Effect of an Unrepaired Fracture of the Ulnar Styloid Base on Outcome After Plate-and-Screw Fixation of a Distal Radial Fracture

Background: The impact of an unrepaired fracture of the ulnar styloid base on recovery after internal fixation of a fracture of the distal part of the radius is uncertain. We evaluated a series of patients with an internally fixed fracture of the distal part of the radius to test the hypothesis that there is no difference in wrist motion or function scores between those with an untreated fracture of the ulnar styloid base and those with no ulnar fracture. Methods: Two cohorts of seventy-six matched patients, one with a fracture of the ulnar styloid base and the other with no ulnar fracture, were retrospectively analyzed by examining data gathered in a prospective study of plate-and-screw fixation of distal radial fractures. Patients were matched for age, sex, AO fracture type, and injury mechanism. The two cohorts were analyzed for differences in motion, grip strength, pain, the Gartland and Werley score, the DASH (Disabilities of the Arm, Shoulder and Hand) score, and the SF-36 (Short Form-36) score at six, twelve, and twenty-four months postoperatively. In a second analysis, sixty-four patients with <2 mm of displacement of a fracture of the ulnar styloid base were compared with forty-nine patients with greater displacement. Differences between cohorts and within cohorts over time were determined with use of regression analysis and the likelihood ratio test. Results: No significant differences were found between patients with an unrepaired fracture of the ulnar styloid base and those with no ulnar fracture at any of the follow-up intervals. However, a trend was observed toward less grip strength at six months (71% [of that on the contralateral side] compared with 79%; mean difference, -8% [95% confidence interval = -15.3% to -0.6%]; p = 0.03) and less flexion (54° compared with 59°; mean difference, -5° [95% confidence interval = -11.7° to -0.8°]; p = 0.02) and ulnar deviation (32° compared with 36°; mean difference, -4° [95% confidence interval = -7° to -0.1°]; p = 0.05) at twenty-four months after surgery in patients with an untreated fracture of the ulnar styloid base. There were no significant differences with regard to any tested outcome measure between the patients with ≥2 mm of displacement of an unrepaired fracture of the ulnar styloid base and those with less displacement. Conclusions: An unrepaired fracture of the base of the ulnar styloid does not appear to influence function or outcome after treatment of a distal radial fracture with plate-and-screw fixation, even when the ulnar fracture was initially displaced ≥2 mm.