Radiographic analysis of anatomic risk factors for scapholunate dissociation.

The aim of this study was to identify anatomic risk factors for scapholunate dissociation. On a PA view of the wrist, in zero position, the scaphoid and lunate diameter and height, lunate tilting angle, lunate uncovering index, lunate fossa inclination, radial inclination and ulnar variance were measured; on a lateral view the scapholunate angle and palmar tilting angle were measured. In a control group (N = 126) first left to right were compared which showed low correlations for radial inclination (r = 0.26), palmar tilt (r = 0.60) and ulnar variance (r = 0.68). These parameters were then measured on the affected hand in the study group, since they are not influenced by the dissociation, and no arthritic changes were seen. A statistically significant difference was found for a low lunate fossa inclination (p = 0.0001) and a low radial inclination (p = 0.0002). These factors may predispose to scapholunate dissociation.