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Timothy B F Woodfield
06-21-1996, 03:26 PM
A week ago I sent a message about measuring torque for wrist
extension and flexion, and methods of measurement via transducer or
EMG. Here is a summary of responses and many thanks to those who did
reply !!! I'll try reply back (but have exams at the moment).


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Date sent: Fri, 14 Jun 1996 00:39:01 -0700 (PDT)
From: kelvin@sfu.ca (Kelvin E. Jones)
Subject: Re: Wrist Extension
To: Timothy B F Woodfield

I've recently been reading a bunch of wrist biomechanics literature and
could pass on a number of references. As far as the joint rotations goes,
you can get a good model of flexion-extension about a single axis of
rotation (Sommer H.J. and Miller N.R, J Biomech Eng 102:311-317, 1980;
Brumbaugh R.B. et al., J Biomech Eng 104:176-181, 1982; Horii E. et al., J
Hand Surg 18A:83-90, 1993). Many of the biomechanical references that I've
been reading came from a great paper on estimation of muscle force from EMG
in the wrist by T.S. Buchanan et al., J Biomech 26:547-560, 1993. This group
also has another paper coming out in J Biomech on isometric moments
generated by wrist muscles (Delp, S.L., Grierson, A.E., and Buchanan, T.S. J
Biomech, in press).

Kelvin Edward Jones, Postdoctoral Fellow
Dept of Physiology, University of Goteborg
Medicinaregatan 11, 413 90 Goteborg, Sweden
tel: +46 31 773 35 02, fax: +46 31 773 35 12, email: kelvin@sfu.ca
Home Page: http://www.sfu.ca/~kelvin
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Date sent: Fri, 14 Jun 1996 10:02:10 -0500
From: anne@www.ortho.lsumc.edu (Anne Hollister, MD)
Subject: Re: Wrist Extension
To: Timothy B F Woodfield

The Greenleaf Medical Co, Palo Alto, Ca has a very simple glove which uses
strain guages to measure wrist position. The device can be coupled with
EMG recorders if necessary, and has been used in evaluation and treatment
of rehab patients with paralysis and in ergonomic evaluation in the
workplace. Ed Klinenberg did his PhD dissertation at UC Berkeley using the
device in the workplace.

The engineer is Stuart Rothenberg.
Address 3145 Porter Drive, Building A202
Palo Alto, California 94304
(415) 843-3640

Anne Hollister, MD
LSUMC-S / Orthopaedic Surgery
1501 Kings Hwy.
Shreveport, LA 71130-3932
email: anne@www.ortho.lsumc.edu

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Date sent: Fri, 14 Jun 1996 14:12:29 -0500 (EST)
From: "Robert Streb [Health Technology]"
Subject: Re: Wrist Extension
To: WOODFITB@cad.canterbury.ac.nz
Organization: SUNY Stony Brook
Priority: normal

In response to your questions about wrist flex and ext. When
measuring those motions in the clinic the triquetrum is the generally
accepted center where the axis is placed. There are rather complex
and accurate dynamometers that will measure torque at the major
joints. The reliability of these test has been in my experience
good (the literature supports this). If I am reading your note
correctly you are building a separate machine for these
motions. My point is it may be accurate enough to use the
triquetrum and the axis of motion. By the way there is some debate
as to the axis of motion, some texts do not agree with the ones you
have paraphrased.

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Date sent: Fri, 14 Jun 1996 15:03:58 +0800
From: iallison@info.curtin.edu.au (Garry Allison)
Subject: Re: Wrist Extension
To: Timothy B F Woodfield

Regarding EMG amplitude normalisation there is no clear cut answer. The
most common method used is the Maximal Isometric effort and this has
obvious advantages in interpretation of the data.... however.... recently
we have addressed similar issues to find:
i. MVIC is not as reliable as submaximal isometric contractions and they
not logistically possible in many clinical populations. (Last year at the
biomech Conference MVIC was recommended with the caveat that the individual
provided a reliable performance)
ii. Using isometric to normalise for other muscle actions particularly
within the SSC model may have limitations.
iii. Using the coefficient of variation of grouped data to justify the
validity of a normalisation technique can cause problems since you may be
removing a proportion of the biological difference. (aside- from the
experience of our most recent work in individuals with chronic low back
pain, the issue of the independence of the amplitude normalisation
technique from the testing task needs to be carefully scrutinised before
interpretation of the data analyses). Indeed using MVIC in one of our
experiments increased the variance in the data.
iv. By manipulating the variance in a population you may/will see a change
in the statistical power of your analysis. The difficulty lies in the
paradox between statitically significantly difference and the clinically
significant difference in the EMG signal amplitude.


Ref.(to others pending).
Allison, GT, Marshall, RN & Singer KP (1993) EMG signal Amplitude
Normalization Technique in Stretch-Shortening Cycle Movements. 3(4) 236 -
244.

The strength factor is difficult and really depends on how you want to use
your data. Using your case in C5-6 individuals then the influence of
'strength' on function is often a non linear association and commonly
demonstarted by a threshold effect. Make sure your assessment is sensitive
enough for the full range.

Hope this helps in some way.

