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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. Read the full PhD of Hannah Jarvis: http://usir.salford.ac.uk/29381/1/HannahJarvis_PhDThesis.pdf Basically it demonstrates that in an asymptomatic population- none of them were "normal" according to Root's crirteria for normalcy, yet they were all asymptomatic BTW- go figure? So, they are all "abnormal" by Roots criteria- right. It then shows that these "abnormals" don't compensate kinematically how Root said they should given their "abnormalities". While I'm with Kevin on lack of kinetics, it has to be noted that Root's criteria for normalcy is all about kinematics, not one kinetic variable in there. Jeff Root will try to move the boundaries now because he above all has the most to lose from this PhD thesis. Some of us have been calling a time to move on for a number of decades; while some of us like Jeff Root have a vested interest (financial) in holding on to the past.... Time will tell who was right, it won't be Jeff nor his dad (who he insists on calling: "Dr Root", as oppose to dad, father etc... it can't just be me who finds that a bit weird? He was your dad, the least you could do might be to acknowledge that? If my daughter started calling me Dr Spooner, I should find that most odd).

    Lets summarise: Jeff's dad said feet with measurable "deformities" should move in a certain way during gait. This study measured feet with said "deformities" and reported that they didn't move in the way Jeff's dad said they would.... Viz. Jeff's dad was wrong in respect to how the variables he advocated measuring would translate into real life kinematic during gait in-vivo. next...

    Climate change? What climate change? God bless Amerika.
    Last edited: Jun 2, 2017
  2. Jeff Root

    Jeff Root Well-Known Member

    Simon, you, Jarvis, Nester, Kirby all have a vested interest. Nester and possibly Jarvis get paid to produce research and doing a PhD will more than pay off in the long run, making it a vested interest as well. If a vested interest is a disqualifying factor, then you, Kevin and others who get paid to lecture and who receive tremendous opportunity to travel for free or at a greatly reduced cost, allowing subsidized vacations (lots of pictures on Facebook to document this) must also acknowledge your vested interest. My vested interest will adapt to what our customer demand. Tissue stress theory hasn't really changed what practitioners do (including orthoses) and has had little influence on how most prescribe their orthoses. If tissue stress theory does influence how practitioners prescribe, it will be reflected in how/what they order and we will provide what our clients want and demand. If tissue stress theory was so fantastic and successful, then from a commercial standpoint, it would be logical for Root Lab to exploit it and market the heck out of it. I'm not aware of any U.S. lab that promotes tissue stress theory and makes the case that it will improve outcomes and therefore, the bottom line for the practitioner. Has there been some revolutionary change in orthoses materials and design due to tissue stress theory that I'm not aware of and that my company currently can't produce?

    Buy the way, when I'm talking with friends, family and close clients, I refer to my father as Mert, dad or my father. On a professional forum like this, I feel it is appropriate to typically refer to him as Dr. Root. If you read my critiques, you will see that I'm challenging logical flaws in the arguments presented by TST advocates who denounce Root's work and then incorporate it in their own practice. Kevin's article above is a great example of this. He uses the argument that heel bisection is a problem with Root theory and yet, he uses heel bisection in his own practice. Have you seem my reply to Kevin. I asked " The significance of the frontal plane orientation of cast and resulting orthotic, and our reliance on heel bisection should not be understated. So if the practitioner doesn’t bisect the heel, the orthotic manufacturer will have to use some other method of orienting the cast in the frontal plane. Since the frontal plane is the only plane that is used to orient the cast when manufacturing a functional foot orthotic, I am interested in how Dr. Kirby suggests practitioners and orthotic manufacturers orient the cast in a more consistent fashion than can be done with the use of heel bisections". I'm looking forward to reading his answer to this question.
  3. There you go...
  4. efuller

    efuller MVP

    Jeff, I agree that an orthotic made with a tissue stress prescription won't look that much different than a Root theory device. We are not debating whether orthotics work, we are debating why they work. I'll bet your lab already makes devices with medial heel skives or Blake inverted devices. I doubt that your lab would have too much trouble with a lateral heel skive either. There might be a phone call to verify that the practitioner really wanted a lateral skive, but after the first few times there wouldn't be any questions. I'll bet your lab could make what I wanted if I sent you a cast that was damaged so that you couldn't bisect the heel but you had the plantar surface. If I asked for a 4 degree intrinsic forefoot valgus post and a heel cup that looked like it was balanced to vertical, but had a 2mm medial heel skive, I'll bet you could make the orthotic that I wanted without having to reference a heel bisection. It might take a phone call and fax with a picture, but I bet your lab could do it.

    Jeff, what do you think of my earlier point about a foot with a rearfoot valgus that had posterior tibial tendon dysfunction. Tissue stress would tell you to add a medial heel skive to the prescription. Classical Root prescription writing would have you balance the heel bisection everted. Wouldn't you agree that the tissue stress approach makes more sense?

  5. Medial heel skive, lateral heel skive, full length devices with functional components extending distal to the shell.... no lab in Amerika is doing any of these things? Denounce tissue stress, then incorporate it in your work...
  6. [​IMG]
  7. I really think FWIW people need to take a step back, these debates do not go anywhere generally and it seems more about a personality clash, I still am of the opinion that the project that we started years ago ( Prescription variables for various diagnosis ) is the way forward for Podiatric discussion. What it would do would be to focus in the problem and come up with a solution and common language by focusing on the project it might a way for " us " to reach common ground and Podiatric biomechanical Language. but it might be just me and people like a carousel
  8. Jeff Root

    Jeff Root Well-Known Member

    All these modifications and techniques existed and were used long before anyone coined the term tissue stress. There has been a natural evolution in foot orthotic therapy/orthotic design since the days of Rohadur, including the use of skives and complex top covers that incorporate all kinds of components and accommodations. The real issue is that many who denounce Root theory incorporate it their work but aren't willing to acknowledge it and are trying to suggest that TST is a totally new and differ approach. It is simply a modification to traditional foot orthotic of the therapy.
  9. Jeff Root

    Jeff Root Well-Known Member

    What is rearfoot valgus? Do you mean rearfoot valgus according to Root's definition? Because if we are to accept the Jarvis conclusion and if we accept the studies that demonstrate that heel bisection is unreliable and question the validity of a neutral position of the STJ, then we can't use the term rearfoot valgus as defined by Root. However, if we accept the fact that there is variability in technique and that some practitioners practice Root's techniques within a reasonable degree of accuracy, while other practitioners do not, then we need to know or qualify the capability of the individual practitioner to replicate the technique in order to determine if his/her measurements and/or observations are within acceptable limits. One of the biggest problems with the Jarvis study is that the entire body of work depends on one practitioners skill to identify these foot types. This problem was acknowledged by that authors who stated that had they used multiple practitioners the results of the study may have been different.

    To answer your question, most practitioners in the U.S. don't measure STJ ROM anymore so treatment has changed as a result of that. I think several of Root's guidelines for writing a prescription for a foot orthotic have changed in modern day practice. For example, Root advocated balancing the heel bisection cast of a foot with rearfoot varus to vertical and a foot with rearfoot valgus to the everted, neutral position. But many, including myself, do not strictly follow those guidelines anymore and haven't, long before TST was mentioned. One of the reasons is that we have, with time and greater experience, determined that we can do things differently than Root recommended and get good results. I'm sure if my father (that's for you Simon) were still alive and practicing today, he would be doing some things differently than he would have back when he was practicing in 60's and early to mid 70's. If we want modern day foot orthotic therapy to be accepted as a valid treatment approach that would be recognized and covered by most health insurance plans, then it will have to be developed and organized so that the benefits (outcomes) can be demonstrated to be worth paying for. Unfortunately, there is so much inconsistency today in the practice of foot orthotic therapy, its not surprising that many, probably most, insurance companies don't cover foot orthotics as a benefit.
  10. Tissue stress theory is a new approach to foot orthosis therapy since it is quite different than the approach to foot orthosis therapy that I was taught by Drs. Merton Root, John Weed, and the rest of the biomechanics department at the California College of Podiatric Medicine (CCPM). Here is what I was taught from 1979-1985 as part of Root theory:

    1. The foot orthosis should be balanced with the heel vertical at all times unless the patient has a peroneal spastic flatfoot, a partially compensated rearfoot varus deformity where the maximally pronated position of the subtalar joint (STJ) has the calcaneus inverted or has a rearfoot valgus deformity.
    We were taught that to balance the heel of the orthosis even 2-3 degrees inverted would cause the patient to have adverse affects from the foot orthosis, which is actually quite amusing now since the range of error of calcaneal bisections among Biomechanics Professors at CCPM was +/- 3 degrees.

