David L Bernholt1, Spencer P Lake2, Ryan M Castile2, Christopher Papangelou3, Oliver Hauck3, Matthew V Smith4. 1. Department of Orthopaedic Surgery, Washington University, St. Louis, MO, USA. 2. Department of Mechanical Engineering & Materials Science, Washington University, St. Louis, MO, USA. 3. Arthrex Inc., Naples, FL, USA. 4. Department of Orthopaedic Surgery, Washington University, St. Louis, MO, USA. Electronic address: mvsmith@wustl.edu.
Abstract
BACKGROUND: Current ulnar collateral ligament (UCL) reconstruction techniques are substantially less stiff and demonstrate lower load to failure compared with the native UCL. UCL repair with the addition of an internal brace has demonstrated superior biomechanical performance compared with docking UCL reconstruction, but internal bracing has not yet been used in UCL reconstruction. HYPOTHESIS/ PURPOSE: To evaluate the time-zero biomechanical performance of a UCL docking technique reconstruction with and without an internal brace compared with native UCL properties. METHODS: Twelve matched pairs of cadaveric elbows were dissected and fixed at 90° for biomechanical testing. A cyclic valgus torque protocol was used to test the anterior band of the UCL in native specimens. After native specimens were failed, palmaris grafts were used for a docking reconstruction with or without internal brace and were subjected to the same valgus torque test protocol. Torsional stiffness, ultimate failure torque, and ulnohumeral gapping were determined. RESULTS: Stiffness in UCL reconstructions using a standard docking technique (3.0 ± 0.4 N m/deg) were significantly less stiff (P < .001) than native UCL (4.0 ± 0.8 N m/deg), whereas reconstructions using an internal brace (3.6 ± 0.6 N m/deg) were not different (P = .120) compared with native. Ultimate failure torque for standard docking (18.3 ± 4.1 N m) was significantly lower (P < .001) than native UCL (36.9 ± 10.1 N m), whereas the internal brace samples (35.3 ± 9.8 N m) were not different (P = .772) than native. CONCLUSION: UCL reconstruction with an internal brace augmentation provides superior stiffness and time-zero failure strength when compared with the standard docking technique.
BACKGROUND: Current ulnar collateral ligament (UCL) reconstruction techniques are substantially less stiff and demonstrate lower load to failure compared with the native UCL. UCL repair with the addition of an internal brace has demonstrated superior biomechanical performance compared with docking UCL reconstruction, but internal bracing has not yet been used in UCL reconstruction. HYPOTHESIS/ PURPOSE: To evaluate the time-zero biomechanical performance of a UCL docking technique reconstruction with and without an internal brace compared with native UCL properties. METHODS: Twelve matched pairs of cadaveric elbows were dissected and fixed at 90° for biomechanical testing. A cyclic valgus torque protocol was used to test the anterior band of the UCL in native specimens. After native specimens were failed, palmaris grafts were used for a docking reconstruction with or without internal brace and were subjected to the same valgus torque test protocol. Torsional stiffness, ultimate failure torque, and ulnohumeral gapping were determined. RESULTS: Stiffness in UCL reconstructions using a standard docking technique (3.0 ± 0.4 N m/deg) were significantly less stiff (P < .001) than native UCL (4.0 ± 0.8 N m/deg), whereas reconstructions using an internal brace (3.6 ± 0.6 N m/deg) were not different (P = .120) compared with native. Ultimate failure torque for standard docking (18.3 ± 4.1 N m) was significantly lower (P < .001) than native UCL (36.9 ± 10.1 N m), whereas the internal brace samples (35.3 ± 9.8 N m) were not different (P = .772) than native. CONCLUSION: UCL reconstruction with an internal brace augmentation provides superior stiffness and time-zero failure strength when compared with the standard docking technique.