Damage due to rolling in total knee replacement—The influence of tractive force

The femoral condyles of a knee prosthesis articulate with a combination of rolling and sliding on the tibial polyethylene plateau. Little is known about potential polyethylene damage due to rolling motion. Since rolling does not exclude the presence of tangential surface loads, this study sought to investigate the influence of tractive rolling on the wear of polyethylene. A “wheel-on-flat” apparatus, consisting of a metal wheel and a polyethylene flat, mimicked contact conditions present in total knee replacement. An increasingly tractive force under conditions of pure rolling was applied. It was found that under rolling kinematics a tangential surface load of up to 17% of the normal load could be transferred through the contact. Surface damage was dependent on the amount of tractive force and appeared more severe with higher forces. In the region of highest tractive force, wear features were identified that resembled perpendicular ridges on surfaces of retrieved tibial polyethylene devices. This suggests that tractive rolling may be a relevant wear mode in total knee replacement.