    2. The foot orthosis should be made of a rigid thermoplastic material but not be made of a shank dependent material such as cork and leather or Plastazote since these shank dependent materials are not "rigid" enough to control abnormal "compensations" in foot.
    Cork and leather orthoses were scoffed by the Root Theory advocates since they were only "acccommodative" orthoses and, since they were not made of "rigid plastic", couldn't possibly cause improved gait function. There was never any discussion that these materials by Dr. Root or his followers at CCPM that possibly these shank dependent devices could just as well improve gait function and reduce pathology for patients just as well, if not better, than a vertically balanced Rohadur orthosis with a dental acrylic 4/4 degree rearfoot post that ended at the metatarsal necks.

    3. The foot orthosis should end at the metatarsal necks and doesn't need forefoot extensions added to it.
    In fact, addition of forefoot extensions to accommodate painful metatarsals was thought to be "chiropody", according to Dr. John Weed at one of the Root Lab Seminars, when I asked Dr. Weed why a plantarflexed 3rd metatarsal head couldn't just be simply accommodated with 1/8" Korex to the sulcus to relieve the plantar 3rd metatarsal head pain. Drs Root and Weed had decided that a plantarflexed 3rd metatarsal "couldn't be treated" with a "functional foot orthosis" and required surgery for treatment. I disagreed with them at this seminar soon after my CCPM Biomechanics Fellowship in 1985 since I had been already successfully treating these conditions with forefoot accommodations to the sulcus on my own patients during my Biomechanics Fellowship.

    4. The calcaneus must be in the vertical position while in relaxed calcaneal stance position (RCSP) in order for the foot to function normally during gait.
    Root Theory, time and again, harped on the vertical heel position as being "normal" and somehow functionally more "stable". I asked John Weed in about 1983 why a maximally pronated STJ foot that had the heel vertical in relaxed bipedal stance, or what Drs. Root and Weed called a "fully compensated rearfoot varus", should be treated at their maximally pronated position with a vertically balanced orthosis since they were advocating this orthosis balancing method as the best treatment for these patients. Dr. Weed didn't have a good explanation for this rather odd aspect of Root Theory.

    5. Each foot has only one correct heel bisection.
    In fact, Mert Root personally scolded me, in front of about 30 other podiatrists at one of the Root seminars in about 1985, when I suggested that the calcaneal bisection line was highly variable depending on the clinician drawing the calcaneal bisection line and, as such, created a problem with the whole Root measurement system. Mert Root became red in the face when I asked him this simple question and practically yelled at me in front of all these other podiatrists, "Even a monkey can be taught to draw an accurate calcaneal bisection line! I don't understand why the podiatrists teaching biomechanics at CCPM can't teach such a simple concept to their students!!" Obviously, Mert Root didn't like some 28 year old podiatrist (i.e. me) challenging his ideas in front of his followers and suggesting that his whole measurement system was fatally plagued with errors due to the inability of even well-trained biomechanics professors to agree on "one correct heel bisection". That experience showed me that, contrary to what others stated about Dr. Root, he was not very open to new ideas that challenged his own ideas. Dogmatic was my thought regarding Dr. Root after that tongue-lashing in public by Dr. Root at one of his seminars. Dr. Weed, on the other hand, would have never done that to anyone in public since he was very open to new ideas.

    6. If a calcaneus is everted by more than two degrees then it will continue pronating until the maximally pronated position of the STJ is reached.

    This bizarre idea was actually formulated into a list of incontrovertible "laws" of foot function by Dr. Bill Orien. I resisted this suggestion that these were in fact "laws" of foot biomechanics as much as I could as a young clinician. In fact, at the 2nd Annual John Weed Memorial Seminar in March 1995 seminar in Palm Springs with Bill Orien as moderator and Irene Davis and Tom McPoil as lecturers, Dr. Orien brought up his feelings that the Root Theories should be considered "laws" since they have been around so long and no one had disproved any of them. That rather presumptuous idea of Dr. Orien's went over like a lead balloon with the other lecturers at the seminar. This idea that Dr. Root's ideas are not able to be challenged since they are pretty much already set in stone pretty much sums up how Dr. Orien felt about anyone challenging Dr. Root's ideas in all my contacts with him over the years.

    7. A functional foot orthosis made from a cast of the foot held in the STJ neutral position will position the STJA in its neutral position while in stance and/or in gait.
    This concept was taught at CCPM but when I questioned John Weed on how this didn't make any sense to me he couldn't really explain how this concept could work. The students at CCPM called it "Biomagic". There was never given a good mechanical explanation given to me by any of my professors of biomechanics at CCPM, including Drs. Root and Weed, as to how a foot orthosis that was taken in the STJ neutral position could somehow make a foot function in the STJ neutral position even though the foot orthosis was being balanced where the STJ was maximally pronated or very close to maximally pronated. The only explanation I got when I asked how orthoses worked was that "they locked the midtarsal joint".

    8. The standard biomechanical examination (Root examination techniques) yields sufficient information to predict how that particular individual's lower extremity will function during gait.
    That was something that I saw was definitely erroneous during my CCPM Biomechanics Fellowship from 1984-1985. However, after speaking to John Weed one day in 1984 during my Biomechanics Fellowship about his "pushing on calcaneus technique" to determine how much "pronation control" features he needed to put into orthoses, I eventually developed the technique further to discover the significance of STJ axis location and how this one measurement parameter was probably as important, if not more important, at predicting gait function and pathology than all the other Root measurements combined (Kirby KA: Methods for determination of positional variations in the subtalar joint axis. JAPMA, 77: 228-234, 1987).

    9. Frontal plane forefoot deformities are congenital disorders, except "forefoot supinatus" deformities or traumatic deformities of the forefoot.
    It is rather more likely that the frontal plane forefoot to rearfoot relationship is an indicator of the differential loading of the medial and lateral columns during weightbearing activities rather than an inherited, unchanging structural deformity which in itself determines the function of the foot.

    10. If a patient stands in relaxed calcaneal stance position (RCSP) with their calcaneus inverted then there must be some abnormality causing the calcaneus to not be vertical (i.e. an inverted calcaneus is always abnormal).
    Of course, if one clinician drew an inverted heel bisection relative to another clinician who drew a more everted heel bisection, depending on the clinician, the patient could go from having an abnormal inverted heel foot to a normal vertical heel foot, all by simply having another clinician draw on what they felt was the "correct" heel bisection. This common reality is one of the biggest "daggers in the heart" of Root biomechanics. Without a standardized, reproducible calcaneal bisection that examiners can agree upon, the whole Root measurement system falls apart since accurate determination of "rearfoot varus", "rearfoot valgus", "forefoot varus", "forefoot valgus", "neutral calcaneal stance position", "relaxed calcaneal stance position" and orthosis balancing position all are based on an this idea that there is only true calcaneal bisection. LaPointe et al showed the calcaneal bisection to have a range of error of 3-6 degrees (LaPointe SJ, Peebles C, Nakra A, Hillstrom H. The reliability of clinical and caliper-based calcaneal bisection measurements. J Am Podiatr Med Assoc. 2001; 91(3):121-126).

