Purpose: To compare the biomechanical strength of the foveal repair (distal ulnar tunnel technique) and the traditional outside-in repair to the capsule in Type IB Triangular Fibrocartilage Complex (TFCC) tears. Materials and Methods: The distal ulna and the TFCC of 8 matched pair cadaveric wrists were dissected. We created a type IB tear in each specimen. In 8 wrists, the tear was repaired with the conventional outside-in technique to the capsule with two 2-0 fiberwire vertical mattress stitches. In the other 8 wrists, the tears were repaired by drilling a 3 mm tunnel at the distal ulna from the lateral cortex to the fovea. The 2-0 fiberwire sutures pierced through the superficial and deep portions of the TFCC, and were recovered out through the tunnel on the lateral cortex. The TFCC was pulled back down to the fovea. The final fixation in this group was obtained by securing the sutures to the cortex with a small anchor coupled with a 3 × 8 mm interference screw in the tunnel after dialing proper suture tension. The strength of the repair was assessed with a materials testing machine (MTM). The repairs were subjected to load until a 2-mm gap was created on the site of the repair, and subsequently increased the load to produce failure. Failure mechanism was obtained for each repair. Results: The foveal repair was statistically stronger (18 + 4 N) than the capsular outside (2.5 + 1 N; P < .05) for the 2-mm gap formation and load to failure (82 + 2 N and 51 + 5 N, respectively; P < .05). Loosening of the sutures was the mechanism of failure for both repairs. Conclusions: The arthroscopic distal ulnar tunnel technique was stronger than the capsular outside-in biomechanically. Type IB TFCC tears compromising both the superficial and deep portion commonly course with distal radioulnar joint (DRUJ) instability. A capsular repair may not be enough under these circumstances. The arthroscopic distal ulnar tunnel is a very reproducible technique, which allows repair of the superficial and distal portions of the TFCC back to the bone (original anatomical point) preventing DRUJ instability.
