Pes anserinus transposition for chronic anteromedial rotational instability of the knee.

Forty-eight men and three women were reviewed an average of thirty-one months after pes anserinus transposition for chronic anteromedial rotational instability of the knee. Their ages ranged from eighteen to forty-two years (average twenty-five years). All but four of the injuries occurred during sport. The interval between injury and operation averaged thirty months. During this time twenty-three patients had had other operations of which eighteen were for excision of menisci. A further sixteen patients required excision of one or both menisci at the time of pes anserinus transposition. After operation large haematomata had to be expressed from four wounds. One patient had a pulmonary embolism All made a complete recovery. Worthwhile improvement of stability during activity was found in forty-two of the fifty-one knees. Pre-existing degeneration of articular cartilage associated with severe instability of long duration was the main cause of failure. Good motivation was important for success. Four grades of disability are described according to the severity of symptoms. It was found that a successful operation gave approximately one grade of improvement on this scale. Arthroscopy is recommended to identify torn menisci and degenerative changes before pes anserinus transposition is undertaken. An important advantage of this operation is its simplicity. When more elaborate ligamentous reconstructions are necessary for severe instability, pes anserinus transposition can be usefully added to complete the repair.