Dynamic biomechanical evaluation of the dorsal intercarpal ligament repair for scapholunate instability.

PURPOSE: A variety of soft tissue surgical procedures have been developed for treatment of scapholunate dissociation. One reconstruction method, using the dorsal intercarpal ligament, has been used clinically with some success. The purpose of this study was to evaluate biomechanically use of the dorsal intercarpal ligament for static scapholunate dissociation.

METHODS: Eight cadaver wrists were tested in a wrist joint motion simulator. Each wrist was moved in continuous cycles of flexion-extension and radial-ulnar deviation. Kinematic data for the scaphoid and lunate were recorded for each wrist in the intact state, after the scapholunate interosseous, dorsal radiocarpal, and dorsal intercarpal ligaments were sectioned, and after reconstruction using the dorsal intercarpal ligament.

RESULTS: Ligamentous sectioning resulted in static scapholunate dissociation. Visually, the repair initially reduced the gap between the scaphoid and lunate, but within a few cycles of wrist motion, there were statistically significant increases in scaphoid flexion, scaphoid ulnar deviation, and lunate extension. In 6 arms, gapping between the scaphoid and lunate was observed. In 2 arms, a gap occurred and the repair also pulled out of the bone junction.

CONCLUSIONS: This study does not support the hypothesis that the dorsal intercarpal ligament repair alone will stabilize the scaphoid and lunate after scapholunate instability in the immediate postoperative period.