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The 5 great FALLACIES of podiatric biomechanics

Discussion in 'Biomechanics, Sports and Foot orthoses' started by AdamPhilps, Jul 7, 2007.

  1. AdamPhilps

    AdamPhilps Welcome New Poster

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    Dear Craig, Simon, Kevin, Bruce, Eric and all other interested or suitably opinionated.

    I've been refreshing my comprehension of pedal biomechanics of late and wondered if you had an opinion on what the 5 greatest mis-truths of this discipline are.

    In other words what concepts most people think/ assume are correct, that havn't yet been tested by science or are likely to be.

    Will value your thoughts...1, 2, 3 , 4, 5 :) !

    Regards. Adam.
  2. Craig Payne

    Craig Payne Moderator

    Re: The 5 great FACTS and FALLACIES of pedal BMX

    1. Excessive pronation is pathologic (its not)
    2. Forefoot varus is common (its extremly rare)
    3. Foot pronation is a compensation for a structural LLD (its not)
    4. 10 degrees is the normal ROM for the ankle joint (its not)
    5. Foot orthoses work by changing the pattern of rearfoot and/or midfoot motion (they don't)
  3. Re: The 5 great FACTS and FALLACIES of podiatric biomechanics

    I like Craig's list. My list changes day to day. Not sure if these are "popular" beliefs, or that a lot of people think them to be right, they're just things that I don't like this morning:

    1. The foot is a tensegrity structure.
    2. The MTJ has oblique and longitudinal axes as described by R,W & O. In fact, anything to do with axes fixed in space i.e., the 42:16 STJ axis and "normal" ranges of motion at joints and their prediction of pathology.
    3. High and Low gear propulsion and it's relationship to foot pathology.
    4. The effects of variation in functional activities and environment on foot/ orthotic interaction are negated by the fact that we walk on hard flat surfaces.
    4. The prescription and manufacture of custom foot orthoses is an accurate and precise process and that foot orthotics work by..... (insert any theory you like, because the truth is that we don't know).

    Could have picked dozen's, but these will do for now.
  4. Re: The 5 great FACTS and FALLACIES of podiatric biomechanics

    As Simon says :) , my list of the current beliefs/things in podiatric biomechanics that bug me most changes frequently. Here is my current list.

    1. Podiatrists who don't know what a moment is, don't understand rotational equilibrium, don't know any modelling concepts and don't grasp the importance of tissue biomechanics, but still consider themselves to be "experts" in biomechanics.
    2. Subtalar joint axis location has little to no effect on the biomechanics of the foot and lower extremity.
    3. Discrete oblique and longitudinal midtarsal joint axes actually exist (and are still being taught by podiatric biomechanics faculty around the world).
    4. Neutral position is the rotational position of the subtalar joint that allows for optimal gait function for all individuals.
    5. Foot orthosis therapy is all about "correcting overpronation", that high-arched, non-rearfoot posted orthoses casted in foam boxes are better than any others in the world, and that any attempt to evert an orthosis past heel vertical to treat patients with symptoms caused by excessive external STJ supination moments is harmful for the patient.

    I could go on but since you only asked for five, I kept it brief.
  5. Scorpio622

    Scorpio622 Active Member

    Re: The 5 great FACTS and FALLACIES of podiatric biomechanics

    FALLACIES in the USA

    1) “Podiatric Biomechanics” is synonymous with foot orthoses, with very little attention to footwear and selective stretching/strengthening.

    2) Subtalar neutral position is the center of the universe.

    3) “Podiatric Biomechanics” is adequately emphasized in the curricula of US podiatry colleges- with well published teachers.

    4) “Podiatric Biomechanics” is for those who don’t perform Podiatric Surgery- and the twain shall never mix.

