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Physical Exam for ACL Tear

- See:
     - Physical Exam of the Knee:

     - Mechanism: ACL Tear:
     - Anteromedial Rotatory Stability:
     - Anterior Cruciate Ligament
     - Anterior Drawer Test
     - Anterolateral Rotatory Instability
     - Clunk Test
     - Lachman
     - Losee Test 
     - Pivot Shift Test
     - Reverse Pivot Shift Test

- Discussion:
    - initial symptoms may be of posterolateral knee pain;
    - hemarthrosis:
           - greater than70% of pts w/ acute hemarthrosis  will have ACL tear;
           - severe swelling of the knee typically develops within two hours of injury because of hemarthrosis;
           - hemarthrosis will develop over 6-24 hours;
           - if effusion develops immediately after injury, one should suspect an osteochondral fracture;
                  - presence or absence of fat in aspirated fluid is key distinction;
           - although swelling is expected, an associated capsular tear will allow fluid to extravasate from the joint which prevents formation of hemarthrosis;
    - consider alterantive dx (quadriceps or patella tendon rupture)

- Exam Findings:
    - gait analysis:
          - always watch the patient walk;
          - a varus thrust may indicate LCL laxity;
          - a varus stance alignment, is a relative contra-indication for immediate ACL reconstruction;
                 - in this case, consider the need for a high tibial osteotomy prior to ACL (or LCL) reconstruction;
                 - these patients may have a significant change in standing vs supine alignment (esp when there is a combination of an ACL and LCL injury);
                 - an opening wedge distraction osteotomy might be preferable in these patients since it is difficult to judge how much correction is required;
    - ROM:
          - acute extension block:
                - may be due to bucket handle meniscus tear, ACL tear (from interposition of ACL between femur and tibia), or from fat pad adhesions to a torn ACL;
                - as is pointed out by KD Shelbourne MD (Arthroscopy Aug 1996 p 492), an acute knee block associated with an ACL tear is usually due to
                       interposition of the ACL between the femur and tibia in the intercondylar notch;
                       - this author emphasizes, the need to perform dedicated physical therapy to restore motion;
                - physical therapy should consists of ROM, stretching, and patellar mobilization;
                - references:
                       - The locked knee. JR Jones and RL Allum.  JBJS. 67-B. 1985. p 488.
                       - Fat pad adhesion to partially torn anterior cruciate ligament: a cause of knee locking.  Am J. Sports Med. Vol 17. 1989. p 92-95.
    - stability:
            - lachman:
            - pivot shift:
            - clunk test:
                   - begins w/ knee in flexion while a valgus stress and internal rotation force are applied;
                   - the thumb pushes the tibia forward, and the clunk of reduction is felt as the knee approaches full extension;
                   - subluxation of lateral femorotibial articulation becomes maximum at about 30 deg of flexion, then as knee extends further, spontaneous relocation occurs;
                   - the relocation takes the form of a sudden jerk;
            - Losee Test:
                   - begins w/ the knee in flexion as external rotation and valgus force are applied;
                   - when the knee is extended, the foot internally rotates & previously subluxated tibia reduces as knee approaches full extension;
            - reverse pivot shift test:
                   - knee begins in flexion while an external rotation and valgus stress are applied;
                   - clunk is appreciatted as the knee is extended;
                   - tibia will subluxate posteriorly with flexion;
            - external recurvatum test:
                   - allows the tibia to posteriorly subluxate and rotate owing to a torn posterolateral capsule;

Lachman test evaluated. Quantification of a clinical observation.

Injury to the anterior cruciate ligament producing the pivot-shift sign.

Long-term functional results in patients with anterolateral rotatory instability treated by iliotibial band transfer.

The lateral pivot shift: a symptom and sign of anterior cruciate ligament insufficiency.

An analysis of the pivot shift phenomenon. The knee motions and subluxations induced by different examiners.

Correlation of joint line tenderness and meniscal lesions in patients with acute anterior cruciate ligament tears.

Ligamentous restraints to anterior-posterior drawer in the human knee:  A biomechanical study. Noyes FR, Grood ES: J Bone Joint Surg 1980;62A:259-270.