Material development for implants

Finding the right implant material isn’t always an easy feat because it has to meet stringent medical and material requirements. Researchers from different branches of science at the Fraunhofer Institute for Ceramic Technologies and Systems, IKTS, are studying ways to optimize and create new implants. Dr. Jörg Opitz is among the esteemed scientists.

Dr. Opitz, what materials have you been researching so far?

Jörg Opitz: The Fraunhofer IKTS primarily studies ceramics such as aluminum oxide and zirconium oxide and their different composites, hydroxyapatite, tricalcium phosphate, and silicon nitride. We develop new ceramic materials and components with advanced mechanical, biological, and optical properties. This plays an important role in traditional implants such as prosthetic knee or hip implants and dental implants that are placed in the jawbone.

What are some issues you are addressing at your Institute?

Opitz: Our team is currently focused on dental implants. The primary concern in this case is how the implant will integrate into the bone tissue. This requires solutions that optimize the osseointegration process and entails material development and manufacturing process development. Another project pertains to the production of biomimetic and biodegradable ceramics for bone replacement in the jaw area. Our goal is to build bone-like structures: a soft, spongy interior structure and a denser outside structure, or dense support structures that enclose porous, spongy areas, respectively. The question in this case is: How can ceramics mimic this setting? One solution is to produce a foam-like structure on the inside and to print biomechanically optimized outer dense layers and structures. The Federal Ministry of Education and Research (BMBF) funds a VIP+ project that validates how these types of complex structures can serve as patient-customized bone replacement material. Another example pertains to finger joint implants. The in-house "FingerKIt" project teams up with partner institutes to study a fully automated process chain to create joint implant devices that are custom-made for patients. The bones in our fingers are unique, necessitating custom solutions. The common treatment often involves finger braces versus finger joint replacement implants. That’s something we plan to change.

Another key issue is surface finishing and functionalization, addressing questions like, “How can we promote bone growth as part of osseointegration or prevent restenosis after stent placement?” (Interview link Dr. Beshchasna). Implant research also always takes the human immune system response into account. That’s the research focus of an IKTS working group at our Leipzig location. The group develops cell-based approaches (macrophage-based models) to standardize in-vitro testing of medical devices. The group also works on methods for non-destructive testing and develops suitable laboratory tools for direct contact quantitative cell tests of materials.

What test methods do you use to review the effectiveness of specific surfaces?

Opitz: Materials scientists initially analyze and characterize materials. The structure of materials is studied down to the nanoscale. Standard laboratory tests review the chemical and mechanical reaction of material. We also developed our own proprietary methods at the Fraunhofer Institute. One example is atomic force acoustic microscopy, which is suitable for thin layers, allowing measurement of the interfaces between soft and hard tissue, for example. The IKTS has also teamed up with partners to develop a high-resolution X-ray Nano-CT system. Conventional hospital CT systems provide resolution on the order of 10 - 100 micrometers, while industrial computed tomography can even reach 2 micrometers. Yet you can achieve even higher resolutions.

Several groups at the Fraunhofer IKTS are working on correlating the data from various tests in one figure to facilitate assessment. This is a key point as materials are getting more and more advanced and complex. Typically, this is not just about one type of material – medical technology, in particular, also increasingly uses composite materials.

How do you support customers in the development of implants?

Opitz: We offer a complete package: materials development and selection, shaping, functionalization, biological material analysis - essentially everything the customer wants and needs. If customers have specific specifications for the implant but there is no suitable material yet, we will find a solution for them. We also look for suitable options if customers already have a finished design and look for the right manufacturing process.

How important is an interdisciplinary approach to you?

Opitz: It is very important. Our Institute collaborates with many different disciplines and features physicists, chemists, biologists, materials scientists, and designers. Everyone contributes their unique perspective and viewpoint to a problem. We are deliberately diversified to cover the different branches of life sciences. At the end of the day, we aim to support the continued development of very durable and customized implants. This allows patients to sustainably recover and preserve their long-term quality of life.