Relationship Between Radiocapitate Distance as a Structural Parameter and Clinical Outcomes After Volar Locking Plate Fixation of Distal Radius Fractures

Purpose Radiocapitate distance (RCD) has been proposed as a radiographic parameter reflecting sagittal carpal alignment after distal radius fracture. However, its clinical significance following volar locking plate (VLP) fixation remains unclear. This study evaluated RCD at 1 year after VLP fixation and investigated its association with radiographic parameters and clinical outcomes. Methods We retrospectively reviewed 145 patients who underwent VLP fixation for distal radius fracture and completed 1-year follow-up. RCD was measured on lateral wrist radiographs as the perpendicular distance from the longitudinal axis of the volar radial cortex to the center of the capitate. Correlation analyses were performed between RCD and conventional radiographic parameters. Univariate and multivariable regression analyses were conducted to assess the association between RCD and Quick Disabilities of the Arm, Shoulder, and Hand ( Quick DASH) score, grip strength, and wrist range of motion. Results RCD was evaluated in 137 patients with complete functional data, and 126 patients were included in the primary analysis for Quick DASH score. The mean final RCD was −2.4 ± 3.0 mm. Final RCD correlated with palmar tilt and radial inclination but not with ulnar variance. In exploratory analyses, ulnar variance was the only radiographic parameter significantly associated with Quick DASH score. RCD was significantly associated with wrist flexion but not with grip strength or wrist extension. In multivariable analysis adjusting for age, sex, and hand dominance, RCD was not an independent predictor of Quick DASH score but remained independently associated with wrist flexion. Conclusions RCD was associated with wrist flexion at 1 year after VLP fixation but was not an independent predictor of Quick DASH score. RCD appears to reflect sagittal carpal alignment dependent on radial reduction quality and may be a candidate structural marker that warrants further investigation. Type of study/level of evidence Retrospective cohort study/Ⅲ.