Wednesday, March 5, 2014

Silk-Based Implants, a Shift from Metal

Scientists in the United States have undertook the process of trying to replace the metal fixtures; screws, rods, and plates that patients have implanted into their body in the cases of fractured or broken bones. The replacement is made from a natural fiber, silk,  an exceptionally strong and versatile protein derived from silkworm cocoons. Leading this research is Samuel Lin, MD, of Division of Plastic and Reconstructive Surgery at BIDMC, and David Kaplan, Tufts chair of biomedical engineering and a leader in the use of silk for biomedical applications. Kaplan and his team have already developed silk based sponges and foams for operation rooms.

Silk has already been used in modern medicine for other implants, one in the Journal of Clinical Investigation, published in July of last year researched the possibility of silk brain implants helping those suffering from epilepsy. Metal implants over time can cause stress to underlying bone, cause stiffness, and can also lead to increased risk of infection. The silk would eventually dissolve in the body, seeing as the composition of the protein is similar to that of bone. What is important to note in the study regarding the replacement of metal plates with silk, is that in the silk implants are successful, it would eliminate the need for surgical removal of the devices, those which can be removed. Also, the silk based screws can deliver antibiotics to help prevent infections from poor healing wounds and promote bone regrowth.

The test so far has only been done on rodents, six laboratory rats, which had a total of 28 silk-based screws implanted into their hind limbs, and then monitored  for eight weeks. Through those eight weeks, the screws kept their mechanical integrity, and showed signs of dissolving after those eight weeks. Post-implantation, silk-based screws are extremely advantageous to clinicians due to silk's radiolucent property, they won't show up on an X-ray, allowing for a more accurate assessment of the healing process. This application was originally treatment for facial injuries, which occur at a rate of several hundred thousands each year, but could potentially help millions of people and improve their quality of life.

Posted By Thomas Flores (5)

9 comments:

  1. Very interesting article. The part that stood out to me most was that the silk screws are able to deliver antibiotics to help prevent infections from poor healing wounds. I think that is amazing compared to what the metal screws could do. Do the silk screws cost a lot more money to produce? Is the procedure more costly and those it take longer to be done compared to the metal screws?

    Posted by Amber Vien

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    1. The silk screws are extremely cost effect, the production is essentially cost free, only requiring the bare minimum of raising the silk worms themselves. Silk worms also became more of a viable resource for these silk based implants because original investment with silk producing spiders was wasteful due to their cannibalistic tendencies.

      Posted by Thomas Flores

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  2. I found this post to be very interesting. I was wondering though whether or not the fact that the silk is an organic substance could cause issues with the patients immune system. I can imagine that the silk has certain "self markers" on the surface which would be identified as foreign to the host. This could illicit an immune response which could be pretty severe. Perhaps there is a method which the scientists use to remove any such markers from the silk, or maybe I am wrong and no such markers exists. Either way, this was a really cool innovation.

    Posted by Tim Daly

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  3. Wow this is a really interesting concept! I think it is really cool that they will eventually dissolve in the body, but I wonder if this can pose any medical implications to people? What happens when the implants degrade, are they simply filtered out of the body?
    Posted by Kristen Whitehead

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  4. I was wondering the same thing as Kristen. It's very cool that the silk can dissolve in the body, but what if it doesn't fix the problem before it dissolves. This is definitely an interesting concept, but it seems like more studies have to be performed. You mentioned that the silk has been used for facial treatment, do you know if the cases have been successful?

    -Samuel Ustayev

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  5. Great innovation here. The fact that it can be used in brain tissue is awesome and hits home with me as me sister suffers from a seizure disorder. I was also wondering what if the screw takes too long to dissolve or dissolves too early, though?

    Posted by Kevin Barisano

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    1. Early degradation of the screws has been a popular question in this post, as stated in the article, the implants take about 8 weeks to begin degrading. A fracture/bone break can take several weeks to months to heal, depending on the severity. This means the screws/plate have already been in the patient for 2 months with time to heal before they start to break down, in addition the screws promote bone regrowth. So not to say that they are going to heal a broken bone in a few weeks, but in the time that has passed the bone may be more healed than it would have been with a metal screw implant, or immobilized in a cast.

      Posted by Thomas Flores

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  6. This is really cool, as things are progressing towards green energy, organic grocery stores, etc, this almost seems like an organic implant. I am having trouble picturing a silk screw, however. Are they solid, and hard like a screw? Or are they more malleable, maybe flexible? It's great that they dissolve in the body, but like others are asking does it just get flushed out? Or does it almost become part of the bone?

    Posted by Steven Yu

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  7. This article was absolutely fascinating! The idea of using a "decomposable" organic substance of a screw makes perfect sense. The only problem would seem to be that silk is extremely expensive, but perhaps this is a non-issue if physicians are using it in relatively small quantities. It seems if that silk can suit the purposes of medicine, perhaps so could the silk from a spider web? I would imagine that that would be cheaper to produce than regular silk!

    -JE

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