Biomechanical Comparison of Ulnar Collateral Ligament Reconstruction With the Docking Technique Versus Repair With Internal Bracing

Abstract

Background: The modified Jobe technique of ulnar collateral ligament (UCL) reconstruction has previously been biomechanically compared with primary repair augmented with internal bracing. However, the docking technique has not been compared with repair with internal bracing. Hypothesis: Load to failure, gapping, and valgus opening angle are similar under valgus loading at 90° of flexion between repair with internal bracing and the docking technique for the UCL. Study Design: Controlled laboratory study. Methods: Nine matched pairs of fresh-frozen cadaveric elbows were potted with the forearm in neutral rotation. The palmaris longus tendon graft was harvested, and the bone was sectioned 14 cm proximal and distal to the elbow joint. First, native UCL testing was performed at 90° of flexion with 0.5 N·m preload, followed by a 5 N·m valgus moment to the elbow in cycles of 1, 10, 100, and 1000 at 1 Hz. The specimens were then loaded to failure at a rate of 0.2 mm/s. Next, the elbows were randomly divided into matched pairs to undergo either UCL reconstruction with docking technique or UCL repair augmented with internal bracing. Last, these specimens underwent testing as aforementioned. Results: Load to failure, gapping, and valgus opening angle did not differ significantly between native ligaments that underwent reconstruction or repair with internal bracing, paired native ligaments and reconstructions, paired native ligaments and repairs augmented with internal bracing, or reconstructions and repairs augmented with internal bracing. Conclusion: UCL reconstruction with docking technique and repair augmented with internal bracing provides valgus stability to the medial elbow comparable to the native ligament at 90°. No significant differences were noted between docking reconstruction and repair techniques for load to failure, gapping, or valgus opening angle during cyclic loading at time zero. Clinical Relevance: Our results suggest that UCL repair with internal bracing has a similar biomechanical profile at the time of initial fixation compared with the docking technique of UCL reconstruction.