Biomechanical comparison between three intramedullary nails and percutaneous compression plate in stable and unstable trochanteric fractures

Background: The best surgical treatment of trochanteric fractures remains controversial and biomechanical literature lacks a comprehensive study. The study compares the behavior of fixation implants for the treatment trochanteric fractures, namely: intramedullary gamma nail, proximal femoral nail, veronail, and extramedullary percutaneous compression plate. Methods: The implants were virtually inserted into 3D femur digital twins characterized by stable and unstable trochanteric fractures. Loadings simulated walking condition without and with crutches, respectively, for stable and unstable fractures. Stresses below the yield point quantified implant safety. Constructs' stiffness, principal strains, and the load-sharing on the fracture rims demonstrated the biomechanical advantages of fixation implant in restoring a physiological condition by comparison with the intact femur. Findings: All implants are safe. Extramedullary plate and proximal femoral nail allowed to better recover the stiffness of the intact femur in the unstable fracture model, and the load acting along the fracture decreased respectively between 17 % and 44 % compared to stable fracture model. The minimum and maximum strain distribution was qualitatively similar for all devices, with extramedullary plate and gamma nail showing strains in the posteromedial area getting closer to the intact condition in stable fracture model. The compressive strains in the unstable fracture model treated with extramedullary plate were closer to the intact condition. Interpretation: All investigated devices could be safely used for stable and unstable intertrochanteric fractures. The extramedullary plate may present some biomechanical advantage with unstable fractures.