Sorry Tim the Journal reference was "Journal of Electromyography and
Kinesiology"

Garry T Allison PhD. Lecturer,
School of Physiotherapy, email:iallison@info.curtin.edu.au
Curtin University of Technology, Tel. +61 9 351 3648
Selby Street, Shenton Park, Fax. +61 9 351 3636
Western Australia 6008
http://www.curtin.edu.au/curtin/dept/physio/pt/staff/allison/

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Date sent: Tue, 18 Jun 1996 02:03:05 +1200
From: kwa0913@acs.tamu.edu (Khaled Al-Eisawi)
Subject: RE: Wrist Extension
To: woodfitb@cad.canterbury.ac.nz


I read the note you posted on the Biomch-L. My masters thesis, which I
completed in May 1994 at Texas A&M University, was about wrist strength
limitations to manual exertion capability. I have a paper that is in review
at this time. Part of my experimental work was measuring wrist flexion and
wrist radial deviation strength at different wrist angle. I used the radial
styloid as an estimate for the center of rotation for the flexion tests.
For the radial deviation tests, I used the palpable groove between the
capitate and the lunate bone. A copy of the thesis is available through
interlibrary loan from Texas A&M University. The thesis title is:
"Evaluation of wrist strength limitations in two-dimensioanl biomechanical
modeling". Please feel free to contact me if I can be of further
assistance. Good luck with your work.

Khaled W. Al-Eisawi
Research Assistant
Safety Engineering Program
Texas A&M University
College Station, TX 77843-3133
USA
Phone: (409) 845-3545
Fax: (409) 845-6443
Email: eisawi@tamu.edu

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Date sent: Fri, 21 Jun 1996 13:27:57 -0700 (PDT)
From: Jeffrey Kumer
Subject: Re: Wrist Extension
To: Timothy B F Woodfield

Tim,
Unfortunately, there are no good methods to keep EMG readings
consistent between subjects. Each subjects will have differing skin
resistance and electrode placement on the muscle belly depending on how
the muscle has been developed. One way to compare between subjects that
I am doing in my thesis is to collect Maximal Voluntary Contractions of
each muscle that you are measuring with EMG. Then, you can normalize the
amount of voltage to that maximal voluntary contraction and get a
percentage of the electrical impulses being recorded by the electrodes.
You may want to look into the details of this method and do pilot work to
see if this is really going to work for you.
Good Luck!!!

Jeff Kumer
University of California, Davis
Exercise Science Department
(916) 752 - 3893
jlkumer@ucdavis.edu

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Date sent: Fri, 14 Jun 1996 08:45:40 -0600
From: tzipple@uomhs.edu
Subject: Wrist Extension -Reply
To: WOODFITB@cad.canterbury.ac.nz

Dear Tim,
This is just an idea, but could you develop a device
that measures flexion and extension seperately (ie.
measure strength of flexion from neutral to full flexion
and extension strength from neutral to full extension)?
If this device allows movement of the wrist and
forearm (slide up or down) for the appropriate axis of
rotation you could measure flexion strength and
extension strength seperately. Or could you develop a
device with two seperate rotation axes (one for flexion
and one for extension) where one axis could be
locked while you measure the appropriate motion?
I applaud you for your efforts. Calculating torque
from distance of center of rotation to grip is a difficult
task considering the changes in instantaneous axis of
rotation throughout the motion of the wrist. As with
many measurements made from joint centers in the
human body, there is seldom a best-fit.
I did my master's thesis on developing a method for
analyzing 3-D human wrist motion using a joint
coordination system at Michigan State University in
1989. I am interested in your developments and would
like to here back from you.

J. Tim Zipple PT, MS, OCS, OMPT
University of Osteopathic Medicine and Health Sci.
3200 Grand Ave.
Des Moines, IA, 50312
E-mail: tzipple@uomhs.edu

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Date sent: Mon, 17 Jun 1996 16:50:26 -0300 (BST)
From: Tim Adlam
Subject: Wrist Measurements
To: woodfitb@cad.canterbury.ac.nz

Tim,
I'm designing a dynamic wrist fixator and am an M.Sc. (Biomedical
Engineering) student at Surrey University in England.

To answer one of your questions,YES, there is a single centre of rotation
in a wrist. This is highly convenient for you and I.

It's just proximal to the proximal head of the capitate.
For references see trhe following as an excellent start. There aren't
many more worth looking at that I've found.

>Jackson et al. Determination of wrist kinematics using a magnetic
>tracking device. Medical Engineering and Physics. v16, p123-, March 1994
This one is very good. Excellent work and all the transformation matrices
are shown. GET IT!

>Youm et al. Kinematics of the wrist. An experimental study of
>radial-ulnar deviation and flexion-extension. Journal of Bone and Joint
>Surgery (American Volume). v60A, n4, p423-431, June 1978.
You'll like this one. It seems to be the first good work on the subject.
GET THIS TOO.

>de Lange et al. Kinematic behaviour of the human wrist joint: a
>roentgen-stereophotogrammetric analysis, Journal of Orthopaedic Research.
>v3, n1, 1985
This one is good as well.

Hope this helps.

I'm very interested in any information you have on wrist loadings re.
fixator stresses. I've had difficulty getting anything. Can you help?

The fixator is a frame attached externally across the joint via bone
screws in the radius and second metacarpal.

Can you help?

Thanks,
Tim Adlam.


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-=\ Tim Adlam
\ BioMedical Engineering
|| Surrey University
|| Guildford
|| SURREY
|| GU2 5XH
|\ \--/
\ \| |
\ / email: mem1ta@surrey.ac.uk
--- tel: (UK) 01483 568 394
(Int.) +44 1483 568 394

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Date sent: Mon, 17 Jun 1996 10:28:20 -0500
From: delp@casbah.acns.nwu.edu (Scott Delp)
Subject: Your biomech/l post: wrist strength
To: woodfitb@cad.canterbury.ac.nz

Tim,

I would be happy to send you a pre-print of our paper entitled: Maximum
isometric moments generated by the wrist muscles in flexion-extension and
radial-ulnar deviation. This paper addresses some of the issues you raised
in your email and will be published in the Journal of Biomechanics in the
next couple months. Please send me your physical mail address if you are
interested.

Scott Delp