Radiological and pathological manifestations of osteochondritis dissecans of the distal femur. A study of 50 cases.

The specimens from 50 operated cases of osteochondritis dissecans of the distal femur were analyzed histopathologically. Radiodensity of the specimens of osteochondritis dissecans was due (a) attached subchondral bone, (b) degenerative secondary calcification of articular cartilage, (c) revascularization with new bone, and, in the free bodies, (d) calcification in new surface layers of cartilage and bone. The pathological findings in the specimens suggested an etiology from trauma rather than avascular necrosis. Half of the specimens of osteochondritis dissecans contained no subchondral bone but only articular cartilage. It was postulated that the relationship of the attached lesions to the intercondylar notch of the femur, which permitted a partially retained blood supply, created a spectrum of different histopathological changes in the subchondral bone of those specimens with attached bone.