Association of lunate morphology, sex, and lunotriquetral interosseous ligament injury with radiologic measurement of the capitate-triquetrum joint.

OBJECTIVE: Radiologic presentation of carpal instability at the radial side of the carpus, e.g. scapholunate diastasis following scapholunate interosseous ligament injury, has been studied extensively. By comparison, presentation at the ulnar-sided carpus has not. The purpose of this study was to assess the effects of lunate morphology, sex, and lunotriquetral interosseous ligament (LTIL) status on the radiologic measurement of the capitate-triquetrum joint (C-T distance). Further, we sought to evaluate the diagnostic accuracy of C-T distance for assessing LTIL injuries.

MATERIALS AND METHODS: We retrospectively identified 223 wrists with wrist radiographs and MR arthrograms with contrast injection. Data collected included sex, lunate morphology and LTIL status from MR arthrography, and C-T distance from radiography. The effects of lunate morphology, sex, and LTIL injury status on C-T distance were evaluated using generalized linear models. Diagnostic performance of C-T distance was assessed by the area under receiver-operator characteristic curve (AUROC).

RESULTS AND CONCLUSION: Lunate morphology, sex, and LTIL injury status all had significant effects on C-T distance; wrists with type II lunates, men, and wrists with LTIL injuries had greater C-T distances than wrists with type I lunates, women, and wrists without LTIL injuries, respectively (p < 0.01). The diagnostic value of the C-T distance for identifying patients with full-thickness LTIL tears was sufficient for women with type I (AUROC = 0.67) and type II lunates (0.60) and good for men with type I (0.72) and type II lunates (0.77). The demonstrated influence of LTIL status on C-T distance supports the use of C-T distance as a tool in assessing for full-thickness LTIL tears.