Masters of Titanium Skeletons

Galina Kostina, "Expert"Professor of the Materials Science Department of the K. E. Tsiolkovsky Russian State Technological University (MATI)

Mikhail Kollerov cheerfully walks down the corridor, waving a travel hair dryer. In his other hand he has a small pre-cooled wire. "I'm going to do a trick now," he says. He bends the wire, turning it into a shapeless squiggle, then turns on the hair dryer and directs warm air to the wire. And the squiggle turns into a neat spring in a matter of minutes. It turns out that the wire "remembered" the shape in which it was before the deformation. This effect, discovered in the middle of the last century, is called the shape memory effect and is especially well manifested in titanium and nickel alloys. One example of its use is braces, which are put to correct the bite. Previously, steel ones were made, which had to be screwed on every few days, corrected, they injured the tissues. Now titanium-nickel alloys are quite actively used in various fields, including medicine. MATI scientists also use them, having invented such technologies for creating implants, which no one in the world has yet thought of.

She remembered what she was like beforeIn Soviet times, the specialists of the MATI (Moscow Aviation Institute of Technology - that was the name of the university at that time) were well known all over the world as excellent materials scientists, creators of new materials and methods of their processing.

They were in demand by the aviation and aerospace complex. This brought not only moral satisfaction, but also the money received under the agreements, which complemented the salaries of teachers. In the early nineties, everything collapsed. "And we began to think where to find an application for our knowledge and skills," says Academician of the Russian Academy of Sciences, Dean and Head of the Materials Science Department of MATI–RGTU, head of the BMSI group of companies (Biomechanical Compatible Implants) Alexander Ilyin. – Moreover, we wanted to find a niche for which it would not be necessary to build a factory and invest a lot of money. And they turned to medicine." We spent a lot of time studying the information and decided to work in the field of creating prostheses and implants. After analyzing the materials from which similar products were made in the world – stainless steel, cobalt and titanium alloys, scientists chose titanium. "It is the best in terms of mechanical compatibility," says Vasily Karpov, associate professor of the Department of Bioengineering. – And in terms of biocompatibility, other materials are inferior to it." It is known that foreign materials that have entered the body are encapsulated by fibrous tissue. And on steel and cobalt alloys, the fibrous shell formed is many times thicker than on titanium. And the thicker it is, the easier it is to disable the implant with physical exertion.

Scientists have started negotiations with traumatologists and orthopedists to discuss which implants they would like to have. Many discussions were in vain, because doctors either could not really explain what they needed, or launched into the field of unscientific fiction. But there were also sensible comments. In any case, the first years were not in vain: now the titanium docks are very adept at biological and medical terminology and know in detail how many operations are done. With their own money, Ilyin and his colleagues bought the necessary equipment, materials and began to try to make various prostheses. They could have worked for a long time only with piece products, but one day a request came from an Italian company: could they make special products made of titanium alloys with shape memory for fixing the sternum after operations, in particular on the heart and blood vessels. Italians were advised to contact the local materials specialists who knew Ilyin's high world reputation. The Italians roughly outlined how such a product should look like. During heart surgery, the sternum is dissected, and then it needs to be returned to its original position and fastened together for fusion. One of the main tools for this used to be a special wire, which was used to stitch the sternum. "But the trouble is that the wire is rigid, and when a person physically strains, for example coughs, the wire stretches and often cuts bones," says Mikhail Kollerov." Theoretically, it was clear that for the manufacture of special fixators for the sternum, the shape memory effect would be very suitable. But no one in the world has yet been able to make a given design that, at a certain temperature, would "remember" the desired shape. An alloy of titanium and nickel – titanium nickelide – has a so-called martensitic transformation temperature, which can range from -70 to +120 degrees. If, for example, a spring made of such an alloy has a transformation temperature of 35-36 degrees, then when it is cooled to 10 degrees, it will bend easily, and after heating to 36 degrees and above, it will "remember" its spring shape. "But the wire obtained from an alloy of titanium and nickel is very heterogeneous in structure, and at one end of it the transformation temperature can be minus seventy degrees, at the other ― plus forty, in the middle some more," Kollerov continues. – It is possible, of course, to cut a hundred meters of pieces from five kilometers of wire with the desired transformation temperature, for example, with the temperature of the human body – 35-36 degrees. The Americans did this in the manufacture of stents in cardiac surgery, but the price per kilogram of such wire was several thousand dollars."

But that wasn't the only problem. Even if they had chosen a wire with the required transformation temperature, it was still necessary to make implants of the desired shape with the specified shape memory characteristics for a batch of tens of thousands of pieces. And MATI came up with what to do to set the products a specific temperature of transformation.

