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Fixing bones with dissolvable glass
physicsworld.com ^
| Oct 1, 2009
| Lewis Brindley
Posted on 10/01/2009 7:35:39 PM PDT by neverdem
Doctoring broken bones in the future could be easier and simpler – thanks to a metallic glass material that can be used to make dissolvable screws, pins or plates.
Bone fractures or breaks are routinely fixed in place with metal implants to encourage healing. These are usually made from corrosion-resistant steel or titanium, but have to be removed in a second operation once the bones have mended.
In an effort to make this extra surgery a thing of the past, materials scientists led by Jörg Löffler at ETH Zurich in Switzerland have designed a metallic glass that dissolves harmlessly in the body. The idea is to make small supporting objects from this material, such as pins or nails, which would disappear over time.
Strength without the bubbles
But the biggest challenge has been finding a suitable material. Requirements include strength, flexibility and durability, coupled with the ability to be absorbed without toxic side-effects. The best candidates for the job are magnesium alloys – but when these dissolve in the body they produce bubbles of hydrogen gas that hinder bone growth.
To get around this problem, the Swiss team adjusted the components of the alloy to 60% magnesium, 35% zinc and 5% calcium, moulded in the form of metallic glass. This is made by rapid cooling of the combined mixture of molten metals – a process that prevents the conventional metallic structure from forming. Instead, the metals have an amorphous glass-like structure that is brittle but strong.
In animal studies, there was no sign that hydrogen bubbles were forming. "By changing the composition of the alloy, we believe that we are changing the corrosion reaction that takes place," explains Bruno Zberg, lead author on the paper, which is published this week in Nature Materials. The team also found that they could adjust the speed of corrosion by varying the zinc content of the alloy, which may prove useful when designing different types of implant.
Slow dissolution
"The glasses usually dissolve at a rate of around one millimetre per month – although it depends on the size of the implant and location in the body," Zberg told physicsworld.com. "Either way, the number of metal ions being released into the bloodstream is relatively low and diluted in the blood quite quickly."
"This is certainly a novel approach and an interesting concept, but there are still issues to address," says Robert Hill at Barts and The London School of Medicine and Dentistry, UK. "Early steel implants suffered from fatigue failure after they became corroded – so it is important to ensure that this new material does not become critically weakened in the same way." Another danger, Hill notes, is that threading on screws could corrode, or fibrous tissue could form around shrinking implants, making them come loose.
A further question remains over whether the dissolving metals will help or hinder the growth of new bone in their vicinity. Zberg notes that this also depends on the quantity being released – but acknowledges that these questions will all need further investigation in the future.
About the author
Lewis Brindley is a freelance science and technology writer based in Chelmsford, UK
TOPICS: Culture/Society; News/Current Events; Testing
KEYWORDS: biodegradableimplant; dissolvablefixator; dissolvableglass; materialscience
1
posted on
10/01/2009 7:35:39 PM PDT
by
neverdem
To: neverdem
2
posted on
10/01/2009 7:43:20 PM PDT
by
OneWingedShark
(Q: Why am I here? A: To do Justly, to love mercy, and to walk humbly with my God.)
To: neverdem
Neat...
Glass Jaw will now have a whole new meaning.
3
posted on
10/01/2009 7:44:56 PM PDT
by
libertarian27
(Ingsoc: Life, Liberty and the Department of Happiness)
To: neverdem
“Increasingly flexible” might be better than “brittle,” but this is still interesting.
4
posted on
10/01/2009 7:45:10 PM PDT
by
TChad
To: neverdem
Bone fractures or breaks are routinely fixed in place with metal implants to encourage healing. These are usually made from corrosion-resistant steel or titanium, but have to be removed in a second operation once the bones have mended. Been there. Done that. It was one of the most difficult times of my life. If they can improve the procedure, God bless.
5
posted on
10/01/2009 7:45:49 PM PDT
by
HoosierHawk
(www.firstsundaymusic.com)
To: neverdem
Gelrin - Bone and Cartilage repair.
This should be out of trials and near FDA aproval if not already available.
Amazing stuff.
6
posted on
10/01/2009 7:47:22 PM PDT
by
PeaceBeWithYou
(De Oppresso Liber! (50 million and counting in Afganistan and Iraq))
To: HoosierHawk
I’m recovering from fractures requiring metal in my leg and wrist. I was told if I ever should choose to have the metal removed from my leg, it would be at least a 6 week recovery. I don’t know if I’d want to go through with that again if I don’t have to. (I bet my husband doesn’t want to either.)
7
posted on
10/01/2009 8:09:35 PM PDT
by
stayathomemom
(Beware of cat attacks while typing!)
To: neverdem
I should think that such advances would prove to be exciting to an aging population ~ too bad the political powers that be view such a population as being a real drag.
To: neverdem
One of the risks involving spine surgery requiring steel screws is that sometimes the screws break and the back problem devolves into paralysis.
Having this new product rather than steel - what an advancement!
9
posted on
10/01/2009 8:40:09 PM PDT
by
SatinDoll
(NO Foreign Nationals as our President!!)
To: neverdem
“Dear Mrs Glotz;
We are sorry to inform you that your universal care insurance plan has not approved your application for “bone enhancement” surgery.
We understand that the latest technology would enable your bones to knit together, yet our council has not yet approved that specific remedy.
Please resubmit your bone enhancement surgery request at 9:45AM EST Feb. 29, 2014, timing is critical, to determine whether you could possibly be covered!
The good news is here’s a $25 coupon for Scooters-B-Us!
Have a nice life!”
10
posted on
10/01/2009 8:46:52 PM PDT
by
aShepard
To: neverdem
I want to know if this could replace hip and knee replacement??
11
posted on
10/01/2009 8:51:34 PM PDT
by
dalereed
To: stayathomemom
I'm no doctor, but if you can live with the metal without too much discomfort and a limited amount of movement, I'd opt to leave things alone.
But that's just my opinion. I now have a permanent pin in my left shoulder. It reduces movement a bit, but prevents dislocation.
12
posted on
10/01/2009 8:53:36 PM PDT
by
HoosierHawk
(www.firstsundaymusic.com)
To: libertarian27
Beat me to it you scoundrel.
What does this do to the prognosis for Rickets?
"Mrs. Jones, you aren't getting enough Mg-Zn-Ca alloy again."
Cheers!
13
posted on
10/01/2009 8:58:52 PM PDT
by
grey_whiskers
(The opinions are solely those of the author and are subject to change without notice.)
To: dalereed
I want to know if this could replace hip and knee replacement?? Doesn't sound like it. These are not artificial joints. This new material is intended to be used in screws and plates for temporary bone fixation, to hold things in proper apposition and alignment to facilitate healing, while permitting limited load bearing.
It is not suprising that ETH Zurich is Swiss. The Swiss have a long history of leadership in bone fixation techniques.
14
posted on
10/01/2009 9:12:19 PM PDT
by
TChad
To: neverdem
I wonder if these new screws could be used also as filler replacements for patients who have previous surgically installed screws removed?
When screws are removed, the bone has to grow to fill in the void. Holes can be problematic, no?
If the replacements dissolved in such a way to enable gradual bone growth, but did eventually melt away, absorbed by the body, that could be a good thing.
Along this line of reasoning, if only for for "replacement fillers" rather than initial installation, perhaps it would be better to have something softer yet?
is there such a thing already, anyone around here know?
15
posted on
10/01/2009 9:29:37 PM PDT
by
BlueDragon
(i don't set off metal detectors at the airport, but i am part stainless...)
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