    5) All podiatrists, by birthright, are the foremost experts on lower extremity biomechanics despite the fact that most practice circa 1979.
  6. DaVinci

    DaVinci Well-Known Member

    Me thinks I have some learning to do to keep up with these guys, but will contribute this one:

    1. Heat molding of shank dependant prefabricated orthotics is a myth (but have to give CP some credit for pointing out the errors of my ways with beleiving this one)
  7. Five more:

    1. Foot orthoses work by "locking the midtarsal joint".
    2. Foot orthoses work by "preventing compensation for forefoot deformities".
    3. Foot orthoses work by "holding the subtalar joint in neutral position".
    4. Plantar fasciitis is primarily caused by "overpronation".
    5. Functional hallux limitus is the cause of excessive subtalar joint pronation.
  8. Cameron

    Cameron Well-Known Member


    With you Craig, but since it is Monday and I am counting the ecological cost of watching Live Earth, here goes

    i. podiatric biomechanics is a precise science
    ii eyeballing is both valid and reliable
    iii. skin line calculations are accurate
    iv. gait analysis is ideal for checkout
    v. bespoke orthoses are better than over the counter foot orthoses

  9. 1. Insoles made by casting the foot are "functional" Any other sort are "simple" and do not affect foot function.

    2. "Correction" is synonmous with "medial wedging". Therefore if an orthotic does not work it needs more "correction".

    3. If a modification works in one patient it works for all therefore if one finds a mod one likes one should use it in EVERY DAMN DEVICE YOU ISSUE :mad:

    4. Orthotics are incapable of making any situation any worse and therefore can be used with impugnity without a proper assessment.

    5. As others have said:-

    In the beginning the science was without form, and darkness was upon the land, and the community was as void. And a voice spake into the darkness saying "let there be sub talar neutral theory" and lo there was sub talar neutral theory. And it was good.

    On the second day.....
    Oh B****X to it; we learned STJ theory at UNI 25 years ago and can't be bothered to update our knowledge so we'll assume thats all there is and make ££££s ( or $$$$$) selling the exact same bog standard STJ neutral carbon fiber devices to EVERYBODY regardless of whats actually wrong with them on the basis that casting the foot makes it a "custom" device even if its always the same prescription! Further, we will patronise the backside off anyone who suggests that any theory or model after STJN gas any relevance or validity whatsoever with snide little remarks to the effect that they are just making things unneccessarily complicated.

    Sorry, that rant got away from me a bit. :eek:

  10. LuckyLisfranc

    LuckyLisfranc Well-Known Member


    If both are fallacies, then where does this leave our average suburban podiatrist? :confused:

    As an 'eye-baller', I choose this as the lesser of two evils. But hey, what would I know. :rolleyes:

  11. drsarbes

    drsarbes Well-Known Member

    1. Indications for orthotic therapy has nothing to do with the patients insurance coverage.
    2. Everything that goes wrong with a foot can be explained biomechanically.
    3. If your knee hurts you must need orthotics.
    4. Post Tib dysfunction is always caused by poor biomechanics (like everything else)
    5. Fusing the 1st MTPJ, STJ or Ankle is perfectly OK Biomechanically, just no joints proximal to these.

  12. Cameron

    Cameron Well-Known Member


    >If both are fallacies, then where does this leave our average suburban podiatrist?

    It's a kinda biomagic, and the secrets are known only to experts that charge fees. :)

    Happy Tuesday

  13. hazelnoakes

    hazelnoakes Active Member

    Ahh the mind boggles reading the above entries!!
    Since what we were taught is incorrect is there any chance of a refund on the university fees? ;)
  14. efuller

    efuller MVP

    At the risk of repeating some good ones.
    1. Position correlates with stress
    2. The Root, Orien, Weed explanation of bunion formation makes sense
    3. Black box explanations are acceptable. For example the midtarsal joint locks is an accepted theory even though there is no discussion of the anatomical structures that would cause "locking."
    4. Forefoot to Rearfoot can be measured repeatedly, and consistantly, across examiners.
    5. Functional Hallux Limitus causes STJ pronation


    Eric Fuller
  15. Here's my list for today:

    1. Orthoses bring the ground up to the foot negating the need for compensation
    2. The midfoot = TNJ and CCJ
    3. The foot is fixed on top of an orthoses
    4. Because I wear orthoses, I should run in neutral shoes
    5. Orthoses improve fertility
  16. Scorpio622

    Scorpio622 Active Member

    The 5 great FACTS of podiatric biomechanics

    Great tread started by a newbie !!!

