[Stabilization of the external condyle of the knee in chronic anterior laxity. Importance of the popliteal muscle].

The authors have made an anatomical and experimental study in cadavers. They consider that one of the main features of chronic anterior instability of the knee is related to the instability of the lateral femoral condyle. This is due to the loss of its two stabilizers: the anterior cruciate ligament and the popliteal muscle. The signs of a lesion of the postero-lateral structures have to be looked for: antero-posterior drawer sign in extension, hypermobility of the tibia in lateral rotation and varus laxity. Such instability leads to arthrosis in the long-term. The proposed treatment is based on a reconstruction of the anterior cruciate ligament, using semitendinosus associated with a postero-lateral reconstruction using either the biceps or the fascia lata, or a free transplant from the patellar ligament. Corrective osteotomy of an associated varus deformity may be indicated.