Degradation of poly(lactide-co-glycolide) and its composites with carbon fibres and hydroxyapatite in rabbit femoral bone

The aim of the present work was to analyse the degradation rate of PGLA copolymer depending on a modifier (hydroxyapatite, carbon fibres) under in vivo conditions (rabbit femoral bone). Also, the influence of the implantation site on the degradation rate of a copolymer (rabbit mandible and femoral bone) was analyzed as a continuation of our previous research.The structural and phase changes of poly(lactide-co-glycolide) and its composite with hydroxyapatite and carbon fibres were determined on the basis of IR and NMR spectroscopy. Additionally, microscopic observations with elemental analyses were performed (SEM, EDS).The addition of a modifying phase accelerates implant degradation. However, modifying additives promote regeneration of the treated bone tissue simultaneously with faster polymer degradation. The compositions of a copolymer and composites are variable during degradation.The process of copolymer degradation in the femoral bone is much faster in comparison with previous studies on mandibles. This may be caused by higher activity of osteoblasts, differences in blood supply and oxygenation of tissue as well as different anatomical structure of these two kinds of bones.FTIR and NMR methods allow for following the changes occurring in the resorbable copolymer structure with time and they are very useful tools in analyzing the degradation mechanism and rate of aliphatic polyesters and their composites.