Influence of elastic recovery of machining surface asperities on the contact stress and plastic strain of polyethylene tibial insert in virgin knee prosthesis

Ultra-high molecular weight polyethylene (UHMWPE) is the sole polymeric material currently used for weight-bearing surfaces in total joint arthroplasty. However, the wear phenomenon of UHMWPE in knee and hip prostheses after total joint arthroplasty is one of the major restriction factors on the longevity of these implants. The authors focused on the microscopic machining surface asperities of the UHMWPE tibial insert of the virgin knee prosthesis as a factor influencing the wear mechanism of the UHMWPE tibial insert. In a previous study performed by the authors, on static contact analysis between the microscopic machining surfaces and the metallic femoral component, the influence of the microscopic machining surface asperities was noted on the stress and plastic strain of the UHMWPE tibial insert. In this study, repeated elasto-plastic contact analyses using the finite element method (FEM) between the machining surface asperities and the femoral component were performed in order to investigate the influence of elastic recovery of the machining surface asperities on the contact stress and plastic strain of the UHMWPE tibial insert. The analytical findings of this study suggest that the elastic recovery of the machining surface asperities of the UHMWPE tibial insert of the virgin knee prosthesis is another possible factor influencing the microscopic failure and/or microscopic wear behavior of the UHMWPE tibial insert in the knee prosthesis after total knee replacement.