A preliminary experimental investigation on the biotribocorrosion of a metal-on-polyethylene hip prosthesis in a hip simulator

Corrosion at the taper/trunnion interface of total hip replacement (THR) often results in severe complications. However, the underlying mechanisms of biotribocorrosion at the taper/trunnion interface during the long-term walking gait cycles remain to be fully understood. In this study, a hip joint simulator was therefore instrumented with an electrochemical cell for in-situ monitoring of the tribocorrosion evolution in a metal-on-polyethylene (MoP) THR during a typical long-term walking gait. In addition, the biotribocorrosion mechanism was investigated via surface and chemical characterizations. The experimental results confirmed that the taper/trunnion interface dominated the contemporary MoP hip joint corrosion. Three cyclic variations in the open circuit potential (OCP) were observed throughout the long-term electrochemical measurements, attributed to the formation and disruption of the adsorbed protein layer. The corrosion exhibited an initial increase at each period, peaking at approximately 0.125 million cycles, followed by a subsequent gradual reduction. Surface and chemical analyses revealed the formation of a tribochemical reaction layer (tribolayer) on the worn surface of the taper/trunnion interface. The surface/chemical characterizations and the electrochemical measurements indicated that the adhesion force of the adsorbed protein layer was weaker than that of the tribolayer. In contrast, the opposite was true for the corrosion resistance. Based on the observations from this study, the tribocorrosion mechanism of the taper/trunnion interface under the long-term walking gait cycles is deduced.

Automated summary

This study investigates the biotribocorrosion mechanism at the taper/trunnion interface of total hip replacement during long-term walking gait cycles. Experimental results show that the interface dominates the corrosion, with cyclic variations in open circuit potential attributed to the adsorbed protein layer. Surface and chemical analyses reveal the formation of a tribolayer on the worn surface, with different adhesion force and corrosion resistance compared to the protein layer. The observations provide insights into preventing complications in total hip replacement.