Finite element analysis of four different fixation methods for the treatment of ipsilateral femoral neck and shaft fractures

Ipsilateral femoral neck and shaft fractures are severe injuries caused by high-energy trauma. In recent years, the incidence and discussion of such fractures have increased significantly. Research and literature on these fractures primarily consist of clinical retrospective analyses, meta-analyses, or case reports. Domestic and international studies have examined surgical timing, blood loss, complications, and healing duration across different treatment approaches for these fractures. Currently, no universally agreed-upon standard exists for managing such fractures in the literature. Finite element analysis was performed to compare the biomechanical characteristics of four different types of fixations for the treatment of ipsilateral femoral neck and shaft fractures (IFNSF), with the objective of determining the optimal choice of internal fixation. Femoral neck and shaft fracture models were simulated in conjunction with four fixation methods, including a femoral locking plate with a cannulated compression screw (plate + CCS), a retrograde nail with a cannulated compression screw (retrograde nail + CCS), a dual construct (InterTan), and a reconstruction nail. These models were assembled, and finite element analysis was conducted utilizing Ansys workbench. The peak von Mises stress for the femoral neck and internal fixation device was the lowest (219.91 MPa and 223.81 MPa, respectively) for the CCS and the highest (392.47 MPa and 388.32 MPa, respectively) for the reconstruction nail. For the A1-A3 type femoral shaft fractures, the peak von Mises stress was highest (102.54 MPa) for the reconstruction nail and lowest (88.554 MPa) for the retrograde nail. For the B2- and C2-type femoral shaft fractures, the peak von Mises stress was the highest (709.32 MPa) for the locking plate, whereas the lowest peak von Mises stress occurred for the retrograde nail (309.32 MPa). The elastic deformation of internal fixation was smallest (7.3365 mm) for the retrograde nail + CCS and largest (17.692 mm) for the plate + CCS. In the treatment of ipsilateral femoral neck and shaft fractures, if the femoral shaft fracture is A1–A3, a retrograde nail with CCS or a femoral locking plate with CCS can achieve optimal mechanical stability. In complex femoral fractures (B2, C2), a retrograde nail with CCS results in superior mechanical stability.