Reflected Liner Hypobaric Seal
I recently had the opportunity to examine several traumatic transfemoral amputees who were using a simple, clever method of vacuum suspension with a gel liner: they reflected the top few inches of a thin gel liner back onto itself thereby creating a proximal hypobaric seal. The rolled edge of the liner terminated about one inch distal to the Ischium.
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John Warren CP has been having selected TF patients reflect the top portion of a thin liner to create a hypobaric seal.
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Volume changes were accommodated by tucking the edge of a limb sock under the folded portion of the liner, and reportedly worked for up to 10 ply reductions. The patients were very pleased with this suspension method and said they found it both reliable and comfortable. All had been using this suspension alternative for at least 4 months and some had been using it for considerably longer. None reported any problems with having the liner roll down the thigh during normal use.
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A limb sock can be used to accommodate volume loss by tucking the proximal edge under the reflected portion of the liner.
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This method was developed by Massachusetts prosthetist, John Warren, CP, who calls this a "flip down socket". The key is to use a synthetic donning sleeve to slide the residual limb fully into the socket without disturbing the reflected liner.
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Use of a synthetic donning sleeve is essential to avoid displacing the liner.
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It works well with a suction socket valve, providing the same atmospheric pressure suspension as other hypobaric methods. Some of the patients preferred to use a hand vacuum pump to further evacuate the socket, thereby creating an augmented vacuum suspension.
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This reflected liner technique works well with a suction valve, or with augmented vacuum.
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All of the patients I spoke with had a mid-thigh or longer residual limb and good or better muscle tone. It may work for patients with shorter residuums or less muscle tone so long as there is sufficient space within the socket to maintain the seal. This suspension method certainly works well with both Ischial Containment and M.A.S. ® sockets but it can probably work with other geometries as well.
The hand vacuum pump is used in the auto repair industry to bleed brakes, and is available from most local auto parts shops as well as online at www.actron.com/product_detail.php?pid=16292.
For additional information, John can be reached via email at . To watch a two minute low resolution Windows movie of donning a socket with this suspension, click here.
