Osteochondritis Dissecans of the Supratrochlear Septum

Abstract

Prior to the discovery of the roentgen ray, Pfitzner described an inconstant accessory bone, recognized on anatomical specimens, lying posterior to and near the supratrochlear fossa of the elbow. This accessory bone he labeled “sesamum cubiti.” The name has been applied until recent years to a process which is now recognized as osteochondritis dissecans of the supratrochlear septum. It has been referred to previously also as a “loose body” within the elbow joint, and in one case as being associated with osteochondromatosis. The findings in these cases are now regarded as due not to an accessory bone but to a true aseptic necrosis similar to that recognized frequently in other bone structures. In the case of the elbow, the changes are believed to be associated with an unusually thin supratrochlear septum. The supratrochlear (olecranon) fossa in this disease presents a characteristic roent-genographic picture, subject to certain variations in individual cases. The appearance is that of a radiolucent area, free of bone trabeculations and sharply outlined at its outer borders by a definite bony ring, which at times may appear serrated. Occupying the radiolucent area are one or more dense, sclerotic fragments of bone. Depending on the stage of the disease, these bone fragments may be incompletely or completely detached from the surrounding normal bone. They may be seen, with the aid of lateral and oblique projections, lying within the foramen in the fossa, or in other cases they may have separated from their original position to lie anywhere within the elbow joint. Most frequently, however, if the fragments have migrated, they lie posterior to the lower end of the humerus. The following case is added to the few previously reported. Case History G. L., a 40-year old fanner, presented himself with swelling and tenderness of the right elbow and a history of intermittent episodes of pain since the age of thirteen. No definite history of injury could be elicited, though the present attack was evidently initiated by the prolonged use of a hammer. Ordinarily the attacks had lasted only a few days and then gradually subsided, but in this instance the symptoms were more prolonged and severe. Physical examination revealed a general thickening of the structures of the posterior aspect of the right elbow. Full pronation and supination were present, but there was a 20 degree limitation of complete extension, and 10 degree limitation of flexion. Roentgenograms showed the typical changes of osteochondritis dissecans of the supratrochlear septum as described above. Mild osteoarthritic changes of the articular surfaces of the elbow joint were also present. Views of the left elbow for comparison showed a thin supratrochlear septum but no evidence of osteochondritis dissecans.