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Langer DynaFlange

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Ray Anthony, Mar 30, 2013.

  1. Ray Anthony

    Ray Anthony Active Member

  2. jsegel

    jsegel Active Member

    I am the inventor of the Dynaflange and have been dispensing versions of it for 3 years. Patients like it, and both recommend it to would be new patients and have returned for additional pair. Take a look at the later posts from the original thread for some good information, especially that of it's originator, Dieter Fellner. The white paper on Langer's site is also helpful too. At the end of the day, the best way to evaluate it is too try it.
    PS this is the beginning of dynamic additions to orthotics and AFO's

    Best Regards Jay
  3. Ray Anthony

    Ray Anthony Active Member

    Hello Jay,

    Many of my patients find the Scholl Air Pillow insole very comfortable!

    In fact, I purchased two pairs of Dynaflange for my practice manager and we ran an n=1 video gait and plantar pressure mapping study on her using the Noraxon/Zebris system (the same system Langer used for their studies I believe?) -- three conditions: barefoot, nylon custom orthoses with 70 Shore EVA rearfoot posts, and Dynaflange. So, I have perhaps taken a closer look than many others.

    The "beginning" of dynamic additions to orthotics you say? Well, I suppose this depends on your definition of "dynamic." An orthotic shell is a "dynamic" component that deforms under load in myriad ways depending on its rigidity and other mechanical properties. The original Root rearfoot post incorporated a "dynamic" pronation skive. A dual density EVA rearfoot post and the kinetic wedge are both "dynamic" additions that have been around for years. Forgive me, your claim that Dynaflange is ". . .the beginning of dynamic additions to orthotics. . ." is somewhat presumptuous and more than a little dismissive of those who have developed far more useful "dynamic" orthotic modifications over the last few decades.


    Ray Anthony
    Last edited: Jul 26, 2013
  4. Well said, Ray. Sounds like propaganda to me also.
  5. jsegel

    jsegel Active Member

    Hi Ray,

    With regard to to the beginning, I was referring to other Dynaflange additions coming in the future, such as the forefoot mod and the rearfoot collar, it wasn't meant in any dismissive way, however you are correct in that other innovations being dynamic depend on your definition. Perhaps I could have used "responsively". I do find the tone curious as I just suggested that you, see what others who have tried say, read the studies and try it, but perhaps it was my lack of clarity. What was the response of the person who tried the devise?
  6. jsegel

    jsegel Active Member

    Kevin, I am surprised at your response as you are an inventor yourself. I have always been respectful of your accomplishments and even called you on several occasions to discuss these matters and invite you into the process with NO response from you. Proof is in the pudding is no propaganda. How about a little support, we all should be working together as we have common goals. Maybe your suggestions make for a better Dynaflange, but comments like the last have no foundation and are not helpful.
  7. Jay:

    Sorry for the abrupt response. Since you are a relative newcomer to Podiatry Arena, you may not know that we have had a whole series of inventors and/or promoters of products (that the posters have a financial interest in) who have, over the years, made unsubstantiated claims about their products here on Podiatry Arena. My response of "sounds like propaganda to me" was based on your claims that the product you invented was "the beginning of dynamic additions to orthotics and AFO's".
    Let's look, Jay, at the definition of propaganda:

    Now let's look at the definition of dynamic:

    When you said that the Dynaflange that you invented was "the beginning of dynamic additions to orthotics and AFO's", was this statement actually based on fact or was it meant to be an idea that you are posting on a public academic discussion forum for medical professionals that was made for the purpose to help your product?

    I agree with Ray Anthony, who, like myself, has also been involved in writing and researching about custom foot orthoses for over a quarter century. In other words, your claim regarding the device you invented being the "beginning of dynamic additions to orthotics and AFO's", like Ray said, "is somewhat presumptuous and more than a little dismissive of those who have developed far more useful "dynamic" orthotic modifications over the last few decades".

    Please tell all of us, Jay, how the Dynaflange is any more dynamic that any number of custom foot orthoses and foot orthosis modifications that have been created by other individuals to treat patients with mechanically-based pathologies of the foot and lower extremity over the past century. In addition, please provide research evidence of your claim that the Dynaflange is "the beginning of dynamic additions to orthotics and AFO's". Please also show how previous foot orthoses and foot orthoses modifications are "not dynamic". If you can't provide references or some sound explanation based on the known laws of physics and engineering as to why the orthotic device is dynamic and others before your time are "not dynamic", then the next question is in order: were your statements then just your personal opinion of the device you invented?

