Material Combinations with Polyethylene and Metasul for Articulating Implants

Abstract

After a break of 20 years, it is now recognized once more that polymer wear particles, in particular, significantly affect the long-term fixation results of cemented and cementless prostheses through necrosis, osteolysis and subsequent loosening; as a result, interest in implant tribology has now increased again. Compared with the natural joint, the tribological situation in an artificial joint is fundamentally changed by the use of artificial, non-porous materials as articulating surfaces. Given the continuously changing loading and velocity conditions in the body, a lubricating film can only be temporary. Solid body contact between the articulating components of the artificial joint is therefore almost always present, with unavoidable high friction values and material wear. The amount of wear per unit of time is a particularly important factor regarding possible osteolysis; in addition to the chemical composition, the size and morphology of the wear particles are also important [18]. Only a few small particles can be carried away by the patient’s peri-articular system, and little or no foreign body reactions are likely. The objective of improvements in materials and their combination as articulating implant components must therefore be directed towards the reduction of the number of wear particles, if possible with a simultaneous reduction of friction.