Biomechanical evaluation of a new reconstruction technique of the ulnar collateral ligament in the elbow with modified bone tunnel placement and interference screw fixation

BackgroundA new method for reconstruction of the anterior bundle of the ulnar collateral ligament using modified bone tunnel placement and interference screw fixation was developed to minimize operative dissection, improve graft tensioning, and reduce associated operative morbidities. The objective of this study was to compare varus–valgus laxity and failure properties of this new ulnar collateral ligament reconstruction to the intact ulnar collateral ligament.MethodsNine matched pairs of cadaveric upper extremities were used, the intact ulnar collateral ligament as the control for the load to failure properties and the contralateral arm for ulnar collateral ligament reconstruction. Varus–valgus laxity was measured at 30°, 50°, 70°, and 90° of elbow flexion for intact, ulnar collateral ligament transected, and ulnar collateral ligament reconstruction. Ulnar collateral ligament reconstruction was performed using a tendon graft passed through a bone tunnel and looped around the medial column of the humerus without dissection of the ulnar nerve. Distally, the graft was looped through a bone tunnel in the proximal ulna. Both ends were secured with interference screws. The specimens were loaded to failure at 50° of flexion at a rate of 30 deg/s. Repeated measures analysis of variance with a P value of 0.05 was used.FindingsElbow laxity significantly increased with ulnar collateral ligament transection. Following reconstruction, varus–valgus laxity at 30° and 50° of elbow flexion was completely restored to the intact state, only partially restored at 70°, and not changed at 90°. There was no significant difference between the yield and ultimate torques for the intact vs. reconstructed elbows. The angular displacement at yield and failure was significantly greater for the reconstructed elbows compared to the intact.InterpretationThis reconstruction technique provides comparable strength to that of the native ligament. While stability was improved, failure occurred at greater angular displacement for the reconstructed limbs.