The BioSA team: (Front row, left to right) Prof. Ing. Maurice Grech; Prof. Ing. Joseph Buhagiar; Christabelle Tonna; and Mr Keith Sammut. (Back row, left to right) Dr Arif Rochman; Mr Ray Gatt; Mr Luke Saliba; Prof. Pierre Schembri Wismayer; Mr Ryan Giordmaina; Elton Galea; and Albert Curmi.

Tough as bones: Biodegradable tailor-made metal scaffolds

Modern medicine has extended our lifespans, but it comes at a price. Additional twilight years bring with them bone ailments like fractures, tumours, and more. Fixing these issues requires bone grafts taken from a different place in the patient’s own body, a potentially painful process. Another solution is a permanent metal implant or other hardware, but with each surgery, bone stock keeps diminishing. 

A team of engineers and medical professionals at the University of Malta and Mater Dei Hospital are working on an alternative solution: metal-based tailor-made bone scaffolds that degrade and allow the patient’s own bone to regrow. 

To create these patient-specific implants, this multidisciplinary team, led by biomaterials engineer Prof. Ing. Joseph Buhagiar, married medical imaging, 3D printing, and powder metallurgy. 

The process starts with the patient going to hospital to get a CT scan of the damaged area. Using a series of X-rays and a laptop, the CT scan produces a 3D image of the bone and the defect within. That 3D image then becomes the base on which the team builds the patient’s implant design. 

Next, they print the template on a 3D printer. But the standard filament printers you’ve seen making puzzle cubes at ComicCon will not work here. ‘Creating the network needed to simulate human bone is super detailed work, and filament printers don’t have that kind of resolution,’ explains Buhagiar. ‘This is why we opted for stereolithography. It uses lasers and liquid polymers to build the template.’ It’s also the machine that makes the elaborate WarHammer models at the other end of ComicCon. 

It was while testing out different polymers and curing techniques for 3D printing that the team was able to create a ‘tackiness’ to the resulting scaffold templates. That stickiness was a great discovery, allowing the powdered metal in the next step to stick to the template without a binder. 

The metal powder used contains specific ratios of iron, manganese, and silver, but the recipe is still being refined. 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. Also, silver and manganese combined 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.  

The team is now in the process of running various tests on their new implants. Their first ‘patients’ were various pork bones bought from a butcher. The surgical trainees conducting the procedure report that ‘the scaffolds were easy to handle and adjust as needed.’ 

The final product — the BioSA implant.

Toxicity and bacterial tests are also underway and looking very positive. Next in line is the mission to find an investor for the technology. ‘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,’ Buhagiar says. 

Stay tuned for an in-depth look at the project in Issue 37 of THINK Magazine (out in March 2022)!

BioSA (R&I-2017-037T) is financed by the Malta Council for Science and Technology through the FUSION: R&I Technology Development Programme.

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