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Tissue Stress Theory: Just a Variation of Root Theory?

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Kevin Kirby, Aug 1, 2015.

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    William Orien, DPM (of Root, Weed and Orien fame) sent a critique letter to Podiatry Today magazine regarding my recently published feature article in the April 2015 issue of Podiatry Today Magazine titled Has Tissue Stress Theory Supplanted Root Theory?

    The magazine gave me a chance to respond to Dr. Orien's letter in the same issue. For those interested, both Dr. Orien's letter and my letter are published here:

    Tissue Stress Theory: Just a Variation on Root Theory?
  2. Craig Payne

    Craig Payne Moderator

    So Root theory is all about the defined criteria for normal, the subtalar joint neutral position, the midtarsal joint locked position, etc and designing foot orthoses to move the foot towards that defined normal.

    And tissue stress theory is about identifying the tissue that has the high load in it and hurts because of that and designing foot orthoses to reduce the load in that tissue.

    So, of course:
    ...not! .... not even close.
  3. drhunt1

    drhunt1 Well-Known Member

    Dr. Orien was careful to call it the Root Paradigm, and not theory...which is correct. I read his response to Kevin's article and agree wholeheartedly with only a few minor exceptions. He calls it the tail wagging the dog...I suggested that it was akin to building a better mousetrap. I like my analogy better. In the 40 years since Root et al published their book, I find it sad, however, that little has been accomplished in expanding their foundational research/publication...which in essence, it was. It was up to those that followed to expand our understanding of foot function and how best to control abnormal forces. Instead, we have McPoil et al driving square pegs into round holes and many Pods worldwide adhering to this description as if it solves/explains anything better. From my perspective, it merely simplifies pathology to a point that doesn't really solve the overlying problems. Simply put, it's a lazy man's guide to biomechanics. I have already submitted an anecdotal example of plantar fasciitis that is the result of more overriding biomechanical pathology. But her example has been presented in my practice multiple times, to the point that hers is no longer an anecdotal variance. Take the blinders off, roll up your sleeves and get busy, while at the same time, quit looking for simpler explanations. Hope this helps.
  4. In the words of the great philosopher, That's the real trick isn't it.

    If I'd had a quid for everyone who claimed that what they did solved the "over (or under)lying problem", I'd have ?83.50*. Sometimes the models seem quite plausible, other times much less so. The bastardised version of root which many practice is one of the less plausible.

    The difference between tissue stress and pretty much every model is profound. As Craig said, its in the direction of effect. The former starts with the pathology, the latter with the cause. But to consider these equally valid is to make a false equivalency. The pathology, the knackered structure, is definitively establish-able. One can KNOW if one is right or wrong, if diagnostic imaging is available.

    But to know the cause, that requires a degree of faith. And it can rarely, if ever, be established whether one is correct or not. Causes are not amenable to empirical validation, still less so when one deals with less proximate causes. You can say "ah, situation X is the cause of pathology Y", but regardless of the confidence with which one says it, this remains a simple assertion. At this point people usually fall back on the "well I've seen 3.14 x 1014 patients and I've got so many anecdotes it counts as evidence" argument.

    To take an eg. I have a bum knee. I can establish, by palpation and functional testing, what structures I think are damaged. If I had an MRI, I could confirm it. And I can introduce an external load sharing agent (an orthotic) to reduce the stress in those tissues, and yes, that helps.
    But the cause? I could give you all the biomechanical data in the world, and it would not tell you the cause of the pathology.


    *This guy was only half sure.
  5. drhunt1

    drhunt1 Well-Known Member

    Robert-thanks for the reply. As I've stated many times on other threads on this blog alone, much of what we do is not amenable to empirical study. Several here have even suggested that my research was bogus because I didn't utilize a "placebo orthotic", (whatever that is). They can't/won't even describe what a placebo orthotic would even look like, in spite of the fact that I asked that very question. So the answer to many of the foot maladies shall reside in successful repetition of treatment, and, as I've suggested before, with the practitioners' ability to recognize patterns.

    Now...about your knee. My guess is that the medial tibial plateau shows excessive wear, and your long standing symptoms have been medial knee pain...correct? Let's start the discussion/exploration there, (although I highly recommend obtaining an MRI of that knee at some point in the near future).

    Give me more information and I shall try to explain the mechanics using the Root paradigm. Simple enough?
  6. Ah well, the placebo orthotic, there's a whole can o worms right there. Can anything placed in the shoe be guaranteed not to have a functional effect? I doubt it. Where might I read your research?

