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The Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) in Bremen, Germany, developed the material and the customisable structures as part of the SCABAEGO (Scaffold Bioactive Glass-Enhanced Osteogenesis) joint research project.
About 800,000 broken bones are treated in German hospitals each year, the researchers said. For approximately 10% of these cases, post-treatment complications occur due to the bone not healing correctly, resulting in painful pseudoarthrosis that can make it impossible to place weight on the bone. For patients, this often means a prolonged stay in hospital with follow-up surgery and long-term treatment, while for clinics, it involves providing time-consuming and expensive therapy.
The project’s aim is to test the hypothesis that using bioactive materials in operations could support the healing process and reduce the risk of infection. IFAM worked with the Department of Trauma and Reconstructive Surgery at the Heidelberg University Hospital, as well as BellaSeno, a Leipzig company specialising in medical engineering.
The Fraunhofer researchers developed the composite material from the biodegradable polymer polycaprolactone (PCL) and bioactive glass. This composite is then used to 3D print customised main and supporting structures for bone fracture sites, called scaffolds.
Prior to this, the structure of the damaged bone is mapped using computer tomography (CT). The custom-fit structure replaces the missing part of the bone. It is then filled with bone marrow taken from the iliac crest in the hip, or from larger long bones, to ensure that the bone replacement material is stable and the fracture site heals safely.
The bioactive glass supports the growth of new bone at the fracture site. Because it is in contact with bodily fluids, the glass turns into hydroxylapatite, a chemical compound derived primarily from calcium phosphate and a substance very similar to bone.
It also raises the pH of its surroundings to alkaline, which researchers expect will inhibit bacterial growth, and therefore the risk of post-operation infections.
“With bioactive glass, we can tackle the problems that clinics face — we can inhibit bacterial growth and provide effective support for bone healing. After six to seven years, the scaffold will be fully biodegraded and converted into bone,” said Dr Tobias Grossner, trauma surgeon and head of experimental trauma surgery at Heidelberg University Hospital.
While bioactive glass is already used to treat bone defects, the researchers were able to combine it with PCL on an industrial scale, to make a composite material suitable for additive manufacturing.
“The innovative composite material should forge significant progress in treatment,” the researchers said. The current conventional technique involves covering the fracture site with a bone cement in an initial operation, which the human body perceives as a foreign substance and protects itself with a bone membrane known as the periosteum. A further surgery can be needed after two months to remove the cement.
The SCABAEGO team is already investigating the concept in vitro and in vivo with preclinical tests, working alongside Heidelberg University Hospital.
The recipe for the composite is also being optimised. The proportion of bioactive glass in the scaffold can range between 10-30%. “We are experimenting with the mixture proportions so that we can leverage the biologically positive characteristics of glass as much as possible, while maintaining the core strength of the scaffold,” said Dr Kai Borcherding, head of the Medical Technology and Life Sciences business unit at IFAM.
The team will be at the Compamed medical engineering trade fair in Düsseldorf, Germany, 13-16 November.
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