Preparation of artificial canine femoral stem with HA–Ti ladder-type coating on plasma-sprayed pure Ti substrate and its performance evaluation

Abstract

An ideal, biological-type, artificial femoral stem prosthesis has good stability and improved bone-prosthesis bonding capacity. In the current study, pure hydroxyapatite (HA)-coated, cementless, artificial femoral stems were prepared by adopting different plasma spray powers and distances and were tested in terms of shear strength. The pure titanium (Ti) substrates, HA coatings, and composite Ti–HA ladder-type coatings prepared under vacuum and atmospheric conditions were examined to compare the shear strengths, microscopic constitutions, and structures of the coatings. The coating was fabricated and the bond strength was improved by adopting 35kW of spray power and an 80mm spray distance. The comparisons show that the shear strength of the Ti coating prepared under vacuum conditions was higher than that of the coating prepared under atmospheric conditions (P<0.05). Moreover, the pressure–shear strength of the Ti+HAG+Ti+V group coating was statistically significantly different from those of the HA+Ti+V and HA+Ti+A groups (P<0.05). The coatings were compared using scanning electron microscopy, X-ray diffraction, and infrared spectrum analysis. The composite HA–Ti ladder-type coating group, where pure Ti substrate was sprayed onto the Ti alloy under vacuum conditions, had a successive laminate structure. In addition, the intergranular bond in the HA surface layer on the gradient coating was compact and highly crystallized. Under vacuum conditions, the plasma-sprayed layer was characterized by higher tightness, moderate porosity, higher bonding strength to HA, and higher HA crystallinity. The proposed coating can be used in new, cementless, artificial femoral stems with improved bone–prosthesis bonding capacity and stability.