Summary: Prosthesis wrist alignment
Oyvind Stavdahl
Description
Collection
Title:
Summary: Prosthesis wrist alignment
Creator:
Oyvind Stavdahl
Date:
11/12/1997
Text:
Dear OANDP-L'ers,
I wish to thank the following persons:
Steve Childs ( <Email Address Redacted> )
J. Thomas Andrew ( <Email Address Redacted> )
who kindly responded to my query on wrist alignment.
Below is my original question and the two replies
(in full because there are only two of them).
Interstingly, Childs and Andrew report opposite opinions and
practice with respect to wrist alignment in that one uses
10 degrees of more of wrist EXTENSION in order to facilitate
grasping (Andrew), while the other uses light ULNAR DEVIATION
in order to put the terminal device closer to the table top etc.,
and FLEXION in order to easily reach the mouth (Childs).
From these two replies, therefore, there seemes to be a discrepancy
between different prosthetists and fitting centres with respect to
wrist alignment.
Tomm Kristensen, CPO, who fits more than half of all upper-limb
prostheses in Norway, tells me he uses slight ulnar deviation and
flexion of reasons similar to those reported by Childs. He adds
that occationally he has fitted prostheses with the wrist slightly
extended. Male amputees have reported that people around them
perceive such prostheses as feminine-looking, and thus ask the
prosthetist to redo it with a straight or flexed wrist. So apparently
there are cosmetic reasons for flexing as opposed to extending.
I welcome further comments on this issue, but conclude that
no particular static wrist posture is The Appropriate One for
upper-limb prostheses.
Sincerely,
Oyvind Stavdahl (Siv.ing., Dr.ing. student)
Department of Engineering Cybernetics
NTNU, The Norwegian University of
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>
------------- Original Query -------------
Dear all,
I am currently looking at wrist alignment in upper-limb
prostheses. A rather old reference (Manual of Upper-Ext.
Prosthetics, UCLA, 1958) suggests certain angles for
ulnar deviation and flexion, but I have been unable to find
more recent publications.
It would be interesting to know your personal opinion on
this issue - at what angle should the wrist be set, and
why (functional and/or cosmetic reasons)? To the extent
that it matters, I am mostly concerned with transradial
amputations and cosmetic/electric hands.
Furthermore I'd be very thankful for references to more
recent literature on this subject, in particular any
publication that builds on actual studies rather than
just expert opinions.
The responses will be compiled and posted as always.
------------- Responses -------------
From: <Email Address Redacted>
Oyvind--
Over 70% of my practice is upper limb prosthetics with a specialty in
externally powered systemms. I worked for the Utah Arm guys for many many
years and helped design and teach the fitting methods used with it.
With respect to hands:
Nearly all prosthetic hands, electric or otherwise, are built nearly the same
way--the back of the hand is in a straight line with the back of the forearm.
This already creates an un-ergonomic alignment requiring the amputee to use
enormous amounts of shoulder movement to achieve grip. Conventional wisdom
(and UCLA's instuctions) recommend some significant amount of wrist flexion
in addition. While this may be somewhat useful in some cases where a hook
type terminal device is used, it only serves to make the functionality of a
hand worse.
In almost every case we fit here in Salt Lake City, the wrist is EXTENDED 10
or more degrees to allow the plam of the open prosthetic hand DIRECT access
to the object being grasped. Observe how you reach out for a glass of water
or a cup. The back of the hand easily creates a 45o angle with the back of
the forearm!!!
Feel free to contact me directly to discuss this issue further.
J. Thomas Andrew, CP
---------------------------------------
From: <Email Address Redacted> (Steven Childs)
Dear Oyvind,
The wrist angle deviations suggested by the old UCLA manual are still
very applicable today. As I learned it, the ulnar deviation put the
terminal device closer to the working surface or table top, and wrist
flexion made it easier to reach the mouth. I am not sure of the actual
angles in degrees, but they are minor. This how I acheive these setings.
After setting the wrist in the proper position accorrding to the
measurements and tracings, slightly tilt the wrist in the ulnar and
flexion deviation. I have never had any trouble with this technique.
