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In-Shoe Pressure Systems

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Kevin Kirby, Feb 2, 2005.


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    Colleagues:

    There are a few systems available commercially that allow the clinician to measure in-shoe pressures with a pressure sensing insole. The ones that I have heard of, the F-scan, EMEDand RS Scan systems, seem to be the most popular systems, but seem to vary in cost and accuracy and other features.

    Since I don't own any of these systems, but may someday possibly consider getting one of these in-shoe systems for my practice and related research, I would be interested in what others think about these systems.
    I am specifically interested in the cost of the systems, cost and durability of replacement insoles, computer requirements for the system, accuracy, sampling frequency, portability and company support.

    I would also like to hear from the research-oriented individuals to see which system they currently use and/or which system they would purchase if they were going to do research using one of these systems and why.

    Thanks in advance.
     
  2. Dave Dunning

    Dave Dunning Welcome New Poster

    Inshoe systems

    HI Kevin,
    You asked about inshoe pressure systems. We are lucky enough to have access to the F_Scan system here at Staffordshire University which we use to teach students on our Masters in Podiatric Biomechanics. It has several benefits; the sensors are thin (though sometimes has a tendency to crease if not carefully cut to size) which means it does not intrude in the shoe too much, they are fairly durable often lasting for 30 or more tests, the system is light and easy for the patient particularly if you have the cabless variety. As far as the accuracy is concerned we have not done any specific tests yet but have found that it is very useful clinically as a comparison such as a pre and post intervention test. I have used the pedar system in the past which I think has a better hysterysis and may be more useful in certain types of research but there is a cost implication. I have no experience of the other systems, but do hope to in the future.
    Hope this is helpful.
    Regards
    Dave
     
  3. Inshoe Pressure Systems

    Dave,

    Thanks for your reply. I was hoping that some of the moderators and other members of Podiatry Arena could also take the time to reply to my request for the benefit of their member podiatrists. I'm sure that many of us would appreciate candid information on the pros and cons of the different in-shoe pressure measurement systems. Certainly, some of the researchers on this forum must have some experience with these systems????
     
  4. Lawrence Bevan

    Lawrence Bevan Active Member

    In shoe systems

    Kevin

    I use F-scan and from what I have seen of the other systems there is no comparison with clinical use. The sensors are so thin and conformable and the software seems geared to what a Podiatrist wants to know. I would say that whilst one can get repeat use from sensors like Dave suggests they do show signs of deterioration after 7-10 tests. This is also influenced by how you use them - running or hard orthotics esp deep heel cups really speed up deterioration. I have a colleague using the system who has decided to charge for each test run done with a sensor to cover the cost. They dont work very well with slip on shoes and certainly not barefeet as they crease up completely as the shoe is put on and at £45 per pair that is annoying.

    The thing I find that is most affected by deterioration is force time curves and timing analysis. Pressure readings can still be meaningful. Example - recently had an individual who's force-time curves suggested an asymmetry that might come from a leg length descrepancy. However there were other signs that the sensor was slightly worn (not even double figures of use!) so I swopped them and low and behold the F/T curves became symmetrical!

    From this evidence I would think that any research with the F-scan would need to show good reliability/repeatability.

    From what Im told the Pedar is more advanced in pressure sensing technology and better for research but is more expensive and the sensors are 3mm thick. No good for many clinical needs and I discounted it from the outset. I think any system that has "permenent" insoles is always going to be tricky - you can bet your size 9 or 10 is always going to get a lot of use and wear out. I believe that they are around £2K to replace per pair and if you wanted to protect yourself against them breaking in the middle of an appointment you would need back up pairs.

    The RScan was used by another colleague in the UK and he found the software did not give him the information he needed and the developers of the software that he spoke to didnt understand what a Podiatrist needed. They also found the sensors failed quite a bit - I think it was three times in one year he was without the system for a month each time because of this. Personally having seen and used this and the FScan only one system gives you the kind of information you need which is why I bought the F-Scan. Thats only my opinion by the way based only on personal experience about 18 months ago not a statement of absolute fact. They may have improved it significantly and everything is now wonderful ! (Some of these companies are so touchy!)

