[Classification of implants with reference to safety considerations]

Implants are listed both in the German Drug Law (Arzneimittelgesetz) and in the Regulations of the Safety of Medical Technical Equipment (Medizingeräteverordnung). In recent time, various guidelines concerning implants have been under discussion in Europe. It is surprising to note that more than one set of guidelines has been thought to be necessary. The present article discusses possible definitions of some of the terms employed in connection with implants, and attempts to identify the differences and common features of implants under aspects of safety, thus providing a broader base for public discussions. An analysis of the implants presently available has shown that it is useful to establish a hierarchy of possible hazards that takes into account the danger to the patient under worst-case conditions. A survey has demonstrated that in the worst case, most implants are associated with only an impairment or inconvenience for the patient, but no threat to life. In contrast, a minority of implants are of such a nature that in the case of severe failure, a life-threatening situation can develop for the patient. Such a hazard is not dependent upon whether the implant has a driving energy source or not. These findings indicate that within the framework of safery considerations, more attention need to be paid to "passive" implants than has been the case so far.