The influence of swing phase load on the electrochemical response,friction,and ion release of metal-on-metal hip prostheses in a friction simulator

Abstract

Abstract

Second-generation metal-on-metal (MoM) hip replacements have been considered as an alternative to commonly used polyethylene-on-metal joint prostheses due to polyethylene wear debris-induced osteolysis. However, the role of corrosion is still not fully understood. Bench tests have been carried out to characterize the relationship and interactions between electrochemical reactions (corrosion), mechanical damage (wear), and biological environments. An investigation of the corrosion response of MoM hip replacements has been conducted in a friction simulator in an initial attempt to reveal the tribocorrosion behaviour of clinically used metallic hip implants. These are the first reported results where electrochemical measurements have been made in-situ in a joint simulator.

A ProSim friction simulator was used with an integrated electrochemical cell in this study of biotribocorrosion. Peak loads of 2 kN with three different swing phase loads, 25, 100, and 300 N were used to determine the effect of different swing loads on the corrosion processes (through electrochemical measurements and the release of metal ions). The three lubricants, NaCl solution, 25 per cent serum, and bovine synovial fluid, were employed as lubricants in this study. All femoral heads of the tested hip implants were 36 mm in diameter and made from a CoCrMo alloy. The open circuit potential (OCP) was monitored while implants were subjected to dynamic loading cycles. The link between swing phase load, lubricant, and ion release is discussed in relation to corrosion processes occurring at the tribological interface.