    Have a nice weekend.:drinks
  8. jsegel

    jsegel Active Member

    Hi Kevin and thank you for your quick response.
    Firstly, I have been in private practice for 30 years and have used many different orthotics. The statements I made in the beginning were to correct misinformation on Dynaflange and Langer. Other statements were made after years of trials, personal, clinical and through independent research. The central core of Dynaflange is Newton's Law of Motion, equal and opposite reaction. When one invokes ground force reaction by weight bearing, the Dynaflange responds. This was compared to a classically posted rear foot Langer device with the same parameters and shell type to limit variables. The concept of being more "dynamic" refers to the design and material. As the rims and wings are plantargrade in nature, they interact with the ground sooner than a flat bottomed device and so it engages earlier. Given that the material has strong properties for reanimation, it is an efficient and dynamic shock absorber capable of returning energy later as the center of pressure changes. Most material that I have seen used, such as open and closed cellular foams have a shorter shelf life and a weaker response to external stimuli. Just today I received independent test results showing,
    "Hello Dr. Segel,
    Our testing facility in the US confirmed what we have hoped/expected – the concave plastic extrinsic post, riveted to a TOG shell appears to be durable enough for patient use. None of the 4 samples tested cracked or showed signs of wear after 450,000 cycles (direct downward force with the forefoot elevated)."

    My point here Kevin is that everyone involved with the Dynaflange product is trying to do the right thing, in the right way and we are still testing today. So, many claims we have clinical data to support, some tests are still maturing but are based on patient feedback over the last 3+ years on trials and computer generated findings.

    With regard to the "beginning", I was referring to a family of Dynaflange products in Langer/TOG pipeline, including a forefoot version, a rearfoot collar and an AFO adaptation. Perhaps I could have worded that better, but I hope that clears up that concern. It wasn't meant to be dismissive, in fact, this just builds on that which has gone before. Do I think that 3D plastic/composites oriented to manage triplane motion are more effective than foams like PPT, yes I do. The studies done by Sally Crawford have shown that in one on one comparison and if there are additional questions (beyond the ones currently being written up by Sally), ask her. She has blogged on Present Podiatry on this subject and I'm sure would be happy to join in here if permitted.

    Which brings us now to my points earlier with you, you're a bright and intuitive guy with a command of the subject matter, I'm sure you can see the theory behind Dynaflange. I would love to have your input. The other thing that can't be dismissed is that people like it, they tell us they can feel the utility and get the benefit. Isn't that what this is all about, helping people?

    Respectfully, Jay

    PS I just send a copy of this communication to Sally Crawford encouraging her to respond on any particulars you might be interested in.
  9. blinda

    blinda MVP

    Last edited: Jul 27, 2013
  10. Jay:

    Thanks for your response and for clarifying what you had meant to say in your first posting.

    Unfortunately, your use of the term "dynamic" or "more dynamic" comparing the Dynaflange to other foot orthosis designs is misleading, at best. All foot orthoses that are placed inside a shoe will first deform and then recoil back toward their unloaded shape in response to the plantar loading and unloading from the foot acting on the dorsal surface of the foot orthosis and therefore are, by definition "dynamic". Some orthosis designs will deform and recoil more and at a different rate than other orthosis designs so some orthoses will possibly be more "dynamic" than others. The important question is whether a foot orthosis that deforms more and recoils more is therapeutically the best foot orthosis design for all patients. I doubt it.

    Therefore, in this regard, if you could provide some data for us that shows that the load-deformation characteristics of the Dynaflange orthosis is unique when compared to all other foot orthosis designs (and not just compared to one type of orthosis made by one orthosis manufacturer) then I would be more impressed by your claims that the Dynaflange orthosis was somehow superior to other orthosis designs.

    Until then, I will just assume that the Dynaflange orthosis is a uniquely designed foot orthosis that may have some benefits for some people, but is probably no more "dynamic" or therapeutic than many other types of foot orthoses that have been used by the podiatric profession for the last four decades.

    Please have Sally Crawford come on Podiatry Arena to discuss these matters with us. I'm sure Simon Spooner and Eric Fuller would also be very interested in how the Dynaflange orthosis is more "dynamic" than other orthosis designs.
  11. jsegel

    jsegel Active Member

    I have forwarded your response to Sally. Thanks for the open mind. I will also reach out to my material science engineer to see what he has for comparative data deformation and resilience. Also please check out the comments of Dieter Fellner and Dennis Shavelson on Present Podiatry
  12. We have already seen plenty of comments from Dennis here on Podiatry Arena.....here is just one sample.....


    A few words of friendly advice: you may be careful who you ask us to read the comments of in the future regarding your product.
  13. jsegel

    jsegel Active Member

    Hi Kevin
    Well that was interesting but I was just referring to the following:

    "Re: DynaFlange™ - The Game Changer in Orthotic Prescription

    I have now had a good amount of wear with the Nike Airmax / Dynaflange combination.

