Development of porous titanium implants for interbody fusion

Abstract

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 oftitanium alloy according to 3D printing technology with selective laser fusion. Materials and methods The original flattened beanshapedcages, with an integral side part and an internal configuration in the shape of three-dimensional 1.5 × 1.8 mm porous latticewere tested. The products were made of Ti6Al4V powder using 3D printing technology with selective laser fusion. Post-processingof the products surface included abrasive blast cleaning using the SLA method and sterilization with ethylene oxide. Experiments onmodeling interbody fusion with replacement of intervertebral discs with cages at levels L4 – L5 and L5 – L6 were performed in 8mongrels. 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 analysismethods were applied. Results X-ray examination demonstrated the contact between the frontal surfaces of the cages and the bonetissue of the vertebral bodies and the development of fusion in all experimental animals. Biochemical analysis did not reveal the signsof intoxication, indicating the danger of the products application. The microrelief of the implants was characterized by microroughnessranged 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 macroscopicallyand submicroscopically visualized in the sawcuts of bone blocks in the porous lattice of the internal part of the implants. ConclusionsExperimental testing of porous implants made of titanium alloy using selective laser fusion has shown their effectiveness in obtaininginterbody fusion and acceptable safety