WSU researchers tested the newly developed material for resistance to fatigue. Credit: Washington State University
Key points:
- Materials used for surgical implants were developed more than 50 years ago and are not well suited to overcoming infections.
- Researchers in Washington state added 10% tantalum and 3% copper to create a nearly infection-resistant metal for implants.
- The implant performed well in both the lab and animal models, showing it could kill 87% of staph infections.
A novel surgical implant developed by Washington State University (WSU) researchers was able to kill 87% of the bacteria that cause staph infections in laboratory tests, while remaining strong and compatible with surrounding tissue like current implants. The work could someday lead to better infection control in many common surgeries, such as hip and knee replacements.
Titanium materials used for hip and knee replacements and other surgical implants were developed more than 50 years ago and are not well suited to overcoming infections. Once an infection sets, doctors try to treat it with systemic antibiotics. In about 7% of implant surgery cases, though, doctors have to perform a revision surgery, removing the implant, cleaning the area, adding antibiotics and putting in another implant.
Using 3D-printing technology, the WSU researchers added 10% tantalum, a corrosion-resistant metal, and 3% copper to the titanium alloy typically used in implants. When bacteria come into contact with the material’s copper surface, almost all of their cell walls rupture. Meanwhile, the tantalum encourages healthy cell growth with surrounding bone and tissue leading to expedited healing for the patient.
The researchers spent three years on a comprehensive study of their implant, assessing its mechanical properties, biology and antibacterial response both in the lab and in animal models. They also studied its wear to make sure that metal ions from the implant won’t wear off and move into nearby tissue causing toxicity.
“The biggest advantage for this type of multifunctional device is that one can use it for infection control as well as for good bone tissue integration,” said co-author Susmita Bose, professor at WSU. “Because infection is such a big issue in today’s surgical world, if any multifunctional device can do both things, there’s nothing like it.”
The researchers are continuing their work, hoping to improve the bacterial death rate to the standard of more than 99% without compromising tissue integration. They also want to make sure that the materials offer good performance under real-world loading conditions patients might use, such as hiking in the case of a knee replacement.