    Quite possibly the closest to "floating" on the ground as I have ever experienced, over the years. Countless combinations of shoes / sneakers / orthotic design later: I have to admit, I'm impressed.

    This of course remains a story of one.

    I will be interested to hear about the expereince of others - both users and providers.


    Disclaimer: I have no vested or financial interest in either Nike shoes or Dynaflange. My only interest is effectiveness & comfort and a pair of feet that are symptom free and happy.
    contact Dieter Fellner"

    Dennis Shavelson

    posted: May 27th, 2013 @ 3:10pm
    Re: Re: DynaFlange™ - The Game Changer in Orthotic Prescription

    "Very impressive


    (It's Jay again)
    I will tell you that it is my goal, as I displayed earlier, to build bridges and work together to create and share ideas. The comments you just posted are certainly proof there is much work to do to create harmony and a supportive Podiatric community of thinkers and doers.
  14. efuller

    efuller MVP

    Jay, you may have a good product. However, I'm somewhat irritated by your posting, actually re-posting testimonials from another website. This is not really discussing the merits of the device. The second thing that irritates me is the claim for better pronation control than a plane solid post. A springy post is just not going to push back against the foot as hard, or in the same location, as a solid post. It will not reduce the pronation moment as much as a solid post.

    If you want sell it as the more cushy orthotic, I can see the rationale for that. I would bet that you could eventually prove the claim that it reduces impact forces. (Just take a fake lower leg and strap on orthotics with different posts and drop it from a height on to a force plate.) On the other hand I really doubt that you are going to get any support without solid data, that I doubt you would be able to produce, that this device is better than a solid post at slowing pronation.

    One other thing that bothers me about this invention. I'm currently wearing some orthotics that I made for myself around 20 years ago. The crepe post is worn, but still appears to be making the device more rigid and supporting the medial heel skive. There were some comments on the other website that there some breakage issues. A rearfoot post that might break really seems like a step backward. Am I really going to ask my patients to pay extra for something that is more likely to break?

  15. jsegel

    jsegel Active Member

    Hi Eric
    The point of the repost was to address the issue of propaganda and countering it with live experiences. Next, to the issue of pronation, my point is that the medial wing, if you will, is oriented close to the STJ axis of rotation (and the ground force reaction portion of the center of pressure gait line), as that section loads, it slows pronation, (Newton's law of motion) then as the pressure is released, the energy stored guides the foot back towards STJ neutral. This can be seen and even felt. There were videos posted to that effect as well. And that is why I call this an efficient management of pronation. A solid plane, I don't believe, has space or that level of resilience needed to manage motion as two components are necessary, the ability to deform and the ability to reanimate or rebound as you like. Perhaps the issue is in terminology, I don't want to stop pronation as it is an important shock absorber, but I do want to manage it in the same way we manage a run away truck. We don't put a "solid plane" or wall to halt the truck, we use loose dirt, water filled barrels and inclines to decelerate the motion in a more system friendly manner.
    As to the issue of fatigue, you may have noted that I posted very recent test results on that very subject earlier today, regarding the safety. Having said that, I'll make two points.
    1. Material fatigue is not a failure of the Dynaflange concept, but a failure of material
    2. I have seen breakage and Langer has found a good product in this specific Delrin

    Do I love the material or the riveting attachment, no, but it has worked well. I am still looking for that dream material, yes, and I am working with a materials expert in California named Colby Young in search of an even better material, but just like the shock absorbers in the first automobiles they were helpful but, suspension system science has come a long way and we are in the early stages of Dynaflange. To date, with the new Delrin, I have had less than 2% breakage after 1 1/2 years of wear, 1 of which was a riveting issue as the holes were drilled to close to the periphery of the addition. So, has it broken, yes, but not often. To manage that expectation, I explain to them what I told you and suggest that they come in and have the top covers and posting refreshed every year or so. And this is what I told my patients over the years anyway regarding care and maintenance of their orthotics.

    Best Regards, Jay
  16. jsegel

    jsegel Active Member

    Good morning Kevin,

    To your quote “Unfortunately, your use of the term "dynamic" or "more dynamic" comparing the Dynaflange to other foot orthosis designs is misleading, at best. All foot orthoses that are placed inside a shoe will first deform and then recoil back toward their unloaded shape in response to the plantar loading and unloading from the foot acting on the dorsal surface of the foot orthosis and therefore are, by definition "dynamic". Some orthosis designs will deform and recoil more and at a different rate than other orthosis designs so some orthoses will possibly be more "dynamic" than others. The important question is whether a foot orthosis that deforms more and recoils more is therapeutically the best foot orthosis design for all patients. I doubt it.”

