Materials science: Fixing bones with silk screws

Bone screws made of silk that could be used to fix broken bones are reported in Nature Communications this week. These biocompatible bone screws may offer many advantages over the use of traditional metal-based ones.

Bone screws are commonly used for fastening broken bones together, so that they may heal and bond. Metal alloys are currently the gold standard for this procedure but suffer from several limitations, including mechanical property mismatch with the surrounding bone (which can lead to bone degradation due to load being taken up by the stiffer metal implant) and the inability to degrade in the body, meaning a second operation is needed to remove the implant. Samuel Lin and colleagues have synthesised silk bone screws that they implant into the hind limbs of rats, and report that the screws function successfully for the eight-week period investigated. The known low stiffness of silk - which is more similar to that of bone - and ability to degrade in the body make silk an attractive candidate as compared to metal- based systems.