Study on the surface characteristics and biomedical reactions of porous pure titanium spray layer deposited by plasma spray process

摘要

The current interest in achieving component stability of total hip replacement is cementless fixation, including bone ingrowth and bone apposition. The porous coating of implant is traditionally manufactured by sintering method. This would decreased the fatigue strength of implant. However, plasma-sprayed porous coating on metal substrate could preserve the original strength of implant. The aim of this study was to evaluate in vitro the physical and chemical characteristics and in vivo the biological responses of plasma-sprayed porous titanium coatings. In phase I, six porous titanium coatings on Ti-6A1-4V substrates were prepared using vacuum plasma spraying (VPS). The results demonstrated there are no oxide found in porous titanium coatings. By SEM, the lower powder feed rate and higher power of T1 possessed better molten structure. However, the higher powder feed rate and lower power of T6 possessed more roughed structure and porosity. By employing the push-out test in the cortex of canine femors, in phase II, the shear strength and histology of porous titanium coatings were assessed. After 6 weeks of implant, the shear strength of T1 and T6 were similarly about 6 MPa. After 12 weeks of implant, the shear strength of Ti was still about 6 MPa, while the value increased to 9 MPa for T6. The results demonstrated that the rougher surface and larger pore (T6) can provide better mechanical interlocking between implant and surrounding hone tissue. Meanwhile, the plasma sprayed coating could still preserve excellent biocompatibility, and no inflammation and foreign body reaction were found.