Dorsal Scaphoid Subluxation on Sagittal Magnetic Resonance Imaging as a Marker for Scapholunate Ligament Tear.

PURPOSE: To evaluate the diagnostic utility of scaphoid dorsal subluxation on magnetic resonance imaging (MRI) as a predictor of scapholunate interosseous ligament (SLIL) tears and compare this with radiographic findings.

METHODS

Thirty-six MRIs were retrospectively reviewed: 18 with known operative findings of complete Geissler IV SLIL tears that were surgically repaired, and 18 MRIs performed for ulnar-sided wrist pain but no SLIL tear. Dorsal subluxation of the scaphoid was measured on the sagittal MRI cut, which demonstrated the maximum subluxation. Independent samples t tests were used to compare radiographic measurements of scapholunate (SL) gap, SL angle, and capitolunate/third metacarpal-lunate angles between the SLIL tear and the control groups and to compare radiographic measurements between wrists that had dorsal subluxation of the scaphoid and wrists that did not have dorsal subluxation. Interrater reliability of subluxation measurements on lateral radiographs and on MRI were calculated using kappa coefficients.

RESULTS

Thirteen of 18 wrists with complete SLIL tears had greater than 10% dorsal subluxation of the scaphoid relative to the scaphoid facet. Average subluxation in this group was 34%. Four of 18 wrists with known SLIL tears had no subluxation. No wrists without SLIL tears (control group) had dorsal subluxation. The SL angle, capitolunate/third metacarpal-lunate angle and SL gap were greater in wrists that had dorsal subluxation of the scaphoid on MRI. Interrater reliability of measurements of dorsal subluxation of the scaphoid was superior on MRI than on lateral x-ray.

CONCLUSIONS

An MRI demonstration of dorsal subluxation of the scaphoid, of as little as 10%, as a predictor of SLIL tear had a sensitivity of 72% and a specificity of 100%. The high positive predictive value indicates that the presence of dorsal subluxation accurately predicts SLIL tear.

TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.