Summary: Total surface bearing (TSB) / Hydrostatic sockets
Charles King
Description
Collection
Title:
Summary: Total surface bearing (TSB) / Hydrostatic sockets
Creator:
Charles King
Date:
1/13/2006
Text:
Thanks to all who have responded. I apologize that I just haven’t had
time this week to send a personal and individual thank you for your efforts.
These are great responses, thanks again - CK
Original question submitted to the list:
Can someone explain to me the technical definition of both the TSB
socket and the Hydrostatic socket? I know that a Hydrostatic socket is
a TSB design but I am not sure exactly what differentiates a TSB socket from
a Hydrostatic socket. Might it be in the way the cast is molded, namely
under vacuum or pressure? You help in clearing up this matter is greatly
appreciated.
Response #1
A total surface bearing socket was defined by UCLA in a special course
when they gave them that all surfaces recieved pressure except for all the
hard sharp areas, and then they got very little relief since the other areas
were pressured by the modification applying a negative pressure so there was
very little adding of any plaster build-ups. This technique could be
successful with a hard socket, then it went to include flexible liners, and
suction. What-ever you get the picture. Hydrostatic liners I believe especially
pertained to gel liners in that the tissues of the residual limb is
suspended in a total surface system that is more fluid. In reference
to orthotics we figure that BOBS or Anterior Overlap braces are also
hydrostatic since we are using compression against the abdomen / skeletal
area trapped in a shell. Hope this helps
Response #2
Good question. I believe they are one and the same.
Response#3
Since I am credited with coining the phrase Total-Surface-Bearing [TSB]
to below-knee socket design, I defined the term TSB in many references-
lectures, papers, and text books [see following book references:
[**Below ]
I define TSB as the condition brought about when the entire surface of
the residual-limb is in total contact with socket while every unit area is
under compression to its proportionate tolerable level.
Hydrostatic refers to the properties of fluids under pressure or when
fluids are in equilibrium. A more appropriate term might be hypobaric = this
term refers to pressure of ambient gases below one atmosphere. The air
surrounding the residual-limb while in a socket incorporating a vacuum
pump or valve creates a condition that could be described as hypobaric. I
use this term when I discuss the use of the roll-on-suction-socket (a
misnomer- the liner is NOT a socket!). However, I use the term HSI
(Hypobaric cushion & Suspension Interface) because it describes the
condition of air between the residual-limb and the liner - thereby
creating a suspensory function. This I feel is an appropriately generic term
that describes the function of the liner in Prosthetics.
**(1)HAIMOVICI'S VASCULAR SURGERY (2nd Edition 1984,
Appleton-Century-Crofts/Norwalk, Connecticut), (3rd Edition 1989,
Appleton& Lange, Norwalk, Connecticut), (4th Edition 1996, Blackwell
Science) the Chapter titled, PROSTHETICS for LOWER LIMB AMPUTEES,
and in(2) LOWER EXTREMITY AMPUTATION, Wes Moore & Jim Malone, 1989, Chaptertitled, NEW DEVELOPMENTS in PROSTHETICS
I hope this helps you a little.
Jan Stokosa, C.P. (name included here with permission)
Response #4
According to Tim Staats original TSB paper, The UCLA Total Surface
Bearing Suction Below-Knee Prosthesis, the total surface bearing below-knee
prosthesis weight is distributed over the entire surface of the residual
limb, including areas which have in the past been considered pressure
sensitive. In TSB, the accuracy of fit and careful use of measurements
has eliminated the need for relief buildups over bony areas of the residual
limb during the plaster cast and model modification procedures. The
resulting corrected model for a TSB socket is thus distinctly different from the
developed in accordance with PTB modification techniques.
Response #5
In my opinion there is a quit a difference between Total surface
bearing(TSB) / Hydrostatic sockets.-TSB socket is what the name says
and the easiest way to achieve this kind of socket is by vacuum casting. The
problem with this type of socket is that if reduction or re-moulding is not
done the bone end will hit the bottom ofthe socket. Later Carl Caspers
introduced the total reduction of the cast by 5-6% to get it more floating when
using the TEC liner. (In my opinion a hand made pressure cast, worked out in a
different way...)
