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Challenging the foundations of the clinical model of foot function

Discussion in 'Biomechanics, Sports and Foot orthoses' started by NewsBot, Jan 31, 2017.

  1. R.S.Steinberg

    R.S.Steinberg Active Member

     
  2. R.S.Steinberg

    R.S.Steinberg Active Member

    I love these discussions. Without the foundation of Root, et. al, Kevin Kirby, Eric Fuller, Craig Payne, Trevor Prior, Beno Nigg would not have anything to talk about. Has our understanding evolved? Of course, thanks to deep thinkers like Dr. Kirby, but the attacks on Root, are more about ego than relevance.
     
  3. mr t

    mr t Active Member

    Hi Simon,

    It's been a while since I posted and I totally missed this one. It seems the discussion got hijacked in a bizarre way, but I did want to clear this up with you if you don't mind as we had a bit of a misunderstanding at this point. We could be having a meaningless semantic argument, but I wanted to clear it up regardless.

    "Taking your two examples, if we milled postive models of the scan that is orientated differently in your CAD system examples, in reality both models would actually be the same when turned into physical objects."

    This is not correct, however it may be my explanation that created this misunderstanding. In the example that I was providing the alignment of the foot determines the generation of the negative orthosis model which forms a 1:1 model of the foot morphology from the ground plane to the foot as it would be machined in full thickness EVA. The frontal plane alignment of the foot prior the creation of this 1:1 negative is therefore a determinant on the application of forces at the foot orthosis interface. The same logic would apply to other methods of manufacture including direct machined poly, 3DP and vacuum as the ground plane still forms as a basic for correction of foot segments or orthosis segments.

    "Of course an accurate measure of angular relationship doesn't matter. As long as an orthosis is basically providing reaction force in roughly the right place, in roughly the right direction, at roughly the right time then that's as good as we can ascertain."?

    I think an accurate measure of angular relationship in terms of providing an initial reference does matter. The second part of your statement I concur with. It's simply easier to apply a change in roughly the right place, in roughly the right direction and at roughly the right time if you utilise a clinical measure to begin the design process. That was all I was trying to point out.

    "Returning to my original point: perhaps you can tell me the relationship between the surface angulation of the forefoot to rearfoot in your CAD system and how this changes the angular relationship of the foot orthosis surface and ultimately how this changes the magnitude, position and timing of the GRF vector in each patient? No, didn't think so."

    No, it can't do that. Please keep in mind I am not advocating my CAD system here. I am just arguing the importance of a reference measure no matter what system is used as I believe it is fundamentally important. All I can currently do is provide a framework for users. In other words capture the morphology of the foot accurately, align the foot according to a well established clinical measurement and then provide a consistent way to apply changes to the foot orthosis interface based on the morphology of the foot from this initially referenced position. I don't tell users what numbers to put in what boxes on any form or pretend to have a magical snake-oil formula. I will simply apply consistent changes at the foot orthosis interface and do my job. I only wished that leaders in the Podiatry field advocate for more consistent foot capture.
    "How do prefabricated device work?"


    The answer is of course that they sometimes apply a change in roughly the right place, in roughly the right direction and at roughly the right time. I'm sure that some people could pick up a strangers pair of prescription glasses and be able to have a minor improvement in sight too, but if they were properly assessed by an Optometrist then I daresay that the perfect lenses for their eyes would be prescribed according to well established measurements.
     
  4. Dr Rich Blake

    Dr Rich Blake Active Member

    Wow! What allegations! I have successfully used the Root modeling in my 40 year practice with wonderful results. That being said this paper should be looked at to see what they were observing and how these 6 groups did not function. I have found that the Root method is fairly accurate, but there are so many influences on the foot, which means it is logical when foot deformities do not behave in some fashion. Example, forefoot varus alone should compensate by heel eversion. This is complicated with equal amounts of tibial Varum not allowing the tibial varum. Root did not say all deformities act one way. He was very clear that make sense of your measurements, since 10 things could affect something like forefoot varus. I believe Dr. Root is known for trying to simplify and teach biomechanics (a new field in podiatry), and his incredible brilliance and humbleness has been lost to so many. He started something that still works, but now we know so much more about axes, and moments, and tissue stress. It is up to us to fine tune the process of this wonderful field. I hope we can look at the data closely. These are wonderful researchers. But if 50% works and 50% doesn’t, the data says nothing works. Rich
     
  5. efuller

    efuller MVP

    You should read Root's 1994 piece in clinics in podiatry. Essentially, he said that his development of the functional foot orthosis was through trial and error and not really based on theory. (sorry don't have the exact quote at hand.) What the paper, that sparked this thread, says is that the measurements were not good at predicting foot function. Rich, the inverted device working better, for some feet, than the classic Root device is an important piece of information in showing that Root's trial and error process was not finished. In fact there is quite a bit of disconnect between foot typing and the theory on how an orthotics work. You can't argue with what works. You can argue the explanation of why it works. The paper is not saying that nothing works, but it is questioning the explanation of why orthoses work.

