ULNAR IMPACTION SYNDROME - MR-IMAGING FINDINGS

PURPOSE: To evaluate magnetic resonance (MR) imaging findings in ulnar impaction syndrome and changes after ulnar recession arthroplasty. MA TERIALS AND METHODS: MR imaging and arthroscopy were performed in 30 w rists in 27 patients (aged 15 - 62 years) in whom ulnar impaction synd rome was diagnosed on the basis of physical examinations. MR imaging w as performed in 11 wrists before and after surgery. T1- and Ta-weighte d spin-echo images were obtained. Signal intensities in the lunate, tr iquetrum, and ulnar head were evaluated. RESULTS: There was focal abno rmal signal intensity of the ulnar aspect of the lunate in 87% of wris ts, of the radial aspects of the triquetrum in 43%, and of the radial aspects of the ulnar head in 10% before surgery. The signal intensity of the abnormalities was decreased on T1-weighted and decreased or inc reased on T2-weighted images. After surgery, the signal intensity of t he lunate shifted from low through slightly low to normal on T1-weight ed and from low through high to normal on T2-weighted images. CONCLUSI ON: Most ulnar impaction syndrome cases have characteristic focal sign al intensity changes in the ulnar part of the lunate. The signal inten sity often returns to normal after ulnar recession arthroplasty.