    11. A foot with an everted forefoot to rearfoot relationship should be treated with an orthosis which is balanced with the heel vertical.
    We again get back to the erroneous assumption proclaimed by the Root theory advocates that heel verticality is the most desirable position for the foot to function in and the orthosis to control the foot in. To place all patients which have a plantarflexed first ray deformity or forefoot valgus deformity in foot orthoses which have been balanced with the heel vertical is much too simplistic of an approach to guarantee optimum orthosis results for all patients. Tissue stress theory will focus on the tissue which is injured, and reducing the stress on that tissue, rather than nearly always "balancing the orthosis vertical to prevent compensation for forefoot to rearfoot deformities" as was taught by Mert Root and his followers.

    In summary, the real issue here is that many who have personal feelings toward Dr. Merton Root and Root Theory are now proclaiming that any new ideas in foot orthosis therapy that are found to be effective suddenly, somehow, become extensions of Root Theory. Even though the medial heel skive, lateral heel skive, reverse Morton's extension, Morton's extension, Blake inverted orthosis and the use of Plastazote and other shank dependent orthosis materials were not proposed nor advocated by Root, these ideas have now somehow become extensions of Root Theory, even though Mert Root didn't think up these ideas and many times advocated not using these ideas since they were not compatible with a "Root Functional Orthoses".

    In reality, Tissue Stress Theory, is a totally separate theory of how foot orthoses should be prescribed. That being said, I do fully acknowledge the wonderful contributions that Dr. Root and his colleagues did make to our progression of knowledge in developing better techniques for treating our patients with foot and lower extremity mechanically-based pathologies. It is time now to move forward, and not stagnate by glorifying the memories of those who have come before us.
  11. Jeff Root

    Jeff Root Well-Known Member

    The Jarvis study doesn't provide a single clue as to how to better treat the foot, it only says what not to do and draws conclusions and makes recommendations that are impractical. I wish the time and effort of these bright individuals had been spent on providing practitioners and orthotic manufactures with information, data and methods that would help improve patient outcomes.
  12. Jeff and Colleagues:

    I agree with you on this problem with the Jarvis et al study. To suggest that we need to eliminate these measurements but then offer no better alternatives does not help anyone, not foot-health clinicians nor their patents. In addition, as I said in my recent article in Podiatry Today, without a study on the kinetics of the foot, how can we know these measurements don't predict injuries in some patients? Doing a kinematics study only, as Jarvis et al did, tells us very little about how the central nervous system may change motor activity in response to certain structural deformities, which may, in turn, result in abnormal tissue stresses. Again as I stated in my Podiatry Today article, I believe the authors overstated the conclusions from the results of their study.

    What then is the much bigger question we must all be asking at this critical juncture of uncertainty in taking measurements of structural variances in foot and lower extremity structure? That question should be: does structure affect function? If you answer yes to this question then the next question becomes, how do we measure structure of the foot and lower extremity reliably so that these measurements can better predict alterations in the kinematics and kinetics of gait? In addition, what measurements better predict the production of foot and lower extremity pathologies over time? Certainly we aren't going to learn anything about the latter question about the production of pathology by only measuring the kinematics of a group of 100 asymptomatic subjects, aged 18-45 years, and then comparing that to a few static clinical measurements.
  13. The study did not set out to offer an alternative, rather it set out to test the validity of the Root model of assessment which for the record contained no kinetic assessments. The clue is in the title:
    Challenging the foundations of the clinical model of foot function: further evidence that the root model assessments fail to appropriately classify foot function

    The orginal PhD thesis that this paper was drawn from was titled:

    I don't see a study here titled: "an alternative model to the Root model of foot biomechanics"?

    This PhD study found that the Root assessment failed to classify foot function- what should the authors have concluded? Carry on using a system which we and others have repeatedly demonstrated to be fundamentally flawed...?

    I don't get it, why do the authors need to provide an alternative? This was not the remit of the study, rather the study was designed to look at an existing model and see if it was valid; it was not.

    The argument that they did not offer an alternative is like criticising an intra-observer, within-day error experiment for not reporting the inter-observer between-day error. Different studies for different purposes... end of story.

    Since the Root assessment protocol did not include any kinetic assessments why should the authors of the present study have included kinetic assessments? Again, that's a different study...

    Stick to what the study tested and what it demonstrated please. It demonstrated that the manner in which Root et al. said the foot should kinematically function given the measured variables of their assesssment protocol was incorrect. So the foot doesn't work how Root et al. said it did, so what's new?
    Last edited: Jun 4, 2017
  14. Jeff Root

    Jeff Root Well-Known Member

    If practitioners and orthotic manufactures don't have a better alternative then what do you expect them to do?
  15. I expect them to interpret the evidence in an educated and unbiased fashion.
  16. Perhaps you should cease trading and place all of your profits from the last 10 years into a research fund to find a model that does appear valid... Alternatively, you can bury your heads in the sand, pretend that global warming isn't happening, put profits in front of scientific evidence and advancement and withdraw from the Paris... sorry, wrong meeting.
    Last edited: Jun 4, 2017
  17. efuller

    efuller MVP

    This not a personality clash. I like Jeff. I have learned from Jeff. I just don't want a continuation of teaching that the Earth is flat. The project you suggest can move forward if we discard some of Root's teachings. There is some conflict in choosing prescription variables between classic Root and tissue stress. In the absence of studies comparing one prescription protocol to another, we have to look at the theory behind why a particular protocol should be chosen. As Jeff recently pointed out Mert did not think arch support, nor support the deformity, nor put the foot into neutral position were reasons that an orthotic would treat a particular condition. So, we don't have any theory for why an orthotic does work from Mert Root.

    Say we had a person with posterior tibial dysfunction. If you did your measurements and found a rearfoot valgus in this foot, classic Root teaching would tell us to make an orthotic off a cast with an everted heel bisection, or without a rearfoot valgus, the vast majority of the time there would be a vertical heel bisection. Using tissue stress you would use an orthotic made off of a cast with a medial heel skive. So we can compare theory or we can do studies. Clinically, I have had patients with orthoses balanced vertical and have used the same cast, but with a medial heel skive added, and seen improved symptoms. Yes, I know this is not a rigorous study. But it is my experience.

    To come to an agreed upon treatment protocol for various pathologies, we have to debate, or research, our way through the points where there is disagreement in prescription writing protocol between paradigms.

  18. efuller

    efuller MVP

    Yes, tissue stress uses some of the same things that are used in Root theory. However, tissue stress does not use neutral position. Is Root theory still Root theory without neutral position? Some, like Daryl Phillips, would say that you need to compare a foot to normal to figure out what is wrong with it. Some Root disciples do believe that an orthotic attempts to move the foot toward a more normal (neutral) position. Other Root disciples believe that an orthotic works by supporting a deformity. Jeff, you have given some of your fathers quotes that he believed an orthotic worked by altering deforming forces. However, he only worked with positions, and did not describe how the forces were altered.

    Tissue stress does not compare to a normal. It looks at the foot as it is and does not imagine that it should be in STJ neutral position. Yes, tissue stress uses thermoplastic orthotic shells pressed over positive casts. Some of those casts will have an intrinsic forefoot valgus post. A different methodology is used to decide whether or not a particular orthotic should have an intrinsic forefoot valgus post. Is this still Root theory? An intrinsic forefoot valgus post is just a wedge. It was an ingenious way to incorporate a wedge into an orthotic shell. Jeff, I will give you that tissue stress theory is not a totally new approach, but it is quite a departure from Root theory. How far does orthotic therapy have to evolve for one paradigm to be completely separate from another? Root theory, without neutral position, ought to be far enough.

