Re: Total Surface Bearing Modifications
Raymond Francis
Description
Collection
Title:
Re: Total Surface Bearing Modifications
Creator:
Raymond Francis
Date:
2/27/2001
Text:
-----Original Message-----
From: Chet X Burdette [SMTP: <Email Address Redacted> ]
Sent: Friday, February 23, 2001 12:02 PM
In response to Chet's observations............. 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?
Mr. Burdette is technically correct. If accurately measured the socket
would be very slightly tighter at the bottom than at the top. Practically
speaking, I am not sure that is of any significance in terms of fitting and
patient comfort. When we fit our test sockets one of the questions we ask
every patient is, are they aware of any place in the socket that is tighter
than any other? When we are finished with the test fitting they can not
tell us of any place in the socket that is tighter than another. In a
successful fitting the patient is not aware of any place in the socket that
is carrying more weight then any other. To me this is the goal of a Total
Surface Bearing Socket.
In teaching this principal of fitting and socket fabrication we wanted to
come up with the simplest and easiest method to change most prosthetist
from the P.T.B. design (which does not provide longevity to our liners) to
the total surface bearing socket. It is ours, as well as other
prosthetist's experience that the total surface bearing socket does provide
the longevity that we were looking for. Having said that, we selected a
simple system that works very well for us. It is just a matter of removing
about 1/2 inch (and that number can vary from 3/8 to 3/4 of an inch
depending on different prosthetist) from the circumference for the positive
cast after it has been poured. We also suggest that the prosthetist can use
a percentage of between four to six percent. These variances are to allow
for the differences in casting tensions and techniques.
As we have studied the wear issues of the Alpha Liner we have found most of
the problems come from the distal section of the socket. Movement at the
bottom of the socket will cause early failure of the liner more than any
other single issue of the fit. Most of the soft tissue is also at the distal
end. In truth if this section ends up just a bit tighter than the proximal
section we don't think that is all too bad. You must remember, we are
talking about a very small amount.
All of these issues are discussed in length at the Alpha Liner seminars that
we offer to the prosthetist in the field. We also offer a video on the
subject. Certainly, the video does not go into the depth of detail that the
seminar covers. We strongly encourage any prosthetist that is using our
Alpha Liners to attend one of our seminars on the subject.
I have read the responses from Mr. McFarland's post. I have to agree with
some of the responses that suggest you should cast over the liner that you
are going to use on the patient. If you use a substitute of some sort you
are not going to get the best results. Cast modification time for me is
down to less then ten minutes. I really think we are getting ourselves in
trouble if we keep trying to second guess the simple system. I know that I
go on the road and cast and produce test sockets on people that I have never
seen before. I, in my opinion, end up with a socket that the test patients
say has and feels as though the pressures are evenly distributed to them.
I also feel that no system is designed to remove that talent and knowledge
of any experienced prosthetist. The suggestions that we make are to bring
you very close to a good fitting socket. You still have to fit the test
socket. You still have to be a prosthetist.
Raymond Francis, C.P.
Chief Prosthetist
The Ohio Willow Wood Co.
15441 Scioto Darby Road
Mt. Sterling, OH 43143
1-800-848-4930
From: Chet X Burdette [SMTP: <Email Address Redacted> ]
Sent: Friday, February 23, 2001 12:02 PM
In response to Chet's observations............. 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?
Mr. Burdette is technically correct. If accurately measured the socket
would be very slightly tighter at the bottom than at the top. Practically
speaking, I am not sure that is of any significance in terms of fitting and
patient comfort. When we fit our test sockets one of the questions we ask
every patient is, are they aware of any place in the socket that is tighter
than any other? When we are finished with the test fitting they can not
tell us of any place in the socket that is tighter than another. In a
successful fitting the patient is not aware of any place in the socket that
is carrying more weight then any other. To me this is the goal of a Total
Surface Bearing Socket.
In teaching this principal of fitting and socket fabrication we wanted to
come up with the simplest and easiest method to change most prosthetist
from the P.T.B. design (which does not provide longevity to our liners) to
the total surface bearing socket. It is ours, as well as other
prosthetist's experience that the total surface bearing socket does provide
the longevity that we were looking for. Having said that, we selected a
simple system that works very well for us. It is just a matter of removing
about 1/2 inch (and that number can vary from 3/8 to 3/4 of an inch
depending on different prosthetist) from the circumference for the positive
cast after it has been poured. We also suggest that the prosthetist can use
a percentage of between four to six percent. These variances are to allow
for the differences in casting tensions and techniques.
As we have studied the wear issues of the Alpha Liner we have found most of
the problems come from the distal section of the socket. Movement at the
bottom of the socket will cause early failure of the liner more than any
other single issue of the fit. Most of the soft tissue is also at the distal
end. In truth if this section ends up just a bit tighter than the proximal
section we don't think that is all too bad. You must remember, we are
talking about a very small amount.
All of these issues are discussed in length at the Alpha Liner seminars that
we offer to the prosthetist in the field. We also offer a video on the
subject. Certainly, the video does not go into the depth of detail that the
seminar covers. We strongly encourage any prosthetist that is using our
Alpha Liners to attend one of our seminars on the subject.
I have read the responses from Mr. McFarland's post. I have to agree with
some of the responses that suggest you should cast over the liner that you
are going to use on the patient. If you use a substitute of some sort you
are not going to get the best results. Cast modification time for me is
down to less then ten minutes. I really think we are getting ourselves in
trouble if we keep trying to second guess the simple system. I know that I
go on the road and cast and produce test sockets on people that I have never
seen before. I, in my opinion, end up with a socket that the test patients
say has and feels as though the pressures are evenly distributed to them.
I also feel that no system is designed to remove that talent and knowledge
of any experienced prosthetist. The suggestions that we make are to bring
you very close to a good fitting socket. You still have to fit the test
socket. You still have to be a prosthetist.
Raymond Francis, C.P.
Chief Prosthetist
The Ohio Willow Wood Co.
15441 Scioto Darby Road
Mt. Sterling, OH 43143
1-800-848-4930
Citation
Raymond Francis, “Re: Total Surface Bearing Modifications,” Digital Resource Foundation for Orthotics and Prosthetics, accessed November 2, 2024, https://library.drfop.org/items/show/215992.