    In light of all this cathartic negativity, I started a list of 5 FACTS of podiatric biomechanics and quickly lost confidence. All of my entries had soft words like "can" or "may"- and I scrapped the list. Are there any bold irrefutable truths ??????
  17. Re: The 5 great FACTS of podiatric biomechanics

    5 Facts of Podiatric Biomechanics

    1. Obesity and gravity will be very good to the podiatric profession over the next few decades.
    2. Those podiatrists that understand mechanical and engineering concepts have an intellectual advantage in treating mechanical problems of the foot and lower extremity.
    3. Custom foot orthoses, when correctly prescibed and adjusted by skilled practitioners, are an extremely effective, safe and underutilized treatment modality.
    4. Researchers will continue to misrepresent the effectiveness of prescription foot orthoses until they understand the concept that skilled orthosis practitioners do not simply hand out cookie-cutter orthoses to patients without needing to occasionally adjust them to improve patient symptoms and improve gait function.
    5. The emphasis on teaching surgery over biomechanics and a lack of post-graduate training programs in biomechanics within the podiatric medical educational system within the United States will result in, within the next two decades, a lack of US trained podiatrists that will be considered experts in podiatric biomechanics.
  18. 1. Since science deals in probabilities, there are few, if any facts in podiatric biomechanics. Our knowledge of the biomechanical function of the foot and lower limb is changing (improving?) day-by-day. However, paraphrasing someone great: "What is a truth today, shall be a half-truth tomorrow and an untruth next year."
    2. There is insufficient good quality scientific evidence regarding the efficacy of custom foot orthoses. It is unlikely that there ever will be due to the inherent nature of custom foot orthoses and the relative lack of funding for such research.
    3. Too many foot orthoses are mis-prescribed by an increasing number of poorly trained individuals.
    4. Patients sometimes wear their orthoses the wrong way around, and still get better.
    5. Biomechanical functional capacity is a function of the interaction of the genotype and the environment, thus it is non-constant and unique to the individual at that instant in time- bring on the obese ;)
  19. Re: The 5 great FACTS of podiatric biomechanics

    I'll ignore the Freudian typo.

    Perhaps Adam had a head start? Was Jim your father Adam? For all who are wondering what I'm barking on about now see Philps, J.W.: The functional foot orthosis. Churchill Livingstone
  20. drsarbes

    drsarbes Well-Known Member

    "Since science deals in probabilities....."
    I've seen this before and I don't agree. Without Mathematics there is no science.
    If I drop a known object inside a vacuum I not only know that it will fall, but at what rate and I can repeat it as often as I'd like. It will drop each and every time. I know this because I can accurately measure the mass, wind resistance and the gravitational pull on the object. I can also measure the time and location of the object within the space provided.
    If biomechanics is "probabilities" then it is only due to the fact that we have not progressed to a point where we can calculate, measure and reproduce indices within that field of science called biomechanics.
    I think this terminology comes from Quantum Physics based on probabilities of locations of subatomic particles. I don’t agree with this either. It’s only “probabilities” because we do not have the ability (at the present time) to measure more accurately.

  21. Dr SArbes,

    You're probably right.
  22. drsarbes

    drsarbes Well-Known Member

    "You're probably right"

    That's one phrase my Ex-Wife NEVER said to me!!!!!!!!!
  23. efuller

    efuller MVP

    Re: The 5 great FACTS of podiatric biomechanics

    1. Things break when they are placed under more stress than they can handle.
    2. Motions are caused by forces and moments (2nd Law)
    3. For every action there is an equal and opposite reaction (3rd law)
    4. Reduction in stress in an injured structure should allow it to heel.
    5. Modeling will lead to understanding how to reduce stress in anatomical structures.