    Here I would both agree and disagree. Certainly, many treatments which are successfully carried out have no trial data to support their use, or at least no outcome studies. However, your statement seems to indicate that anecdotes (and of course the plural of anecdote is anecdotes, NOT data and still less evidence) is what there is. This is not true, there are many conditions and treatment protocols where we have abundant data from well controlled outcome studies.

    By all means. Be an interesting thought experiment.

    Ok, the pain is RHS, anterior, focused slightly inferior to the patella, but becomes broader and more diffuse when severe. There is some swelling and effusion, but little heat. Pain is slightly relieved on cavitation of the joint.

    Lachmann draw test shows a slight anterior deviation on the right, not on the left. Medial and lateral co-lateral ligaments are stable.

    Biomechanically speaking, slight LLD, Right longer. AJC range is 90+15 degrees both sides. STJ and MTJ range and stiffness unremarkable. Slightly enlarged 1st MPJ rhs, but both passive range >60 degrees.
    On relaxed stance, both feet are pronated perhaps a little more than average, with the right noticeably more so than the left. Right knee slightly hyperextended.

    In terms of the root paradigm assessment, Been a while since anyone did those tests with me, but based on self assessment.

    1. Distil 1/3rd lower limb bisection, vertical within measurement tolerance.
    2. Sub talar axis, passes between 1st and 2nd met head bf.
    3. Posterior calc is everted, RF>lf
    4. Ajc dorsiflexion is > 90+10
    5. Forefoot inverted relative to rearfoot, circa 5 degrees, rf>lf.

    cant really say on the other 3.
  7. drhunt1

    drhunt1 Well-Known Member

    Now we're getting somewhere. My pilot study can be read here:


    From your post and measurements, I gather that you're more symptomatic on your right knee? I'm assuming that there was no precipitating event, ie., rugby injury etc. When you read the article, pay close attention to my discussion where I claim that although forefoot to rear foot measurements are important, forefoot to ground are perhaps even more so. You're everted R>L and you have a forefoot varus R>L...right? My conjecture would be that during ambulation, your right tibia is not externally rotating at forefoot loading going into propulsive phase of gait. Remember, Root claims that the foot should be re-supinating just prior to propulsion in the normal gait pattern. If you're not, then excessive wear can and will occur on the medial tibial plateau, (which is consistent with the evidence that shows 90% of prosthetic knee replacement surgeries are performed because the medial cartilage is damaged). You're simply remaining internally rotated at the knee, because the foot is remaining in a pronated position. Your symptoms, however, appear to be not entirely medial, but antero-medial. Plain film radiographs of your right foot in static stance would be helpful to me. I acknowledge that a full medical history would also be helpful, but I'm jumping ahead "to cut to the chase". Take a close look at the orthotic I designed/ordered for one of my RLS patients...that forefoot varus extension might be helpful in your case as well.

    One of the areas that needs further research, is the effect of an orthotic on the gait pattern and foot function after the heel leaves the supporting surface. Podiatry hasn't done much with that...which seems to me an area where "the rubber meets the road".
  8. Interesting thinking.

    First off, I probably should have mentioned that the pain started when I was kicked rather solidly in that knee whilst it was flexed and unloaded (martial arts).

    So the cause in this case is "being kicked in the knee". It's a little simpler than your explanation, but I think it's quite pithy.

    This being sort of the point. One can speculate forever about the aetiology of an msk pathology, but it remains just that, speculation. The absence of a single detail, as in this case, brings the whole house of cards crashing down. What if the cause was "the stupid shoes I wore one day" or "that time I stepped a bit heavily off the bus" that the patient was unaware of.

    Its not falsifiable. Thus, it's not science.

    Whereas working front to back, aiming to reduce the stress in the busted tissue, IS falsifiable, if you discover that the damaged tissue is not the one you thought, or if reducing stress in it leaves symptoms unchanged.

    One could produce such an explanation for the aetiology of any condition, daily, for years, and never be shown wrong. And thus develop a certainty that one is correctly defining the underlying cause of the problem. The confirmation bias is strong here.
  9. Other points of interest.

    Nope. I said that my forefoot was inverted relative to the rearfoot. I did not say whether it was caused by congenital incomplete derotation of the talar neck (forefoot varus) or inversion at the mid tarsal joint (forefoot supinatus). But given the extreme rarity of the true forefoot varus, you would be much safer in assuming forefoot supinatus. Which brings us on to the dreaded forefoot varus extension you recommend.

