Anterior Cruciate Ligament Injuries

Key Features

Essentials of Diagnosis

• Pain and effusion of the knee

• Pain along the lateral joint line

• Positive Lachman test

General Considerations

• The anterior cruciate ligament (ACL) consists of two bundles that prevent anterior subluxation and rotation of the tibia

• Most ACL injuries are noncontact and occur with deceleration, twisting, and cutting motions

• ACL injuries can also occur with knee hyperextension or from a direct blow to the knee—typically on the lateral side—which causes an extreme valgus stress with both ACL and MCL disruption

Clinical Findings

• The athlete often reports hearing or feeling a "pop" followed by swelling that occurs within hours of the injury

• Evaluation of the knee begins with examination of the uninjured knee

Diagnosis

• The Lachman test

  • Provides the most accurate information about knee stability in relation to the ACL

  • Perform by holding the knee in 30 degrees of flexion while supporting the tibia and femur

  • Proximal tibia is pulled anteriorly, and the degree of excursion and the firmness of the endpoint are assessed and compared to the contralateral side

  • All other structures of the knee should be examined to rule out concomitant injuries

• Imaging of the knee includes plain radiographs and an MRI scan

• In skeletally immature athletes, a tibial spine avulsion is frequently seen on radiographs rather than a midsubstance ACL tear

Treatment

• Initial treatment focuses on controlling swelling and pain

• Conservative treatment

  • Includes bracing, strengthening, and restricting physical activity

  • Can be complicated by continued instability and damage to meniscal and articular cartilage

• Surgical reconstruction

  • Typically indicated for young athletes in cutting sports and is also required for persistent instability

  • Can be performed 2–6 weeks following the injury if the swelling and motion of the knee have improved

  • Recent advances in surgical treatment of the skeletally immature athlete have been helpful in dealing with the complicated management of young athletes with ACL tears

• Rehabilitation of the knee

  • Starts immediately after surgery

  • Goals of a structured physical therapy: building strength, muscle reeducation, endurance, agility, and coordination

Outcome

Prognosis

• Return to sport can be achieved by 6 to 9 months after surgery if certain criteria are met

Reference