Biomechanical comparison of ulnar collateral ligament reconstruction with single-tunnel proximal suspensory fixation versus modified docking technique

Abstract

Despite technical advancement, elbow ulnar collateral ligament (UCL) reconstruction is a challenging procedure due to the limitations regarding the challenging tunnel placement and potential injury to the ulnar nerve. Furthermore, current techniques for reconstruction and repair are inferior functionally and biomechanically when compared to native UCL tissue. A modified docking technique using a single-tunnel proximal suspensory fixation may reduce complications and potentially provide a technique for UCL reconstruction that is biomechanically superior. Decreasing the number of bone tunnels decreases the number of places that bone tear through could occur. The purpose was to evaluate and compare the biomechanical performances for 2 elbow UCL reconstruction techniques: (1) standard docking technique (SD) and (2) a proximal single tunnel (PST) technique using a suspensory fixation. We hypothesized that the PST technique would be biomechanically superior to the SD technique. Twelve matched pairs of cadaveric elbows were dissected and fixed at 70 degrees for biomechanical testing. Gracilis grafts were used for a docking reconstruction and the modified reconstruction with a PST suspensory fixation. A cyclic valgus torque protocol was used to precondition specimens for either reconstruction technique and the ulnohumeral gapping was then assessed. Following gapping measurements, postsurgical specimens underwent a valgus rotation applied at a rate of 5°/s until the anterior band of the UCL failed or fracture occurred. Ultimate load to failure, stiffness, and mode of failure were recorded. There were no statistical differences between the two groups. Mean rotational stiffness of the SD (2.3±0.6 Nm/deg) compared to the PST (1.9±0.7 Nm/deg) (P=.41) and mean ultimate failure torque of the SD (30.5±9.2 Nm) compared to the PST (30.9±8.6 Nm) (P=.86) were similar. There was also no statistically significant difference (P=.83) when comparing the native UCL ulnohumeral gapping (6.0±2.0 mm) to the mean ulnohumeral gapping of the SD reconstruction (6.0±1.8 mm). This study compares the biomechanical strength of elbow UCL reconstructions performed using the SP technique to that of a PST technique. Among all tested parameters, including ultimate failure torque, stiffness, and ulnohumeral gapping, there were no statistically significant differences between the 2 techniques.