Wear of the tibial polyethylene component in total knee replacements

Total knee replacement surgery has become a successful procedure in patients with degenerative joint diseases such as osteoarthritis, with a 15-year in vivo survival rate of over 90%. Yet many patients outlive their implant thereby requiring disruptive and costly revision surgery. Aseptic loosening, i. e. loosening without the influence of pathogenic organisms, is the primary reason for implant revision (>40%), and it is caused predominantly by particle-induced osteolysis. Release rate and total quantity of the nano- to micrometersized wear particles at the articulating surfaces have been identified as limiting factors in the longevity of artificial implants. It is therefore of great importance in knee replacement development to understand the basic wear mechanisms and to increase the wear resistance of implant materials. The majority of research thus far has been targeted at investigating implant wear through simulator testing, which, however, has not yet been clinically validated. The tribological interactions, i. e. the interaction of material properties, surface characteristics, lubrication, and the multidirectional loads and motions, are only partially investigated and described. The goal of the present work was the study of the influence of moments and sliding velocities at the implant interface on wear generation in the metal-on-polyethylene articulation of artificial knee joints.