Biodegradable Mg-Zr-Ca alloys for bone implant materials

Mg-Zr-Ca alloys were developed for new biodegradable bone implant materials. The microstructure and mechanical property of the Mg-xZr-yCa [x = 0·5, 1·0% and y = 1·0, 2·0% (wt-% hereafter)] alloys were characterised by optical microscopy, compressive and hardness tests. The in vitro cytotoxicity of the alloys was assessed using osteoblast-like SaOS2 cells. The corrosion behaviour of these alloys was evaluated by soaking the alloys in simulated body fluid (SBF) and modified minimum essential medium (MMEM). Results indicated that the mechanical properties of the Mg-Zr-Ca are in the range of the mechanical properties of natural bone. The corrosion rate and biocompatibility decreases with the increase in the Ca content in the Mg-Zr-Ca alloys. The solutions of SBF and MMEM with the immersion of the Mg-Zr-Ca alloys show strong alkalisation. The Zr addition to the Mg-Zr-Ca alloys leads to an increase in the corrosion resistance, compressive strength and the ductility of the alloys, and a decrease in the elastic modulus of the Mg-Zr-Ca alloys.