    Forefoot varus extensions may be deserving of their own thread. If so, feel free to crack it off into one when you reply if you wish.

    For the sake of terms of reference. Forefoot supinatus is an acquired deformity, caused by plastic changes to the midfoot from high inversion moments to the midfoot. Which in turn are created when high eversion moments from the rearfoot interact with ground reaction force. I'm assuming we agree here.

    A forefoot varus extension will increase inversion moments at the midfoot. Essentially its an effort to invert the rearfoot by inverting the forefoot. Obviously there is a joint between these two points, a coupling which is susceptible to plastic changes (and which already has). This moification will increase those same midfoot inversion moments implicated in the development of the original supinatus. This seems to me to be a bad idea. A very, very bad idea.

    And this, not even mentioning the effect of a forefoot varus extension on the windlass! Increased external dorsiflexion moments on the 1st met, increased internal plantarflexion moments therefore required to activate the windlass, increased intra articular force in the 1st mpj (which is already enlarged), iatrogenic fnHL, lions and tigers and bears, oh my.

    As to the research, having worked 10 years of my professional life almost exclusively in paediatrics (you get to specialize like that in the NHS), I read it with great interest. If I get chance I'll reply on the relevant thread.
  10. drhunt1

    drhunt1 Well-Known Member

    So it was a trick? How could someone seemingly so astute in "all things lower extremity biomechanics", leave out the detail about being kicked in the knee? Why even bother listing what your measurements are? And fwiw, I could give a rat's patootie about lack of talar derotation...it doesn't resolve the patients' issue...does it? Supinatus vs. varus...in the words of the infamous Hillary Clinton: "At this point, what possible difference could it make?" One only needs to view a WB lateral X-Ray to determine that the patient already has a MPE at static stance...examples that I've already shown and am willing to do again, if need be. While many squirm at the idea of supporting this deformity, (by inducing a hallux limitus, or decreasing the function of the peroneus longus, etc.), I suggest that these deformities are already in existence and we need to work around them, or with them. Recommending rocker soled shoes is one way to achieve this. "Casting out" the supinatus is another. The point being, there are many ways to "skin a cat"...I just forwarded one way in that article. I will leave it to others to forward their ideas, after they have reached a similar diagnosis or conclusion....without offering trick scenarios by "leaving out" extremely important details. Thus my sentence: "I am assuming there was no precipitating event". Pretty much covered it...didn't I?

    Hopefully, in the future, correspondences will be much more honest and educational.
  11. Oh I don't know. I'm learning a lot about you. :rolleyes:. Others may be also...

    Are you actually serious when you say you can't see what difference it would make treatment wise, whether an inverted Forefoot is caused by congenital talar neck orientation or if it's an acquired deformity? Because if so, that's quite alarming. You really would defend that position? That you would treat a deformity caused by high mid tarsal inversion moments with a modification designed to increase mid tarsal inversion moments? Truly?

    In a world where an inverted Forefoot was always a Forefoot varus (an assumption you seemed happy to make) , that approach makes sense. With the understanding of Midfoot mechanics we presently enjoy, it's more than a little worrying.

    How can you presume to treat the underlying cause if you are in different to it.
  12. drhunt1

    drhunt1 Well-Known Member

    Determining the cause of said FF varus deformity doesn't necessarily change the approach I use to treat it, (or in the prescription of the orthotic). Waxing poetic about lack of congenital talar derotation is, IMO, an exercise in mental masturbation, above and beyond your inability to actually prove that point. And as rare as you believe a structural FF varus is, I am of the same opinion about acquired varus. An acquired deformity in my world is due to compensation. What force(s) are in play in your world that would lead to a varus compensation at the forefoot? This is no trick question. It drives to the heart of this discussion...doesn't it?
  13. blinda

    blinda MVP

    Yep. Surely did. Never "assume" anything, hence the absolute requirement for full med hx.....
  14. Mental masturbation. What a wonderful turn of phrase.

    Yes, I think the irony of these two statements very nearly caused me to "arrive". To bemoan the lack of focus on the cause of the problem, then in the very same thread to state that the cause of the deformity makes no difference. Which way would you like it? You can pick either, but not both.

    But we digress.

    Regarding your view that acquired Forefoot inversion deformity is rare. You are wrong :).

