While a definition for biomaterials has been difficult to formulate, a widely accepted definition for biomaterials is that:
" A Biomaterial is a nonviable material used in medical device, intended to interact with a biological systems (William 1987)"
A biomaterial is essentially a material that is used and adapted for a medical application. Biomaterials can have a benign function, such as being used for a heart valve, or may be bioactive and used for a more interactive purpose such as hydroxy-apatite coated hip implants (the Furlong Hip, by Joint Replacement Instrumentation Ltd, Sheffield is one such example – such implants are lasting upwards of twenty years). Biomaterials are also used every day in dental applications, surgery, and drug delivery (a construct with impregnated pharmaceutical products can be placed into the body, which permits the prolonged release of a drug over an extended period of time).
The definition of a biomaterial does not just include man-made materials which are constructed of metals or ceramics. A biomaterial may also be an autograft, allograft or xenograft used as a transplant material.
Biomaterials are used in:
Biomaterials must be compatible with the body, and there are often issues of biocompatibility which must be resolved before a product can be placed on the market and used in a clinical setting. Because of this, biomaterials are usually subjected to the same requirements of those suffered by new drug therapies. All manufacturing companies are also required to ensure traceability of all of their products so that if a defective product is discovered, others in the same batch may be traced.
A material should not be toxic, unless specifically engineered to be so (for example “smart” drug delivery systems that target cancer cells and destroy them).
Biocompatibility is difficult to measure, it is defined in terms of success at a specific task.
Understanding of the anatomy and physiology of the action site is essential for a biomaterial to be effective.
Healing is an essential consideration when using biomaterials. The body may experience what is known as a foreign-body reaction after implementation so immuno-suppression may be required.
It is important, during design, to ensure that the implement will fit complementarily and have a beneficial effect with the specific anatomical area of action.
Biomaterials that have a mechanical operation must perform to certain standards and be able to cope with pressures. It is therefore essential that all biomaterials are well designed and are tested. Biomaterials that are used with a mechanical application, such as hip implants, are usually designed using CAD (Computer Aided Design)which allows all of the directional stresses to be calculated, ensuring maximum product life.
Companies and researchers push the boundaries and development of science in general, and biomaterials are no exception.
Ethical considerations are paramount – as are legal considerations and compliance with the law.
As mentioned above, regulation and records are required to be kept by the product manufacturer for much longer than the product life.