Radiological degenerative changes in the distal radioulnar joint after ulnar shortening osteotomy in patients with idiopathic ulnar impaction syndrome: Analysis of factors affecting degenerative lesions.

PURPOSE: To identify factors influencing overall radiologic changes in the distal radioulnar joint after ulnar shortening osteotomy (USO) in patients with idiopathic ulnar impaction syndrome.

MATERIALS AND METHODS: A total of 310 patients who had undergone USO between May 2007 and December 2013 were included in this retrospective case-control study. The patients were classified into two groups (with or without radiologic findings of new arthritic changes), after which the following factors were analyzed: 1) demographic factors; 2) radiologic aspects, including ulnar variance (UV), morphological DRUJ type (classified according to Tolat et al.), and union period after USO; and 3) operative aspects, including the triangular fibrocartilage complex degeneration type, use of a parallel double-blade saw, type of plate used for fixation, and plate position on the volar or dorsal ulnar surface.

RESULTS: Group 1 (no arthritic changes) consisted of 243 patients, whereas Group 2 (arthritic changes) consisted of 67 patients. Univariate and multivariate analyses showed that the presence of lunate cystic changes, amount of shortening, and the union period were significantly associated with newly developed arthritic changes in the distal radioulnar joint (DRUJ) after USO. The morphological DRUJ type was not a significant factor. Arthritic changes were significantly more prevalent in patients with a shortening amount >4.5 mm and a union period <3.25 months.

CONCLUSIONS: Radiologic arthritic changes after USO, were associated with the presence of cystic changes in the lunate, a shortening amount (>4.5 mm), and early bony union (<3.25 months).

TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic level III.