    I thought I'd been plain enough on this point, but I'll say it again. Forefoot inversion deformities are caused by (drumroll) inversion moments applied to the Forefoot (tsssss). Specifically, by ground reaction forces.

    Don't know how I can say it any clearer or more simply. I could try it through the medium of interpretive dance if you like...
  15. drhunt1

    drhunt1 Well-Known Member

    OK...so assuming that we take your scenario as being the case for acquired FF varus...wouldn't that foot pathology be fairly evident, ie., wouldn't we note all the signs of a pronated foot regardless of the cause? Further, how can you know that the deformity secondary to ground reactive force is an acquired one, unless you had a long standing history with this same individual patient and observed a biomechanical digression? But perhaps more importantly, how do you change your Rx for this patient taking into your account that the deformity is acquired? Please offer me an example of what Rx you would write, structural vs. acquired, that best exemplifies your differing approach. TIA.
  16. I've sinned. I was guilty of the sin of bald assertion. Here.
    You would have been right to have called me on that.
    Allow me to make amends.

    The way in which one might tell how much forefoot inversion is caused by talar torsion is simple. One might take a bunch of cadavers, get people to assess their forefoot rearfoot relationships, then dissedt them and measure the tali directly. If the deformity is osseous and congenital there will be a correlation between the two. This, of course, has been done. More than once I believe. Guess what they found.

    Well, the originally defined test was that forefoot varus is a non reducible deformity where the sub talar joint is in neutral AND the lateral column is fully loaded. So the obvious answer to your question would be to manually attempt to reduce the deformity. If you can, its a reducible deformity, much more likely to be supinatus. If you can't, irreducible deformity, much more likely to be forefoot varus.

    I believe the figure for forefoot varus, assessed properly, per the original protocol is about 1.6%. This also dovetails with the research above.

    Which brings me to the second part of your question. It's slightly tricksy, because I would not treat a forefoot supinatus per se. Its not a pathology. And these things don't happen in isolation. But since you asked for an eg

    If the inverted forefoot was acquired, I would work on the basis that it was acquired from High external inversion moments on the forefoot. Or possibly, low internal eversion moments on the forefoot (vis, the windlass not working very well). I would therefore treat it by trying to decrease external forefoot inversion moments (by reducing rearfoot eversion moments) and / or, facilitating the windlass (1st met cutout, kinetic wedge, reverse mortons extension etc.).

    If on the other hand it was a fixed, irreducible deformity (the 1.6%), There would be no benefit to the above, doesn't matter what you do, it ain't reducing. So assuming there was no danger of creating FNHL by blockading the windlass, Id be much more likely to use a forefoot varus extension.
  17. drhunt1

    drhunt1 Well-Known Member

    Cadaver studies are limited because there's no "historical" data available. In other words, unless one has followed a patients' foot structure throughout their life, it is difficult to ascertain any starting point except through speculation. Further, your description of FF varus as reducible vs non-reducible is the same as structural vs. flexible. In a patient with a flexible deformity, this relationship can be "casted out" by plantarflexing the first ray, (or 1st-3rd rays), and presents with very little problems for the practitioner in doing so. That's not what I was referring to. I was discussing a structural deformity, and included the FF to ground relationship as being also important in Rx'ing an orthotic. This becomes even more relevant when the patient presents with a low ROM of the STJ...correction of the FF being even more critical.

    So forget cadaver studies for a moment, and address how your perception of the level of pathology changes your Rx for an orthotic for FF varus as you discussed above.

    I am including a lateral pic of a plain film, WB radiograph for your perusal. Tell me what you see...and this is not a trick question.
  18. efuller

    efuller MVP

    For someone who sings the praises of neutral position theory, you do seem to disagree with a lot of that theory. Supinatus was a concept taught by John Weed when he taught at CCPM. You could call it a compensation for prolonged rearfoot eversion. As the rearfoot everts, the forefoot will have to invert (because ground reaction force supinates the long axis of the MTJ.) This high medial forefoot load will tend to eventually cause a fixed dorsiflexed position of the medial column. This could also result in medial column faulting that you see on lateral x-ray.

    If you measured a forefoot varus, would you treat medial column faulting and first ray pain with a forefoot varus wedge? What is the theory here? If you supinate the STJ with a forefoot varus wedge you will be able to lock up the joints of the first ray???. The forefoot varus wedge is attempting to supinate the STJ by increasing load on the first ray. Don't you think increasing the load on the first ray would tend to make medial column faulting worse.

