Building a better orthopedic implant that won't set off alarms

When Joy Gray-Munro's husband required knee surgery that requiredstainless steel pins and screws implanted in his body, her training as a chemist kicked in.

Gray-Munro, whohadjust accepted a position in the chemistry department at Laurentian University, said,"I knew he would be stuck with thesestainless steel implants likely for the rest of his life. And Ithought, you know what, we can do better."

Ten years later,Gray-Munro and a team of researchers are developing biodegradable orthopedic implant materials.

"We're interested in developingmaterials that would allow animplant to degrade gradually over time but remain non-toxic, give you mechanical support for your bone tissue as it heals,and getrid of the need for asecondary surgery to remove pins and screws that have been put in place to fix a broken bone," said Gray-Munro.

Current implants made of titanium and and stainless steelcan corrode and release toxic metals according to Gray-Munro.

Researchers at Laurentian University believe the solution may bemagnesium alloys.

"Magnesium itself is something your body actually needs. So as these metallic materials degrade, they will release magnesium ions," said Gray-Munro.

Calcium phosphate proves promising

The challenge is to control the degradation rate. Researchers needthe magnesium to remain stable for three to sixmonths to allow for the bone to heal before the screws start corroding away.

By coating small pieces of magnesium with calcium phosphate the researchers have been able to lower the degradation rate by 99 per cent.

"Not only do we want them to degrade at a certain rate," said Gray-Munro, "we also want these materials to induce tissue growth."

Gray-Munrosaid calcium phosphate is proving promising, considering it's a mineral already found in bone.

"Your bone cells recognize the calcium phosphate materials and think it's a nice safe hometo sit down and grow," she said.

As the research continues, Gray-Munro is hoping these new pins can be tested in Canada.

Gray-Munro says one of the benefits of a magnesium pin is that once it dissolves, it won't set off alarms at airport security, something that slows down her husband when he travels.

"He always has to get the wand on the way through," she said.