The biomedical/pharmaceutical industries, but also most technologists, tend to underestimate or utterly overlook this basic, obvious concept which they consider contrary to progress. Replacements for body parts lost through injury, amputation or disease have been in use for millennia. Most of the prostheses were manufactured according to the general indications given by an orthopaedist and were a sort of compromise between the anatomical location they were meant to occupy, the function they had to accomplish and the mechanical stresses they had to endure. In 1986 the definition was enhanced, adding 'non-viable material, used in medical device, intended to interact with biological systems'. A well-known case is that of hip joint prostheses losing surface debris due to the friction between counterparts. The bulk material may have passed all tests and be declared biocompatible, but that is not the case with its debris. A branch of implantology is related to tissue engineering.