1 Introduction

The use of synthetic materials in the body by medical and dental practitioners to provide repair and function has grown remarkably in the last 30 40 years, though the concept of using such artificial materials is very old. For example, Plaster of Paris was pioneered as bone-substitute material towards the end of the nineteenth century, and dental fillings, including amalgam, have been around for well over 150 years. The use of engineered structures fabricated from metals and polymers in orthopaedic surgery has a more recent history, however, beginning with Dr (later Sir) John Charnley s work on the replacement of arthritic hips in the early 1960s.1 ^,2 This surgical repair technique, known as total hip arthroplasty, has seen particularly spectacular growth, and since Charnley s original cemented hip replacements there have been a variety of new materials and new designs for implantable devices, and these are now available not only for hips, but also for knees, toes and fingers.

Synthetic materials used in the body in this way are widely referred to as biomaterials. This use of the term appears to have originated in 1967 with the first International Biomaterials Symposium at Clemson University, South Carolina, since which time it has been used extensively in this way. In many ways to apply the word biomaterials to synthetic materials is not very satisfactory since by analogy with, for example, the word biochemistry, it might be assumed to refer to materials of biological origin. However, within the field of implantable...