Biomechanical comparison of transosseous cortical button and Footprint repair techniques for acute distal biceps tendon ruptures

Background The biceps brachii is the main forearm supinator, which is a direct consequence of its anatomic arrangement. The primary aim of distal biceps rupture is to restore supination strength and function. Cadaveric studies demonstrate that anatomic repairs significantly improve the supination moment when compared to more anterior repairs; however, this has not been tested in the clinical setting. The aim of this study was to compare biomechanical and clinical outcomes of an anatomic repair (Footprint), with a widely used transosseous technique (Endobutton). Methods Twenty-two patients were retrospectively identified from a clinical database (11 Footprint versus 11 Endobutton). Biomechanical performance of strength and endurance for flexion and supination was assessed using a validated isokinetic dynamometry protocol and clinical outcome scores (Quick Disabilities of the Arm, Shoulder and Hand Outcome Measure and the Mayo Elbow Performance Score) were collected for all patients. Results For supination, the Footprint group demonstrated a superior trend for all biomechanical parameters tested. This was statistically significant for mean peak torque, total work of maximal repetition and work in the last third of repetitive testing (p = 0.031, p = 0.036 and p = 0.048). For flexion, the Footprint group demonstrated a superior trend for all biomechanical parameters tested but this was only statistically significant for work in the last third of repetitive testing (p = 0.039). The clinical outcomes were good or excellent for all patients in both groups. Conclusion This study is the first to demonstrate that an anatomic Footprint repair restores superior biomechanical supination strength and endurance compared to a conventional Endobutton technique in a clinical setting. Both techniques, however, provide good or excellent clinical outcomes.