-Hydrostatic socket (later named a semi-hydrostatic socket because the
fluid in side of the residual limb is not constant) or better descript as
Total surface bearing pressure cast socket comes from the original Iceross
concept by Össur Kristinsson. The only equipment that has been on the
market to be able to perform this type of casting is the IceCast tool. You
need to pre stretch the soft tissue with a well fitted liner that counteract
any further elongation before you cast the limb, this to be able to use
enough pressure during the casting. Otherwise the risk is that you get an
elongation of the cast that will create problem for the user.
I have used this equipment for casting and manufacturing of sockets
(incl. the ICEX socket) since it came on the market (12 or 14 years ago) for
all my patients. I do recommend it as a helpful tool although like any other
way in making a good socket you need to practice before you get the sense of
secure with it.
Response #6
The way it was explained to me when I attended school at
UT-Southwestern six or seven years ago, is that a hydrostatic socket is conceptually
solidifying the residual limb into one mass. I think of this like the contours of
a cast taken under vacuum or Iceross's ICEX system. Theoretically, there is
equal pressure throughout the socket.
TSB is conceptually socket contours without the reliefs and depressions
of a PTB design. The cast of a TSB is modified by reducing the positive
model globally. Theoretically, pressure may not be distributed equally
throughout the socket, but the gel liner could cold flow out of high pressure
areas. A total contact socket may include slight reliefs for boney
prominences, only enough to reduce pressure, but not so much to create a lack of
contact.
Response #7
There may be a confusion of terms. One may refer to a socket as
hydrostatic as well as to a casting technique as in hydrostatic casting. It is my
understanding that hydrostatic socket is a socket that utilizes a liner
whose gel has flowing characteristics, that way the pressure on the
surface of the residual limb will be uniform regardless of minor volume
fluctuations. Scientifically speaking a socket cannot be hydrostatic as
this term implies a closed (sealed) system. To be correct, one must call
such a socket quasi-hydrostatic. On the other hand I have made TSB sockets
WITHOUT any gel liners using hydrostatic casting technique.
---------------------------------
Yahoo! Photos – Showcase holiday pictures in hardcover
Photo Books. You design it and we’ll bind it!
time this week to send a personal and individual thank you for your efforts.
These are great responses, thanks again - CK
Original question submitted to the list:
Can someone explain to me the technical definition of both the TSB
socket and the Hydrostatic socket? I know that a Hydrostatic socket is
a TSB design but I am not sure exactly what differentiates a TSB socket from
a Hydrostatic socket. Might it be in the way the cast is molded, namely
under vacuum or pressure? You help in clearing up this matter is greatly
appreciated.
Response #1
A total surface bearing socket was defined by UCLA in a special course
when they gave them that all surfaces recieved pressure except for all the
hard sharp areas, and then they got very little relief since the other areas
were pressured by the modification applying a negative pressure so there was
very little adding of any plaster build-ups. This technique could be
successful with a hard socket, then it went to include flexible liners, and
suction. What-ever you get the picture. Hydrostatic liners I believe especially
pertained to gel liners in that the tissues of the residual limb is
suspended in a total surface system that is more fluid. In reference
to orthotics we figure that BOBS or Anterior Overlap braces are also
hydrostatic since we are using compression against the abdomen / skeletal
area trapped in a shell. Hope this helps
Response #2
Good question. I believe they are one and the same.
Response#3
Since I am credited with coining the phrase Total-Surface-Bearing [TSB]
to below-knee socket design, I defined the term TSB in many references-
lectures, papers, and text books [see following book references:
[**Below ]
I define TSB as the condition brought about when the entire surface of
the residual-limb is in total contact with socket while every unit area is
under compression to its proportionate tolerable level.
Hydrostatic refers to the properties of fluids under pressure or when
fluids are in equilibrium. A more appropriate term might be hypobaric = this
term refers to pressure of ambient gases below one atmosphere. The air
surrounding the residual-limb while in a socket incorporating a vacuum
pump or valve creates a condition that could be described as hypobaric. I
use this term when I discuss the use of the roll-on-suction-socket (a
misnomer- the liner is NOT a socket!). However, I use the term HSI
(Hypobaric cushion & Suspension Interface) because it describes the
condition of air between the residual-limb and the liner - thereby
creating a suspensory function. This I feel is an appropriately generic term
that describes the function of the liner in Prosthetics.
