Partially resorbable composite bone plate with controlled degradation rate, desired mechanical properties and bioactivity

Abstract

Rate of polymer degradation is very important for implantable biomaterials since controlling the degradation rate may complement the biological response and affected mechanical property requirements. In spite of numerous publications on the potential use of combinations of poly lactic acid/bioactive glass fillers for degradable bone plate, little information exists on the controlling degradation rate and its effects on the other aspects such as biomechanical compatibility, bioactivity, etc. Our previous study revealed that a composite bone plate consist of poly l-lactic acid/braided bioactive glass fibers has the initial mechanical properties near to cortical bone. In this study, degradation rate and mechanical behavior of the composite bone plate were assessed, and also degradation rate was controlled by using proper manufacturing process and improving bonding between matrix and reinforcement. Moreover, bioactivity of the composite was considered before and after controlling degradation rate, because of the important role of bioactivity and ion release in healing acceleration. Results showed that degradation process of the composite could be controlled properly. Strength of the treated composite decreased only about 5% through 2 weeks and about 35% after 8 weeks while, the strength loss for the untreated composites was about 50 and 70 percent after 2 weeks and 8 weeks of degradation respectively. Although calcium-phosphate formation on the surface of the composite was postponed in the treated samples, the bioactivity of the composite remained unchanged and bone-like apatite was formed on the composite surface which is important for the application of the composite in bone tissue environment.