Carpal Malalignment as a Predictor of Delayed Carpal Tunnel Syndrome after Colles’ Fracture

BACKGROUND: The present study aimed to clarify whether carpal malalignment associated with distal radius malunion after Colles’ fracture is involved in the onset of delayed carpal tunnel syndrome (DCTS) in elderly women. METHODS: This retrospective case–control study was conducted in 40 female patients with Colles’ fracture treated with a cast, including 10 patients (mean age, 71.6 years) who developed DCTS from 6 weeks to 6 months after injury (DCTS group) and 30 patients (mean age, 73.4 years) without DCTS (control group). Radiological parameters, including the radiocapitate distance (RCD), volar prominence height (VPH), and volar tilt (VT) were measured. Relationships between the RCD and both the VPH and VT were examined, and the involvement of the RCD in the onset of DCTS was analyzed. RESULTS: The RCD showed strong correlations with both the VPH and VT. The mean RCD was significantly lower in the DCTS group than in the control group (−12.8 mm versus −8.4 mm). Logistic regression analysis showed involvement of the RCD in the onset of DCTS, and the threshold value according to receiver operating characteristic curve analysis was −9.9 mm, with an odds ratio of 21. CONCLUSIONS: Dorsal displacement of the capitate due to Colles’ fracture malunion is involved in DCTS accompanied with anatomical alteration of the carpal tunnel. When the center of the head of the capitate is located more than 1 cm dorsally behind the volar cortical line of the radius, careful follow-up should be performed as DCTS may occur within 6 months after injury.