In-vitro and in-silico investigations on the influence of contact pressure on cross-linked polyethylene wear in total knee replacements

Various conflicting trends have previously been reported for the influence of contact pressure on the polyethylene and crosslinked polyethylene wear of total knee replacements. In the present study, the influence of contact pressure on crosslinked polyethylene wear in total knee replacements was investigated using in-vitro knee simulator wear tests and in-silico computational wear simulations. Knee simulator wear tests were conducted under standardized and increased loading. The knee simulator wear test results were predicted using computational wear models with various contact pressure – wear trends to evaluate the accuracy of each approach. The knee simulator wear tests revealed the increase in loading (1.7 fold) to greatly increase crosslinked polyethylene wear (4.49 fold). The computational wear simulations revealed the wear model with the trend of linearly increasing wear with increasing contact pressure to result in improved agreement with the knee simulator results over the non-linear and contact pressure independent models. However, all of the computational wear simulations under-predicted the increase in wear caused by the increase in load. The results suggest that crosslinked polyethylene wear in total knee replacements may increase with increasing contact pressure and that the trends of pin-on-disk tests may not be directly applicable to total knee replacements with regard to contact pressure.