Electrochemically Treated Film Formation on CoCrMo Alloy for Total Hip Replacement (THR)

Metal-on-metal (MoM) bearings, comprised of Cobalt-Chromium-Molybdenum (CoCrMo), have been widely used in total hip replacements, however this material is susceptible to in vivo corrosion and wear (tribocorrosion). Proteins within the synovial fluid surrounding implants can have a profound effect on the corrosion kinetics of MoM implants, but the interaction between the proteins and the implant surface is not thoroughly understood. Studies suggest that carbonaceous films found on hip retrievals may act as a lubricant at articulating surfaces to reduce wear, corrosion, and friction. Therefore, the goal of this study is to induce film formation in a proteinaceous environment through electrochemical treatment and evaluate film effectiveness using electrochemical impedance spectroscopy (EIS) and tribocorrosion. Surface characterization techniques were utilized to understand the homogeneity of film formation. It is hypothesized that promotion of superior film formation occurs at higher protein concentrations allowing for more mechanically resistant film. Results indicate improved corrosion kinetics with increasing protein concentration and tribocorrosion testing shows film formation reduces friction. Understanding corrosion and wear mechanisms of hip joint implants will help to guide future designs and functional needs of implants. In addition, this investigation adds to the knowledge of understanding the role of protein in providing implant protection during loading conditions.