When someone suffers a broken bone, treatment may call for a surgeon to insert screws and plates to help bond the broken sections and allow the fracture to heal. These so-called fixation devices are usually made of metal alloys.
Metal devices have disadvantages: their stiff, unyielding nature can stress underlying bone. They also pose an increased risk of infection. Resorbable fixation devices made of synthetic polymers avoid some of these problems but are difficult to implant and may trigger inflammatory reactions.
Recent research has identified a different substance, tested in an animal model and reported in the March 4 issue of Nature Communications, that may eliminate these disadvantages. That substance: silk.
A team of investigators from HMS, Beth Israel Deaconess Medical Center, and Tufts University School of Engineering has made surgical plates and screws from pure silk protein derived from silkworm cocoons. The devices are absorbed by the body over time, eliminating the need for surgical removal, which can become necessary with metal devices.
“Silk materials are extremely robust,” says co-senior author Samuel Lin, an HMS associate professor of surgery in the Division of Plastic and Reconstructive Surgery at Beth Israel Deaconess. “They maintain structural stability under very high temperatures, can withstand other extreme conditions, and can be easily sterilized.”
According to the authors, silk can stabilize and deliver bioactive components, characteristics that would allow for fixation devices that deliver antibiotics to prevent infection, pharmaceuticals to enhance bone regrowth, and other therapeutics to support healing. In addition, unlike metal devices, silk ones do not show up on x-rays, making it easier for surgeons to use imaging to monitor the healing process.
Although the aim is to use silk-based screws to treat facial injuries, which occur at a rate of several hundred thousand each year, the devices could also be used for many types of bone fractures.