Scapholunate gap with scaphoid nonunion.

Ten of 64 patients reviewed with scaphoid nonunion were found to have scapholunate gaps (SLG). A roentgenographic study of the entire group who were symptomatic, but had no prior surgery, showed the SLG. The SLG indicated severe ligamentous injury and instability, and was always associated with the presence of Doral Intercalated Segment Instability (DISI) and an increased scapholunate angle. Instability was progressive and associated with the early onset of arthritis. In the entire group of nonunions, high frequency of arthritis occurred with a predictable sequence of radioscaphoid and midcarpal degenerative changes. Terminal wrist arthritis in scaphoid nonunion developed in the scapholunate articulation, as a manifestation of rotary subluxation of the distal scaphoid fragment.