Resorbable synthetic polymers as replacements for bone graft.

The potential of resorbable synthetic polymers derived from the poly(alpha-hydroxy acids), poly(lactide) and poly(glycolide), to fulfill a role as bone graft substitutes is reviewed. The various elements of the relationship between the degradation behaviour of resorbable implants and polymer synthesis and chain structure, implant morphology, processing and dimensions have been defined. The production of resorbable polymeric implants has been extensively documented so as to provide a wide basis for selection of an appropriate manufacturing technique. The key requirement of implant dimensional stability over the early stages of bone healing is emphasised so as to provide a stable surface on which osteoblasts and/or their precursor cells may migrate and secrete bone matrix. Minimisation of the content of slow resorbing polymers such as poly(L-lactide) is recommended, consistent with retention of an adequate implant degradation characteristic. The review concludes with a summary of alternative resorbable polymers such as the polyphosphazines which are interesting candidate materials for bone repair and reconstruction.