Wrist alignment responses

Wrist alignment responses

Landry

8/13/1998

Dear all,

A while ago I posted a request for opinions on wrist alignment for below
elbow prostheses. I would like to thank all those who quickly responded.
Your input has been very helpful. I've attached the responses to this
letter for everyone to see.

Thanks again,
john

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 John Landry <Email Address Redacted>
 Institute of Biomedical Engineering Phone: (506)453-4966
 University of New Brunswick Fax : (506)453-4827





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From <Email Address Redacted> Wed Apr 22 11:43:45 1998
Subject: Re: Prosthetic wrist alignment
Dear John,

Wrist alignment for any prosthesis, especially a myoelectric one should be
determined in an expedited fitting, specifically during the dynamic alignment
phase. Having fit thousands of myoelectric prostheses of all levels and
contralateral involvements in my career, I have found that separating a
fitting into 3 distinct phases provides the best results.

The first phase is the Interface Phase which includes casting, fitting
multiple diagnostic sockets with static and dynamic evaluation, harnessing,
and weight application for suspension evaluation. Once the first phase is
completed the Electronic Phase occurs, As its name implies, electrodes are
mounted in the diagnostic interface and EMG evaluation both statically and
dynamically occurs. The components ( electric hand, myo controller, ect.) are
then connected and initial adjustments take place. Verification of components
function at this point will save many hours of frustration after the fitting
and should always occur prior to fabrication.

The last phase called the Alignment Phase includes duplication of the
contralateral limb alignment in a static relax stance. Once alignment lines
are marked on the diagnostic interface a dynamic thermoplastic frame can be
attached that includes a wrist lamination collar. The wrist is then assembled
with or without an electric wrist rotator, a hand attached and the final
dynamic alignment occurs that includes a functional analysis, does patient
have ability to get to mouth and other tasks specific to the goals of that
patient. If limitations occur due to alignment the thermoplastic frame can be
heated and alignment changes can be made. The last aspect of the Alignment
Phase is the component site selection. This determines the best location for
controllers, batteries, etc., taking into account cosmetic, fabrication,
maintenance and functional issues.

I am sorry that there is not the standard 10 degree wrist flexion calculation
that many of us learned in school, but each patient is unique and so are their
wrist alignments.

Sincerely,

John M. Miguelez, CP
President, Advanced Arm Dynamics
Specializing in Upper Extremity Prosthetic Services Worldwide


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From <Email Address Redacted> Wed Apr 22 17:27:03 1998
Subject: Re: Prosthetic wrist alignment

Dear Mr.Landry,

I use a body powered unit with a FM quick disconnect wrist and a Seirra Flex-
after many body powered units, I found this the best combination.

Most of the time, however, I use my myo units. My first was a wrist disartic
which could be manually rotated not quite 360. A revision necessated a new
unit. I went with the Procontrol/electric wrist unit. I have built a flex
wrist for one (manually set)-the other is standard. Having talked to several
myo users it seem that mounting the hand/wrist assy. in line is more practical
then using a slight flex, unless the patient is a very short be or bilateral.
I also strongly reccommend that mounting system other than the elbow cup be
used, as this system is a source of irratation.

I'm not a CPO-just a user.

John Meyer
The Worlds Only Living Kit


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From <Email Address Redacted> Thu Apr 23 03:30:14 1998
Subject: Re: Prosthetic wrist alignment

Dear John,

> What angles are currently being used by prosthetists? I understand =
that it
> can depend greatly on the patient's personal needs, as well as on the
> particular prosthetist's training.

A while ago I posted a very similar question to OANDP-L - the summary =
can be found in=20
the OANDP-L archives.
I let it speak for itself - please write back if you want to discuss the =
topic
further.

Regards,
Oyvind Stavdahl (Siv.ing., Dr.ing. student)
Department of Engineering Cybernetics=20
NTNU, The Norwegian University of=20
Science and Technology Direct line: +47 73 59 43 77
O. Bragstads plass 8 Switchboard: +47 73 59 43 76
N-7034 TRONDHEIM Fax: +47 73 59 43 99
NORWAY Email: <Email Address Redacted>
<URL Redacted>


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From <Email Address Redacted> Thu Apr 23 05:23:42 1998
Subject: Re: Prosthetic wrist alignment

Dear John

I've also been looking for recent information on wrist angles, but couldn't
find it. However, I do know the name of that manual from the fifties you
mentioned. It's about the properties of human limbs and body-powered
prostheses only, but might still be of interest to you.
The name of the book is:

'Human limbs and their substitutes'
by Paul E. Klopsteg and Philip D. Wilson
Originally published 1954
Reprinted 1968
Printed and published by:
HAFNER PUBLISHING COMPANY
31 East 10th Street
New York, N.Y. 10003
(Library of Congress Catalog Card Number 68-59325)

Good luck on your research!

Hans de Visser
Student at the Delft University of Technology, The Netherlands


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From <Email Address Redacted> Thu Apr 23 10:40:05 1998
From: Stephen Naumann < <Email Address Redacted> >
Subject: Re: Prosthetic wrist alignment

John:

We use the OMNI wrist from VASI, which allows the user to adjust wrist
alignment to suit different tasks as needed.

Stephen Naumann, Ph.D., P.Eng
Director Associate Professor
Rehabilitation Engineering Institute of Biomedical Engineering
Department Rosebrugh Building
Bloorview MacMillan Centre 4 Taddle Creek Road
350 Rumsey Road Toronto, Ontario
Toronto, Ontario M5S 1A4
M4G 1R8

Telephone: (416) 424-3861 Fax: (416) 425-1634
e-mail: <Email Address Redacted>
or
<Email Address Redacted>


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From <Email Address Redacted> Tue Apr 28 21:15:34 1998
Subject: Re: Prosthetic wrist alignment

In a message dated 4/22/98 7:15:30 AM, you wrote:

<<I'm currently doing some research on the angles (flexion/extension, and
ulnar/radial deviation) used when aligning a myoelectric hand to the
forearm. This assumes the wrist used is at a fixed angle, and may or may
not have rotation.

I've heard of a manual (published back in the fifties?) which gives
guidelines for wrist alignment, but that only considers body-powered TD's.
Is there a more recent set of guidelines available?

What angles are currently being used by prosthetists?>>

John Landry <Email Address Redacted>

We find that for almost every UNILATERAL myoelectric hand wearer, we prefoer
to EXTEND the quick disconnect wrist 10 to 15 degrees. This positions the
opening of the hand such that there is direct entry to the palm when reaching
for an object, e.g., a can, bottle cup, etc. without the need for extreme
shoulder abduction and external rotation.

On BILATERALs, we prefer to use the Otto Bock ball & socket wrist, even with
electric hand as it allows for any type of flexion or extension.

Feel free to communicate further if desired.

JTA

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