Bio-tribocorrosion mechanisms in orthopaedic devices: Mapping the micro-abrasion–corrosion behaviour of a simulated CoCrMo hip replacement in calf serum solution

• The micro-abrasion–corrosion of CoCr in a physiological solution was investigated.
• Wastage, mechanism and synergism wear maps have been developed.
• Wear maps showed the micro-abrasion–corrosion transition behaviours.
• This is an extensive study linking wear mapping to electrochemical data.
• Wear was inhibited at lower loads due to the presence of denatured protein film.

Load bearing implant prostheses such as orthopaedic hip and knee implants may be considered as tribocorrosion systems since the wear processes are a result of combined mechanical and chemical mechanisms. The long-term success of implant prostheses depends on a number of factors, including age, body weight and activity levels. Pre-clinical testing is therefore crucial in determining the long-term performance, safety and reliability of the implant in-vivo. In this study a CoCrMo alloy - UHMWPE couple were tested in a physiological solution of foetal calf serum (FCS) in 0.9 wt% NaCl to assess the underlying wear mechanisms as a result of applied load (0–5 N) and applied potential (−600, −400, −200, 0 and +200 mV). The transitioning behaviours due to micro-abrasion and corrosion were studied; corresponding micro-abrasion–corrosion wear maps were constructed to indicate the mass loss transitions in scope of wastage, mechanisms of wear and synergies between abrasion–corrosion for simulated hip contact conditions.