Biomechanical comparison of anatomical plating systems for comminuted distal humeral fractures

Purpose Six different mono-axial and poly-axial distal humeral plating systems with an anatomical plate design were compared. The aim of the biomechanical tests was to examine differences regarding system stiffness, median fatigue limit, and failure mechanisms. Method Different configurations of two double plate fixation systems by two manufacturers for the treatment of complex distal humeral fractures (AO/OTA type C2.3) were biomechanically tested in a physiologically relevant setup. Result The 180A degrees Stryker configuration presented itself as the system with the highest stiffness, being significantly stiffer (p < 0.001) than every system other than the poly-axial 180A degrees aap system (p = 0.378). For the median fatigue limit the 180A degrees Stryker and poly-axial aap systems were ranked first and second. The failure mechanism for all 90A degrees systems was a fatigue breakage of the posterolateral plate. The 180A degrees aap systems demonstrated breakage of the most distal screws of the lateral plate. The 180A degrees Stryker system demonstrated screw breakage on both the medial and lateral plates. Discussion Breakage of the posterolateral plate as a failure mechanism for the 90A degrees systems was expected. The 180A degrees systems demonstrated a higher stiffness compared to the 90A degrees constructs for the axial loading. In conclusion, both poly-axial anatomical plating systems provide sufficient stability in this scenario, and the 180A degrees configurations demonstrated superior stiffness.