Steve Childs
---------- The End ---------------------
I wish to thank the following persons:
Steve Childs ( <Email Address Redacted> )
J. Thomas Andrew ( <Email Address Redacted> )
who kindly responded to my query on wrist alignment.
Below is my original question and the two replies
(in full because there are only two of them).
Interstingly, Childs and Andrew report opposite opinions and
practice with respect to wrist alignment in that one uses
10 degrees of more of wrist EXTENSION in order to facilitate
grasping (Andrew), while the other uses light ULNAR DEVIATION
in order to put the terminal device closer to the table top etc.,
and FLEXION in order to easily reach the mouth (Childs).
From these two replies, therefore, there seemes to be a discrepancy
between different prosthetists and fitting centres with respect to
wrist alignment.
Tomm Kristensen, CPO, who fits more than half of all upper-limb
prostheses in Norway, tells me he uses slight ulnar deviation and
flexion of reasons similar to those reported by Childs. He adds
that occationally he has fitted prostheses with the wrist slightly
extended. Male amputees have reported that people around them
perceive such prostheses as feminine-looking, and thus ask the
prosthetist to redo it with a straight or flexed wrist. So apparently
there are cosmetic reasons for flexing as opposed to extending.
I welcome further comments on this issue, but conclude that
no particular static wrist posture is The Appropriate One for
upper-limb prostheses.
Sincerely,
Oyvind Stavdahl (Siv.ing., Dr.ing. student)
Department of Engineering Cybernetics
NTNU, The Norwegian University of
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>
------------- Original Query -------------
Dear all,
I am currently looking at wrist alignment in upper-limb
prostheses. A rather old reference (Manual of Upper-Ext.
Prosthetics, UCLA, 1958) suggests certain angles for
ulnar deviation and flexion, but I have been unable to find
more recent publications.
It would be interesting to know your personal opinion on
this issue - at what angle should the wrist be set, and
why (functional and/or cosmetic reasons)? To the extent
that it matters, I am mostly concerned with transradial
amputations and cosmetic/electric hands.
Furthermore I'd be very thankful for references to more
recent literature on this subject, in particular any
publication that builds on actual studies rather than
just expert opinions.
The responses will be compiled and posted as always.
------------- Responses -------------
From: <Email Address Redacted>
Oyvind--
Over 70% of my practice is upper limb prosthetics with a specialty in
externally powered systemms. I worked for the Utah Arm guys for many many
years and helped design and teach the fitting methods used with it.
With respect to hands:
Nearly all prosthetic hands, electric or otherwise, are built nearly the same
way--the back of the hand is in a straight line with the back of the forearm.
This already creates an un-ergonomic alignment requiring the amputee to use
enormous amounts of shoulder movement to achieve grip. Conventional wisdom
(and UCLA's instuctions) recommend some significant amount of wrist flexion
in addition. While this may be somewhat useful in some cases where a hook
type terminal device is used, it only serves to make the functionality of a
hand worse.
In almost every case we fit here in Salt Lake City, the wrist is EXTENDED 10
or more degrees to allow the plam of the open prosthetic hand DIRECT access
to the object being grasped. Observe how you reach out for a glass of water
or a cup. The back of the hand easily creates a 45o angle with the back of
the forearm!!!
Feel free to contact me directly to discuss this issue further.
J. Thomas Andrew, CP
---------------------------------------
From: <Email Address Redacted> (Steven Childs)
Dear Oyvind,
The wrist angle deviations suggested by the old UCLA manual are still
very applicable today. As I learned it, the ulnar deviation put the
terminal device closer to the working surface or table top, and wrist
flexion made it easier to reach the mouth. I am not sure of the actual
angles in degrees, but they are minor. This how I acheive these setings.
After setting the wrist in the proper position accorrding to the
measurements and tracings, slightly tilt the wrist in the ulnar and
flexion deviation. I have never had any trouble with this technique.
Steve Childs
---------- The End ---------------------
Citation
Oyvind Stavdahl, “Summary: Prosthesis wrist alignment,” Digital Resource Foundation for Orthotics and Prosthetics, accessed November 22, 2024, https://library.drfop.org/items/show/210123.
