Metal devices to fix broken bones may soon be a thing of the past. Using pure silk protein derived from silkworm cocoons, investigators have developed surgical plates and screws that bond the broken sections and enable a fracture to heal.Moreover, these can also be absorbed by the body over time - eliminating the need for surgical removal of the devices.“Unlike metal, the composition of silk protein may be similar to bone composition. Silk materials are extremely robust. They maintain structural stability under very high temperatures and withstand other extreme conditions, and they can be readily sterilised,” explained Samuel Lin from Boston-based Beth Israel Deaconess Medical Center (BIDMC).Metal devices may have disadvantages as they are stiff and unyielding and can cause stress to the underlying bone. They also pose an increased risk of infection and poor wound healing.“Silk can stabilise and deliver bioactive components. The plates and screws made of silk could actually deliver antibiotics to prevent infection,” added David Kaplan from Tufts University School of Engineering and a leader in the use of silk for biomedical applications.
The researchers used silk protein obtained from bombyx mori (B. mori) silkworm cocoons to form the surgical plates and screws.Produced from the glands of the silkworm, the silk protein is folded in complex ways that give it unique properties of both exceptional strength and versatility.To test the new devices, the investigators implanted a total of 28 silk-based screws in six rats.Insertion of screws was straightforward and assessments were then conducted at four weeks and eight weeks, post-implantation.“No screws failed during implantation,” said Kaplan.The use of silk plates and screws can spare patients the complications that can develop when metal or synthetic polymer devices come into contact with fluids.While the initial aim is to use silk-based screws to treat facial injuries, the devices have the potential for the treatment of a variety of different types of bone fractures, said the study published in the journal Nature Communications.