Physical examination in the diagnosis of rotatory instability.

Various tests are used to evaluate rotatory instability. Anteromedial rotatory instability (AMRI) is detected by performing an anterior drawer test with the foot in external rotation. Excessive anterior rotation of the medial tibial plateau indicates laxity of the medial structures. Anterolateral rotatory instability (ALRI) is a manifestation of an anterior cruciate ligament (ACL) deficient knee. The functional disability produced is the pivot shift phenomenon, which is elicited by the MacIntosh, jerk, ALRI, FRD, and Losee tests. Posteromedial rotatory instability is checked by noting a posteromedial displacement of the medial tibial plateau with a valgus stress. This is a relatively unusual type of instability, although it may be part of a severe valgus type. Posterolateral rotatory instability is evaluated by the external rotation recurvatum, posterolateral drawer, and reverse pivot shift tests. The abnormalities produced by these tests will clarify the method to correct the functional deficiency.