Systematic evaluation of the biomechanical characteristics of PFNA, PFBN, and InterTan fixation for intertrochanteric fractures under gradient variations of proximal femoral lateral wall thickness and delineation of optimal fixation domains

Finite element analysis indicates that lateral wall thickness is a decisive factor for the fixation stability of intertrochanteric fractures. Progressive thinning leads to marked increases in stress and displacement for all intramedullary devices, accompanied by characteristic mechanical critical points. PFBN provides superior stability under weak or absent lateral wall conditions, whereas PFNA and InterTan are more sensitive to lateral wall structural variations. These findings suggest that lateral wall thickness should be a core parameter in selecting fixation methods and formulating postoperative weight-bearing strategies, providing critical biomechanical evidence for individualized management of unstable intertrochanteric fractures.