  19. Jeff Root

    Jeff Root Well-Known Member

    Eric, the Rx I frequently recommend for PTTD is balancing the heel of the cast 4 to 6 degrees inverted, a 2 to 4 degree medial heel skive, increase the medial arch height (i.e. decrease medial arch fill), a deep heel cup, especially medially, a wide arch profile, possible a zero degree rearfoot post and possibly, if prominent, accommodating the navicular to prevent navicular irritation. Its not pure Root and its not just TST, it just makes sense mechanically to address the pathological forces of the condition, the symptoms and the functional position of the foot.
  20. Jeff Root

    Jeff Root Well-Known Member

    Correction, that should have read a 2 to 4 millimeter medial heel skive.
  21. drhunt1

    drhunt1 Well-Known Member

    LMBO! A continuation that the Earth is flat? Oh, that's ripe! You and Kevin haven't proven anything, (except that he probably needs therapy for the "terse words" used by Merton in front of his colleagues, thus embarrassing him...he's mentioned it three times now, to my knowledge, so obviously he's been traumatized). TST is just another mouse trap...I've written that before...and you, Simon, Kevin, Jarvis et al., still are floundering in a sea of misinformation, while patting each other on the back for "a job well done". Jeff was spot on when he claimed above all of you have a vested interest in TST. Example? Re-read Kevin's post above...where he lists 11 "things" Merton discussed and taught Kevin while at CCPM. (Sheesh...talk about biting the hand that feeds you!) But why stop at 11...why limit what one was taught by just 11 main points? There are many, many more....I assure you. Are they absolute? Nope...they were a baseline for our continued exploration, research and refinement. Kevin's got a problem with calcaneal bisections? Then it's a good thing most Podiatrists don't perform them anymore...isn't it? Another example: You blindly accept Dr. Green's explanation of the "bullet-hole sign" on lateral X-Ray without questioning it, yet when Merton hands you the directions for the path on biomechanics, you head the other way. Another example: At a recent seminar in Livermore, Kevin, in a question and answer session, stated that the STJ can either supinate the foot, or pronate the foot. Oh really? At that point I walked out because the BS was too deep to breath. I suppose I should've raised my hand and challenged him...but we now know how sensitive Kevin is to criticism...don't we?
    Last edited: Jun 5, 2017
  22. Jeff Root

    Jeff Root Well-Known Member

    Simon, at Root Lab we don't dictate to our customers what to order, they dictate to us what they want to order. Root Lab's Rx form offers a number of devices that are not traditional Root type functional orthoses. This is because we have listened to our customers and have come up with products that satisfy their needs. As for the theories to which they subscribe and the methods which they use to examine, diagnose and treat their patients, that comes from their individual preference, not mine. The influences are from many including Root, Weed, Orien and others such as Kirby, Olson, Blake, Dananberg, Valmassy, etc., etc. Most of our customers don't strictly follow Root's techniques anymore nor do they necessarily take measurements and prescribe based on measurements as Root recommended. What I hope for is that we eventually end up with an organized, practical and effective treatment system (emphasis on system) which is based on a model of function that is logical and evidence based. I suspect that model will contain elements of Root's body of work plus other and new theories on which to base treatment decisions. I'm not attempting to hold onto the past however, I'm not willing to discard clinically effective and proven techniques such as heel bisection, neutral position casting and assessing open chain ROM until someone proves there is a better way to proceed. Jarvis et. al. recommend practitioners discard clinically effective techniques but offer nothing to replace them. How logical, practical and reasonable is that? Not very!
  23. cpoc103

    cpoc103 Active Member

    So I have been following this blog now for 6 months and have to say chaps, you are all going around in circles saying the same things as 6 months ago.
    As a pod and btw would never claim to be in the same league as the authors above, nor have I practiced as long either. However like most pods was thaught root mechanics, and many other theories.
    I would say in my bio exams I would use many root measurements as a guide to foot ROM & QOM as a guide to function, I also use root measurements to explain and show my patients what is going on as it's the easiest and most laymans way of explaining what is going on (btw I also say, "this is leading to stress on what ever is involved"). However when it comes to prescription of devices I use a mix of modified blakes and skives, don't think I've ever used a true root device.
    I whole heartedly agree with messers fuller, Kirby, prior and spooner. As to what we are actually doing is relieving stress on what ever structure is in pain. However, I also agree with Jeff the measurements and techniques root and colleagues gave us many years ago still work, so why just drop them from my arsenal. My objective is not to prove myself to my peers or anyone else for that matter, my objective is to my patients and helping them with their pain and issues.
    The name calling the sarcastic remarks made in this blog from world renown clinicians (and my idols btw, who have helped forge my career) has really left a sour taste in my mouth, I don't find them useful or contribute to advancement of the podiatric biomechanics. As in most medicine there is not a one fits all, there are many theories and devices that will work for many patients, is it not up to the skilled podiatrist to use the appropriate theory.
    I really feel as a profession we are at great risk of loosing biomechanics to other professions, and feel at times the other disciplines must be laughing at the in squabbling among our elites. Don't get me wrong I'm not naive and realize this happens in most disciplines but ours seems to be the pick.
    Let's sort it out once and for all and start to show some form of a united front- because as stated it looks bad, as a student if I was reading all of this I'd be thinking f$&@k I don't want to go down this route. They don't seem to know what their doing. Sorry for rant over!!
  24. drhunt1

    drhunt1 Well-Known Member

    cpoc103-I don't disagree with most of what you wrote...but many of the comments you object to, were from those you seem to admire most...it's their bed...they have to sleep in it. That being written, how many labs are involved in making orthotics with medial skives? I think Jeff could tell us what percentage of the orthotics he makes use it. You could also call your Lab...or KLM, (the largest orthotics Lab in the world), for that matter. I believe you'll find that very few Pods are ordering medial, (or lateral skives), for their patients, opting instead for more conventional prescriptions. Funny you brought up modified Blake orthotics, as I've never really comprehended how or why they would work...except for running orthotics, (but that is a discussion for a later date). If I've ruffled your professional feathers with my acerbic style...believe me, I have my reasons for writing in this manner, as I've stated above. Hang in there...the debate is about to "get good".
  25. Jeff Root

    Jeff Root Well-Known Member

    For a long time the proponents of TST have been saying there is a paradigm shift in progress. The burden is on them to advance their cause by developing TST to the point that it is coherent, reproducible (let's remember that a big criticism of Root theory by them is a lack of reproducibly and reliability in technique), teachable, evidence based and above all, EFFECTIVE. Root developed a highly effective treatment system that in spite of its flaws, has helped millions of people worldwide. I can only hope that by participating in the debate and by challenging the proponents of TST a small fraction as much as they have challenged Root theory, that I'm providing some small degree of motivation for them to improve their product.
  26. cpoc103

    cpoc103 Active Member

    Yeh look I'm Irish we're made pretty tough lol, but I just fear if we don't as a profession come to some sort of agreement we are at risk of not the ones to get foot pain and orths from.
    I look around the world at the different pod conferences and I'm seeing more and more physios lecturing to pods about mechanics than pods, and it was the same at the recent Australasian conference 3 key speakers being physio back-ground, no offense to physios mind you but I'm a podiatrist lol.

    As for labs I think here in Australia and in the U.K. there are probably more labs using the skive technique, than US.
    I look forward to what you have coming!!

  27. cpoc103

    cpoc103 Active Member

    Couldn't agree more Jeff

  28. Col:

    Thanks for your comments. The Tissue Stress Theory is already in wide use worldwide and is advocated by many podiatrists and physical therapists/physiotherapists for determining how best to prescribe foot orthoses without having to take many of the measurements advocated by Root et al. At the end of the post, I have included references on the concepts inherent in Tissue Stress Theory and its clinical use since, contrary to the belief of others, Tissue Stress Theory is just as effective, if not more effective than using the Root system for prescribing foot orthoses (i.e. heel vertical balancing regardless unless patient is maximally pronated with the heel inverted or has a peroneal spastic flatfoot, orthosis ending at metatarsal necks always, 4/4 degree rearfoot posts, no medial heel skive, no lateral heel skive, no forefoot extensions, no accommodations for painful metatarsal heads, no use of shank dependent orthosis materials, etc). If someone is using a medial heel skive and inverting orthoses to treat posterior tibial tendon dysfunction, then they are using Tissue Stress Theory, not Root Theory, to prescribe foot orthoses.

    I will be lecturing in Auckland in March 2018 so maybe you can attend my one day seminar to learn more about it. Good luck in the future with your practice.

