Finite element analysis of implant selection and screw positioning in proximal femoral basicervical fractures

To determine the optimal implant for proximal femoral basicervical fractures by comparing the biomechanical properties of the Dynamic Hip Screw (DHS), Proximal Femoral Nail Anti-Rotation (PFNA), and InterTAN using finite element analysis (FEA). Five fixation configurations were simulated: DHS (central screw AP view), PFNA with central helical blade (PFNA-C), PFNA with inferior helical blade (PFNA-I), InterTAN with central hip screw (InterTAN-C), and InterTAN with inferior hip screw (InterTAN-I). Following construction and validation of an intact femur model, three progressively unstable basicervical fracture patterns (simple, intertrochanteric defect, lateral wall defect) were created and incorporated with the implants. FEA simulated a 700 N load (70 kg patient single-leg stance). Displacement and implant stress distribution were analyzed. Primary comparisons assessed DHS, PFNA-C, and InterTAN-C performance; secondary comparisons evaluated screw position (C vs. I) in cephalomedullary nails (CMN). For simple fractures, DHS, PFNA, and InterTAN exhibited minimal differences in displacement and implant stress. In intertrochanteric and lateral wall defect fractures, significant differences emerged. Displacement was significantly greater with DHS, followed by PFNA, then InterTAN (minimal PFNA-InterTAN difference). Maximum stress was highest with InterTAN, higher with PFNA than DHS, but remained below medical titanium fatigue limits. The inferior screw position demonstrated biomechanical advantages over the central position in CMNs. DHS, PFNA, and InterTAN are suitable for simple basicervical fractures. For fractures with intertrochanteric or lateral wall defects, CMNs (PFNA, InterTAN) provide superior stability over DHS, with InterTAN offering marginally better stability than PFNA. The inferior hip screw position is biomechanically preferable in CMNs.