• BACKGROUND
    • Ulnar shortening osteotomy (USO) is a widely adopted procedure with excellent outcomes. However, delayed union or nonunion has occasionally been observed. The purpose of this retrospective case-control study was to identify variables affecting osseous consolidation after USO in patients with ulnar impaction syndrome.
  • METHODS
    • The study included 325 patients who had undergone USO between March 2008 and March 2014. We evaluated the association between union and basic demographic factors as well as preoperative pain (assessed on a visual analog scale [VAS]), range of wrist motion, grip strength, and modified Mayo wrist score. We also assessed the association of union with radiographic variables such as the degree of dorsal subluxation of the ulna, preoperative and postoperative ulnar variance, morphological type of the distal radioulnar joint, gap at the osteotomy site, and presence of newly developed arthritic changes during the follow-up period. Finally, variables associated with operative conditions, such as degeneration of the triangular fibrocartilage complex, use of a parallel double-blade saw, type of plate used for fixation, number of screws, and plate position on the volar or dorsal ulnar surface were investigated.
  • RESULTS
    • Ulnar union was achieved in 294 patients (group 1), and 31 patients had delayed union or nonunion (group 2). On univariate and multivariate analyses, smoking, low bone mineral density (BMD), a decreased range of motion of the wrist, and use of a double-blade saw were found to be significant factors for an adverse radiographic outcome (nonunion or delayed union).
  • CONCLUSIONS
    • Delayed union or nonunion occurred in about 10% of patients treated with USO. We suggest that it may be preferable to perform USO in nonsmokers, patients with normal bone density, and those without restricted wrist motion. Also, we recommend the use of a single-blade saw when performing the osteotomy.
  • LEVEL OF EVIDENCE
    • Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.