To understand ulnocarpal impaction syndrome, picture where the ulnar bone of the forearm meets the wrist. This will be on the little finger side of the wrist. The two bones are jammed together (ulna against the wrist). The condition usually causes pain along that side of the wrist.
The constant force of the ulna against the ligament (triangular fibrocartilage complex or TFCC) between the two bones causes injury to this area of soft tissue. There are several possible causes of this problem. The first is called a congenital ulna-positive variance. That just means the person was born with a slightly longer ulnar bone (or shorter radius -- the other bone in the forearm) than normal.
Sometimes this problem develops after there has been a wrist or elbow fracture of the radius. Shortening of the radius leaves the ulnar bone longer than the radius with the same end-result: impaction.
Ulnar impaction syndrome is rare without one of these traumatic anatomic changes. But there are some cases that occur when there is repeated loading of the ulna against the wrist bone. This could be a daily work activity such as gripping, a twisting motion of the forearm, and/or tilting the wrist toward the little finger.
Treatment begins with conservative (nonoperative) care. This is usually avoidance of movements that aggravate the symptoms, the use of nonsteroidal antiinflammatory drugs, and the use of a splint. If following a carefully prescribed program with these principals does not change the symptoms in three to six months, then surgery might be advised.
Kavi Sachar, MD. Ulnar-Sided Wrist Pain: Evaluation and Treatment of Triangular Fibrocartilage Complex Tears, Ulnocarpal Impaction Syndrome, and Lunotriquetral Ligament Tears. In The Journal of Hand Surgery. July 2012. Vol. 37A. No. 7. Pp. 1489-1500.
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