Inhibition of of cell proliferation due to trace elements released from oxidized Ti alloy orthopedic implant materials

Titanium alloys are of great significance in orthopedic implants.  However, the stability of the surface in terms of ion release in the human body is responsible for the durability of the implant. Our study tested two alloys Ti-6Al-4V, currently used for implants and γ-TiAl, a potential substitute. The experimentation is focused on analyzing the type and concentration of ions released in a simulated human body environment after the surface of these alloys are modified by oxidation at different temperatures. Studies have demonstrated that toxicity in implant recipients has been attributed to release of ions from implants. HFOB 1.19 cells were grown in culture media previously exposed for 72hrs at 33.5^oC to these surface modified alloys. Cells were allowed to proliferate in this media for 72 more hours at 33.5^oC followed by an indirect MTT assay. The results show that the Ti-6Al-4V alloy oxidized at 700^oC did not sustain cell proliferation when compared to oxidation at 121^oC and 500^oC. The culture media exposed to the oxidized alloys were analyzed by Atomic Absorbance Spectroscopy using a Graphite Furnace to detect type and concentration of ions released from the alloys surfaces. During the analysis quality control samples were added as well as spiked samples to ensure accurate readings. The test results showed that increasing concentrations of vanadium are released as the oxidation temperature increases. Our hypothesis is that the release of vanadium ions from the oxidized Ti-6Al-4V alloys is the reason for the lack of cell proliferation.