    Lawrence
     
  5. Craig Payne

    Craig Payne Moderator

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    Heres my take on it:

    We may want to use in-shoe pressure measuring in 2 situations

    a) Pressure Reduction foot orthoses, footwear , padding
    ie in diabetes and/or hyperkeratosis. All systems are probably equally good at doing that and providing data to find high pressure areas and to detect if foot orthoses, footwear or padding have reduced the high pressure area.

    The unresolved issues here are:
    1) The actual value of using it to find a high pressure areas (any good clinician can do this by look and feel). Arguments could be made that they could detect the *threshold* of pressure at which ulceration happens - but more work is needed on that, especially if that knowledge actually leads to better outcomes.
    2) Do we really need to quantify the amount of pressure reduction? Of what value is knowing that in improving clinical outcomes? Any good clinican can reduce plantar pressure without quantifying it.
    3) It *may* be of value in complex cases in which the intervention does not appear to be working clinically to reduce pressures. BUT, given the costs in $ and time, does that justify the routine use for all or should it be reserved for the complex?
    4) The only evidence I can find for their use is in the prescription of rocker sole shoes. Cavanagh et al found that if the rocker is not placed correctly, then lateral forefoot pressure can be increased, so an argument can be made for the use of in-shoe pressure measuring to assess this is not happening.
    5) Arguments have been made that third party funders should require in-shoe pressure measurement so that the pressure reduction of the intervention has been shown to work (I think that this is a requirement in Germany for therapeutic footwear). I have my doubts, as given the costs and there is no demonstrated improvement in outcomes if this was done.

    b) Functional Foot Orthoses prescription
    This is were there are differences between the systems. We use the Novel Pedar, but am also familiar with the F-scan. We have not used the RS Scan.

    The Pedar is more expensive and is much better at handling large databases and research enterprises. The insoles last a very long time and do not really need replacing unless you use them so much (like we do). We have never had a problem because they are 1.5mm thick. For routine clinical use to get the kind of data that is needed to assess if a foot orthoses is changing the kind of parameters that are related to outcomes, it takes a bit more leg work with the Pedar than the F-Scan to get the numbers and pictures

    The F-Scan is less expensive, but you can only use the insoles a very limited number of times (...at the end of the day, the cost difference between the two systems is not a factor because of this - its capital cost vs consumable costs). The F-Scan is not as good at handling large databases, if doing research. It is better at giving immediate force data for clinical use (they are both equally good at giving immediate clinical data on pressure) - the F-scan is better at giving immediate clinical data on the force time parameters that are important for determining if a foot orthoses has altered the parameters that are assciated with clinical outcomes. This is especially so with the F-Scan modules for CoM and TAM analysis.

    There have been publications comparing the systems and looking at the reliability of each system --- ignore them, as both systems have undergone improvements since the publications.

    The unresolved issues for me are:
    1) Changes in the force/time parameters with foot orthoses that relate to clinical outcomes have documented (discussed in this thread), so an argument can be made to use in-shoe systems to make sure foot orthoses are doing this, but its still early days in the quantification of these parameters and we are only just getting started with the RCT's on this.
    2) Given the extra expense in using this, will the clinical outcomes be "better" enough to justify its routine clinical use.
    3) Clinically we do use it currently in complex cases to manipulate the force time parameters that we want changes in, but we don't use it routinely.
    4) We are testing some simple static clinical tests with and without the use of foot orthoses to see if we can predict that the in-shoe pressure measuring has altered the force-time parameters dynamically in the right direction to those associated with better clinical outcomes.
    5) See (5) above.

    Hope this helps.
     
    Last edited by a moderator: Feb 9, 2005
  6. Craig:

    I knew I could count on you for an excellent reply, Craig. Thanks for that.

    Maybe we could also get Hylton Menz and Jim Woodburn to put their opinions in on the subject, time allowing??

    I think that many members of Podiatry Arena will find this information very useful in regards to whether they should purchase an in-shoe pressure analysis system for their practices (or for their research) and what system would best fit their needs and pocketbook.
     
  7. drgct

    drgct Member

    I have been using F-scan in my private practice for about 10 years (sorry can't comment on the research end of things).

    I believe it is an invaluable tool. It is portable, easy to use, cost effective and information is easy to reproduce and therefore appears to be very accurate. Doing in shoe testing is very easy with the F-scan and sensors seem to have a lifetime of about 8-10 studies. The system paid for itself in a matter of months.

