Hook Plate Versus Suture Anchor Fixation for Thumb Ulnar Collateral Ligament Fracture-Avulsions: A Cadaver Study

Abstract

To compare the biomechanical properties of hook plate fixation and suture anchor fixation for collateral ligament fracture-avulsions of the thumb metacarpophalangeal ulnar collateral ligament (UCL). A thumb UCL fracture-avulsion model was created in 7 matched pairs of cadaver hands. An osteotomy was made parallel to the shaft of the proximal phalanx along the entire insertion of the UCL. The simulated fracture was secured using either a suture anchor tied over bone tunnels in the avulsion fragment or with a hook plate. Specimens were mounted on a servohydraulic load frame and loaded to failure. Motion perpendicular to the osteotomy was measured using an implanted 3-mm differential variable reluctance transducer device. Differences in load to failure and construct stiffness were compared and analyzed using a t test. The hook plate construct failed at significantly higher loads than suture fixation. Mean load to failure in the hook plate construct was 58 N (± 20 N) compared with 27 N (± 19 N) in the suture anchor construct. The difference in construct stiffness was 49 N/mm (± 17 N/mm) for the plate compared with 7 N/mm (± 13 N/mm) for the suture anchor. The main mechanism of failure for the hook plate construct was screw pullout or screw bending. The usual mechanism of failure for the suture anchor construct was anchor pullout. The hook plate construct was biomechanically superior to the suture anchor construct for fixation of thumb metacarpophalangeal joint UCL fracture-avulsions with regard to load to failure. The hook plate construct provides stronger fixation than a suture anchor for thumb UCL fracture-avulsions.