Ulnocarpal impaction syndrome occurs mostly in patients with positive ulnar variance. Ulnar-shortening osteotomy is a commonly used method to correct it, but degenerative changes may appear in the distal radioulnar joint. The authors evaluated outcome after ulnar-shortening osteotomy, particularly the impact of distal radioulnar joint osteoarthritis.A 10-year study was performed of patients who underwent ulnar-shortening osteotomy.Forty-six patients were available for clinical examination and radiography. Twenty-nine wrists showed worsening or new osteoarthritis. A difference of preulnar variance and resection was noted: 4.64 mm and 4.48 mm, respectively, in the osteoarthritis group versus 3.50 mm and 3.38 mm in the group without osteoarthitis. Comparison of patients with osteoarthritis revealed a significant limitation of range of motion in flexion-extension (p = 0.009) and pronosupination (p = 0.028): 102 degrees and 138 degrees, respectively, in the osteroarthritis group versus 124 degrees and 155 degreees in the group without osterarthritis. The type of distal radioulnar joint differed significantly (p = 0.038), with a predominance of type I in the osterarthritis group and type II in the group without osterarthritis. Functional outcome was significantly worse in the osterarthritis group versus the group without osteoarthritis concerning the Patient-Rated Wrist Evaluation score (39.07 versus 22.59, p = 0.031), the Quick Disabilities of the Arm, Shoulder, and Hand score (27.38 versus 19.59, p = 0.017), and the modified Gartland-Werley score (76.72 versus 85.14, p = 0.027).Ulnar-shortening osteotomy modifies the congruence of the distal radioulnar joint, and the type I joint may be at increased risk of arthrosis. Osteoarthritis has a clinical impact, and the amount of ulnar shortening should be limited to what is needed to avoid altering the functional outcome.Therapeutic, III.