Chondral lesions of the femoral condyles: a system of arthroscopic classification.

Based on a study of 167 chondral lesions in 140 knees, six different types of lesions confined to the articular cartilage of the femoral condyles are recognized. They are: type I, linear crack; type II, stellate fracture; type III, flap; type IV, crater; type V, fibrillated; and type VI, degrading. The weight-bearing parts of the surfaces are the site of predilection in most cases. The mechanism behind the injuries is discussed, with types I-IV probably of acute traumatic origin, and types V and VI associated with degenerative processes.