A study of polymers for prostheses.

Abstract

The mechanical repair of parts of the human body destroyed by trauma or disease has been attempted by surgeons with little success over the centuries. Present day technology has provided the orthopaedic surgeon with materials and techniques which allow him not only to repair but also to completely replace malfunctioning joints and to restore his patient to full pain-free activity. Two sites of implantation, the knee and finger joints, are examined in this study, more specifically an investigation of the wear of a prosthetic polymer bearing and the development of an elastomer to replace damaged Joints of the hand. The wear study was undertaken to try and find a replacement for the stainless steel of the Platt interposing membrane type knee prosthesis which is known to fail in service. A more flexible material capable of withstanding the stresses across the knee joint and able to act as a bearing between femur and tibia was sought. The wear behaviour of U.H.M.W. polyethylene was examined and compared with polypropylene suggested as the replacement material for the steel joint. Wear coefficients for the polyethylene were determined when the polymer was mated with several different counter-faces. The effect of polyethylene structure on its wear behaviour was also examined along with the effect of crystalline orientation and physical properties. The development of a prosthetic elastomer is based on a practical need arising out of experience with the current silicone rubber joint. Joint stiffness is the major requirement and blending, physical property evaluation and biological testing of an E.P.D.M./polybutadiene formulation are reported. In both projects recommendations as to the use of the materials under examination are made.

Date of Award	1977
Original language	English
Awarding Institution	University of Bath