Radiographic definition of the dorsal and palmar edges of the distal radius.

The dorsal and palmar edges of the distal radius, as well as the concavity of the articular surface were labeled with wire and radiographs taken from neutral to 30 degrees of added dorsal tilt. The dorsal edge was identified as the structure that protrudes distally in neutral. The palmar edge was found to overlap with the sclerotic subchondral bone of the radius in neutral. With increasing dorsal tilt the profile of the palmar edge appeared as it protruded distal to the sclerotic subchondral line of the radius. The profile of the palmar edge could be distinguished from that of the dorsal edge on the anteroposterior view. The wire, which was placed midway between the dorsal and palmar edges and the concavity of the articular surface corresponded to the prominent sclerotic subchondral bone line of the distal radius. This did not change in position with increasing dorsal tilt. This clarification of the radiologic anatomy is helpful in extending the use of the anteroposterior radiograph for the interpretation of fractures and malunions of the distal radius.