Intra-articular sigmoid notch fractures of the distal radius and their association with arthritis progression and outcomes after volar locking plate fixation: A retrospective study

The relationship between distal radioulnar joint (DRUJ) involvement and subsequent arthritis or functional outcomes remains unclear. This study evaluated associations between DRUJ articular disruption, arthritis severity, and wrist function following volar locking plate fixation. We retrospectively reviewed patients with unstable distal radius fractures who underwent volar locking plate fixation and had a minimum follow-up of 1 year. Preoperative computerized tomography scans were analyzed for DRUJ articular involvement, articular step-off, and volar or dorsal subluxation. Patients were categorized by presence or absence of DRUJ involvement; presence or absence of sigmoid notch articular step-off; and degree of DRUJ subluxation (<10% vs ≥10%). The severity of DRUJ arthritis was assessed using the modified Kellgren–Lawrence criteria on plain radiographs taken at least 1 year after surgery. Functional outcomes were evaluated through grip strength, wrist range of motion, and the Quick Disabilities of the Arm, Shoulder, and Hand score. Fifty-seven patients were included; 47 had DRUJ involvement and 10 did not. Arthritis grades and functional outcomes did not differ significantly between patients with or without DRUJ involvement. Patients with sigmoid notch articular step-off (n = 34) had higher arthritis grades than those without (n = 13) (0.7 ± 0.6 vs 0.2 ± 0.3, P < .05), though functional outcomes were similar. Arthritis grades and function were comparable between patients with subluxation ≥ 10% (n = 18) and < 10% (n = 39). Sigmoid notch involvement was not associated with higher DRUJ arthritis severity or impaired function, whereas articular step-off correlated with increased arthritis grades without functional deficits. These findings suggest that while sigmoid notch involvement alone may not be a major determinant of functional outcome, careful attention to reducing articular step-off may help minimize the risk of radiographic arthritis progression.