    I never claimed that this was the best choice or only for ALL patients, in fact, in my practice, it is one of many choices as my ordering history will verify.
    The claim of “more dynamic” was a reference to the published white paper that I had referred to and the other langer device to limit variables, so it was appropriate. I did not use the term “all” or “every” when making this reference. So in the manner you laid out earlier, let’s define our terms.

    [mawr, mohr] Show IPA
    adjective compar. of much or many with most as superl.
    in greater quantity, amount, measure, degree, or number: I need more money.
    additional or further: Do you need more time? More discussion seems pointless.
    an additional quantity, amount, or number: I would give you more if I had it. He likes her all the more. When I could take no more of such nonsense, I left.
    a greater quantity, amount, or degree:

    [dahy-nam-ik] Show IPA
    adjective Also, dy·nam·i·cal.
    pertaining to or characterized by energy or effective action; vigorously active or forceful; energetic: the dynamic president of the firm.
    of or pertaining to force or power.
    of or pertaining to force related to motion.
    pertaining to the science of dynamics.

    1817, as a term in philosophy; 1827 in the sense "force producing motion," from Fr. dynamique (1762),

    dynamic - 
    activating, aggressive, changing, charismatic, coming on strong, compelling, driving, effective, electric, energetic, energizing, enterprising, forceful, forcible, go-ahead, go-getter, go-getting, highpowered, hyped-up, influential, intense, lively, lusty, magnetic, peppy*, play for keeps, play hard ball, potent, powerful, productive, progressive, red-blooded, strenuous, vehement, vigorous, vitalizing, zippy

    In materials science, fatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading.

    High-cycle fatigue
    When the fatigue occurs above 103 cycles (usually 104 or more), it is usually called High-cycle fatigue. The material is subject to lower loads, usually less than 2/3 of the yield stress. The deformation is in elastic range. The fatigue life is "high-cycle" (103 ~ 106).

    Spring Properties - Chemical and Physical Properties
    While certain materials have come to be regarded as spring materials, they are not specially designed alloys. Spring materials are high strength alloys, which often exhibit the greatest strength in the alloy system. For example: In steels, medium and high-carbon steels are regarded as spring materials. Beryllium copper is frequently specified when a copper base alloy is required. For titanium, cold-worked and aged Ti-13V-11Cr-3A1 is used. The energy storage capacity of a spring is proportional to the square of the maximum operating stress level divided by the modulus. An ideal spring material has high strength properties, a high elastic limit and a low modulus. Because springs are resilient structures designed to undergo large deflections, spring materials must have properties of extensive elastic range. Other factors such as fatigue strength, cost, availability, formability, corrosion resistance, magnetic permeability and electrical conductivity can also be important properties and must be considered in light of cost/benefit. Consequently, careful selections must be made to obtain the best compromise.

    I made this statement earlier and it still holds, As the rims and wings are plantargrade in nature, they interact with the ground sooner than a flat bottomed device and so it engages earlier. Given that the material has strong properties for reanimation, it is an efficient and dynamic shock absorber capable of returning energy later as the center of pressure changes. Most material that I have seen used, such as open and closed cellular foams have a shorter shelf life, life span, less consistency over high cycle (fatigue) and a weaker response to external stimuli.
    In addition, note the properties said to be of importance in “Spring Properties” and compare them to the wealth of information available on Delrin. On the DuPont web site it refers to it’s “long-life cycle” and it’s ability to “retain integrity throughout it’s lifespan” as opposed to materials such as EVA (I chose this because it was mentioned earlier in the thread by Ray. At http://www.makeitfrom.com/compare-m...Acetate-EVA&B=acetal-homopolymer-pom-h-delrin some of the differences are shown in graph format

    By definition, Delrin is able to elongate before breakage to a much higher degree, making it capable of greater deformation and so, greater energy return and retains it’s integrity longer and so, is functional longer yielding “more” dynamic moments, more energy return. Please see specs sheet on Delrin


    I'm sure this doesn't answer all questions but it is a good start. Again, more testing is being done, and some data is still maturing. I will present it when more becomes available, until then, I hope this shows a willingness to delve into the subject at a higher level than those who would make unsubstantiated ( and theoretically unsound) claims for the sake of profit

    Enjoy Sunday Jay
  17. Jay:

    I would like to make some points here before we go any further so I can help you understand some of my complaints with what you are saying about your Dynaflange orthosis. I will go through your points one by one.

    That being said, all foot orthoses obey Newton's Laws of Motion. Your Dynaflange orthoses are no different in that respect when compared to all other types of foot orthoses. Therefore, your comment like "the central core of Dynaflange is Newton's Law of Motion" does not help your explanation and, in fact, to those of us that do understand Newton's Laws of Motion very well, this type of explanation looks like needless fluff.

