Titanium and its alloys have many advantages as surgical implant materials, such as low density, high strength, good toughness, good biocompatibility, non-toxicity, low modulus of elasticity, good corrosion resistance, and low X-ray absorptivity. And so on, thus occupying an increasingly important position in medical metal materials. Titanium and its alloys can be used for the repair and replacement of hard tissues in human body, or for the repair of cardiovascular and soft tissue and the manufacture of artificial organs. It is a special functional material closely related to human life and health. At present, it has become the preferred metal material for replacement or repair products such as artificial joints, artificial bones, broken bone fixators, spinal correction rods, intramedullary nails, artificial heart valves, dental implants, and skull bones. With a world population of nearly 6.5 billion, the problem of global aging is very serious. According to F&S company data, the global orthopedic implant device market has a compound growth rate of 10.4% in the past five years, and is expected to reach US$27.7 billion by 2015, while the Chinese orthopedic implant device market will grow to 16.6 billion yuan. The rate reached 18.1%. It can be seen that titanium and its alloys are the preferred materials for medical metal materials, and their future market demand is very strong. Therefore, it is of great significance to increase the research and development and application of medical titanium and its alloy materials in China.
　
Development status of titanium materials for surgical implants
　
Vanadium-free medical titanium alloy
　
Ti-6Al-7Nb alloy is a medical alloy developed by Sulzer Medical Technology Co., Switzerland. Compared with the Ti-6Al-4V alloy, the Ti-6Al-7Nb alloy uses the non-toxic β-stabilizing element Nb having the same atomic concentration as V instead of V, and its performance is equivalent to the recognized Ti-6Al-4V alloy, which is a kind of safety. And human implant materials with development potential. A variety of alloy implants developed and produced by Ti-6Al-7Nb have been put into clinical application with good results.
　
Another medical titanium alloy Ti-5Al-2.5Fe was developed by Germany. Compared to the Ti-6Al-4V alloy, vanadium is replaced by an inexpensive, non-toxic iron element. Ti-5Al-2.5Fe is a medium-strength material comparable to Ti-6Al-4V in terms of mechanical properties, toughness and fatigue strength.
　
China has also developed these two alloys. Ti-6Al-7Nb and Ti-5Al-2.5Fe jointly developed by Baoti Group Co., Ltd., Beijing Nonferrous Metals Research Institute, Hebei Medical University, Shandong Wendeng Osteopathic Hospital and Tianjin Medical Device Industry Corporation Orthopedic Medical Device No.2 Alloys, experimental studies on biological properties show that the alloy has good biocompatibility and can form a good bone bond with bone tissue.
　
New beta titanium alloy
　
Since the 1990s, there have been reports of potential hazards to V and Al in humans in titanium alloy implant materials. Therefore, the development of advanced medical metal materials with excellent comprehensive mechanical properties and more compatible with human body soft and hard tissue biology and mechanics - the new β-type titanium alloy has become the research focus of biomedical metal materials. A series of new β-type titanium alloys have been developed by adding non-toxic elements such as Nb, Ta, Zr, Mo, and Sn.
　
Ti-Ni alloy
　
Ti-Ni shape memory alloy is a new type of functional material with peculiar shape memory effect, superelasticity, fatigue resistance, wear resistance, corrosion resistance and biocompatibility. Therefore, the alloy is widely used in the medical field.
　
Ti-Ni shape memory alloy has been successfully used in orthopedic clinics, causing the attention of orthopedic experts and clinicians, and is called "magic metal". NTSMA for orthopedic clinical deformation temperature is 0 ° C ~ 5 ° C, the recovery temperature is 37 ° C. After fixing the fracture with NTSMA material, the shape is restored by warming under body temperature or hot saline wet application, but the bone has a limitation on the material recovery, so that a dynamic, continuous nature of pressure or clamping force is generated at the fracture end. Achieve the role of fixed fractures.
　
Porous titanium alloy
　
The surface structure of surgical implants is closely related to the biological behavior after implantation in the body. Compared with dense materials, the introduction of pores significantly reduces the elastic modulus of titanium and its alloys, and the strength and modulus of porous titanium can be adjusted by changing the porosity and pore size to adjust the strength and elastic modulus. Its open through-hole structure promotes the adhesion, growth and regeneration of bone cells, accelerates the healing process, and enables titanium and its alloys to match the elastic modulus of the material under a certain strength. At the same time, the rough surface geometry of the porous titanium alloy can promote the growth of new bone tissue into the pores, not only strengthen the biological fixation of the implant and the bone, but also transfer the stress along the implant to the surrounding bone.
　
Titanium surface activation technology
　
Titanium surface activation technology is one of the key areas of research and development of orthopedic implant materials. The surface of the implant is in direct contact with the human body. Surface modification can improve biocompatibility and reduce wear, thereby reducing the possibility of loosening of the implant and ensuring long-term performance of the implant.
