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Baramki, Hani
07-28-1995, 03:26 AM
Dear netters

a while ago I posted the following querry:


I am interested in measuring pressure in cadaveric intervertebral discs in an
effort to better understand disc pressure distribution. I am planning on
inserting a miniaturized strain gauge pressure sensor through a needle of no
more than 1 to 2 mm diameter. I have looked around in the catalogues that I
have but did not find any strain gauges small enough to fit through the
needle. Any advice or help would be most welcomed.
As is the custom, I will post a summary of all responses received.

So as promised here are the responses I received.
Thanks to all who answered. The information I received was very valuable.

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Dear Dr. Baramki;
I was surprised by your plan to insert a miniature pressure transducer
into IVD. It would be the simplest/easiest way to measure the IVD
pressure. However, the experimental artifact from inserting a foreign
structure into the tissue will be enormous. In fact, I have thought about
doing the same thing to measure the pressure within IVD, but gave up.
Anyhow, here is a company for the miniature pressure transducer;
Precision Measurement Company
P.O. Box 7676
Ann Arbor, MI 48107
Tel/Fax: 313-995-0041

If you receive any other suggestions from other netters, I will
appreciate if you post it later on.

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J.K. 'Francis' Suh, Ph.D.
Assist. Prof.
Dept. of Orthopaedic Surgery
Univ. of Pittsburgh
Pittsburgh, PA 15213
Tel: 412-648-1985
Fax: 412-648-2001
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Try Millar Instruments in Houston, Texas (800) 669-2343. Michelle White
is a clinical specialist who is very sharp. They have 2 and 3 french sizes
(1mm and .67 mm needels) Good Luck.
Michael Orendurff, Shriners Hospital, Portland, OR.



I get mine from a company called Gaeltec
Dunvegan
Isle of Skye
Scotland
IV55 8GU
Telephone +44-1470 521385

They have a U.S. agent Medical Measurements Inc.
53 Main Street
Hackensack
NJ 07601
Telepohone 201-489 9400
The transducer is validated in:

McNally,Donal Stewart; Adams,MA; Goodship,AE (1992): Development and
validation of a new transducer for intradiscal pressure measurement. J.
Biomed. Eng. 14, 495-498.

The technique for geting stress distributions is detailed in:

McNally,Donal Stewart; Adams,MA (1992): Internal disc mechanics as revealed
by stress profilometry. Spine 17, 66-73.
Other ineresting papers in the same series are:

McNally,Donal Stewart; Adams,MA; Goodship,AE (1993): Can intervertebral
disc prolapse be predicted by disc mechanics. Spine 18, 1525-1530.

Adams,MA; McNally,Donal Stewart; Chinn,H; Dolan,P (1994): Posture and the
compressive strength of the lumbar spine. Clin. Biomech. 9, 5-14.

Have fun!

Donal McNally

Donal McNally, Action Research Lecturer in Anatomy, Department of Anatomy
University of Bristol, Southwell Street, Bristol BS2 8EJ
D.S.McNally@bristol.ac.uk - Tel 0117-928 8349 - FAX 0117-925 4794
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Hani-
In my last employment with the Texas Back Institute Research
Foundation, we studied this same subject. We used Millar
Pressure Transducers to measure the intervertebral pressure
during flexion and extension. We were comparing the effects of
spinal instrumentation to disc pressure. We have published the
results:
"Intradiscal pressure measurements above an
instrumented fusion, A cadaveric study", Weinhoffer, Guyer,
Herbert, Griffith; Spine, Vol 20 No 5, 1995.

If you have any further questions, please e-mail me.
--
___________________
Susan L. Weinhoffer
slw2p@virginia.edu
___________________
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Hani,
Hello. In our lab, I have worked on taking IVD measurements from cadaver
specimens for the past two years. If you haven't already seen, I suggest
you look at the ORS Transactions for 1994 and 1995 and look under my name.
This will summarize the work we've been doing. In terms of a pressure
sensor, we purchased ours from Precision Measurement Co in Ann Arbor, MI.
The phone number is (313) 995-0041. There is also another company called
Medical Measurements Incorporated in Hackensack, NJ that we checked into.
They sell microtransducer catheters and the number is (201) 489-5723.

If you do not have access to the ORS Transactions, I can send you copies
via email. Also, I suggest you look at the work of Adams and Hutton as well
as Nachemson. If you have any questions, feel free to contact me.
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Dear Hani:

On page 10 - 12 of White and Punjabi's Clinical Biomechanics of the Spine
you will find a great review of this type work. In particular 3 papers in
which Nachemson and Morris measure IVD pressure via the nucleus. These are
all old papers and technology has changed alot, but they should be good
jumping off points. Hope this helps.

-Bob

-Nachemson A: Lumbar Interdiscal Pressure. Acta Orthop.Scand., 37:177, 1966
-Nachemson A: The Load on Lumbar Discs in Different Positions of the Body.
Clin. Orthop., 45:107, 1966
-Nachemson A and Morris JM: In Vivo Measurement of Interdiscal Pressure.
JBJS, 46:1077, 1964

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Hi, You might try contacting Dr Donal McNally who has worked in this field
recently and may have just the thing. He's in Bristol, UK: via
m.a.adams@bris.ac.uk.
Kim Burton, University of Huddersfield, UK
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Dear Hani,

The person who is the expert now is Donal McNally, University of
Bristol, UK.
from biomch-l list:
D.S.McNally@BRISTOL.AC.UK Donal S. McNally

Ian Stokes
University of Vermont, Department of Orthopaedics and Rehabil.
Burlington, VT 05405-0084, USA
Phone: (+1) 802 656 2250 fax: (+1) 802 656 4247
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My advisor informs me that there are commercial devices
available for that purpose. He believes that one of the makers
is Swedish. There have also been several papers written using
these types of devices. For instance,

McNally D., Adams M: Spine 17:66-73, 1992

I believe that this paper has some information, if not the authors
have used similar devices and described them in other papers.

Also, Adams, MA and Green, TP have an abstract in the 1994
Transactions of the Orthopaedic Research Society that may briefly
discuss such a device.

Good Luck!

Mark Miller
University of Vermont
Mechanical Engineering
119 Votey Building
Burlington, VT 05405
mmiller@emba.uvm.edu

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Interesting concept for studying intervertebral disc pressures, but how are
you
controlling for lack of movement, gravity and the loss of fluid that occurs
due
to tissue death? In addition, fluid mobilization within the disc will be nil
as all mechanism of fluid mobility will have ceased.
Cheers!
Mike Poling, H.B.P.E., M.Sc.(Kin.), C.F.A.
Canadian Back Institute/Lakehead University
Thunder Bay, Ontario, Canada
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You might want to contact Steve Arms, MicroStrain Co., in Burlington,
VT. I used to do some work with him when he was first working on Hall
Effect sensors. Since that time he has developed (apparently) some 1-2mm
cylindrical polyamide sensors that measure pressure by hoop stress. Good
luck!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~
Kimberly A. Dwyer, M.S. Clinical Mechanics Group
Dwyer@ME.QueensU.Ca Mechanical Engineering
Queen's University, Kingston, Canada
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~