**(1)HAIMOVICI'S VASCULAR SURGERY (2nd Edition 1984,
Appleton-Century-Crofts/Norwalk, Connecticut), (3rd Edition 1989,
Appleton& Lange, Norwalk, Connecticut), (4th Edition 1996, Blackwell
Science) the Chapter titled, PROSTHETICS for LOWER LIMB AMPUTEES,
and in(2) LOWER EXTREMITY AMPUTATION, Wes Moore & Jim Malone, 1989, Chaptertitled, NEW DEVELOPMENTS in PROSTHETICS
I hope this helps you a little.
Jan Stokosa, C.P. (name included here with permission)
Response #4
According to Tim Staats original TSB paper, The UCLA Total Surface
Bearing Suction Below-Knee Prosthesis, the total surface bearing below-knee
prosthesis weight is distributed over the entire surface of the residual
limb, including areas which have in the past been considered pressure
sensitive. In TSB, the accuracy of fit and careful use of measurements
has eliminated the need for relief buildups over bony areas of the residual
limb during the plaster cast and model modification procedures. The
resulting corrected model for a TSB socket is thus distinctly different from the
developed in accordance with PTB modification techniques.
Response #5
In my opinion there is a quit a difference between Total surface
bearing(TSB) / Hydrostatic sockets.-TSB socket is what the name says
and the easiest way to achieve this kind of socket is by vacuum casting. The
problem with this type of socket is that if reduction or re-moulding is not
done the bone end will hit the bottom ofthe socket. Later Carl Caspers
introduced the total reduction of the cast by 5-6% to get it more floating when
using the TEC liner. (In my opinion a hand made pressure cast, worked out in a
different way...)
-Hydrostatic socket (later named a semi-hydrostatic socket because the
fluid in side of the residual limb is not constant) or better descript as
Total surface bearing pressure cast socket comes from the original Iceross
concept by Össur Kristinsson. The only equipment that has been on the
market to be able to perform this type of casting is the IceCast tool. You
need to pre stretch the soft tissue with a well fitted liner that counteract
any further elongation before you cast the limb, this to be able to use
enough pressure during the casting. Otherwise the risk is that you get an
elongation of the cast that will create problem for the user.
I have used this equipment for casting and manufacturing of sockets
(incl. the ICEX socket) since it came on the market (12 or 14 years ago) for
all my patients. I do recommend it as a helpful tool although like any other
way in making a good socket you need to practice before you get the sense of
secure with it.
Response #6
The way it was explained to me when I attended school at
UT-Southwestern six or seven years ago, is that a hydrostatic socket is conceptually
solidifying the residual limb into one mass. I think of this like the contours of
a cast taken under vacuum or Iceross's ICEX system. Theoretically, there is
equal pressure throughout the socket.
TSB is conceptually socket contours without the reliefs and depressions
of a PTB design. The cast of a TSB is modified by reducing the positive
model globally. Theoretically, pressure may not be distributed equally
throughout the socket, but the gel liner could cold flow out of high pressure
areas. A total contact socket may include slight reliefs for boney
prominences, only enough to reduce pressure, but not so much to create a lack of
contact.
Response #7
There may be a confusion of terms. One may refer to a socket as
hydrostatic as well as to a casting technique as in hydrostatic casting. It is my
understanding that hydrostatic socket is a socket that utilizes a liner
whose gel has flowing characteristics, that way the pressure on the
surface of the residual limb will be uniform regardless of minor volume
fluctuations. Scientifically speaking a socket cannot be hydrostatic as
this term implies a closed (sealed) system. To be correct, one must call
such a socket quasi-hydrostatic. On the other hand I have made TSB sockets
WITHOUT any gel liners using hydrostatic casting technique.
---------------------------------
Yahoo! Photos – Showcase holiday pictures in hardcover
Photo Books. You design it and we’ll bind it!
Citation
Charles King, “Summary: Total surface bearing (TSB) / Hydrostatic sockets,” Digital Resource Foundation for Orthotics and Prosthetics, accessed November 23, 2024, https://library.drfop.org/items/show/226082.
