Background: Idiopathic ulnar impaction syndrome can be defined as a
degenerative condition of the ulnar aspect of the wrist in patients with
congenital or dynamic positive ulnar variance without a history of fracture or
premature physeal arrest. The purpose of this study was to evaluate the
clinical features of idiopathic ulnar impaction syndrome and the outcomes of
ulnar shortening osteotomy for this group of patients.
Methods: Thirty-one wrists in twenty-nine patients with idiopathic
ulnar impaction syndrome were treated with an ulnar shortening osteotomy.
Ulnar variance was measured on an anteroposterior radiograph of the wrist, and
radioulnar distance was measured on a lateral radiograph, with the forearm in
neutral rotation, to evaluate any displacement of the ulnar head from the
distal aspect of the radius. All patients were followed clinically and
radiographically for a mean of thirty-two months.
Results: An average preoperative ulnar variance of +4.6 mm (range, 2
to 7.5 mm) was reduced to an average of —0.7 mm (range, —4 to +1
mm) postoperatively. Preoperatively, the modified Gartland and Werley score
was an average (and standard deviation) of 69.5 ± 7.6, with twenty-four
wrists rated poor and seven rated fair. Postoperatively, the score improved to
an average of 92.5 ± 8.0, with twenty-four wrists rated excellent;
five, good; one, fair; and one, poor. Dorsal subluxation of the distal aspect
of the ulna was found concomitantly in nine wrists, and it was found to be
reduced by the shortening osteotomy. Seven patients had cystic changes in the
carpal bones preoperatively, but these were not evident one to two years after
Conclusions: Ulnar shortening osteotomy improved wrist function in
patients with idiopathic ulnar impaction syndrome and reduced the subluxation
of the distal radioulnar joint, which is commonly found in these patients.
Degenerative cystic changes of the ulnar carpal bones appear to resolve
following the shortening osteotomy.
Level of Evidence: Therapeutic Level IV. See Instructions
to Authors for a complete description of levels of evidence.