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‘Smart coating’ may lead to safer hip, knee and dental implants
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Researchers at North Carolina State University have developed a new coating that may help surgical implants bond more closely with bone and ward off infection.
According to the researchers, the coating mitigates the risk of implant rejection by fostering bone growth into the implant itself. The coating creates a crystalline layer next to the implant and a predominately amorphous outer layer that touches the surrounding bone. The amorphous layer dissolves over time, releasing calcium and phosphate to encourage bone growth.
“We call it a smart coating because we can tailor the rate at which the amorphous layer dissolves to match the bone growth of each patient,” Afsaneh Rabiei, PhD, a co-author of the paper and an associate professor of mechanical and aerospace engineering at the university, stated in a North Carolina State University press release.
According to the release, the ability to change the layer’s rate of dissolve means that implants can be suited for younger or older patients, whose bones grow at different rates. The bonding may also make the implant more functional, because it helps ensure that the bone and implant share the load.
The researchers have also incorporated silver nanoparticles throughout the coating to ward off infections. In the release, Rabiei stated the silver particles will act as antimicrobial agents as the amorphous layer dissolves.
Researchers noted that the goal is to “provide protection from infection at the implant site for the life of the implant.”
Rabiei stated that the silver is released more quickly after surgery – when there is a higher risk of infection – due to the faster dissolution of the amorphous layer.
“That is another reason we call it smart coating, she stated in the release.
Orthopedics Today editorial board member, Robert T. Trousdale, MD, said that the research is “exciting.”
“Coatings have been placed on orthopedic implants for many years, and appear to facilitate rapid growth,” Trousdale told OrthoSuperSite.com. “Adding silver nanoparticles to ward off infection is potentially an advancement.”
Trousdale cautioned, however, that further research is needed.
“Although this is potentially one way to decrease periprosthetic infection, it is certainly premature for the researchers to state they ‘will provide protection from infection at the implant site for the life of the implant’,” he said.
“Before this statement can be made, well-designed clinical trials of a large scale will need to be done to truly see if the silver nanoparticles actually decrease infection rates,” he added.
- References:
Bai X, More K, Rouleau CM, Rabiei A. Functionally graded hydroxyapatite coatings doped with antibacterial components. Acta Biomater. Article in press. Available online December 5, 2009.