  19. drhunt1

    drhunt1 Well-Known Member

    I've noticed that none of you here have commented on the above radiograph I submitted...and this is not the first time this has occurred. I've submitted this X-Ray before with nary a nibble from the biomechanics gurus. When did I ever state that I adhered COMPLETELY with the Root Paradigm? I've stated consistently that his was the foundation from which we should be adding to...not detracting by attempting to develop "new theories".

    In the X-Ray above, we were also taught that this foot was supinated. I can tell you that it is not. There is no eversion available at the STJ on this patient at static stance. In developing a strategy to successfully treat lateral instability, RLS and GP's in children, (not exclusive maladies, I might add), I had to figure a way to hold the STJ in a more inverted position, (closer to neutral), thus allowing the patient to compensate for closed kinetic chain forces, either from above or below. By not only holding the STJ closer to neutral in the rear foot, but also "bringing the ground up to the hallux", I was able to achieve this, as the patient had better balance, more propulsive strength and was able to better negotiate irregularities in terrain, (CKC force from below), and lateral forces from above. These patients aren't complaining of first ray pain, and if you look carefully at the X-Ray, you will notice she already has a MPE. It's not atypical to note that these patients have a hallux that "looks like a thumb", as the IPJ has to compensate for the hallux limitus deformity. In other words, these patients already have the varus deformity, I'm just supporting it to allow better function, (and avoid having them compensate elsewhere). These patients are complaining of "ankle" pain, (which is actually STJ pain) which can result in a multitude of complaints, from plantar fasciitis, to referred pain distally to RLS and GP's in children. The patient above was recorded during the ambulation video and is part of my presentation...she was the "first" patient I had the animator overlay the skeleton. Her segment starts at 45 seconds into the following video:


    How do I approach supporting the MPE? By suggesting rocker soled shoes with the orthotics inside. The shoe, therefore, compensates for the hallux limitus, (sagittal plane) while the initial patient complaints are addressed with the orthotic, (mainly frontal plane). This type of orthotic does not work in dress-type shoes...and I explain that to the patients prior to casting. The resolution of pain is a motivating factor for the patient to change shoe types. Several of the patients I videotaped/interviewed discussed that very subject.

    The debate about supinatus vs. varus rages on. But I can tell you this...the "Baja Boys" smirk at this suggestion as they are more concerned about reducible vs. non-reducible deformities. If the problem is reducible, they treat it conservatively. If it's not, they proceed to structural correction which produces amazing results. Aligning the rear foot to the lower leg, then aligning the forefoot to the rear foot are procedures they've been performing for quite some time and follows Root precepts. I witnessed/assisted in skewfoot corrections many moons ago, and I can assure you it works just dandy. Now...if you'd care to comment on the above X-ray, that would be a great place to continue.
  20. Nope. Its not a question of the history of the deformity, its a question of the location of the deformity. If ff varus WAS generally forefoot varus, originating from the talar orientation, we would see a correlation between the deformity and the talar orientation.

    The fact that we don't is firm indication that most forefoot inversion deformity does not arise from the talus, but from one of the joints lower down.

    Would love to take credit, but its not MY description. Its THE definition. Check the literature.

    When you say correction of the FF, I'm assuming you mean correcting FOR the FF. Its a small but significant different, because correcting the FF would be be to exert the opposite force to the one which caused it. "Correcting for" I'm assuming you just mean bringing the ground up to it.
    Lets not forget the cadaver studies as they completely refute your opinion on the level and aetiology of one of the more common conditions we see :)

    To your x ray. I'll play. I don't do a lot of xray analysis, which is perhaps why I don't see much. Little bit of dorsal lipping on the MC and 1st mpj joints maybe, nothing to get excited about.

    I'm guessing you want me to say cavus foot?
  21. drhunt1

    drhunt1 Well-Known Member

    You don't "do a lot of X-Ray analysis"? Do you take X-Rays? Plain film radiographs I take in my office...and I burn a LOT of film. It's a great learning tool for the practitioner as well as the patient. Now...if you could, please comment on the "bullet-hole sign" noted in the STJ. Is this foot pronated or supinated? TIA
  22. Rob Kidd

    Rob Kidd Well-Known Member

    Maybe it is time to remind the audience that there is NO relationship between talar head torsion angle and forefoot-hindfoot relationship. this has been demonstrated many times (I am away from home just now so do not have the refs). However, start with with McPoil & Cornwall. When did you lose track of the biology? go back to proper heterachronic modeling and start looking at peramorphic heterchronic models. My advice is to look at the work of the late Steve Gould, and then come out with an informed opinion
  23. Dr. Steven King

    Dr. Steven King Well-Known Member

    OMG !

