Polymer resorbable composites applicable for bone surgery
Jan Chłopek, Anna Morawska-Chochół
Quarterly No. 4, 2009 pages 312-316
DOI:
keywords: resorbable polymers, composite, carbon fibres, PAN, hydroxyapatite, carbon nanotubes, in vitro
abstract The most important functions of implants for bone surgery are providing the correct stabilization of broken bone fragments and proper osteointegration. These requirements can be fulfilled through the appropriate mechanical (high strength and low Young’s modulus) and biological (bioactivity) parameters of implants. Composite materials based on polymer matrix constitute a good basis to obtain such implants. Strength improvement of polymer is possible by fibres addition, and fixation can be influenced by bioactive additives. Moreover, the use of resorbable polymer matrix eliminates the necessity of repeated operation connected with removing implants. In the present work, poly(L-lactide-co-glicolide) - PGLA was modified by addition of two kinds of fibres (short carbon fibres - CF and polyacrylonitrile fibres containing hydroksyapatite nanoparticles - PAN/HAP) and particles (hydroxyapatite nanoparticles - HAP and carbon nanotubes - CNT). The aim of this study was to estimate the influence of modifying phase on mechanical properties of copolymer. Changes of mechanical properties and the influence of additives on degradation rate in simulated biological environment were also studied. Mechanical properties were measured by using Zwick machine, degradation rate was estimated on the basis of pH changes of Ringer solution as a function of incubation time, and additionally SEM microphotographs of composites were also obtained. One of the important advantages of studied composites is their low Young’s modulus. The most effective improvement of polymer strength can be observed in the case of addition of PAN/HAP fibres. High strength and bioactivity are connected in this composite and it makes possible to obtain multifunctional implants. Increase of the strength was also achieved in the case of PGLA with carbon fibres composite. The lowest mechanical proper-ties were observed for composites with hydroxyapatite nanoparticles and carbon nanotubes. Significant influence of carbon fibres and carbon nanotubes on degradation rate was also observed. It can be connected with carbon structure.