Sliding polymers in the joint alloplastic: Fid-Bau Portal

Sliding polymers in the joint alloplastic

Kowalewski, P. / Wieleba, W.

Endoprostheses make it possible to replace a sick or damaged joint with man-made elements. Thanks to numerous clinical trials and to progress in the manufacturing technology, the devices of this type are now more and more modern and reliable. Materials used in endoprostheses have been subject to continuous modifications. The principal reasons of failures in the implantation of artificial joints are the loosening of the graft, often due to the infection caused by products of wear of polymer elements, improper grafting or improper co-operation between the implant and tissue. Additionally, after a dozen or so years of exploitation, needed is the reoperation of the endoprosthesis due to its wear. An improvement in the sliding properties and wear resistance of the polymer elements of endoprostheses will contribute to the reduction of pathologies and reimplantations as well as to the elongation of their service life. Numerous studies have been carried out at present to explain the process of wear of polymer inserts used in hip and knee endoprostheses. In the case of an implanted joint, the forces of friction are higher than those in a natural joint. Additionally, theses forces are variable in time, which adds fatigue aspects and bone/implant integration impacts to the problem. Mechanical and tribological properties of ultra-high molecular weight polyethylene contributed to the fact that this material has been the principal sliding polymer employed in the joint alloplastic. Improvement in reliability and anticipation of wear patterns in endoprosthesis are priorities in the current research.