Silk is an unlikely substitute for steel in any context, but for bone fractures, it may just be the perfect thing.
Steel plates and bolts are often a surgeon’s only tools for fixing fractured bones. The problem is that steel can block new bone cells from repairing the fracture. Removing the steel through further surgery can leave bones brittle.
But now a mix of cocoon silk fibres and biodegradable polymers may one day hold bones together and help them heal from the inside out, thanks to the work of a Swinburne University researcher.
Materials scientist Professor Alan Lau had the idea of mixing animal fibres with other materials, initially considering chicken feathers. The fibres from feathers were difficult to purify so his team found an alternative that was easier to work with: the silk from a silkworm’s cocoon.
In 2008, Professor Lau’s team at Hong Kong Polytechnic University combined cocoon silk fibres with a biodegradable polymer called PLA and found it became harder. Adding around six per cent silk fibre made the biodegradable polymer as strong as bone.
Before this PLA had proved too weak to reinforce bone.
The scientists also found cells can grow around the material as it degrades, showing potential for use in patients. This would also eliminate the need for further surgery.
“At this stage we have a great accomplishment,” says Professor Lau. “But there’s still a long way to go.”
University Professor Lau is now tackling the design of the right pins and screws, speculating that the material could one day be tailored for individual patients by scanning their fracture and 3D printing a shape that fits perfectly.
He is looking for collaborators in Australia to start animal trials and eventually progress the material to patients.
He is optimistic: “If we can find a partner here to continue, this material will progress very fast.”
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