The current issues of Academy Today was put out by the Sub Atmospheric Technology Group of the Lower Limb Society of AAOP. It is a review of the principles and methods as related to transtibial fittings. It is instructional and also answers many of the questions regarding the topic and even offers CEUs if you take the quiz. It is a MUST READ!!

Thanks to Brad Poziembo, prosthetic resident, who shared the responses to his inquiry on the list serve as to problems people are having with elevated vacuum.

Here are the replies he received:

* Patient selection (Ex: cognitive ability)

* Socket tightness due to vacuum pressure

* Sealing Sleeve durability

* Not covered by all insurance companies

* Time consuming finding an air leak

* Tough to get adequate knee flexion

* Donning difficulty

* Not all amputees find reduced perspiration with system

* The amount of time required to get the right fit due tight tolerances

* Difficult to use with AKA and sealing off the proximal brim

* Maintenance

While all these are definately issues that pracitioners face, they can be adresses with careful fitting and adjustment and the results are worth the effort.

Thanks, Brad.

There was a lively discussion on elevated vacuum at the recent ISPO/Uniedas Fronteras meeting in Costa Rica. The theory and approaches to elevated vacuum were presented and discussed. After the presentation, there was  a debate regarding custom liners vs. off-the-shelf liners for elevated vacuum. The argument for custom was that it gives the best fit, the argument for off-the-shelf is that it provides a sufficiently good fit and is readily available. No one reported any problems with an elevated vacuum patient that could be attributed to an off-the-shelf liner. There was also a great deal of interest in the elevated vacuum prosthesis for hip disarticulation, and an overview of the technique was presented.

I was recently surfing elevated vacuum on the internet and ran across some pending patents on elevated vacuum components.  I am not envious of the process. Having been down that road, it is full of potholes. Yes, there are some great successes in elevated vacuum like the Harmony System, but there are a lot more patents that have never yielded enough profits to offset the expense of getting the patent.  So just tread carefully down that road.

To quote Don Lancaster, “Any involvement whatsoever with the patent system is nearly certain to result in a net loss of time, energy, money, and sanity...A patent is simply the right to sue" with absolutely no guarantee of success.

Don says, even if you are willing to blow 25% of your profits on the patent system, your idea must have a  market potential of $12,000,000 in net sales. This is based on what it costs to procure the patent and to sue to defend it. 

I worked it out for the costs of getting the patent alone without the lawsuit and asked myself, "What are the net sales that would yield a net profit more than the patent costs?"  It never pencilled out.  You can still do lots of business with your product without a patent.  You can develop it, make it, sell it, profit from it, even sell the idea to someone else and let them patent it.  Just keep good documentation of your original idea.

If you have that great, unique and profitable product, my hat is off to you, and I am proud to know a few of you who have made a lot of money on your patented product. 
But if you are like most patent owners (including me), make sure you are just doing it for the bragging rights; have fun, spend the money, and frame the patent. But don’t do the math.

Thanks to Southern California Prosthetics for this video. This is an excellent illustration of the hand-pump option and how it works.

There are a number of instances when it would be handy to monitor the level of vacuum in the socket as the patient is walking. When the Harmony system was first taught, TEC recommended temporarily installing a "t"into the vacuum line and connecting a small vacuum guage to the line. You can walk along with the patient and look at the guage. While this is a handy clinical tool, it gives no accurate data and does not record the data. A record would be useful for trouble shooting problems that patients may experience out of the office environment.

Maria Gerschutz reported in the July 2010 JPO that Ohio Willow Wood developed the LimbLogic VS Communicator which is a tool which monitors vacuum levels as they vary with time and with patient usage. The data is collected via a wireless connection to a computer. Presently this is only available for research applications and it is integral into the Limb Logic System.  It should have promising clinical applications for adjustments, for troubleshooting, and for comparing various vacuum pump and socket design strategies.

Good work!!

A few entries ago I introduced you to the Aura sealing sleeve from Evolution Liners. It worked very well for the one patient that we had a chance to try it on. But we just tried to order another one and Craig told us he had to take it off the market due to patent issues. Too bad, because it was unique and Craig put a lot of time into it, but hopefully the parties involved can reach an agreeable arrangment so that amputees will be able to benefit from this device, and at the same time everyone gets treated fairly.

