| Summary: | 碩士 === 中原大學 === 醫學工程研究所 === 95 === Malalignment of knee prosthesis may cause excessive load and increase the contact stress on the artificial knee joint components. Under this situation, polyethylene insert wear in the total knee replacement will increase and cause replacement failure in patients. The objective of this study was to use three-dimensional finite element analysis to investigate the effects of malalignment on the stress distribution in the tibial component of total knee prosthesis and to use Archard’s wear law to predict wear depth under in vivo loading conditions. The finite element model was created according to the design of an existing knee simulator and the knee kinematics and cyclic loading parameters were considered. The friction coefficient between the femoral component and tibial component was set to be 0.04. This study used a quasi-static analysis to simulate dynamic loadings. Three malalignment conditions were considered: varus and valgus 30 and 50, and medial translations of the femoral component relative to the tibial component were simulated. The most severe situation was varus of the femoral component. In comparing with the medial neutral position, the peak contact stress was 65.8MPa in varus 50 situation. In comparing with the lateral neutral position, the peak contact stress was 32.1MPa in valgus 50 situation. When varus/valgus up to 50, the peak contact stress will increase drastically. A mechanical axis within a range of +30 varus/valgus is therefore suggested as allowable range. Simulation results demonstrated that the results of wear depth are similar to clinical research. Therefore, it is feasible to use a quasi-static analysis to simulate dynamic analysis.
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