    Again the same can be said for all types of foot orthoses. When ground reaction force (GRF) acts on the plantar foot that is on a foot orthoses during weightbearing activities, all foot orthoses will "respond" to this GRF. In addition, limiting your comparison of the Dynaflange to only one type of foot orthosis is not good science since we have known for decades that each foot orthosis material and thickness will respond to GRF differently or, as you say, each foot orthoses "responds" differently.

    Do we really want a rearfoot post that is more springy? I can think a few instances where this may be of benefit, but I certainly wouldn't be saying that somehow the Dynaflange is the only orthosis that obey's Newton's Laws of Motion and the only foot orthosis that "responds". That is simply not true.

    I will bet that my rearfoot posted orthoses, made of polypropylene shells and polypropylene rearfoot posts not only interact with the ground as soon as your Dynaflange rearfoot post does but also transmits frontal plane stabilizing forces to the foot at a much faster rate than does your Dynaflange orthosis. In fact, I can guarantee that since your Dynaflange rearfoot post is more weak at controlling frontal plane motion of the rearfoot when compared to my polypropylene shelled and rearfoot posted orthoses, then your Dynaflange orthosis may have very limited application in most feet that suffer from symptoms related to excessive subtalar joint pronation moments.

    Jay, why are you comparing your Dynaflange orthosis to a open and closed foam orthosis material? Why not compare the Dynaflange orthosis to the most commonly used orthosis material: polypropylene? Polypropylene rearfoot posts fused to polypropylene shells never break or snap off. Polypropylene flexes under weightbearing load and then recoils back to its original shape with unloading. Polypropylene "responds" and also obeys Newton's Laws of Motion. Polypropylene has strong properties for "reanimation" (whatever that means). :bang: Polypropylene is an efficient shock absorber and if made flexible enough it can be a very dynamic shock absorber capable of returning energy later as the center of pressure changes.

    Now, Jay, tell us something in the biomechanics or engineering terminology that is accepted by the International Biomechanics Community for the discussion of such matters that the Dynaflange orthosis can do that no other orthosis design can do. Please provide research evidence for this since, as the inventor of the Dynaflange, and having a financial interest in the Dynaflange product, you will always be suspected of biasing your results and your discussions to further your product. By the way, words such as "more dynamic" and "reanimation" are rarely, if ever, used in the biomechanics literature to describe the load-deformation characteristics of a foot orthosis material.

    Whether you like it or not, Jay, this is the way that science and medicine work in today's world: people with a financial interest in a product are always viewed as having a bias for their product. This is why I never patented any of the orthosis modifications I created. I wanted podiatrists to freely use these orthosis modifications so that no podiatrist would ever suspect me of recommending these useful modifications for their patients just because I would make more money for myself if they did use the orthosis modifications that I invented.

    It would be helpful at this point in our discussion for you to post up some of the scientific research that shows how much better the Dynaflange orthosis is from all other types of foot orthoses before we go any further. I take the anecdotal claims of the superiority of a product made by the inventor and patent holder of that product with a grain of salt. Unfortunately, unless you can produce some research evidence otherwise, very few of the others here on Podiatry Arena who lecture nationally and internationally on foot and lower extremity biomechanics will take your claims seriously about your orthosis product. Sorry that this is the case but that is the simple fact of modern medicine and science and is the reason why financial disclaimers are required in all peer-reviewed journals and all academic seminars in today's world.

    Thanks for the discussion and have a nice week.:drinks
  18. jsegel

    jsegel Active Member

    Hi Kevin,

    We have agreement on some issues, clear disagreement on others, yet progress has been made. I certainly understand, that as the inventor, I am seen as bias, though I do try to look at these issues objectively. For that reason, I have asked Sally, who has no stake in Dynaflange, to take the lead. Your questions are valid and I appreciate your patience as we try to answer them to your satisfaction. Have you read the white paper? There is much in the way of clinical analysis to pour through, such as average loading response which consistently happens quicker than without, and perhaps you can comment on the center of pressure analysis presented. This is real clinical data worded appropriately and on point.
    As you have been in research for so long and can see what is needed to validate the honest, positive experiences that people have shared with me. Can you lay out an example of a testing protocol for Dynaflange that Sally could perform on her Noraxon equipment. Then we could post something that is more meaningful to you and the whole Podiatry Arena community?
    Thanks in advance for your consideration Jay
  19. Jay:

    I have not read the white paper. Please post it up on Podiatry Arena or e-mail it to me at kevinakirby@comcast.net and I will post it up on Podiatry Arena for all those who are also interested.
  20. jsegel

    jsegel Active Member

    It's on it's way. Talk soon Best Regards, Jay
  21. admin

    admin Administrator Staff Member

    Jay - can you post this up as an attachment.
  22. Here is the paper Jay was talking about from Podiatry Management in the section on "New Clinical Concepts".

