Dorsal intercarpal ligament capsulodesis for scapholunate dissociation: biomechanical analysis in a cadaver model

The purpose of this study was to evaluate in cadavers a new method for treating scapholunate dissociations, dorsal intercarpal ligament capsulodesis (DILC), and to compare its performance with that of a previously described soft tissue reconstruction, Blatt capsulodesis (BC). A cadaver model was used to simulate normal and abnormal wrist motions. The positions of the scaphoid and lunate and their changes with wrist motion and ligament condition were recorded using biplanar radiographs taken posteroanteriorly and laterally. The scapholunate gap was measured on the posteroanterior radiographs and the scapholunate angle was measured on the lateral view radiographs. Following scapholunate interosseous ligament sectioning, a diastasis developed between the scaphoid and lunate that was maximum in the clenched fist position 2.1 +/- 0.33 mm (mean +/- SEM) with the ligament intact versus 8.0 +/- 1.74 mm after the ligament was sectioned. Dorsal intercarpal ligament capsulodesis reduced gap formation more than BC, including when the specimens were in the clenched fist position: increased gap versus intact specimens equals 1.0 mm for DILC versus 3.7 mm for BC. The differences in diastasis were statistically significant between BC and DILC when the wrist was in extension, radial deviation, and clenched fist positions. After the scapholunate interosseous ligament was divided, the scaphoid flexed relative to the lunate. Both capsulodeses improved scapholunate alignment and there was a trend for DILC to correct the scapholunate angle more than BC. The results demonstrate that DILC is an attractive alternative to BC ex vivo. Because DILC does not tether the scaphoid to the distal radius, as BC does, improved wrist motion, especially flexion, might be possible in vivo. The use of DILC in the treatment of scapholunate dissociation warrants further investigation and clinical trials.