Initially, the wire is used to make products that are necessary in shape, for example, sternum retainers similar to curly braces. Then these products are subjected to such a heat treatment, in which the structure of the material of the fixators changes. By controlling the concentration of nickel in the crystal lattice during this treatment, scientists set a certain temperature of martensitic transformation. As a rule, for medical devices, this is the temperature of the human body. When the surgeon restores the sternum after the operation, he takes out the clamps cooled to 10 degrees, spreads their tips so that they freely enter the small holes specially made in the sternum, and pours warm saline solution over the sternum. At 35 degrees, the retainer "remembers" its original shape, the ends of the bracket bend inward, grasping both parts of the sternum. The bracket becomes strong, but elastic (this is a property of the nickel and titanium alloy and the special shape of the product).

Having learned to control the temperature of transformation, MATI specialists began to make various products with the shape memory effect: fixators for dynamic stabilization of the spine, collarbone, toes and even the skull. One of these fixators ― for correction of chest deformity ― was developed by scientists together with Sergey Rudakov, now a leading researcher at the Institute of Surgery. Vishnevsky. "This deformation is called funnel–shaped, colloquially - "sunken chest", – says Sergey Rudakov. – It occurs in about one case per ten thousand people. This is both a serious cosmetic defect and a threat to internal organs – the heart and lungs, which are compressed by a deformed chest. Previously, various stainless steel or titanium products were used for such correction. They were quite difficult to put and remove, the operation itself was traumatic, the fixators were rigid and not very reliable: due to the mobility of the body, they shifted and even came off." The shape memory design differed favorably from its predecessors in strength, elasticity, and greater ease of use.

The Italians liked the first products with shape memory – fixators for the sternum, and they began to promote them in Europe, however, under their own brand Sterni-fix. "And who would let us in there under our name? – says Ilyin. – Only Russian gas and oil are recognized there. And we had to start a market career. For some reason it didn't work out in Russia." MATI was satisfied with even small sales of about a thousand fixers per year. A few years ago, the first Italian partners of the Russians sold a patent to another Italian company that had been promoting medical devices to the market for a long time, and sales became more fun. Last year, about 15 thousand fixators for the sternum were sold. Orders for 2009 have already grown to 18 thousand. and they can reach 20 thousand.

Titanium hips are lifeIn 1999, Alexander Ilyin created the Ilcom-BMSI group of companies, which included two manufacturing companies – KIMPF (materials with shape memory) and Implant MT (endoprostheses), the MATI-medtech research center engaged in development, and medical co-executors, in particular CITO (Central Institute of Traumatology and Orthopedics N. N. Priorov), Institute of Surgery named after

Vishnevsky, RUDN and other institutes. In addition to fixators with shape memory, specialists worked on technologies for orthopedic endoprostheses. Vasily Karpov, associate professor of the Department of Bioengineering at MATI and technical director of the "Implant MT", shows a small scientific and technical exhibition of the MATI-Medtech IMC: "The idea of endoprosthetics was expressed by the Russian surgeon Pirogov, and the first ivory endoprosthesis was implanted by Gluck in Germany in 1890. But ivory turned out to be a material too fragile. Then prostheses began to be made of stainless steel, since the middle of the last century polymers, cobalt and titanium alloys have been actively used. The first Russian hip prosthesis was developed in 1959 by Professor Konstantin Sivash, who was assisted, by the way, by one of the employees of our institute." But for some reason it turned out that it did not go beyond a few dozen prototypes that were implanted then. The patent was sold to Germany.

In the early nineties in Russia, several institutes and small companies began to develop endoprostheses, and the market was already dominated by products from well-known Western manufacturers. MATI decided to create something different from others, taking into account the shortcomings of the prostheses available on the market. Some companies often use cobalt and titanium alloys for prostheses. But, according to Karpov, this pair of rather dissimilar materials leads to corrosion and further instability of the prosthesis. An important point is the behavior of the material in the so–called friction pair: the prosthesis consists, as a rule, of two parts – a leg with a head replacing a part of the thigh, and a cup that replaces the acetabulum, and these two elements constantly rub against each other while in a biological environment. Bench tests of many imported prostheses show how unstable and unsafe parts made of various metals and alloys, polymers and ceramics can be. For example, particles of the polymer from which cups are made can get into the tissues during friction and cause both instability of the prosthesis and other unpleasant side effects. Cobalt and chromium ions released during friction are very toxic to the body. Titanium, according to the developers, is one of the best materials, but it is not without sin.

