Silk plates and screws for fractured bones may replace synthetic and metal fixation devices.

Surgical treatment of fractured bones sometimes involves inserting plates and screws to hold the broken parts of the bone together and thus help the healing process. As a rule, these surgical devices are manufactured of metal alloys.

However, there is a number of disadvantages associated with such metal implants:

  • They can lead to stress in the bone, as they lack resilience.
  • There is a risk that the wound will heal slower.
  • There is a risk of infection and inflammation.
  • Sometimes, the metal devices have to be removed after bone healing, which results in additional surgery.

Resorbable synthetic implants are more practical, but they may increase a chance of inflammation and are hard to install.

Fractured BonesResearchers from Beth Israel Deaconess Medical Center, Harvard Medical School, and Tufts University School of Engineering have designed surgical fixation devices made of silk protein derived from silkworm cocoons. Such screws and plates are far more advantageous for both patients and surgeons compared to traditional devices.

The results of the research were showed in vitro and using a rodent model.
The silk-derived material is almost as strong as some metal alloys, but its flexibility properties are far more similar to bone than metal. Silk devices can preserve their structure under relatively high temperature, resist other adverse conditions, and they can be easily sterilized.

Moreover, it is possible to stabilize and deliver bioactive substances using silk screws and plates. It means that silk surgical devices can be used to administer antibiotics to avoid infections or other medication to increase and assist restoration of bones.

The research team installed twenty-eight silk-protein screws in six laboratory rats in order to test the devices and an assessment was made four weeks and eight weeks after the surgery.

Silk is slow to absorb liquids, so the new devices preserved their mechanical structure even when in immediate contact with fluids and surrounding tissue. Thus, silk devices avoid the problems arising when polymer or metal comes into contact with fluids.

Another important property of silk screws and plates is that, unlike metal devices, they are not seen on X-ray. In this way they will not block the view of the bone itself and will allow the surgeon to examine how the bone is healing. Like polymer implants, silk devices are resorbable, eliminating the necessity of another surgery for their removal.

The authors intend to go further with their research, test the new material with bigger animals and eventually start clinical trials.