    Craig, I have just realized that I have been expounding the Tissue Stress Theory this whole time while advocating puncture and blast resistant boots for our soldiers.

    I owe Kevin and the Tissue Stress Fan Boys many apologies.

    "And tissue stress theory is about identifying the tissue that has the high load in it and hurts because of that and designing foot orthoses to reduce the load in that tissue."

    Silly me,

  24. Nope. Works a little differently on this side of the water, in the NHS we specialise quite heavily. I work as part of an MDT. I do the conservative biomechanics, and only that. If I want surgery, or diagnostic imaging of any sort, I get it from the relevant clinicians who concentrate on those fields. And to be honest the vast majority of imaging I request these days is diagnostic ultrasound rather than xray. I believe the surgeons irradiate almost everyone who limps in the door. I rarely find the need.

    The bullet hole sign, is generally thought to be a sign of pes cavus. However I could not tell from that xray what the position of the STJ is within its range, or what its range is.

    So what do you see?
  25. Dr. Steven King

    Dr. Steven King Well-Known Member

    Aloha Robert,

    So technically you do not need to look under the hood to see why the car is running poorly?

    I think 20-20 eyesight is great but x-ray vision makes you a Super Friend.

    A Hui Hou,
  26. To be sure. I can also leap small objects in a single bound and run faster than a speeding bullet (until it is fired.)

    The majority of the time I find clinical diagnostic tools quite adequate. Its good to have the option of diagnostic imaging, but I generally only use it in a tie break scenario if the picture remains ambiguous after the clinical assessment.

    And diagnostic imaging is not without its pitfalls if over used. I still get lots of heel pain, of varying natures"confirmed as heel spur on x-ray", mostly by GPs who rely too much on their radiologists for x-rays and not enough on their ears, eyes and their hands for clinical assessment.
  27. Dr. Steven King

    Dr. Steven King Well-Known Member

    Aloha Robert,

    Agreed tools of the trade are just that, tools.

    What-Who makes us different from the tools we use?

    I am sure you could leap medium sized objects with a single bound if you used footwear materials-tools with greater modulus of elasticity than blown foam.

    And you could also run just as fast as a bullet once it is lodged in your bullet proof vest...

    A hui hou,
  28. rdp1210

    rdp1210 Active Member


    I read with interest Dr. Orien's letter and also your response. I think you did a good job of replying, however, there is one major flaw in your argument. You appeal to popularity of a theorem, especially on an international scale, as a measure of truth. I believe such arguments are never a measure of truth, as history is strewn with "scientific" theories that for a time were accepted as truth, and later dispelled. We continue to see new and then newer views in the field of cosmology as people question Newton and Einstein. Today's popular theory is tomorrow's discarded theory.

    I believe that it is time to quit branding general biomechanical theory labels in these and other forums. I believe you and everyone else should quit using the terms "Tissue Stress-Theory" and "Root-Theory" If tissue stress theory is the idea of identifying the structure that is injured and then figuring out the mechanism by which it was injured, then I was practicing it on June 4, 1979, the day after I received my DPM degree. (I believe that's a few days before you entered podiatry school) Yet I always considered that I was practicing what I had been taught in school. I never thought I was practicing something new. I believe if you read chapter 3 in the first edition of Levy and Hetherington's book, c1990, you will see that I wrote greatly on understanding normal motion of the entire lower extremity and normal muscle function by first examining the moments around each of the joints, starting at the hip and moving distally, exerted by ground forces, vertically and horizontally. Was that tissue stress theory? Was it Root? Was it something else? I will only say that it has only one term - "biomechanics".

    I don't mind someone putting names on particular theorems in the field of biomechanics. If we want to talk about neutral position of the STJ, we really should assign it the name of "Lovett & Cotton's STJ Position of normalcy". If we want to talk about twisted plate theory, we should assign it the name of "Steindler's Approach" to supinating the foot. I believe that the one unique postulate by Root, et al., was what I have come to call the Root Postulate. Yet this postulate is based in the Steindler Approach, it just expands it. I don't mind calling a Kirby Skive by that name. It is another addition to the world of biomechanics. I have some reservations about its use, but that argument will not be made until there is research that can support my reservations.

