In the medical profession, the use of metallic materials must be absolutely harmless to human body. When the metal corrosion, will be able to dissolve metal ions, the organism (human body) of the cell tissue has an impact, so to choose not corrosion, high corrosion resistance metal materials, Titanium is a kind of high corrosion resistance materials. The proportion of Titanium and Titanium alloys is increasing from stainless steel to cobalt - and Titanium-based alloys. The amount of Titanium used in healthcare worldwide is about 1,000 terabytes a year

　1. Adaptability of Titanium to human body (compatibility of Titanium to organisms)　

Metal ions can be observed in order to adaptive response to human body, in the laboratory, the Chinese medical experiments with mice lung fiber bud cells (V79 cells) and mouse (20 days after born mice) fiber bud cell tissue (I929 cells), etc., use of metal ions with sensitive cells, cell adaptability evaluation method, by the independent product evaluaTion technology of institutions of administrative legal person (biological evaluation of medical devices standardization technical committee) to provide the elements of the monomer ion (organisms) response to the human body to distinguish, as shown in figure 1 that is divided into three groups.

Certain strong toxicity of vanadium (V), nickel (Ni), copper (Cu), etc., the above elements at the PPM (×10-6) content, cells will die in a short time. Take vanadium (V) and nickel (N) as examples, and the experimental results in V79 cells are shown in figure 2. One-week immersion tests showed that all cells died when nickel was around 10×10-6, compared with two digits when vanadium (V) was around 0.6×10-6. Secondly, when the hard tissue (bone) and soft tissue (muscle) of small animals, such as rats and rabbits, are buried into a metal sheet for test, it is certain that these toxic metals cause necrosis in both hard tissue (bone) and soft tissue (muscle) in contact.　 

The relationship between the formation energy of A-V79 cell population and nickel (Ni) ion concentration;

The relationship between b-V79 cell population formation energy and Vanadium (V) ion concentration;　

The other group is injury-induced. In the state of implantation and attachment, a biological reaction is formed on the fibrous tissue of the contact site, which is excreted to the body. Iron, aluminum, gold and silver are all shown in this way. General metal materials such as SUS 304L stainless steel and SUS 36L stainless steel and cobalt-chromium alloy are of this type. A piece of metal buried in hard tissue, which does not fuse with bone cells, is easily removed without resistance when the test is performed several weeks later.

The reaction between the third group and the organism is definitely the smallest. Titanium (Ti), Zirconium (Zr), Niobium (Nb), Tantalum (Ta) and Platinum (Pt) are applicable for implantation and attachment. When these metals are implanted and attached to the organism, they are closely bound to the hard tissue and the soft tissue, presenting the phenomenon of embodiment.

In this way, Titanium must be less injurious to organisms, and it is a safe metal. When Titanium alloy is used, the corrosion resistance of Titanium alloy is lower than that of pure Titanium alloy. When corrosion occurs, its elements can be dissolved out. It is necessary to select the alloy elements with corrosion resistance and no damage. Ti-6Al-4V alloy in Titanium alloy has been used in aircraft manufacturing and seawater resistant engineering equipment for a long time, with a large number of examples. ELI alloys with good corrosion resistance (low iron, oxygen and hydrogen content) have been introduced in the medical industry. However, recently, as the research and development of Titanium alloys for implantation and attachment, according to the reports of the harmness of the Monomer, Niobium (Nb) was replaced by Vanadium (V) to make Ti-13Nb-13Zr alloy, which has been standardized (ASTM,ISO). There is also the approvable, positive expulsion of aluminum alloy, coming to market.

2. Types of Titanium for medical use　

The American ASTM standard (F standard) for medical use is equivalent to the world standard. In Europe, The ISO standard and ASTM standard are merged into the European standard. Japan is sorting out domestic standards, taking ASTM and ISO corresponding standards for sorting out and starting to make standards based on ISO standards.

Titanium, as represented by the artificial knee joint and hip joint (including the femoral head), is listed in table 1 according to the shape of the Titanium specified in the ASTM standard used for implantation and attachment. For a long time, pure Titanium and Ti-6Al-4V alloys, including powder materials made into various shapes of parts and components.

　3. Medical Titanium application cases

　The most used parts of Titanium materials are artificial femoral joint, artificial knee joint, bone plate, etc., suitable for plastic surgery. By the deformation of joint inflammatory rheumatism [transliterated into mu "leave" marge, its meaning is a kind of severe joint pain, brawn, at the same time also is a kind of allergic disorders - on] causes severe pain, such as that made walking difficult, will suffer from this disease patients in artificial joints, artificial knee joint replacement surgery, pain can disappear completely, can walk. In Japan, 80,000 prosthesis joint replacements and 40,000 knee replacements are performed each year (2005 statistics). With the coming of the aging society in the future, it can be expected to face this demand with what percentage growth rate.

　Titanium is not suitable for all artificial joints. In joints where it often swings, Titanium is not suitable due to its tendency to wear out (ceramics and cobalt alloys are preferred). Titanium alloys are used for implanted parts. In order to bind to biological bone as soon as possible, the surface of the Titanium alloy is bumpy and coated with bone inducers such as apatite and bioglass. In addition, internal bone marrow nails made of Titanium alloy and Titanium alloy plates were used for fracture fixation. Figure 3 shows various examples of implantation and attachment.

　　There is also an increasing trend in the field of dentistry to use implants and attachments. Titanium is rarely used, including pure Titanium, Titanium alloy and shape memory alloy TiNi. Its shapes include plate type, thread type, sleeve type and basket type as shown in figure 4. These components are directly inserted into the jaw to be fixed on the gingival portion, and coated with apatite representing the skeletal component. Titanium is very suitable for general dental metal implantation. There are two methods: precision casting method and superplastic forming method. Compared with the former cobalt and chromium alloy manufacturing, it is light in weight and does not produce stale food. Because the Titanium material is used outside the health insurance diagnosis and treatment, the price is more expensive.

As medical implant (buried), place attachment, when patients with heart rate is low, can be implanted (buried) pacemaker (pacemaker - automatic type ventricular systolic device, to the heart to stimulate, to ensure the heart to beat the normal number of device one by one), to the heart from subclavian vein implanted electrodes line, input electrical signals by the electrodes to a pacemaker, became a pacemaker. Recently, pacemaker products of 20g mass and 6mm thickness are so small that they are connected by electrode wires and buried under the skin. The battery and control circuit are packed into a small container (box), which is made of pure Titanium that is not injurious to the organism. The minimum battery life is six years, so long-term stability and safety are required for this small container. Now, within Japan, nearly 5,000 people are benefiting.

Results of Titanium can also be seen in surgical instruments. Especially in the long period of brain neurosurgery over 10h, a forceps should be lightweight, and a hemostatic forceps should be made of Titanium. Titanium is used in many dental instruments, such as implants, surgical instruments for implantation, and vibrators for scaling removal. In addition to implantation (burial) and attachment, auxiliary equipment and wheelchairs are also being titanized. Because of disease, accident caused by a part of the limb defect, in order to restore the function to make prosthesis, because its main part is made of metal, so from the light, durability (mainly corrosion resistance and fatigue damage), to the biological compatibility (Ni, Cr, etc.), is being applied. In terms of wheelchairs, the main goal is to make the whole wheelchair light. Therefore, almost all metal parts, such as the frame and wheels, are made of Titanium.