Finite Element Analysis of Three Different Intramedullary Nails for Fixture of Unstable Intertrochanteric Fractures

We aimed to analyze the effects of PFNA, InterTAN, and Gamma nails for the fixture of unstable intertrochanteric fractures (UIFs) by finite element analysis. 3D reconstruction models fixed with PFNA, InterTAN, and Gamma nail of the normal femur and unstable intertrochanteric fractures were created. Boundary conditions and load were set in advance, and finite element analysis was performed. Interfragmentary strain theory (IFS) was used to simulate the growth of callus. The Python language was used for the secondary development of ABAQUS to simulate the fracture healing process. The principal strain of the femur and the Von Mises stress of the device component were evaluated and compared by three nail fixation methods under four load conditions. There was no significant difference between InterTAN and Gamma nails in terms of peak strain within the implanted bone and maximum device stress values, and both bone strain and implant stress state were lower in the femur after implantation of PFNA nail fixation. Finite element analyses show that the Gamma nail is more suitable for fixing 31A2.2 intertrochanteric fracture. PFNA is more suitable for fixing UIFs except for 31A2.2 intertrochanteric fracture. Therefore, the implantation of PFNA nails in the femur can withstand more forces during exercise than InterTAN and Gamma nails, which have a faster pre-healing phase and are therefore more suitable for small fractures.