Distal Radius Allograft Versus Distal Tibia Allograft for Anterior Glenoid Reconstruction: A Biomechanical Comparison.

Abstract

BACKGROUND Distal tibial allograft (DTA) is the most widely used allograft for glenoid reconstruction, but distal radius allograft (DRA) has been proposed as a novel graft option with the advantage of providing a more acute radius of curvature in the anterior-posterior plane that is closer to the native glenoid. PURPOSE To utilize a biomechanical testing model to investigate the glenohumeral contact pressure and kinematics of DRA versus DTA reconstructions of anterior glenoid bone loss. STUDY DESIGN Controlled laboratory study. METHODS A total of 11 human cadaveric upper extremities and 11 ankle specimens were utilized. A 30% defect of the anterior glenoid was created and reconstructed with DRA or DTA. A robotic testing system was used to test native joint, DRA, and DTA reconstructions at 60° and 90° of abduction from 0° to 90° of external rotation. Measurements of the center of rotation and humeral head translation were captured using a motion tracking camera. Load and torque data were recorded using a 6-axis load cell. Pressure and contact area were recorded with a pressure mapping sensor pad between the humeral head and the glenoid. RESULTS No significant differences were observed in contact pressure, contact area, translation, load, or torque between the native and allograft reconstruction conditions at 60° or 90° of abduction. No significant differences were found in contact pressure, contact area, translation, load, or torque between the DRA and DTA reconstruction conditions at 60° or 90° of abduction. CONCLUSION The biomechanical data showed comparable compressive forces and glenohumeral joint kinematics between the native joint, DRA, and DTA reconstructions for large anterior glenoid bone loss defects. CLINICAL RELEVANCE These biomechanical data suggest that DRA represents a promising option for reconstruction of large anterior glenoid bone loss defects. The findings warrant further investigation into the variability of distal radius morphology and future clinical evaluation of DRA reconstruction in the setting of critical glenoid bone loss.