

PHYSICAL EXAM

It can be difficult to perform an accurate physical exam after significant hemarthrosis develops.
Loss of normal knee contour secondary to effusion is often present.
The Lachman test is the most sensitive physical examination test and is the “gold standard” for diagnosis (4)[A].
Anterior drawer and pivot-shift tests are positive but are less sensitive tests (4)[A].
Evaluation of the uninjured knee can help establish a baseline when compared to the injured knee.
Testing for other ligamentous, tendon, and meniscal injury is indicated.
Palpate the distal femur and proximal tibia physes for tenderness that might indicate the presence of a physeal fracture.
Tenderness at the ends of long bones is a fracture until proven otherwise in skeletally immature patients.
Perform a complete neurologic and vascular exam of the lower extremity.