    Jay, did you or Langer or Noraxon need to pay Podiatry Management Magazine to have this paper published? I thought this section of Podiatry Management Magazine was basically for paid advertising of products.

    Jay, I did notice that you are a Podiatric Medical Advisor and Research Partner for Noraxon, the same company that Sally Crawford works for. So, since you both have financial interests in Noraxon, and Sally is using Noraxon equipment to validate your "Dynaflange", don't you think there is a conflict of interest there with her performing your "white paper" experiments.

    Here is another article Jay did for Noraxon.

    I liked this comment from you at the end of the article:

    Nothing personal against Sally, of course, Jay, but if you are a "Research Partner" for Noraxon, and Sally works for that same company, in my eyes, you two are "tied at the hip," so to speak, financially.

    I would be interested in knowing if anyone that doesn't have a financial interest in Dynaflange or Noraxon has done any independent testing of the Dynaflange orthosis.
  23. Already done, Craig.:drinks
  24. jsegel

    jsegel Active Member

    Good morning Kevin,

    I appreciate you bringing up these points.

    Neither myself nor Langer, or Noraxon paid for this article to be run. This can be verified by contacting Barry Bloch or David Kagen.

    As to my association with Noraxon and Sally, this came well AFTER this piece was done. In fact, it was my reason for reaching out to you last week as Sally and I are writing an article on the shortcoming of using standard gait cycle parameters when evaluating folks that oblique walk all day such as chefs.

    In addition, I receive NO stipend for this work with Noraxon but it is an opportunity for two minds to collaborate on an interest subject with some great equipment. We have also begun a study on Parkinson's Disease and the effects of drumming (under a protocol set by Rick Bausman) on Patient Gait.

    Also, as to my comparison with EVA, as I mentioned, it was because Ray had mentioned it and it is a commonly in our industry. I am currenly looking for comparisons on Delrin to Polypro and I'll let you know what I find.

    Have a great Monday, Jay
  25. foot_tech

    foot_tech Welcome New Poster

    Hi Dr. Kirby,

    What fun it is to be able to so rapidly get these answers, whatever the results, quantified so fast with technology. But I must say, as everyone is hinting at, far more measurements on more people, in more varieties of footwear, looking at more movement pathways, would have to be completed to answer every facet of what you and others are asking, for any device. More “unique” or most “optimum” solutions are tricky, qualifying titles, and if measured, are results going to be “superior” in every aspect of movement – not only forwards gait? That is the awesome nature of technology – but do you think there is good literature out there and do you think research evidence on any device is going to be free of conditionality?

    What you already know, and what I can say in summary of the small tests that were done is:

    • All foot orthoses obey Newton's Laws of Motion and all orthoses respond to GFR – this is true, and this is where a quick 2 minute comparison test for our patients and their devices, then adjusted devices, might be required for measuring and understanding what these changes in Motion are - so that the patient is treated and educated best. What the reaction and response of the entire kinematic chain is would be a point of focus (not just the material reaction – our bodies will often react differently to the same mechanical change)

    • Depending on where in the system you're looking for the “dynamic” aspect beyond material details (like during “interaction with the ground”) there are a number of measured answers. First in the small study, Jay refers to, using the Noraxon Force Distribution Measurement Treadmill, 23 subjects recorded an average increased loading response phase where the foot is usually re-supinating – this is tested independent of footwear (though it remained the same within-subject, and with random selection). There are many cases when pronation continues through this phase, thus potentially causing a lot of issues, like you hint at. This increased loading response phase was accompanied by increased average step length, decrease in average step width, and reduced average foot abduction. Put these 3 things together and you can paint a better picture of a few “more dynamic” events (based on evidence from the study).
    • Then you must also consider how the dynamic relates to patient specific events. As you said - do you always want springier Rearfoot post? Do you always want a Rearfoot post? In terms of superior-ism….what do you need the aim of a device to have? Likewise, this will be heavily conditional as you are saying.
    • For patients who measured very different left to right center of pressure gait lines without Dynaflange, not only did their loading response increase in the midfoot transition, but the Measured difference in the left to right symmetry improved dramatically with Dynaflange. This type of improvement is only possible when there is something dynamic happening – whether it is more or less than other, broader scale, solutions for particular patients is un-known.
    • When standing and laterally stepping much faster corrections to the Center of pressure shifts were Measured and recorded for every case (increased velocity of movement).
    • There is no quantification or comparisons on “weakness in controlling frontal plane motion”, especially in comparison to various “flat bottomed devices”. I say we test this more fully as has been started using Noraxon’s 3D MyoMotion solution, another fast clinical tool that gives these nice auto reports :)

    Always more to look at! Let me know if I can facilitate anything!


