The latest silk-inspired innovation from the lab of biomedical engineering Professor David Kaplan is receiving media attention: silk-protein surgical screws that could transform the way we heal broken bones. Researchers from Kaplan’s lab and Beth Israel Deaconess Medical Center published their findings in the journal Nature Communications this March.
Surgical screws and plates, or “fixation devices” are used to repair fractured bones and are often made of metal alloys or synthetic polymers. However, metal implants place undue stress on the bone, are prone to infection, and must be surgically removed from the body once a fracture has healed. Synthetic screws are designed to be absorbed by the body, but they can be difficult to set and may cause inflammation.
The research team manufactured plates and screws from the silk protein produced by the Bombyx mori (B. mori) silkworm cocoons. A silk solution was cured into molds that produced easily machinable plates and screws. The silk screws are self-tapping, an improvement from conventional resorbable screws that require careful drilling of a screw hole before insertion of the hardware. In vivo tests showed the screws remain fixed in the bone at four and eight weeks with notable improvements in the healing and resorbtion process.
Professor Kaplan told BBC News: “The future is very exciting. We envision a whole set of orthopaedic devices for repair based on this – from plates and screws to almost any kind of device you can think of where you don’t want hardware left in the body.”
Some added benefits to the silk technology over metal fixation devices include decreased sensitivity to the cold and zero interference with X-ray technology or metal detectors. “One of the other big advantages of silk is that it can stabilize and deliver bioactive components, so that plates and screws made of silk could actually deliver antibiotics to prevent infection, pharmaceuticals to enhance bone regrowth and other therapeutics to support healing,” says Kaplan.
This research was supported by the National Institutes of Health (EB002520).