    One of the questions I posed to you, which really is a philosophical question, is, "Should there be a Subtalar Joint Neutral Position?" Hopefully you've had much more time to think about it since I first posed it to you this spring. What are the advantages of having such a position? What are the disadvantages? This is not a question about where it is, or how to measure it or whether people should try to get the foot to that point. It is a question of saying that it either should or should not exist. [Of course we should also ask whether the number "Zero" should exist. Has anyone ever really found Zero? Greater minds than mine have pondered that question.]

    I believe that there are advantages of having a biomechanical system that states that there is a subtalar joint neutral position. Those advantages I could give a whole lecture on. Discarding it does not give more validity to the "Mcpoil & Hunt" theory, but it makes it more difficult to bring quantitation to the field of "day-to-day-clinical-practice". It makes it more difficult to write a clinical SOAP note. Taking goniometric measurements may have flaws, but at least when I read my notes 10 years from now, knowing that I am clinically reliable, I can determine if there has been some changes in the morphology of that foot. I have read most of McPoil's papers, and find that he confuses normal theory with bell-shaped curves.

    I believe that Bill Orien did state it properly when he stated that their volume 2 book was not an end-all. They intended it to be a beginning, to get the ball rolling. And when you consider the impact of that book you still find it being one of the most often referenced books in the biomechanics literature concerning the foot. If you look at my copy, you will find all types of notes in the margins, of things I question, or don't think they got completely right, or questions they raised, yet it remains invaluable, and I continue to admire the thought processes in the book. I find it interesting that I seem to be able to practice using all of the principles that you may see argued. I use Root principles, and STJ axis principles, and twisted-plate principles, and FHL principles. I continue to work on improving my goniometric approach, and doing all other types of measurements that Root never discussed. Simon would have me believe that the Root criteria of normalcy has to be an all-or-nothing argument. I believe such positioning to be rather shallow in it's approach.

    So with just these few remarks, I leave this discussion to others. There would be much more knowledge available if half the energy used by the common contributors on this site was spent instead on doing research.

    With best wishes,
  29. Rob Kidd

    Rob Kidd Well-Known Member

    Firstly, there may or may not be a subtalar neutral position - but you will need to find a decent definition; one that does not involve the words pronated(ion) or supinated(ion). Otherwise, one will be straight back to the circular world of tautology - a scientific laughing stock

    Secondly, even if there is such a position, what is its basis in biology?

  30. rdp1210

    rdp1210 Active Member

    And with your argument: What is your definition of "Zero"? Can you have such a concept without having the words or concept of "not postive and not negative". Zero is a starting position. Likewise STJ neutral is a starting position. No more and no less. It's a starting position from where we all count or measure, whether it be postive vs. negative, or whether it be pronated vs supinated.

    Remember this is not biology, it is straight mechanics. Can you have a quantitative mechanical system that does not have a zero point from which to measure? Just because people have not agreed where that starting point is, does not mean that we shouldn't have one. If we don't have an existence of the starting point, can we say that anyone is standing either pronated or supinated? You create a bigger problem without than with this concept. Again, I did not pose what the definition should be, I posed the necessity of existence question.

  31. Rob Kidd

    Rob Kidd Well-Known Member

    Not biology, it is straight mechanics? Seriously? If it is alive, or was ever alive, it is about biology. It is not a question of agreeing a starting point, it is a question of having one that is valid. Surely you do not need me to expose yet again the utter stupidity of the Root definition of subtalar neutral? Perhaps you should read the works of, by way of example, Darcy Thompson, "On growth and form" to see the intersection between mechanics and biology. Did we not start with the word "biomechanics"?
  32. drhunt1

    drhunt1 Well-Known Member

    Face palm.
  33. Rob Kidd

    Rob Kidd Well-Known Member

    Face palm? I need someone of greater wisdom than I to explain this too me.
  34. Phil Wells

    Phil Wells Active Member


    I am fascinated by your statement about biology/mechanics - not sure what you are getting at..
    Can you point me towards any suitably basic info on this - I have always believed that mechanics comes first and rather then argue about something I know little about, would love to learn a bit more.

