Stabilizing Effect of Ulnar Shortening Procedure for DRUJ Instability

Ulnar shortening is widely indicated for ulnocarpal abutment syndrome with positive-variance wrist. It also stabilizes the distal radioulnar joint (DRUJ) because of tightening effect on the triangular fibrocartilage complex (TFCC), as long as either the dorsal or palmar portion of the radioulnar ligament (RUL) is attached to the ulnar fovea. In clinical practice, it is very important to check the condition of the RUL through DRUJ arthroscopy, when the ulnar shortening was indicated for DRUJ instability cases. We retrospectively analyzed our case series. Method: There were 663 wrists of 624 patients, who underwent the ulnar shortening procedure done by a single surgeon. Among them, 70 wrists of 68 patients indicated mild to severe DRUJ instability. There were 34 male and 34 female patients. The right wrist was affected in 36 cases, the left in 30, and 2 were bilateral. Age ranged 19–63, with an average of 34 years. Preoperative ulnar variance indicated 2.0 mm (range: 0–6.5). All wrists indicated pain, while there was no limitation of pronosupination range. Mild DRUJ instability, which consisted of greater instability than in the intact contralateral side, was noted in 11 wrists; moderate instability, consisting of a lack of endpoint in the dorsal or the palmar direction, in 41; severe DRUJ instability, consisting of instability without endpoints in both dorsal and palmar directions, in 18. Arthroscopic examination including DRUJ exploration was done before shortening of the ulna. If there was still DRUJ instability, additional open repair or reconstruction of the DRUJ using an extensor carpi ulnaris (ECU) tendon half-slip, was performed. The ulna was shortened by an average of 2.4 mm (range: 2–6.5). We evaluated arthroscopic findings and clinical results using our original DRUJ evaluation system, including pain, range of pronosupination, and DRUJ instability. We also examined the difference of clinical results with severity of DRUJ instability. Results: Palmer 2A tears were found in 43 wrists, Palmer 2C tears in 3, and Palmer 1B tears in 8 through radiocarpal arthroscopy. DRUJ arthroscopy revealed partial dorsal tear of the RUL in 9 wrists and complete avulsion of the RUL at the fovea in 10 wrists. We added open TFCC repair of complete avulsion of the RUL in seven wrists, and three wrists needed reconstruction of the TFCC. Overall clinical results obtained were 59 excellent, 9 good, 1 fair, and 1 poor. Eleven wrists with mild DRUJ instability all obtained excellent clinical results only with ulnar shortening. In 41 wrists with moderate DRUJ instability, ulnar shortening obtained 40 excellent and 1 poor clinical results. However, in severe DRUJ instability wrists, we obtained only eight excellent, nine good, and one fair clinical result even with an additional procedure, i.e., open repair or reconstruction. Conclusion: Ulnar shortening obtained excellent clinical results in the wrists with mild to moderate DRUJ instability. When the RUL was avulsed from the ulnar fovea completely, ulnar shortening could no longer restabilize the DRUJ. In such case, repair or reconstruction of the RUL is necessary.