　
Weigao Group Co., Ltd. and the Institute of Metal Research of the Chinese Academy of Sciences have formed a composite oxide coating on the surface of the titanium alloy by anodizing, hydrothermal treatment and heat treatment. The prepared gradient coating has a complete crystal form and a high surface-inducing ability to induce bone hydroxyapatite layer formation and cell adsorption and proliferation, and has good biocompatibility.
　
Laser near net shape surgical implant
　
Laser near net shape forming technology is a 3D printing manufacturing technology, combined with computer control, gradually using the high energy beam to melt the titanium alloy powder in the molten pool to process into a specific shape of orthopedic implant or dental restoration. The research institutes of Northwestern Polytechnical University have carried out a lot of research on the laser three-dimensional forming process of pure metal such as pure titanium. The mechanical properties and fatigue properties of pure titanium implants prepared by this technology are higher than those of pure titanium, which can meet the dental implant pair. Mechanical performance requirements. At present, domestic research on the processing of titanium-nickel alloy and titanium alloy vascular stents by laser near-net forming technology has also made some progress.
　
Foreign application overview
　
Since its successful development, Ti-Ni alloy with unique shape memory has been used in oral, neurosurgery, cardiovascular, thoracic surgery, otolaryngology, hepatobiliary, urology and gynecology. Products include orthodontic wire and root. Tube, spinal orthopedic rod, bone plate, intramedullary nail, tibia claw, guide wire, guide needle, heart patch, vascular stent, thrombus filter, esophageal stent, respiratory stent, biliary stent, urethral stent, rectal stent, twelve Intestinal stent, external auditory canal, and birth control ring.
　
STYKER Group, one of the global orthopedic specialist group companies, uses the Ti-12Mo-6Zr-2Fe alloy for the hip prosthesis system, which has reached the high standard of orthopedic clinical requirements in terms of quality, function and clinical effects. At the same time, the cervical anterior plate system made of Ti-Mo-Zr-Fe alloy has also been used in clinical practice. Currently, these two products have been introduced to the Chinese market.
　
In the 1980s, Germany developed titanium alloy cast prostheses and used them in clinical practice. Its application promoted the development of modern functional prostheses. Since then, titanium alloy cast prostheses have been promoted and applied.
　
Foreign countries, especially Germany, the United States, Japan and other countries generally carry out cranio-maxillofacial plastic surgery, plastic surgery brings confidence and happiness to people. The internal fixation equipment used in craniomaxillofacial plastic surgery is mainly pure titanium plates of various shapes and specifications and pure titanium screws of various specifications.
　
Domestic application overview
　
Since the 1970s, Baoti Group, a professional manufacturer of titanium and titanium alloys in China, has been working with other research institutes to develop and develop human implant materials such as titanium bones and titanium stents, and has achieved good results. Since the 1970s, China has begun to use domestic titanium and titanium alloy artificial bones and joints for clinical treatment. The artificial femur and hip joints produced are effective after clinical use. In the mid-1980s, the number of domestically produced titanium and titanium alloys used to manufacture human implants continued to increase. In China, femoral head, hip joint, knee joint, elbow joint, shoulder joint and metacarpophalangeal joint made of titanium and titanium alloy have been transplanted into the human body, and very good results have been achieved.
　
China has also made significant progress in developing new beta-type titanium alloys for orthopedic applications and titanium alloys for dental restoration. A variety of medical titanium alloys independently developed by Shenyang Metal Research Institute, Beijing Nonferrous Metal Research Institute, and Northwest Nonferrous Metal Research Institute have been used for surgical implants and vascular stents.
　
In the application of porous titanium alloy, the Tangdu Hospital of the Fourth Military Medical University, the Northwest Nonferrous Metal Research Institute, Shanghai Jiaotong University and other scientific research units have designed and manufactured porous titanium alloy implants, which have been widely used in clinical practice and achieved good results. .
　
The hard tissue defects caused by the aging of the population have become a major problem worldwide. China has a large population and the problem of aging is very serious. There are also many patients who need rehabilitation equipment using medical implant materials. According to statistics, in the past 30 years, the surgical implant market in China has developed at an alarming rate. The average growth rate in the past 10 years has been maintained between 15% and 30%, and it is expected to grow at a rate of more than 10% in the next 10 years. It can be seen that the market prospect of titanium alloy implants in China is very broad.
　
Although China has carried out a lot of research work in the research and development and application of titanium alloy materials for surgical implants, it has made significant progress, but compared with developed countries such as Europe, America and Japan, in titanium alloy implant products. There are big gaps in design, manufacturing, processing, equipment, surface treatment, and process level. Especially in some high-end implant products, domestically produced implants are difficult to meet market demand, and most high-end implants All need to be imported from abroad, which brings unprecedented opportunities and challenges to China's medical materials research units, material manufacturers, medical research institutions, clinical medical experts, etc. These units should strengthen cooperation, work hard to achieve high-end implants. Localization, benefiting the people and promoting the healthy and stable development of China's medical titanium alloy industry.