Tribological behavior of ultra-high molecular weight polyethylene (UHMWPE) for acetabular replacement under frictional heat based on molecular dynamics

Hip prostheses generate higher frictional heat than natural joints at the joint head-socket interface during in vivoservice, resulting in higher temperatures of the contact surfaces and surrounding synovial fluid, which affects the frictional properties of the prosthetic material. In order to clarify the influence mechanism of frictional heat on the tribological behavior of ultra-high molecular weight polyethylene (UHMWPE) for acetabular replacement, the tribological tests of three contact pairs were carried out under different synovial fluid temperatures in this research. Furthermore, the movement processes of the molecular chain structure of UHMWPE during friction were simulated by Materials Studio (MS), and the mechanism of oxidative degradation was discussed. The results show that the temperature of synovial fluid has a significant effect on the friction and wear resistance of UHMWPE and the lubrication characteristics of synovial fluid. At the same time, the action mechanism of the proteins in the synovial fluid that gradually precipitate with the temperature rise to participate in the friction process is related to the friction pair material and contact mode. The synergistic effect of temperature rise and friction will accelerate the oxidative degradation reaction of UHMWPE and form ketone and alcohol oxides on its surface, thus reducing its wear resistance.