Ulnar shortening osteotomy for malunited distal radius fractures: results of a 7-year follow-up with special regard to the grade of radial displacement and post-operative ulnar variance

The treatment of ulnar-sided wrist pain after malunited distal radius fractures remains controversial. Radial corrective osteotomy can restore congruity in the distal radioulnar joint (DRUJ) as well as adequate length of the radius. Ulnar shortening osteotomies leave the radius' angular deformities unchanged, risking secondary DRUJ osteoarthritis. We supposed that, even within the widely accepted limit of 20A degrees, a greater angulation of the radius in the sagittal plane correlates with a higher rate of DRUJ osteoarthritis. Furthermore, we suspected worse results from an ulna shortened to a negative rather than a neutral or positive ulnar variance. For this retrospective study, we reviewed 23 patients a mean 7.2 (range 5.6-8.5) years after ulnar shortening osteotomy for malunion of distal radius fractures. We compared 14 patients with up to 10A degrees dorsal or palmar displacement from the normal palmar tilt of 10A degrees to 9 patients with more than 10A degrees displacement, and 15 patients whose post-operative ulnar variance was neutral or positive to 8 who had a negative one. Ulnar-sided wrist pain decreased enough to satisfy 21 of the 23 patients. Clinical results tended to be better when radial displacement was minor and when post-operative ulnar variance was positive or neutral. A shorter ulna significantly increased the rate of DRUJ osteoarthritis, whereas a greater degree of radial displacement only increased the rate slightly. Radial corrective osteotomy should be discussed as alternative when displacement of the radius in the sagittal plane exceeds 10A degrees. The ulna should be shortened moderately to reduce the risk of osteoarthritis in the distal radioulnar joint.