Silk is an amazingly strong material, yet it also harmlessly biodegrades when left in the body. This has led to its use in experimental brain implants, heart patches, and even bio-electronics. According to a new study conducted by scientists at Tufts University School of Engineering and Beth Israel Deaconess Medical Center, it may now also find use in the production of better plates and screws used for securing broken bones.
Currently, in some cases, the two ends of a broken bone must be held together in proper alignment using metal alloy plates that are screwed into the bone material. Because the metal is stiffer than the bone beneath it, however, those plates can subject the bone to stress when it's unable to flex. Their presence can also allow infection to set in, plus a second surgery is required in instances where plans call for the plates and screws to be removed after the bone has healed.
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Resorbable synthetic polymers can be used instead of metal, eliminating some of those problems, although they're comparatively difficult to implant and can cause inflammatory reactions.
It turns out, however, that pure silk protein from silkworm cocoons can be used to create plates and screws that are strong, biodegradable and that will be readily accepted by the body. The researchers tested a total of 28 screws made from the protein, in lab trials using rats.
Not only did the screws remain securely in place until they eventually dissolved, but they also didn't show up in X-rays – this could be of great help to doctors, who want to see the fracture itself without the added clutter of metal bits and pieces blocking the view.
Additionally, it's possible that compounds such as antibiotics or other therapeutics could be added to the silk fixation devices, to be dispersed to the fracture site over time.
The scientists are now planning to experiment on larger animals, with human trials farther down the road. A paper on the research was recently published in the journal Nature Communications.