  26. jsegel

    jsegel Active Member

    Hi Kevin,
    Just a quick response to your reference to polypro. You and the folks at Langer on in the of the same opinion but here, I find better results with full contact (even a bit vaulted) orthotics with Delrin derivatives as it has better resilience and the patient response on reorder favors these delrin devices. I was able to find the comparison of some of the properties of these two materials and will send it to your email.

    On the use of the word reanimation, it is just in keeping with the analogy of the Dynaflange acting as a sort of living hinge, but certainly the purpose was to convey the ideas of loading response, elasticity, recoil and resilience. Jay
  27. Lab Guy

    Lab Guy Well-Known Member

    I perceive that Langer wants a monopoly on rearfoot posts with their Dynaflange. If other orthotic labs want to use the technology, there will be a sizeable price they will have to pay.

  28. As I said previously, I quite like the idea of this modification, even if the name is a bit gash. However, I find some of the claims and moreover, the terminology being used here rather less palatable, for example: "vaulted", what is this supposed to mean? The first "dynamic" modification claim is patently non-science:bash: Stick to the science and loose the QVC shopping channel approach.

    Speaking of patents, I think there is a future in new designs for foot orthoses, like Kevin I'm not overly impressed with patents. As I understand it, the "kinetic wedge" was patented by Langer- I know of lots and lots of people who've used modifications resembling kinetic wedges in their foot orthoses over hundreds and thousands of times and never paid a penny in royalties to Howard or Langer. Steven, it's very easy to produce something similar which doesn't fall foul of the patent here. Ultimately, foot orthoses alter the kinetics at the foot-orthosis interface- lot's of ways to skin cats and end up with similar interface kinetics. The real trick is in getting the interface kinetics right for the given patient and their given problem. Has there been any studies of interface kinetics yet with this modification?

    Anyway, back to the science- has there been any finite element analyses of this modification? Can it be calibrated in terms of it's load/ deformation characteristics?
  29. jsegel

    jsegel Active Member

    Hi Steve,

    On the subject of Dynaflange, it's quite the opposite. Jason, the man in charge now, is very amenable to a reasonable sub-licensing agreement as it is part of their right. They are good people, and if you think it might be to any labs' advantage, have them contact Jason Kraus at 800/645-5520
    Kind Regards Jay
  30. You really are just here in an attempt to sell aren't you, Jay? But you haven't proved that it works yet... If anyone pays to use this design, they are off their heads.
  31. Simon:

    I agree. I don't feel any urge to try the Dynaflange orthotic and pay a licensing fee since I can get probably the same or a very similar biomechanical effect by putting a piece of PPT or Spenco insole material under the rearfoot post of my patient's existing orthoses, for next to no cost at all (and which I have already been doing for the past 25 years with good to excellent results in select patients).

    By the way, I did like the QVC shopping analogy. Very appropriate in this regard.:drinks
  32. No, Jay. The Dynaflange is a dead hinge, not a "living hinge". It will not "reanimate" to a "living hinge" unless you take it up to Dr. Frankenstein's castle and hook your dead hinge to try to make it a living hinge with his lightning electrodes.

    Jay, I think you had better stick to accepted biomechanics terminology rather than making up new marketing terms to describe your product. It will make you look more like a scientist and less like a salesman to all of us who are critical of such behavior.

    I am getting bored now. When you get a chance to have some truly independent testing of the Dynaflange orthosis idea with 3D motion analysis and inverse dynamics against other types of orthoses, then please post them up here on Podiatry Arena. Motion of CoP pathway is not used by any serious biomechanics lab when assessing the kinetics of orthoses.

    Until then, I will keep putting the occasional Spenco or PPT insole material under the rearfoot posts of my dynamic, reanimated, responsive polypropylene orthoses and plastazote foot orthoses to make them even more dynamic, reanimated and responsive.....at no extra charge to my patients and at very little cost to my practice.
  33. jsegel

    jsegel Active Member

    Hi there Kevin,

    I'd like to address some points you brought up for consideration viz;
    Quote "..provide references or some sound explanation based on the known laws of physics and engineering as to why the orthotic device is dynamic..."

    The physics behind the mechanical utility inherent to the design and material in Dynaflange is "elastic energy" defined and described below. From the design standpoint, I laid out the behavior of the plantargrade wings and rims when deformed in response to a loading force, the body. Now add in the benefits of a material such as delrin, which has a higher degree of deformation and so, a greater ability to absorb energy according to the chart comparison of mechanical properties of the said delrin vs polypropylene.


