Similar Biomechanics Between the Double-Cortical Button and Docking Techniques for Ulnar Collateral Ligament Reconstruction: A Cadaveric Evaluation.

Abstract

The docking technique is widely used to perform ulnar collateral ligament (UCL) reconstructions because of its high failure torque and reliable clinical outcomes. A double-cortical button technique was recently described, with advantages including the ability to tension the graft at the ulnar and humeral attachments and the creation of single bone tunnels. To compare the biomechanics between the docking and double-button UCL reconstruction techniques using cadaveric specimens. We hypothesized that there would be no difference in postoperative stiffness or maximum strength between the techniques. Controlled laboratory study. Eight matched pairs of cadaveric elbow joints underwent controlled humeral valgus torsion cycles in a test frame. Toe region stiffness, elastic region stiffness, and maximum torque were measured during a 4-step protocol: intact, injured, reconstructed (10 and 1000 cycles), and ramp to failure. Graft strains were calculated using 3-dimensional motion capture. After 10 cycles, intact ligaments from the docking and double-button groupsexhibited mean ± SD elastic torsional stiffness of 1.60 ± 0.49 and 1.64 ± 0.35 N·m/deg (P = .827), while docking (1.10 ± 0.39 N·m/deg) and double-button (1.05 ± 0.29 N·m/deg) reconstructions were lower (P = .754). There were no significant differences in maximum torque between the docking (3.45 ± 1.35 N·m) and double-button (3.25 ± 1.31 N·m) groups (P = .777). Similarly, differences in maximum graft strains were not significant between the docking (8.1% ± 7.2%) and double-button (5.5% ± 3.1%) groups (P = .645). The groups demonstrated similar decreases in these measures after cyclic loading. Ramp-to-failure testing showed no significant differences in ultimate torque between the docking (8.93 ± 3.9 N·m) and double-button (9.56 ± 3.5 N·m) groups (P = .739). The biomechanical behavior of the double-button technique was not significantly different from that of the docking technique. Both reconstruction techniques restored joint stability, but neither fully recapitulated preinjury joint stiffness. With its procedural advantages, results preliminarily support the use of the double-button reconstruction technique for UCL reconstruction as a reliable single-tunnel technique for primary or revision cases.