Specific characteristics of mechanically and biologically compatible titanium alloy rods for use in spinal fixation applications

摘要

For implant rods as spinal fixation system, low Young's modulus, easy bending to an intended shape (low spring-back), and retaining initial bended shape during a long implantation (low aging-back) are essential properties. The rods were fabricated using a biomedical P-type titanium alloy, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ), and their above-mentioned properties were evaluated in comparison with conventional biomaterials, commercially pure titanium, Ti-6A1-4V ELI, and SUS316L stainless steel. In the results of an animal experiment using implant rods made by TNTZ subjected to solution treatment with low Young's modulus, no negative effects are seen in the radiographs, and no inflammatory cells are observed in histological observation. In spite of low Young's modulus, the spring-back of TNTZ subjected to solution treatment is comparable to that of Ti-6AI-4V ELI. Further, its aging-back is quite small among the other materials.