Tribo-corrosion analysis of wear and metal ion release interactions from metal-on-metal and ceramic-on-metal contacts for the application in artificial hip prostheses

Abstract

Osteolysis induced by polyethylene wear debris from metal-on-polyethylene total joint replacements is one of the major reasons for the renewed interest in metal-on-metal (MoM) bearings for total hip arthroplasty. However, long-term clinical performance is as yet unknown for the second generation MoM hip prostheses. The main concerns are the released metal ions and metallic wear debris from the artificial joints. It is well known that the metal ion release processes (corrosion) are electrochemical in nature. When two contacted components are in relative motion, wear can occur and it can accelerate corrosion. The role of corrosion in the generation of metallic wear debris is still not well understood. This paper addresses this point and makes a comparison of MoM and ceramic-on-metal (CoM) contacts. In this paper, tests were conducted on a pin-on-plate tester with an integrated electrochemical cell in 25 per cent bovine serum to determine the effects of pin rotation on the wear and metal ion release of two different combinations (metal pins with metal plates and metal pins with medical grade Alumina plates). The overall wear and released metallic ions were reduced with rotational movement of the pin in addition to the reciprocating action of the plate. For the CoM combination, a reduction of wear was associated with a more noble open circuit potential compared with the MoM combination.