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5 Reasons Why Above-Knee Suction Sockets Lose Suspension

Posted by Bryan Potok, CPO on

Nowadays there are so many ways to suspend an above-the-knee prosthetic socket. One of the most popular is using suction with a one-way valve. Many above-knee amputees prefer this method because it can create the greatest sensation of oneness with their prosthesis, and when a suction socket fits well, it works exceedingly well. 

Suction suspension is a effective method to suspend a prosthesis.

The popularity of suction sockets is due in part to the fact that it doesn’t rely on expensive liners or other components to make it work. However, applying an above-knee suction socket requires the use of donning aids similar to either a nylon Launch Donning Sheath or a lotion to powder type product

One of the issues with above-the-knee suction suspension is the difficulty in avoiding drastic size fluctuations in your residual limb. And as we all know, that's tough to do this time of year. The key is keeping the size of your residual limb within a very specific range. Understanding suction suspension offers little room for size changes requires you to stick to a prosthetic maintenance schedule to maintain the best socket fit and suspension. In this short read, we’ll discuss a few reasons why suction suspension fails and what you can do about it.

1. Clogged One-Way Suction Valve

Currently, there are too many variations of the suction valve available on the market, and most of them require cleaning. Often, dead skin, dirt, and grime can accumulate inside the valve and clog it, which affects suction. But most valves are easy to disassemble and clean. It’s important to have your Prosthetist check and clean your valve once every 3-4 months.

2. Weight Change

Both gaining and losing weight can affect how your residual limb sits inside your socket and directly impact your socket’s suction suspension. If you lose weight, your socket can become loose, introducing air into the socket and causing suspension failure. You can correct the effects of weight loss by using volume pads to tighten your socket. 

Meanwhile, weight gain can also cause suction loss when you can no longer apply your socket onto your limb correctly. This causes an “adductor roll” to form along the inside brim, which creates its own set of uncomfortable issues. Essentially, suction failure happens when you’re unable to pull all of your skin inside the socket completely.  

3. The Back Brim is Too Wide

When the back or posterior brim is too wide, sitting down can create a loss of suction. This is because when the lip or shelf of the back brim hits the chair, the chair pushes into the back of your residual limb, which introduces air into the front part of the socket. This can be easily remedied by your Prosthetist by trimming the posterior brim so that when you sit on a hard surface, the shelf or lip doesn’t extend past your bottom.  

4. Wallet Hallow

Sometimes, the area in the back where most people place their wallets, can become loose and allow air into the system . And when this area is loose, you can expect to hear a “farting” sound. This can be remedied at home with volume pads which can effectively tighten the area and match the contouring of your femur better. 

5. Unsuccessful Donning of Prosthesis

Expecting to apply your prosthesis correctly on the first try doesn’t always work out. It can take multiple attempts to get your socket on successfully with all of your skin and tissue properly inside the socket. In these instances, consider using a different type of donning aid. 

Many prefer to use powder and ace bandages while some prefer liquid powder or a nylon bag style donning aid. Experiment with different donning aids to find the one that works best for you. If you have questions about the different methods to apply a suction socket, contact us.  

In summary, a suction suspending socket is a great way to hold your prosthesis in place and create that "bond." However, it requires a degree of upkeep, like maintaining your weight and a consistent prosthetic checkup schedule.

What are your thoughts on suction suspension? Please leave a comment below. 

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  • I had my prosthesis create a ring one inch below the upper rim running the whole perimeter of my prosthesis that protrudes 1/4 inch. Thus in the morning when I don my leg it’s ok. But as the day goes on and I sit or lose volume, this rim stops air escape, especially in the corners. And then, I just use the valve to let out any air.

    I’m surprised that this little bump isn’t used in more prosthetics.

    edward chaczyk on

  • 🇺🇸
    Awesome article, wish I would have seen it about 4 months ago, the information you put out about SUCTION LOSS would have saved me a few Headaches…………
    Thank Goodness I have a new Prosthetist now & she has solved my suction loss & explained every step in your article……
    Once again “THANKS”

    Thomas Marshall on

  • Being disabled with use of only one hand to put on my prosthesis, I cannot use a donning sheath. Every one’s not the same. Suction valve is the only thing I can use with lotion/powder. When I sit down, I sometimes loose suction – goes with the ’territory.".

    V. Galizia on

  • My socket is tight in the morning and by the end of the day I have to stick pads on each side and put on a sock or two. I lost my leg four years ago

    Stephen Anderson on

  • Most of my trouble is as a result of sweating. I have had my current suction socket for nearly ten years without change. Using a shrinker to maintain residual limb size helps tremendously, even with liberal weight gains and losses. I also clean the valve every night while recharging. RevoFit has an adjustable socket that looks promising. Anybody have any applied knowledge of how well or badly it works?

    Robert on

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