    Eric
     
  6. Dr Rich Blake

    Dr Rich Blake Active Member

    Thanks Eric, I think we both were honored to be with Dr. Root during those days. He was a researcher at heart, and knew he had major flaws in his suggested theories. But in the 1970s and early 1980s, they were the only theories we had. And for the most part has had incredible success. Your point on his trial and error theories were unfinished is exactly true. I think if providers want to think about the patients mechanics and prescribe accordingly, we need to understand when does Root apply, Inverted apply, Subtalar Axis deviations apply, DC Wedge apply, Tissue Stress apply, etc. If we just want the lab to make something with a bit of info, Sole Supports or Shavelson or DeCaro or whoever can take the responsibility. For me, I want the challenge and satisfaction to decide what theory to use on any individual patient.
    As for why orthotic devices work, I think so many factors apply. Slowing motion, positional change, change in motion, taking a joint off of subluxatory range, giving muscles more power, or shifting weight from a sore area to a non sore area. We both know this is a small part. When I am treating patients with various modifications, I try to make sense of the function (s) I am influencing.
    Thanks for helping me understand these discussions which I was not involved with when initiated. My deepest respect, Rich
     
  7. Brian A. Rothbart

    Brian A. Rothbart Active Member

    Root et al was one of the first in our profession to offer an understanding of foot function. He defined and classified a series of foot structures (e.g, forefoot varus and valgus, rearfoot varus and valgus) that altered foot function, which he then linked to foot pathology (bunions, hammertoes, heel spurs etc). Later this was extended to pathology in the leg and knee. All very laudable and commendable but unfortunately flawed.

    The flaw was that they were defining foot structures that, from an embryological point of view, could not exist. When one revisits foot embryogenesis, it becomes apparent (from an ontogenetic perspective) that only four foot structures are possible:
    1. Clubfoot Deformity
    2. PreClinical Clubfoot Deformity
    3. Primus Metatarsus Supinatus foot structure
    4. Plantargrade foot
    It also becomes apparent that Root's classification of forefoot and rearfoot abnormalities are specious.

    If one wants to do their own research on what I have written above, I would suggest:
    1. Carlson's Human Embryology and Developmental Biology
    2. Rothbart BA, 2002. Medial Column Foot Systems: An Innovative Tool for Improving Posture. Journal of Bodywork and Movement Therapies (6)1:37-46
    3. My research website: Embryology, The Key to Understanding the etiology of abnormal foot structures
    My 2002 paper and research website have distilled a very dry and labyrinthine subject into a more concise and readable presentation on foot embryogenesis.

    Be that as it may, once this is understood, it then becomes straight forward how these 4 distinct foot function determine foot function.

    I hope in the near future a discussion on foot embyogenesis is initiated. The outcomes of this discussion would potentially change how we view foot pathology and how we treat it.
     
  8. Dr Rich Blake

    Dr Rich Blake Active Member

    Thank you!
     
  9. Rob Kidd

    Rob Kidd Well-Known Member




    And your basis for this claim, is?

    If you take the trouble to visit the fossil record - admittedly thin - then you will find that the observed changes in foot anatomy from an archetypal apes model to that of Homo, closely align to the body planes. And then you will note that the genetics controlling growth also aligns to the body planes vis: proximo-distal = hox genes; caudo-cranial (lateral medial does not work in embryology) - sonic hedgehog genes; dorso plantar = Wnt Systems (admittedly poorly understood).

    It is only a very minor leap of faith to suggest that if these control normal growth, they also control abnormal growth.


    So please explain, how does your 1-4 above fit with this undeniably true information?

