Tuesday, January 5, 2010

Biodegradable Magnesium, Could We be looking into the Future of Spinal Implants?

Biodegradable polymer implants have exhibited some success especially in small joints. Many researchers believe that magnesium has emerged as a primary candidate for biodegradable metal implants. Considering the magnesium is the eleventh most abundant element by mass in the human body, its ions are essential to all living cells where they play an important role in manipulating biological phosphate compounds like DNA , RNA and ATP. The only challenge that magnesium has presented is that it produces hydrogen which can prolong the healing process and could potentially harm the body. The advantage of biodegradable implants is that they dissolve upon fulfillment of their intended function. Obviously this minimizes the long-term problem like inflammation, or in the case of stents, restenosis.

The way magnesium works is that it offers greater strength than polymers and as it corrodes it releases inert ions. The Swiss (who else) Federal Institute of Technology in Zurich has developed a magnesium based glass that has not exhibited the release of hydrogen during its clinical trials. Jorg Loffler and his colleagues have identified a way to circumvent this challenge by adding zinc to the magnesium to form a magnesium based metallic glass. Herr Loffler has developed a rapid cooling process that permits more flexibility in the process quickly cooling the molten material resulting in an amorphous structure that he compares to that of window glass.

By exhibiting no hydrogen , the biocompatible metallic glass could actually serve as the basis for the next generation of biodegradable thickness, as much as 5mm in thickness. This could possibly be used for bone implants. It's like Alice in Wonderland peering through the looking glass. Could this be the future? TSB wants to know what our readers think?

7 comments:

  1. Good luck getting this through the FDA. FDA has a problem with metal wear debris and the residual effects. So, some questions, what would be the particulate size, where would they travel in the blood stream, how much is too much, what is the rate of degradation, does it change over time or by size of material or location in the body, what effect does sterilization and oxidation have on the magnesium, etc.? The debris from a small screw is probably equivalent to the amount of debris from a MOM hip over 10 years. So, if multiple screws and a plate are used in a fx healing scenario, what would the long-term effect of that be?

    Last, this is essentially accelerating the rusting process of a metal. How would a patient feel about this?

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  2. Sounds innovative.

    Doesnt both Danek and Depuy have resorable cervical plates made of some sort of poly mix?

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  3. Cost containment and health care reform are going to set back innovation in the medical area quite significantly. Interesting ideas will not be moved on for lack of ability to get them past the regulatory and reimbursement hurdles. Look at the investments make in disc arthroplasty as an example. Some big companies got burned and this will have a negative impact on future endeavors.

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  4. Ever seen a pic from a MOM THA pseudotumor?

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  5. Each person has a different rate of metabolizing resorbable material hence sterile abcess formation.

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  6. Metallic Glasses hold great promise - really, but they are not strong enough “Kryptonite” to defeat the FDA/VC's/Insurers/Providers... sadly

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  7. I don't think the FDA will be the big problem here, especially for ortho applications. First, the cardio industry will demonstrate (or not) if resorbable metal is safe through their current trials of resorbable metal stents. Second, the type of "debris" from wear and resorption are totally different. The particle size is orders of magnitude different, and the mechanism of breakdown is totally different (mechanical vs. chemical). Safety with respect to "metal" doesn't worry me here. I don't think you'd want to overshoot on applications--stick to fixation (probably outside of spine).

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