Objective: The proximal femoral laterally bionic intramedullary nail (PFLBN) is a novel cephalomedullary fixation system incorporating an additional lateral wall screw. This study aimed to compare the stress distribution and displacement characteristics of PFLBN with those of proximal femoral nail antirotation (PFNA) and proximal femoral bionic nail (PFBN) in AO/OTA 31-A3.1 intertrochanteric fractures using finite element analysis.
Method: Finite element models of an AO/OTA 31-A3.1 intertrochanteric femoral fracture were constructed based on computed tomography data from a healthy adult femur. Three fixation constructs (PFNA, PFBN, and PFLBN) were simulated under axial loading representing single-leg stance equivalent to three times body weight (2100 N). Von Mises stress distribution and displacement patterns of the femur and implants were evaluated.
Result: In all models, peak implant stress was concentrated at the junction between the main nail and the cephalocervical component. Compared with PFNA, the PFLBN model demonstrated a 17.2% reduction in peak implant stress and a 23.2% reduction in peak femoral stress. Maximum femoral and implant displacements in the PFLBN model were reduced by 19.5% and 19.2%, respectively. Notably, the PFLBN exhibited the highest construct stiffness and effectively mitigated stress concentration on the medial femoral cortex through the load-redistribution mechanism of the lateral wall screw. While the PFBN showed improved metrics over the PFNA, the PFLBN provided superior mechanical stability specifically for the simulated lateral wall deficiency.
Conclusion: Under axial single-leg stance loading, PFLBN exhibited lower peak stresses and smaller displacements than PFNA and PFBN in this finite element model of AO/OTA 31-A3.1 fractures. These computational findings describe differences in stress redistribution and construct behavior and warrant further experimental and clinical validation.
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