Development of porous titanium implants for interbody fusion

Relevance Application of 3D printing using the method of selective laser fusion for production of intervertebral cages is a topical trend of the spinal surgery. Purpose Assessment of the efficiency and safety of original interbody fusion implant application made of titanium alloy according to 3D printing technology with selective laser fusion. Materials and methods The original flattened bean-shaped cages, with an integral side part and an internal configuration in the shape of three-dimensional 1.5 × 1.8 mm porous lattice were tested . The products were made of Ti6Al4V powder using 3D printing technology with selective laser fusion. Post-processing of the products surface included abrasive blast cleaning using the SLA method and sterilization with ethylene oxide. Experiments on modeling interbody fusion with replacement of intervertebral discs with cages at levels L4 - L5 and L5 - L6 were performed in 8 mongrels. Additional primary stabilization of the lumbar spine was produced with an external fixator within 30 days after implantation. The total follow-up period lasted 180 days. Radiography, scanning electron microscopy, roentgenospectral and biochemical analysis methods were applied. Results X-ray examination demonstrated the contact between the frontal surfaces of the cages and the bone tissue of the vertebral bodies and the development of fusion in all experimental animals. Biochemical analysis did not reveal the signs of intoxication, indicating the danger of the products application. The microrelief of the implants was characterized by microroughness ranged from 1to 50 µm. In the surface layer of products, in addition to the elements of titanium, aluminum and vanadium, the carbon, oxygen, silicon, trace amounts of other organic and inorganic elements were found. Newly formed bone trabeculae were macroscopically and submicroscopically visualized in the sawcuts of bone blocks in the porous lattice of the internal part of the implants. Conclusions Experimental testing of porous implants made of titanium alloy using selective laser fusion has shown their effectiveness in obtaining interbody fusion and acceptable safety.