    For a clinician, the data relative to force, timing, trajectory etc. is easy to discern and compare for purposes of symmetry. The information that one can obtain can be done quite simply and with good knowledge of biomechanics as well as understanding the data generated can be a great benefit when writing orthotic prescriptions.

    I have not used any other system but found that F-scan has served my needs and the needs of my patients very well. Treatment outcomes have been greatly enhanced and orthoses made using in shoe pressure mapping vs. conventional biomechanics alone give information that results in orthotic prescriptions that have positive effects not only on the foot but also on many postural musculoskeletal conditions.

    I hope this information is helpful.

    Regards,

    George C. Trachtenberg DPM
    400 Plaza Drive, Suite B
    Vestal, NY 13850

    www.georgetrachtenberg.com
     
  8. George,

    I appreciate your very glowing and positive comments on the F-scan system by Tekscan. I have seen that you commonly give lectures for Tekscan at various seminars around the country. I'll be lecturing at the Western Podiatry Congress in June before you give your lecture "Clinical value of in-shoe pressure analysis for evaluating pathology and orthoses".
     
  9. drgct

    drgct Member

    Hi Kevin,

    I have given some lectures on F-scan at various times. Tekscan had asked me to give those lectures because of my positive experience and success with in-shoe pressure mapping and patient outcomes.

    Relative to the Western Conference, I was invited by them to lecture and not Tekscan. Since our lectures are in close proximity, I think we will finally have the opportunity to meet each other. I very much look forward to meeting you and seeing you in Anaheim this coming June.

    With your reputation in Biomechanics and the work you do in this area, I can understand your interest in obtaining an In-Shoe Pressure mapping system. I hope you find something that meets your need for both clinical and research models. It would be exciting to see someone with your ability use such a tool. I am sure it would be exciting to validate your theories and outcomes with this type of data. Anyway I am sure you would enjoy integrating a tool such as this in your already successful and glowing career.

    Thanks for taking the time to respond. Looking forward to meeting you!

    Sincerely,

    George Trachtenberg
     
  10. Ken

    Ken Member

    The system that I use is AcuStep. The sensors are so thin you cant tell that they are in your shoe and they dont wear out. The entire system fits in a case that is easy to travel with. The best thing about it is that I measure a patient, email the files to AcuStep and the orthotics are on my doorstep within a week. They have a policy that they get the order out the door within 48 hours of receiving the email. You might want to check out their website.
     
  11. drgct

    drgct Member


    Dear Ken,

    I am not familiar with AcuStep. I don't understand why you have to e-mail the files to them. Do you write the prescription or do they make the orthoses based on the finding you e-mail to them?

    George
     
  12. Ken

    Ken Member

    Their system comes with a laptop, sensors etc. On the laptop is a program that I enter all the patients info, like the shoe size, arch height and so on. After that, I have the patient put the sensor in their shoe and walk around. Then I upload the info from the sensor to the laptop and email everything to AcuStep. They make the orthotic from the data to off load peak pressures along with any other mods I ask for.
     
  13. drgct

    drgct Member


    Hi Ken,

    This system is not something I would use. I evaluate the patient myself and interpret the data myself also. I then write a prescription for the patient and send it to a lab of my choice for construction of the orthoses.

    I as the practitioner would rather make all decisions about my patient's care then to turn that responsibility over to a lab.

    Sincerely,

    George
     
  14. Ken

    Ken Member

    Trust me you still have total control. On the program you can watch the patients walking patterns, you can request posting in forefoot and and in the heel. They offer everything.
     
  15. Craig Payne

    Craig Payne Moderator

    Articles:
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  16. drgct

    drgct Member

    Ken,

    In your last posting you said "they (AcuStep) makes the orthotic from the data to off load peak pressures..."

    This to me says that they are involved in the formulation of the prescription. In my opinion, the lab only needs the practitioner's Rx to make the orthoses. The treatment should be in the practitioner's hands and the lab should not be involved in the evaluation and treatment of your patient. That is the responsibility of the doctor.

