The researchers from the Department of Mechanical Engineering, Faculty of Mechanical Engineering, the Brno University of Technology came up with an original way of solving the worldwide problem of joint wear. Their design and technology replace a worn or damaged joint only to the extent necessary, remove certain birth defects, preserve the maximum of the patient's bone mass and are the first in the world to provide the joint with the necessary flexibility.

The surgery of damaged or worn joints is one of the most common surgical procedures. For the patient, this is a difficult intervention in the body. At present, the bone has to be adjusted to the chosen implant, so the patient loses a healthy part of the tissue locally to a relatively large extent. In addition, metal replacements cannot provide sufficient springing and can cause secondary health problems (bone death at the implant site, back pain, etc.).

"When I first became acquainted with knee surgery during my work in Sheffield, UK, as a layman, I was literally shocked at how much damage to the human body occurs. That was 1997, and since then I've been thinking about how to solve joint implants that adapt to the patient, not the other way around. For many years, I thought that we might not invent anything new, but our final solution is original and at a high technological level. Especially in recent years, it has been a pleasure to observe how our team manages to integrate partial steps of advanced design and technology," Miroslav Píška from the Institute of Manufacturing Technology, FME BUT, who worked on the invention with his team for more than twenty years, recalls.

In contrast to current solutions, the implant design developed at BUT is subject to high precision in the patient's actual joint, replacing cartilage and necrotic bone tissue, and not the patient's joint is modified according to the finished implant. It is tailor-made on the basis of a model based on CT images of the patient's joint. The new implant is also significantly lighter than existing castings, forgings or workpieces, while being sufficiently strong and durable. It is made of metal powder by the EBM (Electron Beam Melting) method, i.e. by melting with an electron beam in a vacuum.

It was the search for suitable material and technology that took the scientific team years of work. "About ten years ago, in cooperation with Czech companies, 3D printing laser technologies were tested in our country, but they also did not end up very encouragingly. The application of 3D printing from a titanium alloy in a vacuum using an electron beam proved to be suitable,“ the co-author of the invention Katrin Bučková, who worked on the research as a student and the research became the main topic for her bachelor's and master's thesis, says. "I was able to communicate with excellent experts in 3D modelling, materials engineering and specialists directly in foreign companies, of which the Swedish company GE ARCAM was very helpful. In the end, the analysis of successful fatigue tests at the Institute of Physics of Materials of the Academy of Sciences decided, where the samples lasted even 13 million cycles without failure. Tests have confirmed that this is an exceptionally high-quality material," the co-author of the invention adds.

There is no need for a robotic arm to insert the implant into the patient's body, as the researchers previously intended. "Instead, a special template is created, with which the implant is precisely positioned and fixed. The reinforcing rib gives the implant high rigidity and resistance to damage, for example, if the operated person later falls off. And the mentioned elasticity is obtained by suitably placing a resilient member – for example of silicone – in the assembly of the opposite piece. Its mechanical properties can be further adjusted with respect to the patient's weight and the expected dynamics of his walking, which will relieve, among other things, the spine," Miroslav Píška explains. He adds that since the flexible part is "hidden" inside the opposite piece, the implant is also suitable for patients allergic to silicone.

The radiologist Petr Krupa from the University Hospital Ostrava also collaborated on the development with the scientific team. "This system is a top example of so-called tailored surgery, or tailor-made surgery, with minimal intervention in the biological system. As a result, there is minimal trauma to the patient and his tissues while achieving maximum therapeutic results in remodelling the original function of the pathologically altered joint. The result can be a better restoration of the patient's physical abilities and a shortening of his rehabilitation time," Krupa says.

The scientific team has already applied for a patent. Several orthopaedic and veterinary clinics are interested in using the invention. The researchers are now working on further steps to help bring promising technology into clinical practice.