Effect of Angular Mismatch on Tribocorrosion at Taper-Trunnion Junction Using a Finite Element Model Considering Mechanical and Chemical Wear

Wear debris and metal ions arising from tribocorrosion at the taper-trunnion junction have been associated with early complications after total hip replacement. Wear and electrochemical phenomena occur simultaneously in this tribo-system, however, chemical wear has been usually neglected in previous computational studies on the interface damage. In this study, we developed a finite element model incorporating both the mechanical and chemical wear processes, and then investigated the effect of taper mismatch on the tribocorrosion at a CoCr/Ti6Al4V taper interface. This model was initially verified through a ball-on-disk wear testing and then applied to the study of degradation mechanism at the taper-trunnion junction. It was found that material loss at the taper-trunnion junction was linearly related to the number of gait cycles and chemical wear was evident, contributing up to 26 % to total material loss. A taper mismatch as small as possible was not necessarily beneficial to minimize the material loss. Instead, a larger positive taper mismatch helped reduce total wear volume but maximized the contribution of chemical wear. The model with a negative taper mismatch performed better than the ones with a positive taper mismatch in terms of corrosion resistance. These findings would benefit preoperative planning and the design of implant with reduced risk of tribocorrosion and failure.