    References on Tissue Stress Theory

    Kirby KA: Methods for determination of positional variations in the subtalar joint axis. JAPMA, 77: 228-234, 1987.

    Kirby KA: Rotational equilibrium across the subtalar joint axis. JAPMA, 79: 1-14, 1989.

    Kirby KA: The medial heel skive technique: improving pronation control in foot orthoses. JAPMA, 82: 177-188, 1992.

    Kirby KA: Foot and Lower Extremity Biomechanics: A Ten Year Collection of Precision Intricast Newsletters. Precision Intricast, Inc., Payson, Arizona, 1997.

    McPoil TG, Hunt GC: Evaluation and management of foot and ankle disorders: Present problems and future directions. JOSPT, 21:381-388, 1995.

    Fuller EA: Center of pressure and its theoretical relationship to foot pathology. JAPMA, 89 (6):278-291, 1999.

    Kirby KA: Conservative treatment of posterior tibial dysfunction. Podiatry Management, 19:73-82, 2000.

    Kirby KA.: What future direction should podiatric biomechanics take? Clinics in Podiatric Medicine and Surgery, 18 (4):719-723, 2001.

    Kirby KA: Subtalar joint axis location and rotational equilibrium theory of foot function. JAPMA, 91:465-488, 2001.

    Kirby KA: Foot and Lower Extremity Biomechanics II: Precision Intricast Newsletters, 1997-2002. Precision Intricast, Inc., Payson, AZ, 2002.

    Kirby KA: Emerging concepts in podiatric biomechanics. Podiatry Today. 19 (12)36-48, 2006.

    Kirby KA: Are Root biomechanics dying? Podiatry Today. 22 (4):58-65, 2009.

    Kirby KA: Foot and Lower Extremity Biomechanics III: Precision Intricast Newsletters, 2002-2008. Precision Intricast, Inc., Payson, AZ, 2009.

    Fuller EA, Kirby KA: Subtalar joint equilibrium and tissue stress approach to biomechanical therapy of the foot and lower extremity. In Albert SF, Curran SA (eds): Biomechanics of the Lower Extremity: Theory and Practice, Volume 1. Bipedmed, LLC, Denver, 2013, pp. 205-264.

    Kirby KA: Foot and Lower Extremity Biomechanics IV: Precision Intricast Newsletters, 2009-2013. Precision Intricast, Inc., Payson, AZ, 2014.

    Kirby KA: Should podiatrists think more like engineers? Podiatry Today, 27(4):90, 2014.

    Kirby KA: Can foot orthoses have an impact for knee osteoarthritis? Podiatry Today, 28(10):50-60, 2015.

    Kirby KA: Prescribing orthoses: Has tissue stress theory supplanted Root theory? Podiatry Today, 34(4):36-44, 2015.

    Kirby KA: How do foot orthoses work? Podiatry Management, 35(9):137-142, 2016.
  29. Jeff Root

    Jeff Root Well-Known Member

    No Kevin, if someone has identified a foot with forefoot varus/supinatus and an everted heel as typically occurs with PTTD, is casting the foot in the neutral STJ position and is inverting the heel bisection of the cast, is employing intrinsic forefoot correction, then they are using aspects of Root theory and tissue stress theory. Look at what you said. You said they are inverting the cast. What is your reference for inversion of the cast? A Root heel bisection. You still have not answered my question about heel bisections on Podiatry Today. Tell me exactly what percent of your orthotic above is unique to TST and what aspect of it comes from Root theory? I thing its 90% Root and 10% TST. Call it what you want, but any intellectually honest person would acknowledge the origin what you are doing and the DNA point to Root theory.
  30. cpoc103

    cpoc103 Active Member

    Many thanks for this Kevin appreciated.
    So I do tend to use the TST theory a lot, my issue however is if there are no measurements been taken/ employed how do you know how much correction needs to be prescribed? Whether this is skive or inverted heel. This is where I'm struggling with TST, as stated above the practice I work for uses a lot of modified blakes, so if I where to completely abandon the ideas of no need to do measurements then how would I know how much correction to use???

  31. Col:

    A new reference of mine just came up on Google which talks a little about the history of how Root contributed to foot orthoses and about foot orthosis research. It isn't the whole chapter but it was just recently published.



  32. Jeff Root

    Jeff Root Well-Known Member

    On Podiatry Today's website Kevin writes "My main problem with Root and colleagues’ measurements, a system I taught during my biomechanics fellowship at the California College of Podiatric Medicine (CCPM) to hundreds of podiatry students from 1984–1985, is that it relies too heavily on calcaneal bisections. Excellent research from 16 years ago by LaPointe and coworkers has shown that visual bisection of the calcaneus produces errors ranging from 3 to 6 degrees.11 This is a serious problem for the Root measurement system since the calcaneal bisection is the main reference marker for determining resting calcaneal stance position, neutral calcaneal stance position, the degree of “rearfoot varus/valgus deformity” and the degree of “forefoot varus/valgus deformity.” Anecdotally, during my biomechanics fellowship, I saw differences in calcaneal bisections of up to 3 to 5 degrees between different biomechanics faculty at CCPM and up to 5 to 10 degrees between different fourth-year podiatry students".
    Kevin goes on to then write "A much better approach for making foot orthoses for patients and an approach recommended within the paper by Jarvis and colleagues is the tissue stress approach.1 In the tissue stress approach, the clinician concentrates not on heel bisections, subtalar joint neutral position or “foot deformities,” but concentrates rather on the location and functions of the patient’s injured tissues, and then designs a prescription foot orthosis based on reducing the stress on the injured tissue, improving gait function and not causing any other pathologies to occur. The tissue stress approach eliminates the need to perform accurate calcaneal bisections and instead focuses on treating the injured tissues of the patient, which greatly simplifies and improves the therapeutic effectiveness of the foot orthosis prescription process".

    Since the frontal plane is the only plane that is used to orient a positive cast when making a functional type foot orthosis, I asked Kevin to tell the readers how he would suggest that practitioners and orthotic manufacturers orient the cast in a more consistent fashion than can be done with the use of heel bisections. Kevoin hasn't responded to my request. In addition, a heel bisection is the reference for determining ff varus, ff supinatus, ff valgus, rf varus, rf valgus, an inverted or everted or vertical heel position, etc. If Root's system is so flawed, why do clinicians and TST advocates continue to use these terms that derive their modern day meaning from Root's heel bisection technique? I think those who don't believe that TST incorporates a significant amount of Root theory are in denial.
  33. Jeff:

    I never said that the concepts of Tissue Stress Theory don't incorporate a significant amount of the contributions that your father (Mert Root) and his colleagues made within the evolution of custom foot orthosis theory. In fact, if you read any of the numerous articles or book chapters I have written on the history of foot orthosis therapy, I fully acknowledge your father's contributions to where we are now.

    In fact, here is an excerpt from a book chapter I wrote 25 years ago. Do you think, Jeff, that I gave your father enough credit in this chapter, or should I have only have mentioned our father's name and his contributions when talking about the history of foot orthosis therapy?

    "One of the earliest descriptions of the conservative treatment of pes valgus deformity was given by Durlacher) an English chiropodist. In 1845, Durlacher described the use of a built-up leather inlay, which was used in the treatment of mechanical foot problems. In 1874 Hugh Owen Thomas, an English surgeon, described the use of leather shoe sole additions in the treatment of foot disorders. The Thomas heel, which is an elongation of the medial side of the heel of the shoe, is still used today either by itself or in combination with arch supports for the treatment of pediatric pes valgus deformity.

    In 1888 Royal Whitman, an orthopedic surgeon, was one of the first to describe in detail the clinical pathomechanics of the pes valgus deformity. One of his greatest contributions was in persuading the orthopedic community of his era to realize that severe foot deformities such as clubfoot or the polio foot were not the only foot deformities deserving of medical attention. He believed that "weakfoot" in itself should be considered a significant medical entity since he had long recognized that painful problems often developed as a result of "overwork" imposed upon the muscles and ligaments in flatfoot deformity.