  35. Jeff Root

    Jeff Root Well-Known Member


    If you grasp the forefoot, fully pronate the MTJ and move the foot at the STJ in the open chain, there is a distinctive feel at the neutral position of the STJ in most feet as the foot transitions between a supinated and a pronated position. I suspect that anatomically this occurs as the head of the talus transitions between the anterior and middle facets of the calcaneus. The anterior facet is inclined in the sagittal plane. The middle facet is inverted. I believe that when the head of the talus is in the bottom of the valley between the anterior and middle facets maximum congruity occurs and this corresponds with the neutral position of the STJ. As you supinate and pronate the STJ in the open chain there is a distinctive feel in the change of direction of motion of the forefoot in space and you can visually appreciate changes in the frontal plane motion of the foot. This transition, which is triplane in nature, occurs at the neutral position and can be appreciated clinically.

  36. Jeff Root

    Jeff Root Well-Known Member

    Correction: I should have written "The anterior facet is everted and the middle facet declines anterior in the sagittal plane". Please forgive me, I'm functioning on about two hours of sleep after driving almost 600 miles for 12 hours and arriving home at 5 a.m. today. About half of the drive was on narrow, winding mountain roads in the dark :dizzy: Maybe I should take up coffee :morning: again!
  37. Yet this supposition doesn't fit with the available data:
    Yan-xi Chen, Guang-rong Yu, Jiong Mei, Jia-qian Zhou, Wen Wang: Assessment of subtalar joint neutral position a cadaveric study: Med. J. Chin Med J (Engl) 2008 Apr;121(8):735-9:

    "Subtalar joint (STJ) neutral position is the position typically used by clinicians to obtain a cast representation of a patient's foot before fabrication of biomechanical functional orthosis. But no method for measuring STJ neutral position has been proven accurate and reproducible by different testers. This study was conducted to investigate the STJ neutral position in normal feet in cadavers.
    Twelve fresh-frozen specimens of amputated lower legs were used. Pressure-sensitive films were inserted into the anterior and posterior articulation of STJ. The contact areas for various foot positions and under axial loads of 600 N were determined based on the gray level of the digitized film. The STJ neutral positions were determined as the ankle-foot position where the maximum contact area was achieved, because the neutral position of a joint was defined as the position where the concave and convex surfaces were completely congruous.
    In ankle-foot neutral position, the contact area of STJ was (2.79 +/- 0.24) cm(2). In the range of motion of adduction-abduction (ADD-ABD), the maximum contact area was (3.00 +/- 0.26) cm(2) when the foot was positioned 10 degrees of ABD (F = 221.361, P < 0.05). In the range of motion of dorsiflexion-plantarflexion (DF-PF), the maximum contact area was (3.61 +/- 0.25) cm(2) when the foot was positioned 20 degrees of DF (F = 121.067, P < 0.05). In the range of motion of inversion-eversion (INV-EV), the maximum contact area was (3.14 +/- 0.26) cm(2) when the foot was positioned 10 degrees of EV (F = 256.252, P < 0.05).
    Joints, such as STJ, therefore, are not necessarily in neutral position when the ankle-foot is placed in the traditional concept of neutral position. The results demonstrate that the most approximate STJ neutral position was in the foot position of 10 degrees of abduction, 20 degrees of dorsiflexion and 10 degrees of eversion."
  38. Jeff Root

    Jeff Root Well-Known Member


    See my bolding: Abducted, dorseflexed and everted to what reference? Cardinal body planes of a cadavor? And what anatomical features were used to determine this?

  39. Read the paper, Jeff.
  40. Daryl:

    Thanks for your opinions. I don't agree with most of what you contend, but since these are the same ideas that we have been arguing about for decades, I'm not really surprised.

    I really don't have the time or inclination to go around these same stumps again with you since I am currently preparing lectures for the 10th Biennial Congress 2015 for the Podiatry Association in South Africa in Stellenbosch. I will be one of the keynote speakers along with my good friends and colleagues, Simon Spooner and Howard Dananberg. My keynote address?...Tissue Stress Theory: Changing the Paradigm in Biomechanical Therapy for the Foot and Lower Extremity.

    Since I've given this lecture as a keynote address at the 2015 Biomechanics Summer School in Manchester just a few months ago in June, I've already been invited to give this lecture again by two groups, an Australian podiatry organization and a British prosthetist/orthotist organization. Seems like many well-informed and intelligent clinicians from around the world also want to hear more modern ideas regarding how foot orthoses should be best prescribed for patients.

    That being said, I will let you know if anything at all about Root theory is mentioned at the South Africa seminar, other than in historical context of how Root biomechanics was previously taught as dogma but with no research literature to support it.


    Have a nice week.

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