Tribocorrosion of hard-on-hard total hip replacements with metal and ceramic counterfaces under standard and adverse loading conditions

• Microseparation increased corrosive contribution to the degradation of 28 mm MoM THRs.
• Currents measured during articulation saw a near order of magnitude increase.
• Current transients displayed similar patterns for MoM and MoC under standard gait.
• Adverse loading conditions may change the pathway of material loss for THRs.

28 mm Metal-on-Metal (MoM) and Metal-on-Ceramic (MoC) Total Hip Replacements were articulated to 1 million cycles under both Standard Gait and Microseparation conditions. The hip simulator was fully instrumented with a three-electrode electrochemical cell to facilitate monitoring of corrosive degradation. The estimated volume loss from corrosion at the bearing surface was seen to increase by nearly an order of magnitude for both devices, representing as much as 17% of total degradation. Anodic current transients also displayed near order of magnitude increases in the peak current for both bearing couples. An adverse loading scenario could cause as much as an order of magnitude increase in the metallic ions released into the joint capsule as well as an increased volume of wear debris.