[Avulsion fractures of the knee and upper ankle joint. Classification and therapy].

Injuries of the joint surface interfere with joint mechanics. Avulsed fragments should be reattached to prevent development of arthrosis. Of 150 fractures of the knee joint 72% were osteochondral and 28% chondral avulsion. About half of the chondral lesions could be refixed successfully. If replantation is impossible, this cartilage defect has to be smoothed and, when indicated, connected to spongy bone by subchondral drilling.