Part 3 TSB Mod. Responses

Part 3 TSB Mod. Responses

Chet X Burdette

3/1/2001

Original Post:
The following is more of an observation than a question. I have always
believed that a TSB socket should distribute pressure evenly to the
entire surface of the limb. I usually do a x-percent (percent of the
measured circumfurence) over the entire mold top to bottom. The
percentage I take off depends on several factors including tissue density
and thickness/style of liner.
Anyway, it has always bothered me that OWW suggests you take off an even
.5inch or 13mm of circumference from the entire mold. This in most cases
doesn't result in even pressure distribution since most limbs taper in
size from top to bottom. For example removing that 13mm from a level on
the mold with a circ. of 34cm results in a 3.8% reduction in circ. Now
lets say this patient's limb tapers to a circ. of 29cm further down.
Removing 13mm at this level results in a 4.5% reduction of circumference.
 So wouldn't this modification produce a socket that was tighter at the
bottom than the top? Is this their intended result or just a result of
oversimplified instructions?
Chet Burdette CPO
Mountain State Prosthetics LLC
Charleston, WV
New Responses:
____________________
Hi Chet,
After reading all the postings regarding the modifications, I though that
I
would share with you some of my experiences.
I have been using Alpha liners for a few years now and for almost two
years
I have been casting exclusively with the Tracer CAD system. Using a
Narrow
MLsocket. The simplified method of casting is, first I take
circumferential
and ML measurements at about 9 points on a typical TT, the levels are
measured at measured distances from the distal end of the residuum. The
circumference measurements are take tight or tighter than I would take a
PTB
measurement, the ML measurements differ in tightness depending on the
position on the residuum. I then trace the residuum using the Tracer Cad
system, after tracing I resize the model back to my measurements.
This casting technique has worked very well, with minimal need to provide
a
second check socket ( only about 10 % need to have a second check
socket).
the sockets also are slightly tighter at the distal end , to allow for
more
of a plug fit in this area, this reduces pistoning in the socket and
ensures
a hydrostatic fit.
The Tracer allows me to feel the soft and hard areas of the residuum so
that
accurately I can exert more pressure on weight bearing areas and soft
tissue
and less pressure on bony prominences.
The rectification that I typically use is somewhere between an ICECAST
pressure cast shape and the traditional TT modifications, the ICECAST
casting does not give enough definition to control among other things
rotation, and the traditional TT modifications are too severe for Alpha
liners and are not necessary with the added benefits of casting under
compression from the Alpha liners combined with the casting technique
mentioned above.
Points to consider are that there are no reductions except to the actual
tight measurements. ( Tight being defined as when measuring the tape is
normally pulled tight then released then pulled tight again then released
to
the middle between loose and tight, this is the tight the tight that I
refer
to.) That a true total contact cast is produced and that there is little
negative displacement and control of rotation, total contact and
hydrostatic
fit.
Hope this helps
Gary Seaman
<Email Address Redacted>
<Email Address Redacted>
www.seamanpo.com
__________________________
Chet: Thanks for starting this discussion. I have a few thoughts to
contribute:
1) Modification is important, but ultimately the technique is secondary
in
importance to the test socket fitting process. The goal of the
modification
is to obtain the test socket; the goal of the test socket fitting is to
determine the appropriate socket contours. I think this was Mr. Francis'
point. Whatever actual differences in percentage reduction
proximal/distal
occur using OWW's technique is not really the point, if the end result in
the
test socket is appropriate.
2) I had tremendous problems with the Alpha liners blewing out until I
used OWW's modification technique. For over a year I recorded RL
measurements (over liner), un-modified mold measurements, and modified
mold
measurements. I also documented the problems in the test socket fittings
on
the same form. I have not done a detailed study of the numbers, but I
was
able to monitor my habits and results, and make some changes in how I
modify. One change, for instance, is that I flatten the popliteal area
more
to reduce rotation, since this was a consistent problem. Another was to
relieve the ADT slightly, as another respondant reported. This goes
along
with the other posts that discussed developing an individual style that
works.
3) My experience supports Mr. Francis' reports regarding failure at the
distal end of the liners. This may be due, in some cases, to normal,
non-uniform RL shrinkage. If the distal end reduces in size more than
the
proximal end, the addition of socks will be limited by proximal
tightness,
and yet will not adequately maintain contact on the distal end.
4) Related to this - I have observed that the gel material protects the
skin
so effectively from breakdown that some patients return after several
months
of excessive distal end contact with callousing on the distal tibia -
without
skin breakdown. In a pelite liner they would probably have felt the
distal
pressure sooner, and added socks or come in for an adjustment. I wonder
if
others have had this experience?
5) I recently obtained an Icecast system, and have provided several
socket
using that method. I have noticed that the proximal ML dimension of the
socket seems to be too large, and am planning on watching that more
closely.
I have been using the Iceross Dermo liners in an attempt to find a more
durable option to the Alpha, but maintain some of the Alpha's
characteristics.
6) The tendency in our profession to adapt any particular technique or
process to our own liking is a dynamic that I find interesting, humorous,
and
a little frustrating. If OWW had stated that the mold should be modified
following strict percentage reduction guidelines, my bet is that people
would
be writing you strongly in support of a universal 1/2 reduction - makes
it
simpler. It's amazing to me how may ingenious ways we come up with to
accomplish the same task - with many different ways to obtain a
successful
result. On the other hand, if we don't bother to follow the advice of
those
who developed the product (in whose best interest it is for us to be
successful in its use), should we be surprised if our results differ from
theirs?
7) I've given up my search for the perfect prosthetic system, although
I'm
still somewhat of a sucker for good marketing. I try not to dismiss any
of
the products or systems, and maintain some objectivity about what I'm
using.
Nothing works for everyone, which makes our job a lot more interesting!
John Brinkmann, CPO
________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today! For your FREE software, visit:
<URL Redacted>.

                          ********************
To unsubscribe, send a message to: <Email Address Redacted> with
the words UNSUB OANDP-L in the body of the
message.

If you have a problem unsubscribing,or have other
questions, send e-mail to the moderator
Paul E. Prusakowski,CPO at <Email Address Redacted>

OANDP-L is a forum for the discussion of topics
related to Orthotics and Prosthetics.

Public commercial postings are forbidden. Responses to inquiries
should not be sent to the entire oandp-l list.