Maltese researchers have developed a new kind of bone graft that degrades over time and allows a patient’s own bones to regrow in its place.
The Biodegradable Iron for Orthopaedic Scaffold Applications project, or BioSA, is a joint effort by the Faculty of Engineering at the University of Malta and Mater Dei hospital.
Led by biomaterials engineer Joseph Buhagiar, the research team has come up with a new implant that is tailor-made through medical imaging, 3D printing and powder metallurgy.
In a statement on Thursday, the research team said that treating bone ailments like fractures or tumours came at a price, often requiring painful surgeries to create a graft, or installing permanent metal hardware that causes the bone stock to diminish over time.
The BioSA implant would provide an alternative solution to these as a metal-based bone scaffold that degrades over time and allows the patient’s own bones to regrow.
To kick-start the process, patients would need to visit the hospital and get a CT scan of the damaged area. A 3D model of the bone and its defect is created through a series of images, and the team will then design the patient’s implant.
Rather than using a standard filament printer, which is often used to mould thin plastic layers in 3D printing, the researchers have opted for stereolithography.
Joseph Buhagiar and Christabelle Tonna reviewing an implant under a Scanning Electron Microscope. Photo: University of Malta“Creating the network needed to simulate human bone is super detailed work, and filament printers don’t have that kind of resolution,” Buhagiar said.
“This is why we opted for stereolithography. It uses lasers and liquid polymers to build the template.”
While testing out different materials, the team was also able to develop a recipe that resulted in a tacky substance that allows powdered metal to stick to the template without requiring a binding agent.
“The metal powder contains specific ratios of iron, manganese, and silver, but the recipe is still being refined,” Buhagiar explains.
“Iron gives the scaffold the strength it needs to support the body. Manganese makes the implant non-magnetic; a required quality for implants due to imaging technology that works with very strong magnets. Silver is antibacterial. Silver and manganese combined also give the implant the corrosion response it needs to break down as the patient’s own bone regenerates and takes over, much like how a forest would reclaim an abandoned house,” explains Buhagiar.
The final step is to bake the template covered in metal powder. At 450°C, the polymer template burns away, and at 1120°C, sintering happens as the metal powders join to form a solid implant.
Tested on pig bones
Having tested the first of their implants successfully on pig bones, the project is now seeking investors to take their innovation to the next step: human trials.
“Toxicity and bacterial tests are also underway and looking very positive. Next in line is the mission to find an investor for the technology,” Buhagiar said.
‘It is now time to pass this knowledge and project on. The BioSA project needs to go to people who can move the scaffolds on to human trials so we can hopefully one day see them used to better a patient’s life.”