SOFT-TISSUE AND CANCELLOUS BONE REACTION TO THE IMPLANTATION OF NOVELBIODEGRADABLE PINS AND PLATES IN RABBITS

Biodegradable implants for osteosynthesis have had insufficient streng th and a fast degradation rate. We produce a polymer based lactide to increase the molecular weight and strength of the implant and delay th e degradation rate. This novel fiber-reinforced material in the form o f plates and pins was tested in vitro for mechanical performance and i n vivo in a neutral mechanical environment to assess biocompatibility. 21 rabbits with implants in the tibia and femoral condyles were kille d at 1, 6, 12 months after implantation. Only a mild foreign-body reac tion was observed and the implant was encapsulated by a thin 0.8-1.6 m m layer of connective tissue. Only a few lymphocytes and giant cells w ere detected in the early stages, dense fibroblasts in the middle stag e, and gi ant cells clearing material particles in the late stage. In conclusion, the novel fiber-reinforced polymer based on polylactides w as found mechanically superior to former degradable implants and bioco mpatible, showing no late inflammatory tissue response.