    George Trachtenberg DPM
     
  17. Ken

    Ken Member

  18. Ken:

    A two-dimensional pressure sensing insole cannot possibly determine the three-dimensional plantar contours of the feet of your patients. However, you are relying on a two-dimensional pressure insole system to make a three-dimensional in-shoe foot orthosis for your patients. Don't you think that by taking measurements of the arch height of the patient and having the lab interpret that information along with your pressure insole data that you are losing out on very valuable three-dimensional image information that would improve the therapeutic effectiveness of your foot orthoses? If your goal is to improve your patient's symptoms, then taking a three-dimensional image of your patient's foot would give you a much more therapeutically effective prescription foot orthosis for your patients.

    Does acustep truly produce a custom insole for your patient or does it just use an over-the-counter orthosis that it takes off the shelf of their warehouse that looks like it fairly closely fits the pressure image that you provide it? If your patient's orthosis is not made off of a three dimensional image of the foot then it would not be considered a prescription foot orthosis but rather would be considered a pre-made foot orthosis with prescription modifications added to it.
     
  19. Craig Payne

    Craig Payne Moderator

    Articles:
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    No it dosen't. It might give you a pretty 3-d picture of the pressure pattern - that has absolutly no relationshp to the 3-d shape of the foot.
     
  20. Ken

    Ken Member

  21. drgct

    drgct Member

    Ken,

    I agree with Kevin and Craig. Additionally biomechanics not just about alleviating pressure. It is about bringing gait toward normalcy.

    George Trachtenberg DPM
     
  22. Craig Payne

    Craig Payne Moderator

    Articles:
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    No where in that article do they give any information that makes me confident they know what they are doing - they through out some irrelavent mathematical stuff and through in some refereces --- none of that makes any sense to support the claim you can use pressure data to get a shape - is nonsensical. The simple fact remains (and was discussed here) you can not get a 3-d foot shape from a 2-d pressure platform or inshoe system - to claim otherwise is a scam.
     
  23. Ken

    Ken Member

    Why dont you take the time to research what AcuStep really does with building an orthotic from an individuals peak pressures before making an assumption like yours. I dont think any average joe can get in bio-mechanics magazine with just "irrelavent mathematical stuff".
     
  24. Craig Payne

    Craig Payne Moderator

    Articles:
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    I have taken the time to research several systems that claim to do this and thats why I would never use them for this. We have research data that shows you can not get any correlation that is close between peak (or any other) pressures and arch/foot shape.

    Please explain to me where in that article, what I call "irrelavent mathematical stuff", has anythging to actually do with translating the pressure data into a foot or arch shape.

    Please show me anywhere where anyone explains how pressure data can be converted into a foot shape? (there is nothing in that article that explains it - they just simply state it)

    Its nothing but marketing hype.
     
  25. drgct

    drgct Member

    Ken,

    I thank you for the complement as I have been in the Biomechanics Trade journal and therefore appreciate by inference that I am not the average Joe.

    I also lecture and do workshops on in-shoe pressure mapping so I do understand the concept of peak pressures (and other parameters) of in-shoe pressure mapping.

    In regards to the article you indicated, I read it the day you suggested it and I was not impressed. This is not to say that you are not happy with your arrangement with AcuStep as I am sure you and others are.

    I just do not conceptually accept what you are doing as being appropriate for me or my patients.

    I hope you and your patients enjoy continued success with your treatment model.

    George Trachtenberg DPM
     
  26. Ken

    Ken Member

    Hello Craig:
    What you are saying is true in that AcuStep does not develop a 3D foot shape from a 2D pressure platform. What is accomplished is the development of a 3D top orthotic surface that redistributes peak pressures determined from dynamic in-shoe foot pressure analysis. This is not a static representation. If you read the article carefully, you would see outcomes before and after orthotic fabrication that confirms that it works.
     
  27. Ken: Why don't you have George and Jeryl Fullen join in on this discussion so that we can ask them personally about the claims they make in their article that was published in Biomechanics Magazine. I agree with Craig and George that the article has some good information in it that is mixed with marketing hype that seems geared to sell a shoe insole system that is based on pressure mapping the plantar foot. In other words, I was not at all impressed by their article even though I'm sure that their insoles often times do work for patients much in the same way that $30.00 over-the-counter insoles work for patients by offering "pressure levelling" and other catchy quasi-biomechanical phrases.