Yes, in most cases, more vacuum is better.

Some prosthetists have reported that too much vacuum in an elevated vacuum socket causes discomfort and "pulling" and too little fails to provide linkage between the socket and the residual limb. The argument goes that there is a "sweet spot" at around 10"Hg. One set of pump instructions even recommends "only enough to suspend the socket".  This is not a good reference since actually the the socket can be suspended with no vaccum at all using just the sealing sleeve. The goal is to achieve the best possible linkage, which is achieved with maximum possible vacuum.

Experience suggests that, just as in traditional suction sockets, discomfort and pulling occurs when there is lack of total contact or a lack of even socket pressures. If the fit of the socket is correct, the vacuum can be much higher and the linkage much better. I suggest that, if there is pulling and discomfort, check the socket fit distally BEFORE simply having the patient use less vacuum. The exceptions would be with invaginated and severe scarring and adhesions where vacuum may intially have to be reduced.

Evolution Liners recently introduced the Aura Sealing Sheath. When used with elevated vacuum, it allows the prosthetist to use a custom silicon or polyurethane liner and then apply a sealing ring between the liner and the socket just below the socket brim (the prosthetist determines the height of the sealing ring).  This system trumps the complexity of the double wall system and maintains the a more secure proximal skin contact than the single wall systems in which the liner is reflected over the outside of the socket.

For transfemoral applications, there are now three socket design options listed here with thier advantages:

1. Double wall socket- Provides ultimate vacuum and suspension in any range of motion.  Because the liner and sleeve make up most of the inner socket, it is flexible and conforms to variations in residual limb volume more than any of the other designs.

2. Single Wall System With Aura Sealing Sleeve- Provides many of the advantages of the double wall system but much simpler and lighter.

3. Single Wall System With Liner Reflected Over Proximal Brim of Socket-  The simplest elevated vacuum system, though less flexible and accomodating than the others. 

The Aura Sealing Sleeve is a valuable addition to the prosthetist's choices of socket componenets.

There was an excellent set of questions posted by a colleague on the O and P listserv. I will reprint  them here and comment with my initials on each question:

 1. What sleeves have you found to be the best? Obviously, the sleeves tend to be one of the weakest points of the system, and I'm wondering which sleeves have had the greatest durability in actual practice, rather than just theory. I've had patients using the OWW Alpha Flex sleeve, but they haven't lasted longer than their warranty period yet.

JB: For transfemoral, flexiblity is unimportant so resitance to wear, tear, and puncture is key. I have has good success with the Harmony sleeve or its equivalent.  For transtibial, the ALPS Easy Sleeve or its equivalent has worked well.

2. Which of the electronic pumps do you prefer, and why? I got disgusted with the harmony ePulse, due to my having to send nearly every one of them back, but I've heard it's been retooled. I've only used two limblogics, and I wonder how well they do, and how reliable they are.

JB: I have heard no complaints from any pump other than the ePulse, which did not work. I have not tried it lately either. DAW has a new one which looks promising and attaches around the pylon resulting in no added build height.

 3. What do you think of the Harmony mechanical pump in comparison to the electronic ones?

JB: The harmony is an excellent choice if there is suffient room for it with the desired componentry.  

4. Is there some other elevated vacuum suspension mechanism you may know of that you prefer?

JB: Evolution has recently released some exciting componentry. One is a distal attachment plate with a built in resevoir for vacuum, and the other is a sealing liner that allows the prosthetist to decide on the vertical location of the seal  on the liner. They also offer custom made liners fro elevated vacuum.

5. Does your answer differ between AK and BK patients, and why?

JB: Choice of suspension mechanism certainly depends on AK and BK, due to the often limited space available bewteen the AK distal socket and the knee. Almost any system can be used, but it is much less cumbersome if the pump fits between socket and knee.  

6. Especially regarding BK patients, how effective have you found it for them vs other types of suspension?

JB: Harmony offers the advantage of no chargin required, very simple to use, and the built in vertical shock absorber.