Prediction of total knee arthroplasty polyethylene wear using the wear index

The predictive value of the wear index for total knee arthroplasty polyethylene wear was determined using a numeric and in vitro model. The wear index was defined as the deformation x the sliding velocity. Four commercially available total knee prostheses were modeled for this study. Deformation and sliding velocity were calculated from the 3-dimensional geometry of the components and the gait kinematic inputs using Hertz's formula. A knee simulation test was performed under the same conditions, and the surface of the inserts was compared with the wear index. This study showed good agreement between the numeric model and the simulation test, suggesting that the wear index is a reliable predictor of total knee arthroplasty polyethylene wear through its incorporation of contact stress and kinematics.