Fig. 5.
This graph illustrates the Stribeck curves for different bearing combination materials. Under ideal in vivo conditions, we assume that a ceramic-on-ceramic (CoC) bearing will be operating with fluid film lubrication with a coefficient of friction of around 0.0618. Metal-on-polyethylene bearings, on the other hand, operate under conditions of boundary lubrication with a coefficient of friction of around 0.0418,25, and an increase in contact pressure in this situation does not lead to an increase in the coefficient of friction25. In ceramic articulations, a loss of fluid film lubrication may result in a coefficient of friction as high as 0.7 or 1.019. MoM = metal on metal.