The effect of displacement control input parameters on tibiofemoral prosthetic knee wear

The mechanisms of UHMWPE wear at the tibiofemoral articulation of a total k nee replacement are potentially highly dependent on the cyclic direction of motion, the relative amounts of rolling versus sliding, and the loading of the contacting surfaces as previously described for hip components [3]. Th e simulated wear rate, for a standard test protocol utilizing the Insall-Bu rstein (R) (1) II Modular Knee System (IB-II) knee prosthesis, for normal w alking gait was found to be 17.0 mg/10(6) cycles on a Boston AMTI knee simu lator. When the anterior/posterior (A/P) translation input was reduced by 5 0%, the wear rate was reduced approximately 37% to 10.6 mg/10(6) cycles. El iminating either the A/P translation or tibial rotation reduced the wear ra te to 1.7 mg/10(6) cycles and 0.69 mg/10(6) cycles, respectively. These res ults cannot be explained by sliding distance effects alone and suggest that the UHMWPE wear rate is sensitive to other parameters, such as the magnitu de of multidirectional shear motion and the ratio of rolling/sliding contac t kinematics in combination with the applied load. (C) 2001 Elsevier Scienc e B.V. All rights reserved.