Design and preparation of nickel-titanium implant for lumbar vertebra

Abstract

The growing number of spine diseases and surgeries has resulted in advancements in equipment and implants. On the other hand, given the uniqueness of the anatomy of the spine, particularly in terms of mechanical characteristics, selecting the type of implant is critical. In addition to high biocompatibility and superelasticity, the implant utilized in the spine needs properties like strength, fatigue resistance, and elastic modulus close to the bone, which is found in nitinol. NiTi alloy lumbar-like samples were prepared by sintering and mechanical braiding method. The mechanical properties study revealed that the elastic modulus of the sample was 3.5 GPa, and the compressive strength at 6 % strain was 200 MPa. NiTi alloy is thermoelastic, making it a good candidate for placement in bone tissue. The biocompatibility and non-toxicity of the bone cells, with cell viability of over 4 × 104 cells within 48 h, indicate that the produced implant has suitable cellular biocompatibility. Besides, the differential scanning calorimetric test shows that the austenite start and finish temperatures are 26 and 51 °C, respectively, and martensite start and finish temperatures are − 2 and − 33 °C, respectively. These values are consistent with the body temperature of 37 °C. The corrosion test also indicates that the implant has a good corrosion resistance of about 0.3 ohm cm2. Developing this kind of implant is intended to make treating spinal problems easier.