Anterior Cruciate Ligament Integrity

Description

Mr Sam Oussedik gives his expert insights and describes how the pivot shift test is a critical assessment for determining the rotational stability of the knee, particularly in relation to the integrity of the anterior cruciate ligament (ACL). This test is especially sensitive in patients who exhibit gross physiological laxity, where it may yield a positive result even when the ACL is intact. Conducting the test involves assessing the knee in full extension, identifying the anterior subluxation of the lateral tibial condyle when internal rotation is applied against the femur. The medial collateral ligament plays a vital role as a pivot point during this movement, highlighting its importance in the knee's stability.



During the test, as the knee is flexed, the iliotibial band transitions from exerting an extensor moment to pulling the tibia back into joint alignment due to its drop behind the center of rotation. This dynamic causes a characteristic "clunk" as the subluxed lateral tibial plateau returns to its proper position. The clunk's significance varies, with grades indicating the severity of instability from a minor glide to a more explosive pivot shift.



Surgeons may interpret the results of this test as indicators of gross rotational instability and consider additional surgical interventions, such as lateral extra-articular tenodesis, to mitigate the risks associated with persistent internal rotation of the tibia relative to the femur.

DOI: 10.1302/3114-251260

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