Updates on Ulnar Impaction Syndrome

Abstract

Ulnar impaction syndrome is one of the common causes of ulnar-sided wrist pain. The pain is usually aggravated by ulnar deviation during a power grip, especially when the forearm is in a pronated position. The most common predisposing factor of ulnar impaction syndrome is ulnar positive variance, which is an increased ulnar length relative to the radius of the radiocarpal joint. However, it can also occur in patients with ulnar neutral or negative variance because ulnar variance can increase during functional activities, including pronation and power gripping. In these patients, the triangular fibrocartilage complex (TFCC) may be thickened. If conservative treatments-lifestyle modification, medication, or wrist splinting-are unsuccessful, surgical treatments, such as wafer procedure or ulnar shortening osteotomy can be considered. The wafer procedure is an effective treatment for ulnar impaction syndrome. It removes the distal 2 to 4 mm of the ulnar head, while preserving the ulnar styloid process from fracturing via a limited open or an arthroscopic approach. The advantages of the wafer procedure are that it does not require bone healing or internal fixation and provides direct access to TFCC. However, it is a technically demanding procedure and is contraindicated in patients with distal radio-ulnar joint (DRUJ) instability, lunotriquetral instability, ulnar minus variance, and with an ulnar positive variance of more than 4 mm. Ulnar shortening osteotomy is the most popular method for the treatment of ulnar impaction syndrome. It can effectively relieve ulnar impaction symptoms and stabilize DRUJ. However, an excessive amount of shortening may increase the peak pressure at DRUJ, which results in DRUJ arthritis. There is also a possibility of delayed union or nonunion in the osteotomy site. To prevent delayed union or nonunion, we should make an effort to decrease the gap in the osteotomy site during surgery. A serial follow-up is also recommended to evaluate the occurrence of arthritis in DRUJ after ulnar shortening.