Finite element analysis of long proximal femoral bionic nail (PFBN) fixation for femoral shaft fractures combined with ipsilateral femoral neck fractures

Objective: Femoral reconstruction nails (RN) and three cannulated screws combined with a plate (TCP) are commonly employed for the treatment of ipsilateral femoral neck and shaft fractures (IFNSF). However, these fixation strategies are associated with a considerable incidence of postoperative complications, reflecting the biomechanical challenges of this fracture pattern. Therefore, this study aims to compare the biomechanical performance of a novel long proximal femoral bionic nail (PFBN) with these conventional fixation methods for the treatment of this complex fracture pattern. Methods: Computed tomography (CT) data of the femur were obtained from a healthy adult male volunteer to reconstruct a three-dimensional femoral model using Mimics 21.0 and Geomagic Studio 2013. A combined femoral shaft and ipsilateral femoral neck fracture model was then established in UG 12.0. Three internal fixation constructs-the long PFBN, RN, and TCP-were designed and assembled to simulate surgical fixation. Finite element analysis was subsequently performed using Abaqus 2022 to evaluate stress distribution and displacement characteristics among the three fixation constructs. Results: Under the three loading conditions, the long PFBN exhibited lower or comparable stress and displacement within the fixation constructs. Compared with the TCP construct, the long PFBN showed a more uniform stress distribution. In most loading scenarios, its mechanical performance was comparable to, or slightly better than, that of the RN construct. Analysis of fracture-site micromotion indicated that tangential micromotion at the femoral neck fracture interface in the long PFBN construct was intermediate between that of the RN and TCP constructs. Conclusion: In this finite element analysis, the long PFBN demonstrated relatively favorable biomechanical performance under axial, bending, and torsional loading conditions. These findings may provide preliminary biomechanical insights into the comparative performance of different fixation strategies for this complex fracture pattern.