Background This study assessed the structural/mechanical stability of fixation constructs with a femoral neck system (FNS) via finite element analysis after simulating femoral neck fractures and explored the clinical implications.
Methods We simulated subcapital, transcervical, basicervical, and vertical fracture models using a right femur (SAWBONES) and imported the implant model of FNS to Ansys (Ansys 19.0, Ansys Inc.) to place the implant in the optimal position. The distal end of the femur model was completely fixed and was abducted 7°. The force vector was set laterally at an angle of 3° and posteriorly at an angle of 15° in the vertical ground. The analysis was conducted using Ansys software with the von Mises stress (VMS) in megapascals (MPa).
Results The maximum VMS of the fracture site was 67.01 MPa for a subcapital, 68.56 MPa for a transcervical, 344.54 MPa for a basicervical, and 130.59 MPa for a vertical model. The maximum VMS of FNS was 840.34 MPa for a subcapital, 637.37 MPa for a transcervical, 464.07 MPa for a basicervical, and 421.01 MPa for a vertical model. The stress distribution of basicervical and vertical fractures differed significantly, and the basicervical fracture had higher VMS at the bone, implant, and fracture sites.
Conclusions FNS fixation should be performed with consideration the osseous anchorage in the femoral head, and this technique might be appropriate for vertical fractures. Regarding the VMS at the fracture site, FNS might be applied cautiously only to basicervical fractures with anatomical reduction without a gap or comminution. Level of evidence: IV.
Purpose This study examined the structural and mechanical stability as well as the clinical significance of various fixation constructs for distal tibial fractures using finite element analysis. Materials and Methods Fracture models with 20 mm and 120 mm defects were produced, and implants of an intramedullary nail and anatomical plate model were applied. An axial load of 800 N with 60% distribution in the medial compartment and 40% in the lateral compartment was applied and analyzed using Ansys ® software. Results In the intramedullary nail model, the maximum von Mises stress occurred at the primary lag screw hole and adjacent medial cortex, while in the plate model, it occurred at the locking holes around the fracture. The maximum shear stress on the bone and metal implant in the fracture model with a 20 mm defect was highest in the plate assembly model, and in the fracture model with a 120 mm defect, it was highest in the two-lag screw assembly model. Conclusion Based on an analysis of the maximum shear stress distribution, securing the fixation strength of the primary lag screw hole is crucial, and the assembly model of the intramedullary nail with two lag screws and a blocking screw applied was the model that best withstood the optimal load. Securing the locking hole directly above the fracture is believed to provide the maximum fixation strength because the maximum pressure in the plate model is concentrated in the proximal locking hole and the surrounding cortex.
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How to obtain the desired results from distal tibial nailing based on anatomy, biomechanics, and reduction techniques Jungtae Ahn, Se-Lin Jeong, Gu-Hee Jung Journal of Musculoskeletal Trauma.2025; 38(2): 74. CrossRef