    Please ask them also how they can determine the three-dimensional medial longitudinal arch contours of a foot that does not contact the pressure insole. In other words, if the pressure insole is not registering pressure in a certain area of the foot, such as the medial longitudinal arch, how high do you make the insole in that area?! This is analagous to asking an engineer to determine the three dimensional shape of an arched structure by only knowing what the pressures or forces are between the two bases of the structure and the ground. He will tell you that it can't be done.

    Don't worry Ken, you are not the first clinician to be taken in by marketing hype by individuals that claim their pressure insole systems can make accurate three dimensional foot orthoses. And I'm sure that this won't be the last one that I will see. However, I am getting tired of trying to understand why this is so hard for otherwise intelligent clinicians to figure this out for themselves.
     
  28. drgct

    drgct Member

    Ken,

    Kevin and Craig make excellent points that I think are worth your consideration.

    It is not that peak pressure or in-shoe pressure mapping does not have any value, as I believe it does. I believe that if one looks at the data that is obtained from in-shoe analysis, one can make educated determinations as to the abnormalities in gait patterns that are present (particularly when the clinical information supports the data or the data clarifies the clinical information), however an orthotic device that has any value must also represent the actual contours of the neutral position foot involved as well as other factors such as superstructure abnormalities and joint ranges of motion.

    If these other factors are not considered, one can still certainly offset pressure at different locations on the foot but at what expense? If structure and function is not considered, the offset pressure may transfer as a problem elsewhere in the foot or proximal structures. It also begs the question...are we treating only the symptoms that are presented rather than the underlying etiology?

    Perhaps we should use a Harris Mat (ink print) of the foot and fax the print to the lab and have them make an orthotic. The approach you are using doesn't seem that far removed from that concept.

    Sorry Ken, but it just doesn't wash for me!

    Sincerely,

    George
     
  29. mimmypod

    mimmypod Member

    Hello Craig,

    I am a final year podiatry student at UniSA and wonder if you, or anyone may know of any articles that actually explain how to interpret the in-shoe pressure analysis of such systems as the F-Scan. There seems to be a lot of technical information available on what the F-Scan does but not on how to interpret the information/findings.

    Regards,
    Miriam
     
  30. drgct

    drgct Member

    Mimmypod,

    I agree that there is not a good printed resource to go to for one to learn how to interpret F-Scan. Many F-Scan users that are not self-taught depend on users meetings and/or one-on-one consultation with another user to understand and learn interpretation.

    There are Case Studies/Monographs available through Tekscan, Inc, that can be useful and do to a large extent demonstrate interpretation.

    George Trachtenberg DPM
     
  31. Craig Payne

    Craig Payne Moderator

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    mimmypod

    There is not yet any real good documentation apart from good clinical experience (we are working on it; ie testing various models of function in prospective studies). However, at this years Boot Camp we will be spending time on it. Brigidaire Bruce Williams will be doing some practical workshops and I will be talking about some of our preliminary evidence.

    BTW - we have a mimmypod and a mimipod here at Podiatry Arena - to avoid confusion, I am married to only one of them :rolleyes:
     
  32. mimmypod

    mimmypod Member

    Thank you Craig!

    Both You and George have confirmed my hunch that there is very little in the way of available information on how to interpret F-Scan results. Thank you for your prompt post to my question! It is very much appreciated.

    The 'Boot Camp 05' sounds absolutely fantastic and wish I could go, however looks like I may have to wait until next year to attend. Will there be any information available from the workshops to people who are unable to attend? Love to learn more about the F-Scan applications.

    FYI:
    I couldn't resist the name "Mimmypod" as people often call me Mimmy :)

    With many thanks.

    Regards,
    Miriam
     
  33. mimmypod

    mimmypod Member

    Thank you George, it is really helpful to know that one needs to place a lot of importance on 'user meetings/workshops' to learn about the clinical interpretation of systems like F-Scan.

    Thanks for the tip about contacting Tekscan for acquiring 'case studies', its a good idea.

    Its great to be able to ask people like yourself and Craig for guidance. Thank you very much!!

    Regards,
    Miriam
     
  34. mimmypod

    mimmypod Member

    Hi Craig,

    I previously responded to your much appreciated information regarding my pressure analysis question. However, I can not see my response anywhere. Very sorry about that! I want to now thank you for taking the time to fill me in in what you know.

    Thank you!
    mimmy
     
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