Why do artificial joint replacements wear out after just a few years, while human cartilage can last a lifetime? This is the question research teams around the world are trying to answer — including scientists at the Faculty of Mechanical Engineering at BUT. In the field of biotribology, they combine engineering with medicine to better understand friction and wear in living organisms. The interdisciplinary nature of the research also attracted Daniel Němeček, who has received the Brno Ph.D. Talent award for his work and was also recognized in the Werner von Siemens Award competition.

“I didn’t want to do purely mechanical engineering — I was looking for something with broader overlap. Biotribology is essentially a step from engineering toward medicine,” says doctoral student Daniel Němeček from the Institute of Machine and Industrial Design, who has been involved in the field since his bachelor’s studies. At that time, he tested hip implants with textured surfaces; later, his research shifted toward hydrogels, materials that aim to mimic natural cartilage.

“Hydrogels are water-based materials, and cartilage itself is largely composed of water, so we are trying to replicate it. In terms of friction, hydrogels can achieve values very similar to cartilage, but the major issue is their strength and wear resistance. A hydrogel may become damaged within a very short time, whereas cartilage functions for decades,” explains Němeček.

This discrepancy remains one of the major unanswered questions in current research. “At first glance, these materials behave similarly, but they differ in key properties. I would like to understand what we are still missing — what the crucial mechanism is,” Němeček reflects.

Research into joint implants carried out by BUT biotribologists extends far beyond a single type of material. Several research directions are being pursued simultaneously — from possible implant surface modifications and hydrogels to the use of so-called 2D nanomaterials, which have the potential to significantly reduce friction and wear. “A 2D material can be imagined as a sheet of paper, but fifty thousand to one hundred thousand times thinner. If we manage to incorporate it effectively into metal implants, it could fundamentally change their properties and greatly extend implant lifespan,” explains David Nečas, Němeček’s supervisor.

The research on 2D materials is linked to a project funded by the Czech Science Foundation, led by Nečas, under which both Němeček’s dissertation and his Brno Ph.D. Talent project fall. The motivation is clear: current joint replacements have limited durability, and some patients require repeat surgery. “Implants typically last ten to twenty years. Approximately five to ten percent of all major joint surgeries are therefore revision procedures. These are more demanding, more expensive, and represent a considerable physical and psychological burden for patients,” says Nečas.

The topic has a truly global dimension. Millions of hip and knee replacements are performed worldwide every year. As populations continue to age, these numbers are expected to rise further, with additional significant growth anticipated due to increasingly accessible healthcare in countries such as India and China. “In the relatively near future, this could amount to tens of millions of surgeries annually. Any improvement in implant durability therefore has an enormous global impact,” Nečas points out.

Surround Yourself with the Best

David Nečas approaches his work based on a lesson he learned during his own doctoral studies: science is fundamentally about collaboration — ideally international collaboration. This spring, together with colleagues from Imperial College London, TU Wien, Leibniz University Hannover, and industrial partners, he prepared a Horizon Europe project proposal. “If we want to be among the best, we have to collaborate with the best. This project focuses not only on research, but also on team development and support for young scientists,” explains Nečas. The project is expected to include internships, workshops, and intensive exchange of expertise.

For Daniel Němeček, the international dimension combined with interdisciplinary research is one of the main reasons he chose to pursue doctoral studies. If the project succeeds, he will have the opportunity to collaborate with leading experts in the field — a prospect he strongly hopes for. “I enjoy meeting inspiring people. I wouldn’t want to spend my life closed away only in an office or laboratory,” says the Brno Ph.D. Talent award recipient, who sees the recognition as confirmation that he is on the right path. “It’s encouragement that what I’m doing matters.”

In addition to researching new materials, the team is also addressing broader tribological questions. One of them is so-called superlubricity — a state of extremely low friction — both in joints and in machines. “Today, we can already achieve it under laboratory conditions. The biggest challenge is transferring these findings from the micro-world to the macro-world. There is enormous potential here as well, because estimates suggest that up to one quarter of all generated energy is lost due to friction and wear. If we could achieve superlubricity in machines, humanity would become dramatically more energy-efficient as a planet,” Nečas concludes.