Biocompatibility of an interspinous implant made of titanium alloys

BACKGROUND: At present, metal implants are widely used in neuro-orthopedics, of which titanium alloys are of particular interest. A team of authors developed an original combined implant for posterior spinal fusion as an import substitution, which can be used from one-way access during minimally invasive operations on the lumbar spine. The implant was manufactured at the Endocarbon Enterprise in Penza. For better osseointegration, it is made of VT6 alloy and titanium nickelide. The middle part of the implant is laser-treated to create an uneven surface in the hope of better integration in the tissues of the body. This study was conducted to assess the cytotoxicity and biocompatibility of this implant for its further application in clinical practice. 
AIM: To determine the cytotoxicity of an interspinous implant made of titanium alloys for its further introduction into spinal surgery. 
MATERIALS AND METHODS: To determine the cytotoxicity of titanium samples of interspinous implants, a methyltetrazolium test was conducted to assess the viability of stromal cells in the presence of a nutrient medium after incubation with the test material. The biocompatibility of the material was analyzed using scanning electron microscopy of samples 1 and 7 days after cell culture. 
RESULTS: The viability of cells cultured in the presence of a nutrient medium after incubation with samples of titanium VT6 was 105% and that of titanium nickelide was 98%, which were comparable to the viability of cells in a standard nutrient medium. With electron microscopy, after 1 day of cultivation, cells form a monolayer on a titanium surface, all cells were well spread out and formed intercellular contacts, and after 7 days of cultivation, the number of cells increased and they formed a dense monolayer. 
CONCLUSIONS: The interspinous implant, which includes alloys of titanium VT6 and titanium nickelide, is biocompatible with cultured cells and can be introduced into spinal surgery.