Anterolateral rotary instability associated with chronic anterior cruciate insufficiency.

Patients with anterior cruciate tears identified by previous surgery were examined for anterolateral rotary instability of the knee. Twenty-four of 30 patients returning for examination had positive tests for anterolateral rotary instability using the techniques described by both Slocum and MacIntosh. The presence of anterolateral rotary instability was directly related to the attainment of full extension of the operative knee. Inherent ligamentous laxity and the degree of combined instabilities were thought to amplify the anterolateral rotary instability tests. Quadriceps rehabilitation, pes anserines transfers and semimembranosus transfers were thought not to influence anterolateral rotary instability.