Resorbable polyesters: composition, properties, applications.

Synthetic polymers, in particular polyesters based on lactic acid, glycolic acid and other raw materials are described for medical and technical applications. Their main advantages are compatibility and safety. As they are degradable in the human body they are particularly suitable for implants needed only temporarily for the healing process. Resorbable polyesters are produced by direct polycondensation or ring opening polymerization resulting in a broad range of polymers with different features. The main properties such as degradation (hydrolytic and thermal), crystallinity and mechanical strengths are discussed. These polyesters, which can be processed like other thermo-plastic polymers by extrusion and injection moulding, are used mainly for wound closure products (sutures, staples, clips), fracture fixation devices (nails, screws, plates) and parenteral depot systems for the sustained release of drugs. Possibilities for polymer and process improvement to develop better implants and additional applications are presented.