Ulnar shortening osteotomy in distal radius malunion or isolated ulnar impaction syndrome: comparing outcome from two etiologies

Both distal radius malunion causing ulnar impaction syndrome and isolated ulnar impaction syndrome can treated by ulnar shortening osteotomy (USO). This study compared the same treatment in two different etiologies: ulnar shortening osteotomy (USO) in isolated ulnar impactions syndrome and distal radius malunion.

We retrospectively reviewed 32 patients with extra-articular distal radius malunions treated for ulnar impaction with USO. This group was compared to a 1:1 age- and sex-matched cohort treated with isolated ulnar impaction syndrome in the same surgery. Pain visual analog scale (VAS), wrist motion, grip strength, radiographic parameters, DASH score and perioperative complications were analyzed.

In both treatments, the VAS scores all were improved from 4.2 to 2.8 and 3.8 to 1.2 in distal radius malunion group and ulnar impaction group, respectively. The mean operative time had no significant difference. The preoperative wrist range of motion (ROM) showed more limited in distal radius malunion group and no improvement in pronation and supination following the USO. There was no difference in ulnar variance between two groups. Most of the sigmoid inclination were reverted after surgery in distal radius malunion group. The last DASH score showed 10.2 and 29.8 in ulnar impaction group and distal radius malunion group, respectively (p=0.02). There were 2 and 1 re-operation following USO for painful nonunion in distal radius malunion group and isolated ulnar impaction syndrome group, respectively. 2 patients had subsequent DRUJ osteoarthritis in malunion group at the last follow-up.

Both etiologies had improved in grip strength, and VAS with restoration of the radioulnar length relationship was observed in both cohorts. However, USO had more effective in the isolated ulnar impaction syndrome rather than distal radius malunion. USO may cause potential subsequent osteoarthritis of DRUJ due to deteriorating sigmoid reverse inclination.

Keywords: USO, distal radius malunion, ulnar impaction