Biocompatible materials

There are many different types of biocompatible products used for a multitude of applications. It appears that existing definitions of biocompatibility may  be relatively general and inclusive of a wide range of properties for materials as distinct as metals, ceramics, polymers, hydroxyapatites, exogenous and autogenous grafting products to name a few.

Biocompatibility is not dictated by the chemical composition of the material alone: Medical implants are nearly always designed for mechanical function and may not be regarded as biocompatible if they fail due to poor macroscopic design and surface characteristics causing pathology in surrounding tissues or fracture of the implant device itself. Chemical, structural and mechanical integrity must also be maintained over a long period of time within the physiological environment of the living human being. In the case of materials intended for use in metal implants, by- products of corrosion and wear are of distinct importance.

International standards ASTM 1537-08, ASTM F75 – 07, BS7252-4:1997 and ISO5832-4:1996 offer important guidance for manufacturers of medical devices concerning the composition and engineering characteristics of the materials which are used to create such devices. In the case of metallic alloys such as cobalt chromium, stainless steel and titanium, biocompatibility is not a quality of the alloy per se. Such alloys only become biocompatible once they are engineered into the final medical device. A more accurate description may be one of biocompatible potential.

Cobalt chromium molybdenum alloys such as Alexium Osseous^{TM  ­}from MD Alloys are very popular for use in surgical implants. This is due to their biocompatibility when expertly cast, forged or machined into surgical implants. Alexium Osseous demonstrates strength with excellent resistance to wear which is particularly important for longevity of load bearing joint surfaces.

Patrick Coffey, Managing Director MD Alloys Ltd

Comments