Biomechanical study using the finite element analysis of a new method for fixation of coronal fracture of the femoral condyle

Aims & objectives: Surgical treatment of Hoffa's fracture is often challenging for orthopedic surgeons. Current surgical techniques recommend stabilization of most of these fractures using a plate and screws. The objective this study was to design, simulate using Finite Element Analysis (FEA), and to describe the mechanical behavior of a specific orthopedic implant model to treat a Letenneur type III Hoffa fracture. Materials & methods: From CT scan images in DICOM format, a 3D bone model was created and modeled using Invesalius and Meshmixer software. The orthopedic implants were modeled by SolidWorks software. Subsequently, virtual surgical planning was performed with anatomical reduction of the fracture, including the selection and positioning of the implants. Ansys software was used to perform FEA of the fracture fixation types. Bone-implant systems were discretized, the mechanical and tribological properties were defined, boundary conditions were established, and force was applied based on literature data. Six domains (bone-implant systems) were defined according to the types and combinations of implants used in Hoffa fracture fixation. Mechanical stability was analyzed by measuring the relative displacement of bone fragments and the maximum von Mises stress in the implants. Results: FEA was assessed through visual analysis of the color gradient indicating bone displacement and implant stress. Quantitative measurements of bone displacement and maximum von Mises stress in the implants were performed. The FEA analysis showed that the system fixed with the developed implant model presented the smallest relative displacement of the distal bone fragment when subjected to a load of 1357.70 N. Conclusion: The developed implant model demonstrated the greatest mechanical stiffness, with the smallest relative displacement of the distal bone fragment when compared to traditional osteosynthesis methods for this type of fracture in the FEA.