New implant designs for bioresorbable devices in orthopaedic surgery.

From today's point of view it is not possible to transfer the designs of metal implants in orthopaedic surgery to biodegradable polymers. The attempt of a simple mimicry of metal implants for those made of polymers was condemned to fail from the very beginning. In this paper some fundamental limitations of implants made from biodegradable polymers (PGA and PLA) are experimentally demonstrated. Fixing devices adapted to the characteristic properties of polymers and adjusted to the specific therapeutic problems have to be developed. The creation of new implant devices made of biodegradable polymers depends on the influence of manufacturing processes, composite materials, fibre reinforcement, coating, specific erosion processes and the development of new implant designs. The basis for a new implant philosophy is discussed.