Summer U

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

Researchers at Laurentian University are working on developing orthopedic implants such as pins and screws made of magnesium, a metal that readily dissolves in the body.

Laurentian University researchers are developing bone screws that dissolve after bone has healed

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

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

      Ten years later, Gray-Munro and a team of researchers are developing biodegradable orthopedic implant materials. 
      Joy Gray-Munro, associate professor chemistry and biochemistry at Laurentian University (CBC/Markus Schwabe)

      "We're interested in developing materials that would allow an implant to degrade gradually over time but remain non-toxic, give you mechanical support for your bone tissue as it heals, and get rid of the need for a secondary 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 steel  can corrode and release toxic metals according to Gray-Munro. 

      Researchers at Laurentian University believe the solution may be magnesium 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 need the magnesium to remain stable for three to six months 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-Munro said 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 home to 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. 

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