Review Question - QID 216810

In cases of anterior cruciate ligament (ACL) rupture, the lateral tibial plateau is initially subluxed anteriorly on the femur. With pivot shift testing, the iliotibial (IT) band tightens and leads to reduction of the plateau.

ACL injuries are very common, and are usually non-contact injuries resulting from a valgus, twisting moment with the knee in slight flexion. The two primary tests for evaluating ACL rupture are the Lachman test and the pivot shift maneuver. Lachman testing provides the most sensitive evaluation for diagnosing ACL rupture but preferentially evaluates the anteromedial bundle through the anterior translation of the tibia on the femur. The pivot shift maneuver evaluates the rotational integrity of the ACL and its posterolateral bundle. It is performed with the knee positioned in extension and brought into slight flexion with valgus and internal rotation forces on the knee. The lateral tibial plateau, which is initially subluxed anteriorly in extension, is reduced by the IT band during this maneuver as the IT band tightens.

Galway et al. review the lateral pivot shift during ACL rupture, noting that the rotational forces involved in injury cause the lateral tibial plateau to sublux anteriorly. They discuss associated injuries that can be caused by this mechanism. They reiterate that this rotational instability continues to cause patients to complain of their knee feeling unstable if not adequately addressed.

Lane et al. published a review of the pivot shift test for evaluation of ACL ruptures. They go on to review the specific anatomy and technique involved in performing the pivot shift maneuver. They note that the pivot shift maneuver better correlates with functional instability and patient outcomes than other tests and preventing any residual rotational laxity should be a primary goal of ACL reconstruction.

Incorrect Answers:
Answer 1: Pivot shift maneuver evaluates the posterolateral bundle of the ACL, which controls rotational stability
Answer 2: Lateral tibial plateau is initially subluxed and reduces with pivot shift maneuver, not the medial plateau.
Answer 4: Anterior femoral tunnel placement will over tighten the ACL graft in flexion. Pivot shift would be affected by a graft placed too vertically.
Answer 5: Lachman testing is the most sensitive evaluation for ACL rupture as the Pivot shift can be technically difficult and tough to elicit without complete relaxation.