IN-VIVO STUDY OF STAINLESS-STEEL AND TI-13NB-13ZR BONE PLATES IN A SHEEP MODEL

A sheep study was performed to compare the in vivo performance of bone plates of 316L stainless steel and a new titanium alloy, titanium + 1 3% niobium + 13% zirconium (Ti-13Nb-13Zr), which had been subjected to a diffusion hardening treatment to produce a blue, wear resistant sur face, Bone plates and screws of stainless steel and diffusion hardened Ti-13Nb-13Zr were implanted in adult sheep, in one group (with unoste otomized femurs) for 16 weeks, and in the other (with osteotomized fem urs) for 8 weeks, At harvest, the diffusion hardened Ti-13Nb-13Zr devi ces had superior fixation strength, with greater screw torque out stre ngth and fewer loose screws, In the osteotomized animals, the femurs w ith diffusion hardened Ti-13Nb-13Zr plates had higher torsional streng th after removal of the implants; however, the difference was not stat istically significant. In the unosteotomized animals, the torsional st rength of the femurs was identical for both materials. There was a sli ghtly reduced incidence of infection (bacterial adhesion) for the shee p with diffusion hardened Ti-13Nb-13Zr implants. In a parallel in vitr o study, the magnetic resonance imaging compatibility of Ti-13Nb-13Zr was significantly superior to that of stainless steel. This indicates that diffusion hardened Ti-13Nb-13Zr may be an attractive alternative material for osteosynthesis.