Titanium oxide forms on the surface of titanium in the form of a thin film. And when the leg of the prosthesis is fixed, for example, with the help of special cement in the bone, at the slightest movement, this film begins to slide and opens titanium for corrosion. MATI scientists have developed an innovative technology to create a monolithic composite with the required properties. With the help of thermohydrogen treatment of titanium and its bombardment with nitrogen atoms, first nitrided titanium is formed on the surface of titanium, and with a large addition of nitrogen, titanium nitride, or ceramics, is an excellent surface for friction. "If conventional ceramic elements are used in the prosthesis, they cannot withstand the load due to fragility," says Karpov, "we get a thin ceramic surface as part of a single composite material. It's very strong."

The head of the endoprosthetics department of CITO, Doctor of Medical Sciences Nikolay Zagorodny, believes that unique developments have been created in MATI. CITO uses both hip and knee prostheses. And Professor Alexander Balberkin, head of the Department of Adult Bone Pathology at CITO, notes that MATI endoprostheses are successfully used in clinical practice in cases of joint and bone lesions as a result of oncological diseases. Vasily Karpov gave many examples when patients with osteosarcoma literally saved their lives: "I remember a healthy man from Siberia, he almost cried when the doctor listed the options: to live for several months, amputate a leg with further unpredictable consequences, go abroad for surgery for 45 thousand euros. And finally, the last thing: to put a domestic prosthesis from the MOTHER. The patient gladly agreed to the latter. Several years have passed. There's nothing wrong with him, his leg is intact, he walks normally."

Unfortunately, these endoprostheses were not really needed in Russia. Despite the authoritative assessments of some well-known orthopedists, 90% of products go abroad. Now Alexander Ilyin is finalizing negotiations with a German company on the creation of a joint production of endoprostheses. In his opinion, this is a mutually beneficial cooperation: the Germans are strong in machining, we are in new titanium processing technologies. Therefore, some of the products or parts will be manufactured in Germany, some in Russia, and depending on the country of supply, they will be sold under a German, joint or Russian brand. For example, one of the partners of Russians in South Korea sells their products in their country and in some other Asian countries under the Russian brand "Davydov Fixators", where historically trust in our medicine and in medical products is higher. In Europe, Russian names are treated with skepticism. To be ashamed to say, in Russia itself, too.

Where did such a miracle come fromAlexander Ilyin likes to repeat: to learn how to play football well, you need to play football all the time.

It's the same with innovation. If they are not supported or supported only declaratively, there will be no innovative breakthrough. "A couple of years ago, a lot of noise was raised around nanotechnology," he says, "and we have been using plasma nanotechnology in production for more than ten years and practically no one needs it in our country." Now only a few clinics and medical centers use the unique developments of MATI. "But they were the first to whom we turned: here, look at what wonderful implants we made. They took them, and they were lying around," Ilyin continues. – And only when a report on the long-term results of using our prostheses in the EU was made at one of the conferences of traumatologists and orthopedists in Europe, Russian doctors asked the speakers: where did such a miracle come from? They were surprised: yes, from Russia! Only then they began to come to us slowly."

Ilyin complains about the strange Russian mentality: we don't believe in our own, Russian means bad. In addition, in the early nineties, Western companies firmly occupied the market and tamed doctors to themselves. "I will speak directly: we still have socialist, planned healthcare in the worst form, – says Sergey Rudakov. – Planned purchases are carried out by a federal institution, where officials are sitting, purchasing what they like. I remember a case when a hospital needed good cheap domestic catheters that cost a penny, and instead of them a budget institution supplied French devices for $ 12 apiece. They're good, but why? The same thing happens with implants."

According to Rudakov, operations for which implants and prosthetics are needed in Russia are done ten times less than required. The most annoying thing is that many people do not know about such operations at all: "I remember doing an operation for a girl about a breast deformity. She suffered a personal tragedy because of this, and if she had been operated on as a child, as it should be, everything would have turned out differently. A lot of people do not know that such defects can be corrected very well. But there are areas in which no quotas are issued for such operations."

Such operations in Russia are done according to quotas for budget money. But, of course, there are not enough of them. Rudakov says that last year he made about 35 quota operations and the same number of paid ones. But not everyone is ready to pay several hundred thousand rubles. There is no steady demand – there is no opportunity for our innovative companies to develop. Alexander Ilyin believes that now, at a time of crisis, it's time to start rebuilding: "Let's finally really engage in high-tech areas. Give your own a chance. If the government does not help innovators, then at least let it spend budget money on the purchase of a domestic competitive and often unique product. It was done in Japan. That's what they do in China."

Portal "Eternal youth" www.vechnayamolodost.ru16.02.2009