Saturday, March 2, 2024

Updated responses to – Heat issues in sockets

Steve Middleton

Updated responses….
Thank you to those who took the time to respond.
The response has mostly been about patients dealing with sweat /perspiration issues, thankfully this has not been a concern for me. When I do get any perspiration I am easily able to drain it through the suction socket valve.

Posted Question –

To: [email protected]
Subject: [OANDP-L] Heat issues in sockets

I am in my early 50’s for 10 years I have been a very active above knee amputee.
I presently use a heat moulded thermoplastic suction socket, skin fit with no liner. To don the socket, I use the dry pull sock method. I do not require a belt even during high activity.

I cycle both road and mountain bike’s extensively and for the most part have very few issues on longer rides. Perspiration has not been a concern because I can drain the socket of moisture through the vacuum valve. Extreme heat, for example a climate of plus 86 deg F (30 deg C) and humidity does create great discomfort and redness then some swelling. Thus cooling is an issue.

What ideas or suggestions do any of you have for a way to keep this socket cooling during an activity period?
Is there possibly some new device / materials for such an application?

I do not wish to start wearing a sock or liner and realise some of these now have Thermodynamic properties.

Steve Middleton Ak amputee

– – Responses were……

Being from Florida I’m amused by your “Extreme” heat of 86, where do you live, the north pole?
The affect of the external environmental temperature is primarily on the rest of your body, not just the residuum. The higher the outside temp and humidity, the more difficult for the body to maintain its normal of 98.6.
The body is an efficient heat producing engine, the more activity the more heat must be dissipated. We keep cool by perspiration evaporating on the skin. The efficiency of this system depends on the surrounding temp and humidity relative to our core temp.
Unfortunately the materials we use to fabricate prosthetic systems are good insulators. The amputation results in a major decrease of skin surface area, couple this with the insulative properties of the prosthesis and its no wonder the residuum feels hot and overall perspiration increases.
Theoretically, the way to solve the problem is to design and fabricate the prosthetic interface of a material that is heat conductive, not insulative.
This means metal. Most metals are highly reactive with the body’s skin, salts, electrical charge, and pirspiration. Stainless and titanium come to mind as being good candidates. Aluminum may also be a candidate if an applied protective coating can be found that doesn’t lessen heat conductivity.
With the metal interface internal surface maintaining suspension vacuum, socket shape, and weight transfer, it is a simple task to design the outer interface surface and the rest of the prosthesis to dissipate the internal heat of the residuum.
For high activity, or “extreme” external temps, an auxiliary cooling system may be added, maintaining whatever residuum temp the wearer desires. This removable system must be part of the initial design and fabrication.
So far this has been rather simple and straight forward. Now the hard part.
How deep are your pockets? Is the “problem” really distressing enough to warrant these costly solutions? Finding an innovative prosthetist able to handle both the fitting of the prosthesis and managing the actual design and fabrication of the overall system.
Good luck
Morris Gallo, LPO
Mr Feldman was good enough to forward two articles – Which I will review and post the outcome.
– Types of Thermoplastics – Prosthetic Primer: Materials Used in Prosthetics Part I
– Kinematic and Kinetic Comparison of the Conventional and ISNY Above-Knee Socket

Hi Steve,
OK. Everything is fine except the heat. You have a thermoplastic liner so that means it was made with a flat or cone sheet of thermoplastic. Just going over the basics. A socket made with resin sets with a chemical
reaction and is a thermosetting plastic socket. The more layers of
plastic, or resin, or thickness of a socket will retain heat.
Attached is some information for you, and you may bring it to your prosthetist to discuss your options.
Let him know you seriously want to have or attempt some solution, and that you will make the financial commitment for his time (he has costs and time just like you) if he will provide or refer a O and P lab that will provide you such a socket. The ISNY system is a complete new system, total contact and suction. There are some new flexible plastics available since that article was written for longer lasting activity. As long as your sensible and the socket is not too thin I think you will be happy.
Steve, I do not have all the answers but I hope this helps.
Rick Feldman, CPO (abc/usa)
Hi Steve,
Recently at a conference in Vegas we learned about brimless AK sockets which may help for the bike riding comfort. I live here in Arizona and we would jump up and down for 86 degree days. Perspiration is an issue all over. I have heard about some people having success with antiperspirant creams, we use liner liner sock with success for BK’s, not so much AK’s.

Joseph S. Pongratz, CPO, FAAOP
President, Director of Clinical Services Pongratz Orthotics and Prosthetics, Inc.
Consider higher strength antiperspirants. However, apply to a dry, clean, residual limb before bed time. NOT before prosthetic use. Use daily for 2 weeks then you can back off to 3x/wk. Best of luck.

I am a cyclist and have several patients who cycle in our hot southern climate as well. Each of them, even the transtibials, have gone to a thin flexible socket in a judiciously trimmed frame for cooling. Most find this allows more rapid cooling, especially if they can keep the socket from being covered by clothing which can act as another insulating layer that traps air. You obviously still use the valve and have the added benefit of greater flexibility at the proximal socket margins for increased comfort when cycling in the seated position.
Jim Rogers, CPO, FAAOP


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