| Topic: |
Science > Physics |
| User: |
"Ian Stirling" |
| Date: |
08 Jan 2005 01:07:02 PM |
| Object: |
Sensing position of bone under flesh. |
I'm wondering how I might make an arm brace, to unload the elbow joint
(for example), and allow use of the arm, when the joint is in poor
condition.
However it's obvious that I need a way to sense the position of the bones.
CAT/NMR/... are of course practically useless.
So, I need to localise the bones under the skin in order to check they are
not stressing the joint.
Neglecting the risks of the actuators pulling the arm off, is there a
better way to do this than several 'simple' 1d ultrasound scanners?
.
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| User: "Andy Resnick" |
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| Title: Re: Sensing position of bone under flesh. |
10 Jan 2005 08:12:57 AM |
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Ian Stirling wrote:
I'm wondering how I might make an arm brace, to unload the elbow joint
(for example), and allow use of the arm, when the joint is in poor
condition.
However it's obvious that I need a way to sense the position of the bones.
CAT/NMR/... are of course practically useless.
So, I need to localise the bones under the skin in order to check they are
not stressing the joint.
Neglecting the risks of the actuators pulling the arm off, is there a
better way to do this than several 'simple' 1d ultrasound scanners?
Is this a different concept from leg braces used when someone blows out
a knee? For example:
http://www.atnrc.org/r+d/rd_adl/compbrace/brace.jpg
I think the idea there is to simply wrap parts around the upper and
lower leg, and connect the two with a metal brace, thus loading the
brace and not the knee. It's not clear why you need to know the
positions of the bones. I don't know if the loads experienced by the
elbow joint are entirely dissimilar to that of a knee.
More details would help- timescales, lengthscales, type of injury being
repaired, etc. etc.
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
CWRU School of Medicine
tanspose 'op' for mail
.
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| User: "Ian Stirling" |
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| Title: Re: Sensing position of bone under flesh. |
10 Jan 2005 09:01:07 AM |
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Andy Resnick <axr67@op.cwru.edu> wrote:
Ian Stirling wrote:
I'm wondering how I might make an arm brace, to unload the elbow joint
(for example), and allow use of the arm, when the joint is in poor
condition.
However it's obvious that I need a way to sense the position of the bones.
CAT/NMR/... are of course practically useless.
So, I need to localise the bones under the skin in order to check they are
not stressing the joint.
Neglecting the risks of the actuators pulling the arm off, is there a
better way to do this than several 'simple' 1d ultrasound scanners?
Is this a different concept from leg braces used when someone blows out
a knee? For example:
http://www.atnrc.org/r+d/rd_adl/compbrace/brace.jpg
I think the idea there is to simply wrap parts around the upper and
lower leg, and connect the two with a metal brace, thus loading the
brace and not the knee. It's not clear why you need to know the
positions of the bones. I don't know if the loads experienced by the
elbow joint are entirely dissimilar to that of a knee.
More details would help- timescales, lengthscales, type of injury being
repaired, etc. etc.
I'm wondering about alleviating arthritus (sp?) in the joint.
The point is that unless you know the load on the joint (which is possible,
but would be a bit more invasive as it'd need a force measuring glove/shoe.)
the best you can do is to support the flesh so that it unloads the joint
at a given force.
And even then, fitting will be very critical.
If you could measure the position of the bones, then you could do a little
better, as you can keep the joint so that the bones almost touch, over
a range of loads.
.
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| User: "Andy Resnick" |
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| Title: Re: Sensing position of bone under flesh. |
10 Jan 2005 01:57:55 PM |
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Ian Stirling wrote:
Andy Resnick <axr67@op.cwru.edu> wrote:
Ian Stirling wrote:
I'm wondering how I might make an arm brace, to unload the elbow joint
(for example), and allow use of the arm, when the joint is in poor
condition.
However it's obvious that I need a way to sense the position of the bones.
CAT/NMR/... are of course practically useless.
So, I need to localise the bones under the skin in order to check they are
not stressing the joint.
Neglecting the risks of the actuators pulling the arm off, is there a
better way to do this than several 'simple' 1d ultrasound scanners?
Is this a different concept from leg braces used when someone blows out
a knee? For example:
http://www.atnrc.org/r+d/rd_adl/compbrace/brace.jpg
I think the idea there is to simply wrap parts around the upper and
lower leg, and connect the two with a metal brace, thus loading the
brace and not the knee. It's not clear why you need to know the
positions of the bones. I don't know if the loads experienced by the
elbow joint are entirely dissimilar to that of a knee.
More details would help- timescales, lengthscales, type of injury being
repaired, etc. etc.
I'm wondering about alleviating arthritus (sp?) in the joint.
Ah... my (limited) understanding of rheumatoid arthritis is that it is
an inflammation of the synoviums (synovii?) which surround the bone.
Osteoarthritis is a degenerative cartilage dsease, and occurs when bone
rubs against bone. ("A crunching or grating sound is heard"... yummy!).
Unloading the joint won't reverse the disease. It may help relieve
pain, however.
The point is that unless you know the load on the joint (which is possible,
but would be a bit more invasive as it'd need a force measuring glove/shoe.)
the best you can do is to support the flesh so that it unloads the joint
at a given force.
And even then, fitting will be very critical.
Most of the bone loading/unloading studies I have seen are, IMHO,
suspect. Typically, the investigator doesn't mention that if one side
of the bone is in compression, the other side is in tension.
Questions about "neutral lines", surfaces of zero strain, are met with
deer-in-the-headlights looks. There are lots of studies using rats.
A quick search of PubMed (the most amazing site ever!)
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi
using the search terms "bone loading joint elbow" turned up 48
articles. Good luck!
If you could measure the position of the bones, then you could do a little
better, as you can keep the joint so that the bones almost touch, over
a range of loads.
I'm not sure, but I think the preferred mode of treatment, once the
disease gets that bad, is to simply replace the joint with an artifical
one. Cadavers are a rich source of cartilage, and I know a couple of
people who got new cartilage in their knees (younger people, thrashed
their knees due to competetive swimming). Now that you mention it,
almost all of the arthritis stuff I hear about is in regards to knees or
fingers.... I wonder how much a problem elbow degeneration is.
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
CWRU School of Medicine
tanspose 'op' for mail
.
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| User: "tj Frazir" |
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| Title: Re: Sensing position of bone under flesh. |
10 Jan 2005 09:29:51 AM |
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Oh , put slots where the joint nuts go and put the brace on the arm
wile the nuts are not tite.
Move the arm and the motion will center the joint pivit position.
Once the arm swings in and out without moving thenut positon ,,then
titen it.
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| User: "tj Frazir" |
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| Title: Re: Sensing position of bone under flesh. |
10 Jan 2005 09:24:33 AM |
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Wile you sit ..
ok,, counterweight your for'arm .
mke your arm near weightless by wire and counterweight to a sling.
Add or take wieghts off till you get the comfort you want.
Put a pully in the overhead anywhere you spend allot of time.
Slide a rod up on the back side of your wheel chair. .Counterwhieght
your arm so you can still use it .
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