For orthopaedic implants to be successful, bone must meld to the metal that these artificial hips, knees and shoulders are made of.
A team of Brown University engineers, led by Thomas Webster, has discovered a new material that could significantly increase this success rate.
The team took titanium – the most popular implant material around – and chemically treated it and applied an electrical current to it. This process, called anodization, creates a pitted coating in the surface of the titanium. Webster and his team packed those pits with a cobalt catalyst and then ran the samples through a chemical process that involved heating them to a scorching 700° C. That caused carbon nanotubes to sprout from each pit.
Researchers then placed human osteoblasts, or bone-forming cells, onto the nanotube-covered samples as well as onto samples of plain and anodized titanium. The samples were placed in an incubator. After three weeks, the team found that the bone cells grew twice as fast on the titanium covered in nanotubes. Cells interacting with the nanotubes also made significantly more calcium – the essential ingredient for healthy bones.
Results are published in Nanotechnology.
“What we found is possibly a terrific new material for joint replacement and other implants,” said Webster, associate professor of engineering at Brown. “Right now, bone doesn't always properly meld to implants. Osteoblasts don't grow or grow fast enough. Adding carbon nanotubes to anodized titanium appears to encourage that cell growth and function.”