Titanium niobium zirconium tantalum alloy in medical applications

The number of fractures, bone defects and bone loss caused by war, traffic accidents, industrial injuries, sports injuries, diseases and natural disasters is as high as millions of people worldwide every year. The annual sales of international orthopedic repair equipment, with 14.7 billion US dollars, accounts for about 1/10 of the annual sales of the world's medical equipment industry, and the annual growth rate is as high as 26%. About 80 percent of the nearly 1 million bone repair surgeries performed in the United States each year require artificial implants. However, the current huge market demand for biomedical materials and products for bone repair shows that the varieties and specifications are not complete, the quantity is insufficient, and the material composition is unsatisfactory, which cannot meet the needs of medical treatment and society.

Titanium alloy is widely used in the field of human bone repair metal materials, depending on the type of titanium alloy (alpha + beta, alpha, beta), usually the application and development of biomedical titanium alloys can be divided into three generations, the first generation of pure titanium and Ti-6Al-4V, the alloy high modulus of elasticity (about 110 GPa), is still the most widely used surgical implant materials, but aluminum (AI) and vanadium (V) are biological toxicity element, long-term use can cause damage to the human body; The second generation of + alloy represented by Ti-5Al-2.5Fe and Ti-6Al-7Nb has similar mechanical properties as the first generation. Although it contains the toxic element vanadium (V), compared with the first generation, the toxic element aluminum (Al) is reduced, which is also applied in the surgical field at present. Type into the early 1990 s, the third generation of beta titanium as medical material obtained in-depth study, compared with the former two generations, added the non-toxic or low toxic to the human body the transition elements, such as Nb, Mo, Ta, Zr, Sn, etc.) the beta type of titanium alloy has a lower modulus of elasticity, higher tensile strength, fracture toughness, better wear resistance, super elasticity and shape memory effect and so on characteristics, thus become research hot spot in the beta type titanium alloy. Titanium niobium tantalum zirconium alloy (Ti-Nb-Ta-Zr) is a new type of titanium alloy in China in recent years, for the latest international research results, with low elastic modulus, GPa is better than that of similar foreign products, basic comparative with the elastic modulus of cortical bone, and the strength of 800-900 MPa, non-toxic effect to human body, its constituent elements if applied to clinical will be much better than all the existing orthopaedic implants (steel plates, screws, nails, etc.).

There are many kinds of biomedical materials, among which metal materials have higher strength and toughness, corrosion resistance, wear resistance, malleability and reproducibility, and casting strength does not decrease. Therefore, at present, most of the stainless steel implanted in human body in clinical application is austenitic steel, with AIS316, 316L and 317 commonly used models. In order to meet the characteristics of high strength, its elastic modulus is often high, and the stress shielding effect brought by high elastic modulus often leads to osteoporosis or re-fracture. In addition, these metal materials often contain elements that are potentially toxic to human body, such as Al and V. Pure titanium metal relative density similar to bone, are widely used in artificial root, artificial mandible and skull repair, etc., but the intensity of the pure titanium is low, cannot satisfy the as orthopedic implants requirement for strength, for example LISS (Less Invasive Stablilization System, LISS) of the elastic modulus of 80 GPa, but strength is 10% Less than stainless steel, is about 400 MPa, this is where the LISS more regret. Titanium alloy has good performance and has been used as the preferred material for artificial joints, steel plates, screws, pedicle screws, dentures and other products.

Biomedical titanium alloy must be corrosion-resistant, biocompatible and meet the biomechanical characteristics of human body before it can be used in clinical treatment. Many studies have found that due to the direct contact of the implant with human tissue, the current biomedical titanium alloy material has metal ions dissolved out of the human tissue in contact. For biomedical alloys containing Al, V, Ni and other elements, although surface modification technology and coating treatment have been adopted to significantly reduce the possibility of toxic elements invading the body and causing harm, their long-term use is still limited by the potential toxic effects of toxic elements. Therefore, in order to pursue safety, it is very necessary to research and develop biomedical metal materials more suitable for human body, which also has important practical significance and practical value.