    Whitman's conservative treatment of weakfoot consisted of a metal foot brace, which had a medial and lateral flange and was designed to produce an inversion motion once the patient stepped down on it. The inversion motion of the plate would cause the medial flange to press rather vigorously into the area of the navicular, thus causing a decrease in foot pronation either by force or by pain. According to Schuster, P.W. Roberts, a physician, developed a metal brace in 1912 that was similar in function to the Whitman brace but smaller in size and that actually had a deep inverted heel and medial and lateral heel clips. Unfortunately, it seemed that the design of the Roberts brace was fairly extreme; it applied too much force through too little surface area and was difficult to adjust.

    It was an orthopedic brace-maker turned podiatrist, Otto F. Schuster, who in the 1920s combined some of the better ideas of the Whitman brace and the Roberts brace into the Roberts-Whitman brace. The Roberts-Whitman brace consisted of a metal brace, with a deep inverted heel cup, as in the Roberts brace, but which was made broader, like the Whitman brace (Fig. 13-1B). In effect, the deep inverted heel cup placed enough supination torque on the heel that the navicular would no longer press as hard into the medial flange of the device, thereby improving medial arch comfort and improving pronation control of the foot.

    In 1950 Ben Levy, a podiatrist, described a technique for producing an arch support (Fig. 13-1C) that incorporated a toe crest. The resultant Levy mold consisted of a thick leather cover supported plantarly by a hardened latex mixture and filler, known as "rubber butter." The mold was easily adjustable and actually would shape itself to the foot over time.

    In 1958 and 1959 Merton L. Root, a podiatrist, began work on an improvement of the Levy mold, which at the time was the most popular of the podiatric treatments for pes valgus deformity.4 Root had found that the Levy mold could control excessive pronation, but it was not durable and soon became hygienically distasteful. His experimentation with thermoplastics led him to the thermoplastic material Rohadur, which could be heated and pressed over a plaster model of the foot to form an exceedingly durable and lightweight orthotic device (Fig. 13-2A). This new plastic orthosis, which was made from a non-weight-bearing cast of the foot held in the subtalar joint neutral position, is now known as the Root Functional Orthosis. Today, there are many modifications of the Root Functional Orthosis, and these modified versions are the most common types of foot orthoses used within the podiatric medical community in the treatment of pes valgus deformity.

    In 1967 W. H. Henderson and J. W. Campbell, while working at the University of California Biomechanics Laboratory (U.C.B.L.), developed a characteristically shaped thin polypropylene foot orthosis, the U .C.B.L., which has an extremely high heel cup and medial and lateral flanges. Even though the "wrap-around" design of the U.C.B.L. has been widely accepted by the orthopedic community as one of the most effective conservative means of treating pediatric pes valgus deformity, the U.C.B.L. has not been nearly as popular as an orthotic device within the podiatric community (Fig. 13-2B)."

    [From "Kirby KA, Green DR: Evaluation and Nonoperative Management of Pes Valgus, pp. 295-327, in DeValentine, S.(ed), Foot and Ankle Disorders in Children. Churchill-Livingstone, New York, 1992.]

    Therefore, please don't continue to claim that I am saying that your father's contributions aren't important. What I am saying is that some of your father's contributions were very good, but some of his ideas were erroneous. That being said, those of us who have been trying to come up with better methods to make orthoses, evaluate patients, and treat patients that directly contradicts one or more of Dr. Root's ideas may then, unfortunately, have to receive scorn from one of Mert Root's family members for trying to advance podiatric biomechanics theory for the good of all of our patients.

    Wouldn't your father want people like me, or Eric Fuller, or Simon Spooner, or Craig Payne, or Chris Nester, or any of the others who have contributed to our current thinking on foot biomechanics topics, to think independently so we could come up with better ideas than your father did within his lifetime? From what I know of your father, I think he would welcome our independent thought processes so that we could push forward the concepts of foot biomechanics and foot orthosis therapy for our patients.

    Didn't your father state that he thought his ideas would be replaced within 10-15 years of writing his books? Well, it is now 40 years since Normal and Abnormal Function of the Foot was published and it is clear that your father's predictions were right, many of his original ideas are now being replaced, as he fully expected. So I don't understand what the problem is, Jeff. We are replacing Mert Root's bad ideas with better ideas, just as he thought would have happened over 20 years ago. You should be glad that your father was so prescient.

    And by the way, Jeff, I have been ordering orthoses from Precision Intricast Orthosis Lab now for the past 20 years by simply telling the lab how many degrees the plane of the plantar forefoot should be either inverted or everted from the ground, and not relying only on the calcaneal bisection to balance the positive cast/orthosis. Therefore, there is more than one way to make effective custom foot orthoses, and not all of these ways were thought up by your father.
  34. Col:

    Tissue Stress Theory does take time to master and relies on the clinician knowing their anatomy, knowing the basics of foot biomechanics, understanding basic physics concepts and knowing the function of all the structural components of the foot and lower extremity. I have been writing on the concepts of tissue stress now for 25 years and still don't think I have covered everything that I do clinically with foot orthoses using Tissue Stress Theory concepts.

    Here is an excerpt that Eric Fuller and I wrote 12 years ago on Tissue Stress Theory from a book chapter we wrote together. If you want a copy of that chapter, then please send me a private request at my e-mail (kevinakirby@comcast), and I will send it your way to help you better understand the concepts of Tissue Stress Theory.


    There are several important steps in the clinical application of the tissue stress approach that allow the clinician to efficiently and effectively treat the many mechanically based pathologies which can affect the foot and lower extremity. First of all, the anatomical structure that is the source of the patient’s complaints must be identified as specifically as possible. This relies on the clinician having a detailed appreciation of the anatomy of the foot and lower extremity, including surface anatomical landmarks. Structures that are not easily palpable may be stressed utilizing specific clinical tests in order to determine the exact identity of the painful structure. These tests may include assessing pain production during manual pressure on specific anatomical structures, during muscular activity against resistance and/or during the passive range of motion of joints. Noninvasive and invasive diagnostic tests may also be necessary in many cases.

    The second step is to determine the structural and/or functional variables that may be the source of the pathological forces on the injured structure. Clinical data derived from a biomechanical examination of the foot and lower extremity such as muscle testing, range of motion examination and gait evaluation are all integral parts of understanding how pathological forces may be generated to cause injury in the individual. In addition, creating a model of the various structural and functional variables that may be affecting the stress on a specific structure will give insight in to how external loads may be altered in order to reduce the stress on a structure. These models may be either simple or complex with the more simple models often being sufficiently accurate to predict how clinical methods of treatment may mechanically affect the stresses on a specific anatomical structure16.

    Third, a mechanical and therapeutic treatment plan must be formulated that will be most effective at accomplishing the following goals of treatment for each patient: 1) reduce the pathological loading forces on the injured structural components, 2) optimize overall gait function, and 3) prevent any other pathologies or symptoms from occurring20 (Table 1). The appropriate use of the tissue stress approach allows the astute clinician to efficiently and effectively treat even the most difficult mechanical pathologies of the foot and lower extremity."

