Biomedical Titanium Alloy Materials And Applications

Titanium alloy materials for biomedical applications are a class of functional structural materials used in biomedical engineering, specifically for the production and manufacture of surgical implants and orthopedic devices. The production and preparation of titanium alloys involves metallurgy, pressure processing, composite materials and chemical industry, and is recognized as a high-tech product in the world. Titanium and titanium alloys are gradually entering the civilian consumer field from the aerospace, aviation and defense industry. Such as health care industry implants, medical devices; sports and leisure industry titanium golf clubs and titanium eyeglass frames, titanium watches, titanium bicycles and other products, the demand for titanium processing materials is increasing. With the vigorous development of biotechnology and major breakthroughs, biomedical metal materials and products industry will develop into a pillar industry of the world economy. Among them, titanium and its alloys with light weight, low modulus of elasticity, non-toxic, non-magnetic, corrosion resistance, high strength, good toughness and other excellent comprehensive performance, in recent years, the demand for rapid and steady growth. At the same time, as titanium alloys begin to enter the field of orthopedics and other new potential market demand, the future of titanium alloys market will appear more rapid growth.
1 Research progress of medical titanium alloy
1.1 Classification of medical titanium alloy
Titanium alloys can be divided into 3 categories according to the type of microstructure of the material: α-type, α+β-type and β-type titanium alloys.
1.2 The development trend of medical titanium alloy
Literature research found that domestic and foreign researchers and scholars agree that the development of medical titanium alloys has gone through three iconic stages, the first stage is represented by pure titanium and Ti-6Al-4V alloy; the second stage is represented by the new α + β alloy with Ti-5A1-2.5Fe, Ti-6A1-7Nb; the third stage is the development of α+β alloys with better biocompatibility and lower elastic modulus; the third stage is to develop the α+β alloy with better biocompatibility and lower elastic modulus. and lower elastic modulus β-titanium alloys. Ideal biomedical titanium alloy materials must meet the following conditions: good biocompatibility, low modulus of elasticity, low density, good corrosion resistance, non-toxicity, high yield strength, long fatigue life, large plasticity at room temperature, easy to form, easy casting. The important alloys that have been widely used in implant materials are Ti-6A1-4V and Ti-6A1-4VELI. It has been reported in the literature that V element can cause malignant tissue reaction, which may have toxic side effects on the human body, and Al can cause osteoporosis and mental disorders and other disorders; in order to solve this problem, the current biomaterials scientists are committed to exploring and researching the new biomedical titanium alloys that don't contain V and Al. In order to solve this problem, current biomaterials scientists are committed to exploring and researching new biomaterials that do not contain V, Al titanium alloys for medical use, and before that it is necessary to figure out what kind of alloying elements are suitable for adding non-toxic and biocompatible. It has been found that β titanium alloys containing non-toxic elements such as molybdenum, niobium, tantalum, zirconium, etc. contain a higher content of β stabilizing elements, and compared with α + β titanium alloys, they have a lower modulus of elasticity (E = 55 ~ 80GPa) as well as better shear properties and toughness, which is more suitable for implantation into the human body as an implant.

2 Application of titanium alloy
2.1 Medical basis of titanium alloy
The advantages of using titanium and titanium alloys as human implants are mainly: (1) density (20 ℃) = 4.5g/cm3, lightweight. Implanted in the human body: to reduce the human body load, as a medical device: to reduce the operating load of medical personnel. (2)Low modulus of elasticity, pure titanium is 108,500MPa, implanted in the body: closer to the human body's natural bone, conducive to bone grafting, to reduce the stress shielding effect of the bone on the implant. (3)Non-magnetic, not affected by electromagnetic fields and thunderstorms, which is favorable to the safety of the human body after use. (4)Non-toxicity, no toxic side effects on the human body as an implant. (5) corrosion resistance (bio-inert metal materials), excellent corrosion resistance in the environment of human blood immersion, to ensure good compatibility with human blood and cellular tissues, as implants do not produce human contamination, allergic reactions will not occur, which is the basis for the application of titanium and titanium alloy conditions. (6) high strength, good toughness, due to trauma, tumors and other factors leading to bone, joint damage, in order to establish a solid bone support, must be used with the help of curved plates, screws, artificial bone and joints, etc., these implants should be left in the body for a long time, will be subject to the human body's bending, twisting, extrusion, muscle contraction and other roles, the requirements of implants with high strength and toughness.

