Designing a 20 mm incision to protect the dorsal branch of the ulnar nerve during arthroscopic repair of triangular fibrocartilage complex injuries: cadaver study and preliminary clinical results

Abstract The ulnar-sided approach for arthroscopic peripheral triangular fibrocartilage complex (TFCC) repair may be associated with injury to the dorsal branch of the ulnar nerve (DBUN). The goal of this study was to develop a small incision to help minimize DBUN injury. Ten cadaveric upper limbs were used to measure the anatomic parameters of the DBUN. Based on these measured anatomical relationships, a 20 mm longitudinal incision with the ulnar styloid process as the midpoint was designed to explore and protect the DBUN. Three additional cadaveric upper limbs were used to test the feasibility of this method. Then this method was applied in 15 patients with TFCC injury (IB type). In 10 cadavers, the DBUN was located volar to the ulnar styloid process. The mean linear distance between the DBUN and the ulnar styloid process was 8.04 mm (range: 7.02–8.82 mm) in the transverse-volar direction and 13.78 mm (range: 11.06–16.02 mm) in the longitudinal-distal volar direction. In three additional cadavers, the DBUN was successfully explored and retracted with this incision, creating a safer space for passing sutures and tying knots. This modified method was used successfully in 15 patients, and the DBUN was protected during surgery. There were no complications, and most importantly, no injuries to the DBUN at the 6-month follow-up visit. Therefore, we recommend that a 20 mm longitudinal incision with the ulnar styloid process as the midpoint be made prior to passing sutures during the arthroscopic repair of TFCC tears to avoid injuring the various branches of the DBUN.