    [From: Fuller EA, Kirby KA: Subtalar joint equilibrium and tissue stress approach to biomechanical therapy of the foot and lower extremity. In Albert SF, Curran SA (eds): Biomechanics of the Lower Extremity: Theory and Practice, Volume 1. Bipedmed, LLC, Denver, 2013, pp. 205-264.]
  35. Jeff Root

    Jeff Root Well-Known Member

    Kevin, you are missing the point if you think that I'm concerned about my father getting credit for his work. My point regarding the Jarvis e.t. a.l. study is their conclusion that we should stop assessing open chain ROM, STJ neutral, ff to rf, etc., etc. My point is that TST advocates who attempt to use the argument that Root's examination techniques, orthotic prescription writing protocol and theories are unreliable or inaccurate and suggest that as a result of this they should be discarded; but offer no better alternative, and in practice employ many of Root's techniques is frustrating to me. For example, you mentioned that when you order orthoses you direct the lab orient the cast by placing the forefoot in a certain angle relative to the ground. Okay, what is the significance of that angle and how do you determine what angle is best for any given patient? How do you cast the foot and how does this influence the forefoot angle? What studies have been done to support this approach? In addition, in many cases the metatarsals are not in a common plane and the plantar aspect of the forefoot is convex in shape. As a result, how do you measure the plane of the forefoot? Has anyone tested the reliability of this technique and tested the method that you use to determine the prescribed angle? How much inter and intra practitioner variability exists with this technique? If the TST advocates have new theories and techniques, then publish them and put them out there for researchers to test. You guys are doing exactly what you criticized Root for, advancing theories and techniques that lack an evidence base.
    • Informative Informative x 1
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  36. Jeff, the Jarvis study demonstrated that your father's assessment techniques as outlined in vol. 1 do not predict foot function as outlined in vol.2 , nor explain differentiation of "foot function" by their usage, so can you explain why you think that they should still be employed? It just make no sense to continue measuring these things which have no diagnostic value nor are capable of differentiating/ predicting variation in kinematic function between individuals. We should not do away with these measures because....?????? If the answer is because no-one has come up with the measurements that we should employ as an alternative, then that is a none starter; we don't continue with the invalid because of a fear of a lack of alternative. If it's rubbish, it's rubbish; get rid of, don't perpetuate the problem.

    To summarise, the weight of evidence as of 2017 strongly suggests that Root et al.'s measurement system is unreliable, lacks validity and has little, if any specificity. But it's formulaic and seems so plausible... grow up Podiatry.

    How do I know what angle of posting to apply? I don't but nor does anyone else, whether they measure things or not; we use an educated guess- that's what everyone has been doing, even those measuring your father's variables- they are guessing because every patient is an experiment of n=1. This is what the Jarvis data shows and the gold standard in-vivo bone-pin data shows: viva variation. Moreover, when measurements are made by drawing lines onto the skin and/or cast, the inherent error makes for even more guess work, the inter-lab variation in prescription interpretation adds even more error. I know people don't like that because they want some formulaic recipe, but it just doesn't exist; people, get over it and move on; if only you could, hmmm. What's more, that foot orthoses "work" despite all of the error, demonstrates that an accurate prescription is rarely required anyway. Move along, move along...
    Last edited: Jun 6, 2017
  37. efuller

    efuller MVP

    This a problem with education in general. A student will progress through school(s) thinking there is a correct answer that you can look up in the back of the textbook. We are trying to sort this out once and for all. The problem is that there is disagreement with what is the correct answer to put in the back of the textbook. This has gone on throughout the history of science. See Thomas Kuhn's book on the nature of scientific revolutions. Just one example is that it was generally accepted that the Earth was the center of the solar system. Observations started popping up that didn't make sense with that belief. Galileo nearly got burned at the stake for questioning those beliefs.

    So, the student has to examine competing ideas and decide for themselves what to believe. This does make life harder, but life is not simple. Both sides of this debate believe that orthotics work. We just disagree on the explanation of how they work.

  38. Trevor Prior

    Trevor Prior Active Member


    Welcome to the debate and you have made some excellent comments. As you will be aware, there is much we do not know about foot function and optimum treatment. Many of the practitioners you referred to have been practising for years and their practice has evolved and thus management/prescriptions have a fair amount based on experience.

    When I teach many podiatrists who feel they have no or a basic understanding, they do need a reference point. Joint moments are the resultant of the position of the joints and the amount and direction of the force. As a result, alignment does have a role to play in the stress placed on tissues and thus an understanding/appreciation of the relative alignment can help to guide management. Examples of tibial varum and patient’s with insufficient rearfoot motion to allow the heel to achieve perpendicular have been provided previously in this and other threads.

    I have no problem practitioners considering the alignments that were described by Root et al as long as they appreciate that any bisections they use are likely to be unreliable, that the foot does not function around a magical position and that these measures are not predictive of dynamic function.

    A personal opinion is that alignment does contribute to the dynamic function but by varying degrees in varying individuals dependent upon many other factors such as strength, flexibility and neuromotor control. Our skill is to try and determine the relevant contributions.

    Kevin has indicated that the aim of tissue stress is reduce pathological forces, optimise gait and all prevent other pathologies / symptoms (paraphrased I know).

    It is the second and third aims of tissue stress that I feel remains the great unanswered. How this is achieved is yet to be described, how can one predict these aims without some form of objective assessment? This is particularly true for loading proximal structures – how many of us have had patients who developed knee or hip / back pain post orthoses over the years?

    The further one moves away from the foot the less easy it is to apply tissue stress theory as it stands as there are so many contributing factors which may help explain the above but also makes treating proximal problems more difficult; patellar tendinopathy and lower back pain would be two good examples.

    Eric makes a great point about both sides of the debate agreeing regarding orthoses but not how - this is the crux.

    There is still much work to be done but these discussions help us to formulate ideas that hopefully lead to research. I believe the answer is out there but what we really need is a workshop of some form whereby we look at all of the contributing factors, agree some principles or variants of and then determine appropriate research to evaluate. It does not require all of the thinkers to actually undertake the research, unless they wish, but to contribute to the formulation of the principles and the research studies that others can undertake, would be a massive step forward.

    You are correct about physios etc. and bio but they generally take a very simplistic approach because of all the great unknowns.
  39. Col:

    This comment from Eric Fuller needs to be elaborated on further. (Eric was the first person to introduce me to the works of Kuhn nearly 20 years ago.) Here is an excerpt from the book chapter that Eric and I wrote together 12 years ago that I mentioned in my last posting where we more fully discuss the principles of Thomas Kuhn as it applies to Root Biomechanics and Tissue Stress Theory.


    A question that immediately presents itself to the health professional when confronted by a different method of treating patients with mechanically based pathologies of the foot and lower extremity is “why is a new approach to mechanical foot therapy needed since there has been a generally accepted approach that has worked quite well over the last forty years?!”

    To obtain a broader view of why it is sometimes necessary to change our ideas regarding new information in any field of science or medicine, it is important to take a brief look at the history of scientific progress to see how and why change occurs. Science does not always progress continually and systematically forward. In his classic treatise on scientific progress, Kuhn[1] has described a process where a group of people will have a generally agreed upon set of ideas, which is described as a paradigm. A group of scientists can base its research questions on these generally accepted ideas. Like scientists, a group of medical practitoners can also have a generally accepted model by which to treat patients. Over time, research in a paradigm progresses and there may be a number of observations that become inconsistent with the existing paradigm, which Kuhn terms as “anomalies”. If the anomalies are only minor then the paradigm will change, to accommodate the anomalies, and survive. However, if there are enough anomalies, then the original paradigm is discarded and a new paradigm will emerge that will replace the old paradigm. Over history this process of changing paradigms has occurred numerous times within both the fields of science and medicine1.

    The history of podiatric biomechanics and mechanical foot therapy has also progressed in jumps from paradigm to paradigm[2]. From 1845 when one of the earliest built-up in-shoe leather custom insoles was first described by Lewis Durlacher (a British chiropodist) to the foot orthoses developed by Whitman, Roberts, Schuster, and Levy in the century that followed, ideas have been continually changing regarding the principles and practice of mechanical foot therapy[3],[4]. One of the largest paradigm shifts in mechanical foot therapy in the late 1950s when Dr. Merton Root developed his Root Functional Orthosis, which remains the model for most modern foot orthoses that are in use today within the podiatric medical profession[5].

    Root and his coworkers also published a foot classification system in 1971 that compared an individual foot with an idealized normal foot[6]. However, over the last few decades, some of the ideas of the Root paradigm have come into question2,[7],[8]. Others have noted that new paradigms are being proposed to take the place of the Root paradigm2,[9]. Kuhn has noted that in the history of science, when there is discontent with an established paradigm, multiple paradigms are proposed to serve as replacements and eventually one paradigm becomes the dominant paradigm for that period in time1.