    You are probably right, it is important to illustrate the positive.


    Eric Fuller
  24. efuller

    efuller MVP

    Heisenberg uncertainty applied to anatomical structures:
    The problem with knowing the exact force in an anatomical structure is that the method used to measure the force will alter the force. Additionally, the expense of accurate measurement may be too high to be performed consistantly. There will always be some art to medicine. I agree we should strive to find and perfect measures in biomechanics, however I doubt that the perfected measures will be used consistently at a clinical level throughout the world.

    Another problem, does the pain cause the gait or does the gait cause the pain? Both can be true. Which one are you looking at when you perform your measurements?

    I've thought long and hard about what measures would be needed to improve treatment of foot biomechanics. It is really hard to predict forces in anatomical structures. If you chose a clinical condition I could tell you where you would have measurement error that would effect the prediction of whether or not that condition would develop. The measurement error would put you back into thinking about probabilities of damage. I doubt it is possible to progress to the point where there is no measurement error.

    Although, I agree with your point that we should try and advance as far as we can so that we can acurately know our limitations.


    Eric Fuller
  25. admin

    admin Administrator Staff Member

    Re: The 5 great FACTS of podiatric biomechanics

    Here is the great man himself:
  26. Re: The 5 great FACTS of podiatric biomechanics

    Speaking of the book: Philps, J.W.: The functional foot orthosis. Churchill Livingstone; how does one write a whole 180 page book on functional foot orthoses without a single reference to the previously published works of any other authors?! :confused: :eek:

    As far as I'm concerned, this lack of any reference to the previously published works of Root et al in Jim Philps' book constitutes plagiarism.

    pla·gia·rism [pláyjə rìzzəm]
    (plural pla·gia·risms)
    1. stealing somebody’s work or idea: copying what somebody else has written or taking somebody’s else’s idea and trying to pass it off as original
    2. something plagiarized: something copied from somebody else’s work, or somebody else’s idea that somebody presents as his or her own

    Microsoft® Encarta® Reference Library 2005. © 1993-2004 Microsoft Corporation. All rights reserved.
  27. Re: The 5 great FACTS of podiatric biomechanics

    How many references in Root et al's three books?
  28. CraigT

    CraigT Well-Known Member

    Ok- we have a good range of facts and fallacies... not easy to come up with 5 new ones, but here goes...
    1- Sports orthoses must be soft
    2- 'Rigid' orthoses don't allow the foot to move
    3- You can create a 3D orthosis accurately from a pressure map of the foot.
    4- If a pair of orthoses do not improve symptoms, then they are not 'working'
    5- A 'wear in' period of 2 months for orthoses is acceptable.

    Following on from above...
    1- Sports orthoses can be rigid
    2- A rigid orthosis does not stop all foot movement
    3- Orthoses should be reviewed to ensure that they are achieving the aims they are designed for.
    4- A well designed orthosis should improve function, but sometimes the symptoms are not related.
    5- Orthoses should be comfortable under the foot in a very short time.

    There are possibly some contentious ones there... I await the grilling.

    While I am on contentious 'facts and fallacies'

    OK, I'll bite... I agree that not all pronation is pathological, but is your statement too broad??? Do you include pronation moments in your definition?

    While I know of many instances where an OTC orthosis may give as acceptable results as custom orthoses, to say that your statement is a fallacy is, in my eyes, a bit of a stretch...
    A custom orthoses should always be at least as good as the very best OTC device- if this is not the case, then you have a problem with your custom devices!
  29. Re: The 5 great FACTS of podiatric biomechanics


    In Volume I (Root ML, Orien WP, Weed JH, RJ Hughes: Biomechanical Examination of the Foot, Volume 1. Clinical Biomechanics Corporation, Los Angeles, 1971), there are 95 references.

