Osteochondritis dissecans of the posterior femoral condyle.

Osteochondritis dissecans of the posterior femoral condyle is an uncommon condition. In many respects--the large size of the joint, involvement of the weight-bearing surface, natural history, method of treatment, and the population affected--it differs from the more usual condition found in the intercondylar region. In 14 cases (16 involved knees), representing the total number of cases found in the province of British Columbia during a five-year period, nearly every patient was a young male athlete. If the patient is treated before the age of 15 years, the condition may heal spontaneously or with a regimen of restricted activity. From this time, the lesion remains fairly stable and mildly symptom-producing, often for many years, until finally the osteochondral surface fragment breaks free into the joint. Once the fragment has separated, surgery becomes mandatory. To prevent degenerative joint changes and major disability is a challenge to the surgeon. Fragment removal, even with drilling of the base, has proved ineffectual. The fragment must be replaced and stable and exact anatomic realignment of the weight-bearing condylar surface restored. Multiple drilling perforations through the sclerotic base are required to stimulate revascularization. Because of the difficulty, and sometimes impossibility, of successfully meeting these exacting surgical requirements, the operation should be performed before the osteochondral fragment breaks free. The surgical technique is designed to restore vascularity to the ischemic bone and to maintain the normal contour of the condylar surface, without violating the articular cartilage surface.