28.11.2023

After a bone fracture, some patients experience healing disorders that require surgical treatment. To enable effective outcomes in these cases, the Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM is researching a new composite material for use in the operating theater as part of the joint project SCABAEGO (Scaffold Bioactive Glass-Enhanced Osteogenesis), funded by the German Federal Ministry of Education and Research BMBF. The aim is to inhibit bacterial growth at the sites and to efficiently build up new bone material. In addition to the Fraunhofer IFAM, the Clinic for Trauma and Reconstructive Surgery at Heidelberg University Hospital and BellaSeno GmbH, a medical technology specialist from Leipzig, Germany, are involved in the project. COMPAMED-tradefair.com spoke to Dr. Kai Borcherding, Head of the Medical Technology and Life Sciences Business Unit at Fraunhofer IFAM.

Picture: a man stands in a suit at his stand during COMPAMED 2023 and smiles into the camera - Kai Borcherding; Copyright: Messe Düsseldorf/beta-web

Dr. Kai Borcherding at the COMPAMED 2023.

Dr. Borcherding, in the joint project SCABAEGO you are developing a new material for a support scaffold for bone healing, as is needed after bone fractures, for example. What exactly is the composite made of?

Dr. Kai Borcherding: We are bringing two materials together: A biodegradable polymer called polycaprolactone, abbreviated PCL, and bioactive glass. The PCL is mixed with the glass and a solvent and then processed over several stages. At the end of the process, the solvent is removed by drying and the remaining composite is finely granulated. Together, this results in a bioactive composite from which a scaffold is produced using additive manufacturing. This can be made individually for patients by producing the print template from a CT image of the defect. Each scaffold is therefore unique.

However, one of the challenges of our project is to find a processing method that is suitable for high throughput on an industrial scale. We want a composite mixture that considers both the positive properties of glass and the necessary strength of the scaffold. So far, we have experimented with a 10 to 30 percent proportion of bioactive glass in the scaffold.

You are still looking for the optimum mixing ratio?

Borcherding: Yes, that's right. From a technical point of view, we initially produced different concentrations. Bioactive glass is quite hard, so it must be optimally distributed in the plastic so that the composite is suitable for subsequent printing. However, the more filler there is in the composite, the more difficult it is to print. However, we were able to overcome this hurdle. The second step will now be to prove the positive properties of the bioactive glass for the scaffold.

Photo: a femur with an attached support frame in front of a blue-green background; Copyright: Fraunhofer IFAM

The scaffold was developed in the SCABAEGO project and can be individually adapted to large tubular bones, among other things. This requires a CT scan of the bone. It is then printed using a 3D process.

What do you hope to achieve with the material?

Borcherding: We hope that the material and the application will promote bone healing and inhibit the growth of bacteria. This is because the bioactive glass in the scaffold raises the pH value of the surrounding environment into the alkaline range. This environment can inhibit bacterial growth. Our aim is to reduce the overall risk of infection after bone surgery. The therapy should also have a positive effect on bone healing, which we will investigate within the project.

Does the scaffold have to be removed later or does it remain in the body?

Borcherding: It remains in the body, and something is even added to it. The scaffold is filled with the patient's own bone material during the operation. This is obtained from the femur or iliac crest, for example. Alternatively, bone substitute material is also possible. This allows the bone to heal stably afterwards.

Would it be conceivable and desirable to print the individual scaffold directly in the clinic or would it still be printed outside?

Borcherding: Many doctors have wanted to be able to print directly on site at the clinic for a long time. However, I think there is still a long way to go before this can be implemented due to regulatory hurdles.

Image: Printing the support frame using a 3D printer; Copyright: bellaSeno

A 3D printer prints the scaffold from the composite material.

At what stage of the study are you currently? Has the scaffold already been tested in vivo?

Borcherding: We are currently in the first year of the project. This means that we still have two years to refine the composite and the print. In the first year, we looked at what requirements we have for the material and the scaffold and what technical processing is conceivable. We considered how the material should be created and what concentrations we need. We have now evaluated all of this so that we have been able to build a demonstrator, which we also presented at COMPAMED 2023.

However, we have not yet decided whether we will ultimately retain the current composite mixture. This will be decided after the in vitro tests that are currently being carried out. This will check whether the cells react to the scaffold as desired. If these tests results are as hoped, in vivo tests will then be carried out.

As already mentioned, you were at COMPAMED 2023 and presented the bone scaffold. What was the feedback from visitors about the demonstrator?

Borcherding: Very positive. There were many people from the hospital sector who were interested in the idea and the scaffold. Many questions were also asked, and other ideas discussed. It was a very, very good exchange.