    In Volume II (Root ML, Orien WP, Weed JH: Normal and Abnormal Function of the Foot. Clinical Biomechanics Corp., Los Angeles, CA, 1977), there are 43 references in Chapter 1, 55 references in Chapter 2, 44 references in Chapter 3, 8 references in Chapter 4, 9 references in Chapter 5, 37 references in Chapter 6, 22 references in Chapter 7, 70 references in Chapter 8, 97 references in Chapter 9 and 88 references in Chapter 10.

    In "Volume III) (Root, M.L., J.H. Weed and W.P. Orien: Neutral Position Casting Techniques, Clinical Biomechanics Corp., Los Angeles, 1978) there are no references.

    So to answer the original question, "How many references in Root et al's three books?, the correct answer would be 568.

    However, on the other hand, in the book by Jim Philps [Course Supervisor, School of Health Sciences (Podiatry), Central Institue of Technology, Heretaunga, New Zealand] (Philps, JW: The Functional Foot Orthosis. Churchill Livingstone, New York, 1990) published 19 years after Root et al's Volume I, there are no references.

    In fact, from my reading of the book, there is not a single mention of the prior published work of Drs. Merton Root, John Weed or William Orien within his book even though the first chapter of the book is nearly identical to the Root et al's Volume I. The third chapter of Philps' book discusses neutral position plaster casting with absolutely no mention of Root et al's "Neutral Position Casting Techniques" book published 12 years before Philps' book.

    If this is not plagiarism then it is complete ignorance by a podiatric educator to the prior published works of the individuals who spent most of their professional lives starting and developing the field of podiatric biomechanics. Churchill Livingstone should never have published a book like this without any references to prior published works.
    Last edited: Jul 12, 2007
  30. Craig Payne

    Craig Payne Moderator

    Think way back to that first lecture I gave you in second year biomechanics....what did I say back then? "Half of what I teach you this semester is wrong, the problem is I do not know which half it is" :)
  31. Craig Payne

    Craig Payne Moderator

    Pronation is a motion. Pronated is a position. Motion and position are not painful. Its the forces that drive a motion and then needed to stop a motion that actually do the tissue damage to cause pain. There is a very very very very poor correlation between a pronated position or the motion of pronation and the forces needed to stop it.
  32. Cameron

    Cameron Well-Known Member


    I have long been an advocate for dropping podiatric biomechanics from the common core curriculum in undergraduate podiatry programs. Many may recall the (long) theme 'throw the baby out with the bathwater" on podiatry maibase, which later Craig developed into a paper. As a purist I would advocate a bioengineering curriculum incorporating foot mechanics, foot orthotics and prosthetics would be far superior to the existing podiatry biomechanics syllabuses and give a far more comprehensive understanding to students, not to mention uniform professional approach to biomechanics.

    Before you reach for your ramipril, as I am unlikely to influence anything now, just rest easy. :) I am just chewing the fat.

    Once schooled in first principle mechanics then I have no problem with senior undergraduate students electing to complete a podiatric biomechanics unit and or as part of a professional management unit for graduates preparing for professional life. Then they can reflect from an informed perspective. If money making is important (it is) then risk and liability management would for me be a preferred approach and would link to other modalities.

    The technical skill on how to make foot orthoses however I believe has nothing to do with podiatry (per se) and should be a stand alone qualification. There are still some centres of podiatry education who continue the traditional training of undergraduate to make orthotic devices. The cost of consumables alone would make this prohibitive and a manger's nightmare, especially in university curriculum which are already crammed too full of content. Dropping this component would I feel give greater latitude.

