Mechanical characterization of biodegradable implants.

The mechanical properties of degradable implant materials are low in comparison to metals used in orthopaedic surgery. There are possibilities to improve the strength of degradable implants by self-fibre-reinforcement, high molecular weight or special manufacturing processes. However, the moduli of the materials cannot be increased significantly by these techniques. Comparison of the mechanical properties of the most important materials are shown. Creep and relaxation are characteristic properties of degradable materials and limit the use of load-carrying implants. The rate of degradation in vitro and in vivo shows larger differences between the various materials and range from a few weeks up to 3 years.