    The application of the principles of Newtonian mechanics to the analysis of human locomotion has been occurring within the scientific community from as early as 1836[10]. These early efforts at the mechanical analysis of gait were limited by their inability to accurately measure the forces and motions needed for their calculations[11]. Cavanagh11 described how the work of Jules Marey and Edward Muybridge, two of the earliest pioneers in gait analysis, contributed improvements in the measurement of forces and motion that led to further advances in applying mechanical analysis to gait. Around the turn of the twentieth century attempts to apply mechanical analysis to gait were limited by the fact that it took over 1000 hours to process the data generated from a single step[12].

    In more modern times, improved measurement techniques has lead to the exploration of assessing clinical pathology with mechanical measures and has explored the potential for actual measurement and prediction of pathology[13],[14],[15]. The technique of modeling has been shown to have positive results in the prediction of the stresses that occur within the tissues of the body[16].

    The idea that one should consider the pathological stresses on an injured tissue more than one should consider the apparent “deformities” of the foot and lower extremity in determining an appropriate mechanical foot therapy is not totally new. In 1992, Kirby[17] noted that by using models of the foot and lower extremities, an intelligent prediction could be made as to whether one of the structural components of the foot is under tensile, compression and/or torsional loading stresses during gait. He felt that the analysis of externally measurable deformities of the foot and lower extremity did not give near enough information so as to allow prediction of the mechanical behavior of the foot during gait and was, therefore, insufficient to prescribe the best foot orthoses.

    In 1995, McPoil and Hunt8 promoted the idea that mechanical foot therapy should be directed toward resolving tissue stress in what they called “the tissue stress model”. They claimed that the tissue stress model serves “as the basis for developing an examination and management paradigm for treating individuals with foot disorders”. They also claimed that one of the benefits of this tissue stress model was that it did not rely on the use of “unreliable measurement techniques” currently in use to measure deformities within the podiatric profession.

    In 1996, Fuller[18] reviewed the concept of tissue stress along with the use of computerized gait evaluation techniques and modeling of the foot and lower extremity to help predict the stress in a specific anatomical structure. More recently, Fuller has promoted the idea of a tissue stress treatment model that explains how a clinician can use rearfoot and forefoot wedging to serve as a basis for mechanical foot therapy[19]. Kirby has also recently reviewed the biomechanical nature of tissue stress and the clinical application of the tissue stress approach to mechanical foot therapy where a stepwise approach to its use was introduced for the clinician[20].

    Even though the medical literature had only discussed the importance of using the tissue stress approach a little over a decade ago, this approach of mechanical treatment of foot and lower extremity pathology has been used for many more years with gratifying results by the authors in their own clinical practices. The concepts of subtalar joint axis spatial location and rotational equilibrium help explain the production of abnormal internal stresses within the tissues of the foot and lower extremity. This emerging model of mechanical foot therapy will hopefully serve as a new paradigm of mechanical treatment of foot and lower extremity pathologies. The authors fully expect that, in the future, further refinements in this model of mechanical foot treatment will eventually add yet another paradigm to the treatment model alternatives for clinicians who specialize in treatment of mechanically based pathologies of the foot and lower extremity."

    [From: Fuller EA, Kirby KA: Subtalar joint equilibrium and tissue stress approach to biomechanical therapy of the foot and lower extremity. In Albert SF, Curran SA (eds): Biomechanics of the Lower Extremity: Theory and Practice, Volume 1. Bipedmed, LLC, Denver, 2013, pp. 205-264.]

    [1] Kuhn, Thomas S. The Structure of Scientific Revolutions(2nd ed). University of Chicago Press, Chicago, 1970.
    [2] Payne CB. The past, present, and future of podiatric biomechanics. J Am Podiatr Med Assoc. 1998 Feb;88(2):53-63.
    [3] Schuster, R.O.: A history of orthopedics in podiatry. JAPA, 64(5):332-345, 1974
    [4] Kirby KA, Green DR: Evaluation and Nonoperative Management of Pes Valgus, pp. 295-327, in DeValentine, S.(ed), Foot and Ankle Disorders in Children. Churchill-Livingstone, New York, 1992.)
    [5] Root ML Development of the functional foot orthosis. Clinics in Podiatric Medicine and Surgery 1994 Apr,11 (2),
    [6] Root, M.L., W.P. Orien , J.H. Weed and R.J. Hughes: Biomechanical Examination of the Foot, Volume 1. Clinical Biomechanics Corporation, Los Angeles, 1971
    [7] Rega R, Green DR. The extensor hallucis longus and the flexor hallucis longus tendons in hallux abducto valgus. J Am Podiatry Assoc. 1978 Jul;68(7):467-72
    [8] McPoil, T.G. and G.C. Hunt: Evaluation and management of foot and ankle disorders: Present problems and future directions. JOSPT, 21:381-388, 1995.
    [9] Lee WE. Podiatric biomechanics. An historical appraisal and discussion of the Root model as a clinical system of approach in the present context of theoretical uncertainty. Clin Podiatr Med Surg. 2001 Oct;18(4):555-684
    [10] Weber, W. and Weber, E. Mechanik der Menschlichen Gehwerkzeuge. (The Mechanics of Human Locomotion) Gottingen: Dieterichschen Buchhandlung. 1836. Cited in Cavanagh PR. Biomechanics: a bridge builder among the sport sciences. J.B Wolffe Memorial Lecture Medicine and Science in Sports and Exercise Vol. 22 No. 5 p.546-557
    [11] Cavanagh PR. Biomechanics: a bridge builder among the sport sciences. J.B Wolffe Memorial Lecture Medicne and Science in Sports and Exercise Vol. 22 No. 5 p.546-557
    [12] Braune W. and Fischer O. The Human Gait P. Maquet and R Furlong (Translators) Berlin Springer Verlag , 1987 (English Translation) of W. Braune and O. Fisher (1895-1904) Der Gang des Menschen. B. G. Tuebner sited in Cavanagh PR. Biomechanics: a bridge builder among the sport sciences. J.B Wolffe Memorial Lecture Medicine and Science in Sports and Exercise Vol. 22 No. 5 p.546-557
    [13] Winter DA, Bishop PJ Lower extremity injury. Biomechanical factors associated with chronic injury to the lower extremity. Sports Medicine 14(3) 149-153 1992.
    [14] Nigg BM, Bobbert M; On the potential of various approaches in load analysis to reduce the frequency of sports injuries. J Biomech 1990;23 Suppl 1:3-12
    [15] Winter, DA Concerning the scientific basis for the diagnosis of pathological gait and for rehabilitation protocols Pysiotherapy Canada vol. 37 No. 4 p245-252 1985
    [16] Morlock M, Nigg BM, Theoretical considerations and practical results on the influence of the representation of the foot for the estimation of internal forces with models. Clin. Biomech. (6) 1, 1991
    [17] Kirby KA: Thinking like an engineer. (March 1992). In Kirby KA.: Foot and Lower Extremity Biomechanics: A Ten Year Collection of Precision Intricast Newsletters. Precision Intricast, Inc., Payson, Arizona, 1997.
    [18] Fuller, E.A.: Computerized gait evaluation. pp. 179-205, in Valmassy, R.L.(editor), Clinical Biomechanics of the Lower Extremities, Mosby-Year Book, St. Louis, 1996.
    [19] Fuller, E.A.: Reinventing biomechanics. Podiatry Today, 13:3, December 2000.
    [20] Kirby, Kevin A.: Foot and Lower Extremity Biomechanics II: Precision Intricast Newsletters, 1997-2002. Precision Intricast, Inc., Payson, AZ, 2002.
  40. And I'm sure you agree that any reference point or "system" for those with "no or a basic understanding" should have demonstrable validity, reliability and specificity... the Root system doesn't tick any of these boxes, and that my friends is the ugly truth, whether Jeff Root wants to admit that, or not. What is it that Craig says? Biologically plausible, theoretically coherent... etc, yet again, the Root system does not tick the right boxes to be a contender in anything more than an historical perspective.

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