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

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 CoCrMo alloy and UHMWPE couple was 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 (0-5N) 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.