In this study, titania and hydroxyapatite nanopowder mixtures are deposited on medical grade titanium substrates by HVOF spraying. To assess bioperformance, human mesenchymal stem cells (hMSCs) were cultured from 1 to 21 days on the surface of HVOF-sprayed TiO 2 and TiO 2 -HA samples. Plasma sprayed HA and uncoated Ti-6Al-4V substrates were used as controls. The active cultures were evaluated for cell proliferation, cytoskeleton organization, and cell-substrate interaction. The results for HVOF-sprayed TiO 2 -HA nanocomposite coatings show strong evidence of bone growth, proliferation, and attachment with cell-substrate interaction levels superior to those of air plasma sprayed HA coatings. Although there are no clear explanations for this favorable behavior, the topography and chemical composition of the surface of the coating appear to be playing important roles.

The aging baby boomer population coupled with an increase in life expectancy is leading to a rising number of active elderly persons in occidental countries. As a result, the orthopedic implant industry is facing numerous challenges such as the need to extend implant life, reduce the incidence of revision surgery and improve implant performance. This paper reports results of an investigation on the bioperformance of newly developed coating-substrate systems. Hydroxyapatite (HA) and nano-titania (nano-TiO 2 ) coatings were produced on Ti-6Al-4V and fiber reinforced polymer composite substrates. In vitro studies were conducted in order to determine the capacity of bioactive coatings developed to sustain osteoblast cells (fetal rat calvaria) adherence, growth and differentiation. As revealed by SEM observations and alkaline phosphatase activity (ALP), cell adhesion and proliferation demonstrated that HA coatings over a polymer composite are at least as good as HA coatings made over Ti-6Al-4V substrate in terms of osteoblast cell activity. Nano-TiO 2 coatings produced by high-velocity oxy fuel (HVOF) spraying led to different results. For short term cell culture (4.5 and 24 hrs), the osteoblasts appeared more flattened when grown on nano-TiO 2 than on HA. The surface cell coverage after 7 days of incubation was also more complete on nano-TiO 2 than HA. Preliminary results indicate that osteoblast activity after 15 days of incubation on nano-TiO 2 is equivalent to or greater than that observed on HA.