IS case 533: Ulnar impaction syndrome
Imaging Sciences URMC 2010
Publication Date: 2010-09-11
AP view of the right wrist demonstrated positive ulnar variance, with subchondral lucencies in the ulnar articular surfaces of the lunate and triquetrum with associated concavity of the ulnar aspect of the lunate.
Ulnar impaction syndrome is a phenomenon, which presents clinically with ulnar sided wrist pain that can be exaggerated by ulnar deviation of the wrist. Ulnar impaction syndrome results from repeated abutting of the distal ulna against the lunate and triquetrium. It is predisposed to occur in patients with positive ulnar variance. Ulnar impaction syndrome results in damage and degenerative changes most pronounced in the distal ulna and proximal lunate; however, it can also result in injury to the triquetrium and the triangular fibrocartilage complex.
On plain radiography of the wrist, ulnar impaction syndrome should be suspected in the appropriate clinical setting when positive ulnar variance is present. Positive ulnar variance is defined by the ulna being at least 3mm longer than the radius at the distal radioulnar joint, when the wrist is in a neutral position. Additional findings, which should be present to support the diagnosis of ulnar impaction syndrome are subchondral sclerosis and cyst formation at the ulna, lunate and triquetrium.
On MR imaging of the wrist, findings of ulnar impaction syndrome include marrow edema, subchondral sclerosis, cartilage wear and subchondral cysts at opposing ends of the ulna, lunate and triquetrium. MR may also demonstrate triangular fibrocartilage thinning or tear, if present.
Treatment options for symptomatic ulnar impaction syndrome include shortening osteotomy, the wafer procedure and debridement of the TFCC. The wafer procedure involves removing 2-4 mm of the distal ulnar head, leaving the styloid process TFCC and attached ligaments intact, with a goal of creating 2mm of negative ulnar variance.
- Cerezal L, del Piñal F, Abascal F, et al. Imaging findings in ulnar-sided wrist impaction syndromes. Radiographics. 2002 Jan-Feb;22(1):105-21. PMID: 11796902