Osteochondral fractures: mechanisms of injury and fate of fragments.

Osteochondral fractures, although relatively common, are frequently misdiagnosed by both clinicians and radiologists. In many of these cases positive radiographic findings are present although subtle. This paper reviews the mechanisms of injury by which osteochondral fractures occur and discusses the radiographic features of such fractures. An analysis of 43 surgical cases of osteochondral fractures in different sites was undertaken with respect to the radiographic, surgical, and histopathologic findings. Fragments consisting of cartilage alone or cartilage and bone were analyzed in terms of their radiographic features acutely and chronically after the trauma. The pathologic changes occurring within the original fragments are differentiated from those of surface growth in the older loose bodies. Attached fragments react differently than loose fragments. Typical cases from the knee joint are illustrated.