Numerical analysis of the effects of material parameters on the lubrication mechanism for knee prosthesis

Abstract

The tibial component of current knee prostheses made of Ultra Hig Molecular Weigth Polyethylene (UHMWPE) has a high degree of wear that causes knee inflammation, prosthesis loosening and and subsequent replacement in no mor than 15 years. In order to know which materials properties of UHMWPE have more influence on wear, a steady state lubrication model with non- Newtonian wynovial fluid has been studied trough numerical solution. The results show that UHMWPE has a very high elastic modulus that makes difficult a well lubricated artificial joint and includes the formatio of very thin lubricating films between the mofing surfaces with the same magnitude of roughness components. This study shows that the use of deformable porous materials in the tibial component could cause the lubricating film thickness to be higher than the average roughness and the pressure levels to be lower than the one predicted for UHMWPE. These two facts imply friction and wear reductio.