    That energy is returned to the body as the center of pressure changes and the dynaflange returns to its original shape. As posted earlier, "energetic" is a synonym for dynamic thus, more energy absorbed, more energy returned equals "more dynamic." As well as the already stated durability and inherent resilient nature of delrin allows for more gait cycles before material fatigue or failure. In contrast and as an example, a flat piece of either of these plastics will show an incalculable amount of deformation when bearing a load on a 2 dimensional surface. So, for this elastic energy to manifest, both appropriate material and design are necessary. The dynaflange has a highly 3 dimensional rear foot post attached to a three dimensional shell that allows the combined unit to off-load and mitigate ground force reactive forces.

    From Wikipedia, the free encyclopedia
    "Elastic energy is the potential mechanical energy stored in the configuration of a material or physical system as work is performed to distort its volume or shape. Elasticity theory primarily develops an analytical understanding of the mechanics of solid bodies and materials.[1] The elastic potential energy equation is used in calculations of positions of mechanical equilibrium. The energy is potential as it will be converted into another form of energy, such as kinetic. Mathematically, the equation can be stated as

    The essence of elasticity is reversibility. Forces applied to an elastic material transfer energy into the material which, upon yielding that energy to its surroundings, can recover its original shape. However, all materials have limits to the degree of distortion they can endure without breaking or irreversibly altering their internal structure. Hence, the characterizations of solid materials include specification, usually in terms of strains, of its elastic limits. Beyond the elastic limit, a material is no longer storing all of the energy from mechanical work performed on it in the form of elastic energy.

    Elastic energy of or within a substance is static energy of configuration. It corresponds to energy stored principally by changing the inter-atomic distances between nuclei. Thermal energy is the randomized distribution of kinetic energy within the material, resulting in statistical fluctuations of the material about the equilibrium configuration. There is some interaction, however. For example, for some solid objects, twisting, bending, and other distortions may generate thermal energy, causing the material's temperature to rise. Thermal energy in solids is often carried by internal elastic waves, called phonons. Elastic waves that are large on the scale of an isolated object usually produce macroscopic vibrations sufficiently lacking in randomization that their oscillations are merely the repetitive exchange between (elastic) potential energy within the object and the kinetic energy of motion of the object as a whole.

    Elastic potential energy in mechanical systems

    Components of mechanical systems will store elastic potential energy if they are deformed when forces are applied to the system. Energy is transferred to an object (i.e. work is done on it) any time a force external to it displaces or deforms the object. The quantity of energy transferred by work to the object is computed as the vector dot product of the force and the displacement of the object. As forces are applied to the system they are distributed internally to its component parts. While some of the energy transferred can end up stored as kinetic energy of acquired velocity, the deformation of the shape of component objects results in stored elastic energy.

    A prototypical elastic component is a coiled spring. The linear elastic performance of a spring is parametrized by a constant of proportionality, called the spring constant. This constant is usually denoted as k (see also Hooke's Law) and depends on the geometry, cross sectional area, undeformed length and nature of the material from which the coil is fashioned. Within a certain range of deformation, k remains constant and is defined as the negative ratio of displacement to the magnitude of the restoring force produced by the spring at that displacement."

    Have a nice week, Jay
  34. jsegel

    jsegel Active Member

    Hi Simon,
    Regarding "here to sell", not really my thing, I was just responding to Steven about the idea of "monopoly." Any one who knows me will tell you that money is not a prime motivator in my life. I have spent far more money than I am ever likely to receive. Further more, if you look at the way that I book patients, my office is all about quality care, generosity and time spend to do a complete job.
    That are certain facts that cannot be brushed away, I have provided research on loading response, step length, COP, physics, alignment, videos, sound biomechanical discourse and most important, patient RESULTS. What is clear is that is one wants to find issues, they will find issues.
    The utility can be felt. With that in mind, send Langer a cast of you and I will PAY them to make you a pair. Then we'll have something to talk about. Perhaps as a veteran of this site and a scholar, you will be able to add to the discussion in ways more familiar in tone and substance to this community than I. You have been a gentleman to me in the past, and now I'm requesting that you be a supportive colleague to a guy with an idea that patients respond to. There are so few in our field that are thinkers, doers and practitioners, we should be those who encourage others visions actively with our hearts and HANDS. There is no risk to you
  35. Craig Payne

    Craig Payne Moderator

    Why do so many brands try to damage their brand by making stuff up for:
    What has it got to do with "proprioception"?

  36. foot_tech

    foot_tech Welcome New Poster

    I think the term preconception is used everywhere. If something is stimulating a different or altering response than normal it is termed proprioceptive. Even Google says that social media creates "social proprioception". The market loves it. I understand that variability and adjustments in some neuromuscular or biomechanical stimuli, or even environmental and psychological stimuli can be beneficial, thus maybe it is not damaging for devices, like Dynaflange, that also do this?

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