engleski

Materials and tribology in hip replacement

Biomaterials for orthopaedic applications have moved from materials available for different industrial applications into the development of materials with abilities to interact with the biological environment in the last 60 years. The choice of material used for designing a medical implant is governed by biocompatibility, bioadhesion, biofunctionality, mechanical properties, corrosion resistance, etc. Three categories of materials are presently used in prosthetic devices: metals, polymers and ceramics. Many engineering components can be improved with a coating (surface engineering). Coatings are applied to orthopedic components and other medical devices for a variety of reasons. For the long term success of cementless implants is crucial bone ingrowth around and with the porous surfaces. A variety of roughened surfaces and three-dimensional (3-D) porous surfaces have been used to enhance biological fixation on orthopedic implants for over 30 years. The porous coatings can take various forms and require different technologies such as: thermal spraying (wire arc deposition and plasma spraying), ion implantation (ion-beam- assisted deposition), vapor deposition processes (physical vapor deposition process and chemical vapor deposition processes). The coating can act as a protective layer on top of a bulk material or a brittle, wear resistant material can be improved by the support of a more ductile bulk material. Failures of total joint replacements can be due to several factors including insufficient fixation and positioning, mechanical loosening and infections. One of the most critical factors is related to tribology, i.e. wear of the cup, head or liner. It is the produced wear particles rather than the material loss from the joint surfaces that become the limiting factor. The most important demands on the material combination in the implant are high wear resistance, smooth bearing surface to reduce future wear particles and biocompatibility.

biomaterials; orthopaedics implants; tribology

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