The continuous advancement of medical skills has prolonged the life span of human beings. With the development of new applications of metal grade alloys in surgery, new developments have been made. It is understood that in 2016, 50 million surgical operations were performed in the United States. With the increase of the number of surgical operations every year, the demand for minimally invasive surgery is also increasing. Because of its many advantages, including short rehabilitation time, the overall impact of surgery on patients is small.

Stainless steel is still a common material for medical devices because of its comprehensive function, biocompatibility and low cost. Titanium, cobalt, chromium alloys and other materials have also advanced skills. Nickel-titanium alloy (UNSN01555) is a kind of nickel-titanium shape memory alloy. It is also a leader in medical metal materials. It has been widely used in various medical applications.

Nickel-titanium alloy guides the way forward

Nickel-titanium alloy is a special material with superelasticity and shape recall properties. It contains 55% nickel and 45% titanium and is an excellent material for medical implants. Nickel-titanium alloys have excellent biocompatibility and properties, so many applications of stainless steel have been replaced by nickel-titanium alloys in the past.

The three major applications of nickel-titanium alloy medical wire are vascular guide wire, diagnostic guide wire and dental arch wire. Hundreds of tons of nickel are used in the production of nickel-titanium alloy and stainless steel medical wires every year. According to a study report released in 2014 by Grand View Research, the global planning for wire guide applications is estimated to reach $2.19 billion by 2020. In the next six years, the increasing prevalence of disease prevention and the increasing population base in the elderly will further promote the demand for wire guide.

The guide wire is a very thin flexible medical wire that penetrates the body to guide larger instruments, such as catheters, central venous catheters or feeding esophagus. Although guidewire was used in coronary artery surgery, it has become an integral part of more and more medical procedures with its steady increase in usage and expansion to more medical professions. "Compared with stainless steel wire, the superelasticity of nickel-titanium alloy wire is 16 times higher, and it can satiate 8% strain, while stainless steel wire can only satiate about 0.5% strain before initial shape deformation occurs. For example, take a paper clip made of nickel-titanium alloy and bend it into a 90 degree angle, it will bounce back to its original shape. David Plumely, Nickel-Titanium Alloy Product Manager, Weinberg Metal Company, a direct distributor of nickel-titanium alloys, stainless steel and special medical wires, said, "Nickel-Titanium alloy wires have excellent'Push ability', excellent longitudinal flexibility and can maintain their flatness. These are precious properties of the guide wire. In the past 10 years, the annual growth rate of the output value of our nickel-titanium alloys has reached 10%, and there are still opportunities for continuous growth in the future, including medical and non-medical areas. Another important application of nickel-titanium alloys is to strengthen conduit polymer pipes, in which weaving nickel-titanium alloys are used as reinforcing materials between surface and inner polymer layers.

Structures that can be used to large strains

Nickel-titanium alloy is an excellent material in the field of medical device engineering planning because of its outstanding ability to adapt to large strains and its physiological and chemical compatibility with human body. One of the most important applications of nickel-titanium alloys is scaffolding. NiTi alloy stents can be manufactured at one temperature, folded into smaller scales at another temperature, and then pierced into the artery to heat it to above the temperature change and restore the original scale.

Nickel-titanium alloy stent is made of a drill pipe, which is processed according to the precise scale requirements and then formed by laser incision. The stents used to treat aneurysms are usually 25.4 mm (1 inch) in diameter and can be "tightened" to a diameter of only 6 mm to 7 mm (1/4 inch), then inserted into the delivery device tube and the patient's aorta. The stent expands itself and forms the original shape, and then allows the doctor to correct the aneurysm.

Application of High Strength Stainless Steel

"There are many applications of austenitic stainless steel medical wires of type 302 (UNSS30200), Type 304 (UNSS30400) and type 316L (UNSS31603)." Austin Lucas of Fort Wayne Metals said. These very fine medical wires are between 0.1016 mm and 2.54 mm in diameter and can become thinner after stretching. "Stainless steel alloys are excellent materials because they can reach high strength (400 - 500 + kilopounds / square inches) at low temperatures, such as 450 kilopounds / square inches for 0.127 mm wire. This is very important for the production of very small, very fine parts. They have been widely used in the fields of vascular therapy, neurotherapy, endoscopy, orthopaedic surgery, orthodontics and dental implantation.

In cardiac surgery, it is necessary to split the rib skeleton by splitting the sternum so that the surgeon can operate on the heart. At the end of the operation, the ribs need to be pulled back together and closed by the sternal closure wire. Closed wire is generally made of 316L stainless steel medical wire. Type 304 stainless steel medical wire is often used as a guide wire for initial entry into veins and arteries during vascular surgery. Some brackets are planned to use 304 stainless steel. Other common uses of 304 and 302 stainless steel include tube needles, catheters, springs, suture needles and mandrels. In many surgical interventions, U-shaped nails are often used to close the wound. These U-nails are made of 316L and 304 stainless steel wires. The latter grade is also used in dental arch wire.

Silk thread, guide pin and stitching needle

Kirschner wire (abbreviated as "K wire") and round bone needle are made of implant grade 316L and corrected.