Computed tomography–based predictors of ulnar-sided complications after distal radius fracture fixation

Ulnar-sided complications after distal radius fracture fixation remain frequent and poorly understood. This study aimed to identify CT-based risk factors for poor ulnar-sided outcomes (PUO). Sigmoid notch involvement and inadequate reduction are associated with PUO, whereas ulnar styloid fractures and native DRUJ anatomy are not. A retrospective single-center study included 75 wrists treated with volar plating, with systematic pre- and postoperative CT scans. PUO at 6 months was defined by limited pronosupination, ulnar-sided pain, or DRUJ instability. CT analysis assessed sigmoid notch involvement, DRUJ congruence, fracture pattern, anatomical variants, and reduction quality. PUO occurred in 32/75 wrists (42.6%). Sigmoid notch involvement (p = 0.01), postoperative reduction defect (p = 0.01), and DRUJ incongruity (preoperative p = 0.01; postoperative p = 0.04) were significantly associated with PUO. Ulnar styloid fractures and DRUJ anatomical variants were not. Multifragmentary sigmoid notch fractures, particularly involving the volar rim, were associated with higher PUO risk (p = 0.04). Poor ulnar-sided outcomes after distal radius fracture fixation are primarily related to sigmoid notch involvement and reduction quality. Systematic CT assessment may help identify high-risk patterns and optimize surgical planning. III.