Optimization of the geometry of total knee implant in the sagittal plane using FEA.

The aim of this research was to investigate the optimization of the geometry of an UHMWPE type of knee implant in the sagittal plane with minimum amount of wear. Finite element analysis has been used to analyze our proposed 780 models consisting of different design parameters. Maximum stress occurring in the whole tibial component, on the surface or subsurface of the plate, was considered as a design parameter to evaluate the wear condition. By avoiding the small contact area and high stresses in the tibial part, the maximum safe flexion angles have been determined. Other effective design factors such as implant stability, roll back distance, patella lever arm, and minimum bone resection have also been considered. Taking into account the variable parameters in the geometry of the implant parts, all possible models for the femoral component, which is made from metal, and the tibial component, which is made from UHMWPE, have been built in ANSYS and analyzed in the sagittal plane. By considering the effective mechanisms of wear in polyethylene, the results of the analyses were used to find the optimized geometry of a knee implant. This is the model, which is expected to experience the minimum wear, besides having some other properties of an ideal knee prosthesis.