2.2 Medical and orthopedic fields of titanium alloys
Market situation with the development of titanium alloys, titanium varieties and price reductions, titanium applications in the civil industry has increased exponentially. CFDA will be divided into three classes of medical devices according to their safety from high to low, and respectively by the three levels of government supervision and management, titanium and titanium alloy material implants belong to the third class of medical devices, and high-value consumables class. Sub-segment market share of more than 5% of the sub-industry, including in vitro diagnostics, cardiac, diagnostic imaging, orthopedics, ophthalmology, orthopedics six major segments. Among them, in vitro diagnostics, orthopedics and cardiac intervention is the fastest growing high-value consumables in China. The application of biomedical titanium and its alloys has gone through three landmark stages: the early application of the early 1950s, first in the United Kingdom and the United States, commercially pure titanium was used to manufacture bone plates, screws, intramedullary nails and hip joints. Swiss Mathys also used Ti-6A1-7Nb alloy to manufacture non-expanded intramedullary nailing systems (including tibia, humerus, femur) and hollow screws for the treatment of femoral neck fractures. Porous Ni-Ti (PNT) alloy bioactive material manufacturing cervical, lumbar interbody fusion (Cage) Canada BIORTHEX company developed the use of porous Ni-Ti alloy patented material ACTIPOREORE gamma manufacturing cervical, lumbar interbody fusion for orthopaedic spinal injury treatment. The new beta titanium alloy can take into account orthopedics, dentistry and vascular intervention and other uses of advanced materials orthopedic medical device industry accounted for more than 9% of the global medical device market share, and is still in the rapid growth. The orthopedic medical devices market is divided into four main segments trauma, joint, spine and others. Among them, trauma is the only segment that has not been occupied by foreign companies to occupy a major market share, mainly because the products in this field are low-tech, easy to imitate, less difficult to operate, and many second- and third-level hospitals can be carried out, so foreign companies can not be fully covered. Trauma products can be divided into internal fixation and external fixation devices, internal fixation trauma products including intramedullary nails, plates and screws, etc. In 2012, trauma accounted for 34% of the domestic orthopaedic market, 28% of the joints, 20% of the spine, and 18% of the other. Large joints are high-end medical devices with high technical barriers. At present, mainstream hospitals are mainly importing orthopedic materials, and there is still a gap between domestic and imported products in terms of technology, design, research and development, materials, and surface treatment process. Artificial joints are mainly categorized into artificial knee, hip, elbow, shoulder, finger and toe joints, etc., of which the most important joint replacements include hip and knee joints, which together account for more than 95% of the global joint replacement market. Spinal implant devices include thoracolumbar spine nail plate system, cervical spine nail plate system and fusion system, etc., of which intervertebral fusion system is mainly used in the treatment of intervertebral disc replacement, which is also the most important segment, accounting for about half of the entire spinal implant market.
The superior performance of titanium alloys has resulted in their leading position in the medical field. The material design and preparation technology of titanium alloys have developed rapidly with the breakthroughs in biotechnology and the large demand for medical applications. The currently produced medical titanium alloys are mainly α+β type titanium alloys. From the point of view of the preparation process, the production of TC4 (TC4ELI) currently occupies the main market share. β-type titanium alloys have become the research hotspot of new medical titanium alloys due to their advantages in biocompatibility and mechanical compatibility, which is the most promising technology in the field of medical implants. In the future, the production technology of titanium alloys should be developed in the direction of low modulus, high strength, good biocompatibility and mechanical compatibility. From the development trend, β-type titanium alloy will become the future development direction and the mainstream of the medical titanium alloy market.