    Among other places, you will find this detailed in: (particularly in ***)

    Zipfel B., DeSilva J.M., Kidd R.S., Carlson K.J., Churchill S.E., Berger L.R. 2011 The Foot and Ankle of Australopithecus sediba. Science 333 1417-1420

    Kidd R.S and Oxnard C.E. 2005. Little Foot and Big Thoughts – a Re-evaluation of the Stw573 Foot from Sterkfontein, South Africa. Journal of Comparative Human Biology 55:3 189-212***

    Kidd R.S., O’Higgins P. and Oxnard C.E.. 1996. The OH8 Foot: a reappraisal of the functional morphology of the hindfoot utilizing a multivariate analysis. The Journal of Human Evolution. 31: 269-291



    Rob
    (dragged out of retirement - again)
     
  10. Brian A. Rothbart

    Brian A. Rothbart Active Member

    Hi Rob,

    I was hoping you would jump into this discussion.

    To answer your question regarding how my 1-4 foot classification fits into foot embryogenesis, let's first succinctly review normal lower limb development:

    Looking at the embryogenesis of the lower extremity, the ontogenetic (torsional) development of the lower limb axiomatically occurs centrally to distally.
    • At week 3pf, the lower limb bud sits at right angles to the rump of the embryo. The soles of the feet and posterior compartments of the leg and thigh face cephalad.
    • Week 8pf, the limb bud is rotating 90 degrees around its longitudinal axis. This places the soles of the feet and posterior surfaces of the thigh and leg facing one another.
    • At this point, the thigh and leg continue to unwind (the process of decentralization), so that by 10pf only the feet remains in supinatus (soles facing one another).
    This is where my 1-4 classification fits in:

    At week 10pf the talus migrates to sit on top of the calcaneus.

    These two bones then begin to unwind around their longitudinal axis

    Clubfoot Deformity: the ontogenetic unwinding of the entire lateral column of the foot ends prematurely.

    PreClinical Clubfoot Deformity: The cuboid completes its ontogenetic development but the calcaneus remains in supinatus

    I have suggested to both Zipfel and Silva that 'calcaneal supinatus' could be the 'maker' to differentiate and trace the lineage of Homo Sapiens from the rather bushy phylogeny of other two legged, upright walkers. (See Tracing the Human Lineage on my research website)

    Want I find most compelling is the supinatus found in the heel bone of H.Naledi, which Berger suggests is in the direct lineage of H.sapiens.

    Primus Metatarsus Supinatus foot structure: The calcaneus completes its' ontogenetic development, but the talus remains in supinatus (and along with it, the entire medial column of the foot).

    Plantargrade foot: The talus completes its' ontogenetic development

    This is a very abbreviated presentation on how my foot classification fits into the process of embryogenesis. If you would like to expand this discussion, I would be very pleased to do so.

    Understand, my 1-4 classification of foot structures, dovetails into the Ontogeny - Phylogeny Calcaneal Model which I proposed. It has engendered a lively debate (in a forum on Researchgate.net), some agreeing and others disagreeing with my proposed model.

    I have not attached the myriad of publications and embryological references. I can do so, if you request.

    Brian
     
    Last edited: Nov 28, 2019
  11. Rob Kidd

    Rob Kidd Well-Known Member


    You have made some woefully simplistic assumptions, some of which are simply wrong.

    For instance, your statement that at the "10pf the talus migrates to sit on top of the calcaneus", is simply not true. I refer you to pages 26 & 67 of Freddy Wood Jones' text "Structure and Function as seen in the Foot", you will see quite clearly that the talus lies medially to a laterally positioned calcaneus. And, as is found in the reptilian model - but not in any (adult) primates, the fibulares (calcaneus) is articulated with the fibula. What not occurs is a translation of the calcaneus from being lateral, to being medial (ish), to eventually being positioned beneath the talus - the talus does not translate - it is locked in the ankle mortice from a very early stage.

    Since the talus and calcaneus are respectively the hindmost component of the medial and lateral columns it is enticing to make the leap to them dragging along the two columns - this is likely to be a simplistic explanation of their development.

    Whatever may be compelling to believe, there is no evidence at all that any prehuman specimens is the fossil record are direct descendants or antecedants of any other.

    I have not spoken to Bernie Z for some time about these issues - he was of course a PhD student of mine many years ago.

    I think you may consider my contribution to this debate complete.

    Rob
     
  12. Brian A. Rothbart

    Brian A. Rothbart Active Member

    The talus lies along side of the calcaneus and then migrates to sit on top of it. If this migration does not occur exactly at 10pf, I apologize for my poor memory.

    It is factual that the calcaneus and cuboid direct the ontogenetic development of the medial and lateral columns of the foot respectively. And It is from this understanding that underpins my 1-4 classification. You have made no challenge to this classification. Do you accede it credible?

