Mending broken bones with glass

24 May 2012

Author: Jonathan Moore



A young materials engineer is developing glass as an alternative implant for healing fractured bones.
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It has been said that mothers are always right.

This may be the case for Jake Cao.

Cao is an engineer and PhD candidate at the University of New South Wales (UNSW). His research is in materials, an area he selected because “everything is made of something”, which makes it interesting, he says. As one of a group of researchers studying different types of metallic glass at UNSW, Cao was offered the opportunity to work with a bioabsorbable material.

“I picked the bioabsorbable glass because my mum is an orthopaedic specialist,” Cao says. “I had a chat with her about it and she saw some great potential in the technology.”

What Cao’s mum, and a team of engineering researchers, saw was that this material might offer an alternative to metals currently used as surgical implants for bone setting and healing – such as stainless steel and titanium screws, plates and nails. Traditional implants can cause heavy metal poisoning in the body as the material corrodes and enters the blood stream. But a metallic glass implant that only lasts long enough to serve its purpose, before its constituents are naturally absorbed as nutrients in the body, could speed healing time and eliminate the need for a second surgery to remove the implant.

“There are a lot of issues with all current implant materials. If you use any material that’s not natural inside the body you’re going to have problems occasionally,” Cao says. “That’s why we’re only using elements that already exist inside the body.”

Cao is collaborating with researchers at several Australian universities and fellow members of the Australian Research Council (ARC) Center of Excellence for Design in Light Metals for this work. The ARC Centre of Excellence engages six major research-intensive universities and all of the leading light alloy research groups in the university sector in Australia and has been a pivotal financial supporter for Cao’s team.

While the medical device industry is very heavily regulated and the road towards the standardised use of this class of material as a surgical implant may be long, Cao believes they are on to something very special.

“Old implants basically just hold two pieces of bone together,” Cao says. “They align the two broken bones and you just heal over time. But this material has calcium and magnesium in it. Bone is predominately calcium and other studies have shown that by having magnesium near a wound it actually causes the precipitation of something called calcium phosphate, which initiates the growth of new bones.”

Using lab facilities at UNSW and Monash University and with input from local orthopaedic device developers the team, led by Professor Michael Ferry, Dr Philip Boughton and Dr Kevin Laws, are working towards controlling and commercialising this unconventional and versatile material for medical use.

“It's rare to come across a material that's structural, rigid, and looks like metal, but can disappear when it’s done its job,” Boughton says. “This is a relatively new class of material so there are processing differences. You can't cut or polish or process this in the same way you would with standard metals. Instead, it's a bit like “Terminator 2” in the sense that we have a liquid metal that we push into a mold – once it has set we don't have to do any further processing. Once you've set it up you can mass produce components at high tolerances with this very nice finish.”

The engineering researchers make metallic glass in UNSW’s lab facility before testing it in a special incubator at Monash University which simulates natural body conditions by mimicking physiologic temperature and surrounding body fluid, complete with neurons and vitamins to accurate pH levels. What they seek is evidence, proof of concept, firm data to publish and share with their international peers so that their findings might progress to working solutions. The Australian team and European counterparts are well on the way to translating this new type of biomaterial into use in the next generation of medical implants.

“The Swiss have some of the leading researchers in this area,” Boughton says. “It’s good to know they're on the same track as us. In fact, we've been sharing research ideas so we've got a good bridge over there, and while we've still got some good home grown ideas we're working in a world class kind of setting.”

Boughton says Australia has one of the world’s best environments for medical device development. “We're actually in a hotspot,” he says. “We've had companies like Cochlear and ResMed… We've got a small but critical mass industry so it wouldn't be hard for us to translate what we already have into a working treatment for patients. I think we're certainly heading towards something that's very special, very novel.”

But when the time comes for this novel new material to be laid out on a surgical tray, what will the public think of their bones mending with the help of a “glass” implant?

“I guess that’s a problem for the marketing people,” Cao laughs.

Perhaps one day, after the marketing people have done their work, children and adults mended with glass will be thankful for engineers who are interested in what everything is made of.