[Development of new, biodegradable implants].

The advantage of biodegradable implants is that they do degrade after they have fulfilled their function. Therefore, a second operation for removing metal implants is not necessary. Additionally, the healing process may be stimulated by the successive loss of the mechanical properties of the implant during degradation, corresponding with the increasing loading on the healing tissue. The most important materials are polylactide, polyglycolide and their copolymers, and polydioxanone. The mechanical properties of these polymers were improved by special fabrication techniques. Nevertheless, the materials have disadvantages relating to their stiffness and relaxation behavior. Therefore, their use has to be restricted to nearly unloaded situations. The degradation behavior of the materials can be controlled by the production of copolymers and by the molecular weight of the polymers. The degradation behavior cannot be predicted exactly in vivo, as it is influenced not only by the chemistry and the implant design but also by the localization of the implant in the tissue. In general, the biocompatibility of the polymers used today is good and the observed complication rate is very low. Osteolytic reactions, which can sometimes be observed, have no clinical consequences in most instances. The clinical applications comprise resorbable pins and screws for the fixation of small bony fragments, interference screws for the surgery of the anterior cruciate ligament, resorbable augmentation devices for ligaments and tendons, resorbable membranes for guided bone regeneration in maxillofacial surgery, and a lot more. Future developments are expected in the field of tissue engineering and drug release.