    In reality foot orthoses have become the major extra curricular earner for pods and despite absence of evidence to support their efficaciousness there is just no way now you can pull them out of the equation. The industry expects graduates to be conversant with theory and practice. As a theorist and observer I believe this situation exemplifies a potentially dangerous dichotomy played out in a profession rationally based on craft and not thought. Because we want our therapies to work (our incomes depend on it) we will blindly ignore all the signals to the contrary, in the total commitment and belief in the doctrine, "it must work!"

    What say you?

  33. efuller

    efuller MVP

    I disagree. If you are going to order an orthosis you should know how it is made and how varius prescription variables and modifications will alter the finished product. It is important to understand how an intrinsic forefoot post will alter the shape of an orthosis to achieve its effect. I don't know if Kevin would have ever come up with the medial heel skive if he had not made orthoses from plaster casts. I would agree that there are some parts of the biomechanics curriculum that could be cut, but students need to understand what prescription variables to order and what they will do. Now all we have to do is prove they do what we think. :)
  34. Cameron

    Cameron Well-Known Member

    no problem with disagreeing, Eric.

    >Now all we have to do is prove they do what we think.

    Not a concept I can accept as a scientist.

    Have a good one
  35. javier

    javier Senior Member


    From an emotional approach I would approve enthusiastically your proposal, but from a rational point of view it is necessary to know where we come from for not making the same mistakes.

  36. Cameron

    Cameron Well-Known Member


    I have no problem with history and evolution of therapies, it is just in my "curriculum" model, this material is not essential for all. Make an ideal ellective unit however.

    As a pragmatist I also accept foot orthoses are so implicit with modern practice as to make the subject inseparable. My real dilemma is, I see intellectual conflict in a science course reliant on doctrine which by its very nature, cannot be questioned.

  37. Cameron

    Cameron Well-Known Member

    Kevin et al

    Tidying out the garden shed and came across Jim Philp's Functional Foot Orthoses (Second addition). The book is as I recalled it, a bench text (not a referenced text or intellectual thesis). Like Neal's orginal Common Foot Disorders it represented an eclectic collection of lecture/lab notes and I remember Jim used his book in the orthotic labs at the CIT with his students.
    Roots' casting manual may have been out of print or not available in NZ at the time.

    Skimming the content there was no references required as he is only outlining his techniqiues which would come from conventional wisdom (out there information).

    In the past Churchill Livingstone were rather lax in the standards of publication they produced and certainly pod text was more pod lore, than research based text books. I am constantly fascinated with the Common Foot Discorders series which is now in its umteenth edition in its twenty five year history. Still is rather eclectic in content but does remind all how podiatry has been developing over the last quarter of a century. What still knocks me out and my major criticism of the text (and I am a good friend of the editor in chief), is the absence of reference to patients. It has all to do with techniques and I would classify this as a bench text.

  38. Cameron:

    Since when did conventional wisdom have someone measuring "forefoot to rearfoot relationship" and using the neutral suspension casting technique with plaster slipper? Looks like a copy of Root et al's books to me, no matter what kind of textbook you call it. The bottom line is that Philps' book should have had references, no questions about that one in my opinion.
  39. Stanley

    Stanley Well-Known Member

    1. The first article discussing moments (or pronatory torque) of the foot was after 1978, and prior to that time podiatrists using orthoses did not help anyone.
    2. Understanding moments is essential to the treatment of every patient with an abnormal gait.
    3. To practice good podiatric biomechanics one does not need to know manipulations, as manipulations do not result in any change.
    4. Leg length cannot be a factor in pronation.
    5. Blake originated the concept of over correcting the rearfoot of orthoses.
  40. mahtay2000

    mahtay2000 Banya Bagus Makan Man

    Good Morning/Evening all,

    As a late-comer to this thread, please forgive me answering the original question-my 5 fallacies;

    1. My lecturer said so, so it is fact.

    2. My boss said so, so it is fact.

    3. It worked for my last pt, so it will work for this one.

    4. It's worked for years, so I don't need to explore a new theory.

    5. I believe it, so it is fact.

    That's what I encounter on a daily basis.


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