    I disagree with your statement that 'there is no evidence that any prehuman species in the fossil record are direct antecedents of H.sapiens. Extrapolating from my proposed Ontogenic Phylogenic Calcaneal Model: I opine that H.naledi would qualify as a direct descendent of H.sapiens. However, time will tell if my model is right or wrong.

    I quote from my research site:

    "This OPCM is based on my clinical research which entailed the discovery of a previously unrecognized inherited foot structure, the PreClinical Clubfoot Deformity (Structure). The hallmark of this foot structure is the structural twist (supinatus) in the posterior aspect of the calcaneus. This is the same structural twist found in the fossilized calcaneus of the H.naledi but lacking in the A.africanus. From this the OPCM would conclude that H.naledi is a direct descendant of H.sapien, A.africanus is not.

    The PreClinical Foot Structure appears to be at least 2 million years ago and possibly older.

    The most common foot structure in our population today is the PreClinical Clubfoot Structure/Deformity. The least common is the Plantargrade Foot Structure (heel bone and talus no longer retains any supinatus/structural twist).

    I opine that the homo sapien foot is still very early in its anthropological evolution, evolving from the bipedal dysfunctional PreClinical Clubfoot structure towards the very stable bipedal plantargrade foot structure."

    As a side note, I also have had this same discussion with Bernard. And admittedly, I am not a university trained paleoanthropologist, only by interest.

    Brian
     
    Last edited: Nov 28, 2019
  13. Dennis Kiper

    Dennis Kiper Well-Known Member

     
  14. Brian A. Rothbart

    Brian A. Rothbart Active Member

    Unfortunately, we (as Podiatrists) tend to be myopic in our vision. Until we finally start investigating the global impact foot function has on physiology (including brain chemistry), we will remain stuck in Root Biomechanics, or some iteration of it.

    Foot function is predominantly driven by foot structure. And the key to all this lies in our understanding of human embryology. A subject no one, to date, wishes to engage in.
     
  15. Dennis Kiper

    Dennis Kiper Well-Known Member


    I have to challenge this, because while embryology is impportant to our overall understanding, it is not the key to foot function. After some 30 yrs of utilizing hydrodynamic technology, I have found the key to foot function is mechanical efficiency of the functional mechanics of gait. And the global impact it might have is the degree of tissue efficiency it can result in.
     
  16. Brian A. Rothbart

    Brian A. Rothbart Active Member

    Your comment is well taken Dennis. Allow me to clarify.

    Foot function (pronation/supination patterns of motion during stance phase) is determined, in large part, by the structure of the foot. When one studies the ontogenetic development of the embryological foot, it clarifies the 4 possible post natal foot structures (clubfoot, PreClinical Clubfoot, Primus Metatarsus Supinatus and Plantargrade) Each of these foot structures direct a specific pronation/supination pattern of motion during stance phase.

    I have linked each of these specific patterns of motion to specific postural distortions. And each specific postural distortion pattern to a sequela of symptoms (foot to jaw). I have published on my postural research as well as presenting it on my research website.
     
  17. Dennis Kiper

    Dennis Kiper Well-Known Member

    I believe you are correct in your statement. However, there are still a POM of the MTJ of each of your structures (exception: flat feet). This is what makes HD technology so effective in non-subluxed MTJ and some anomolies. To me, this is where biomechanics should begin as primary—not the rearfoot.
    Because you can modify a Rx volume to fit the specific pronation/supination/over-pronation by as little as .02 mg to make a difference in the POM (in all 3 planes simultaneously throughout stance) and mechanical efficiency. It mirrors the bio-mechanics of the foot from HC to HO by simple displacement. Some structures will balance better than others, but the ability to increase mechanical efficiency of the functional mechanics (to its max) and that brings max tissue efficiency as well is what podiatry should bring to the world. The sooner the public recognizes that this is what makes a difference over a lifetime to the individual’s biomechanical health. It’s no different than brushing your teeth for health. It’s an orthotic for everyone who fits the technology, every single day, to reduce and minimize normal wear and tear. And who knows what significance this has for runners.
    Flat feet, rearfoot and some forefoot anomolies require a different technology. Your research is important, but we as a scientific group should first fix 70 yrs of poor performance technology first, in my humble opinion.
     
  18. Brian A. Rothbart

    Brian A. Rothbart Active Member

    Hi Dennis,

    I totally agree with you! Our biomechanical models need to be 'modernized' (e.g., global biomechanics, not just foot biomechanics). In this forum, we seem to be stuck in foot biomechanics.
     
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