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What is the "normal foot"?

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Craig Payne, Jun 20, 2005.

  1. Craig Payne

    Craig Payne Moderator


    Members do not see these Ads. Sign Up.
    This is one of those metaphysical (meta-podiatric :confused: ) questions that philosophers in the profession and in other disciplines have been contemplating for many a moon ..... I had one such moments of contemplation recently as I prepare for a seminar. There have been many attempts to define it, many being of no use practically.

    Traditionally, the definitions of normality have focused on appearance (eg arch height) or function (eg excessive pronation). A lot of this was encapsulated in those biophysical criteria that Mert Root originally promulgated - ie vertical calc; subtalar joint neutral; lower 1/3 of tibia; forefoot/rearfoot relationship etc.

    The profession has become hung up on motion and positon (esp a pronated foot) as being a problem, so "normal" probably has to be the the opposite of this ---- this has beome so ingrained in the mindset of the profession, its sometimes difficult to move outside it.

    The problematic nature of all this, is that there are a lot of people out there that do not meet this "mindset" definition of "normal", but function without symptoms; can run fast etc (there was some discussion on that in this thread on elite athletes).

    Then there is the paradox that we have also discussed (link):
    A lot of our recent work has focused on forces in the foot and altering them. It should be intuitive that tissues get damaged by force and not motion or position of the foot; ie excessive pronation is a motion -- how can that motion actually do damage? Surely its the forces associated with that motion are what actually damage the tissues. This would probably explain why some people with severely pronated feet do not get symptoms --- ie the forces weren't high enough ---- so are these people in need of orthoses to change alignment if the forces are low. Also what we may consider a "normal" foot may have high forces..... as they have "mechanical" symptoms, we use a foot orthoses anyway to change aligment and they get better :confused:

    In the 'metaphysical' moment of contemplation I had, maybe the definition of the normal foot (from a clinical biomechanical viewpoint) should simply be:
    "The normal foot is the foot in which the forces are below the threshold for tissue damage" (ie the tissue stress model) .... maybe all we are doing with foot orthoses when patients get better is simply altering the forces, so they are below that threshold (as stated above altering the position or motion is not correlated to symptom reduction).

    What say you?
    Last edited by a moderator: Jun 21, 2005
  2. Mark Egan

    Mark Egan Active Member

    Normal Foot

    Dear Craig,

    After reading your piece I recieved a reading from a chiropractor who uses ART (Active Release Techniques) which was developed by Leahy within it he proposed the following proportional model for repetitive motion injury -

    "I= insult to the tissue
    N=number of repetitions
    F=force or tension of each repetition as a percentage of maximum muscle strength
    A=amplitude of each repetition
    R=relaxation time between repitition (lack of pressure or tension on the tissue involved).

    I= NF/ AR

    Thus damage to tissues results from and is proportional to (high repetitions) (high force) (small motion) (short relaxation time)"

    Could you say that orthotics work??? because they reduce force and increase relaxation time and thus reduce tissue damage?
  3. The Normal Foot, What Should Be the Criteria?

    Hopefully, within the next year, the chapter that Eric Fuller and I wrote, titled "Subtalar Joint Equilibrium and Tissue Stress Approach to Biomechanical Therapy of the Foot and Lower Extremity", will be published in Stephen Albert's book. Tissue stress is definitely the way to go for designing mechanical treatment methods for foot and lower extremity mechanical pathology. However, I don't think that tissue stress is the best way to define normalcy in the foot of the human.

    I actually like that, over 30 years ago, Mert Root was trying to come up some values for a "normal foot" by using an ideal set of morphological criteria that he thought would tend to allow the foot to function normally. The problem is that these criteria are based on static observations for a structure of the body that has its main function in interacting dynamically with the ground under loads that are often times many times the individual's body weight. Therefore, any criteria for normalcy needs to include dynamic evaluation of foot function since it is "normal" dynamic function of the foot that is the most critical for allowing weightbearing activities to occur with a minimum risk of injury.

    These criteria need to include structure and function, and need to be not just based on the absence of symptoms (such as many "famous" researchers have elected to use as their criteria for normalcy in their foot kinematic studies). For example, I wouldn't consider a foot that has a minimal medial longitidunal arch, a maximally pronated STJ, and a functional hallux limitus to be normal, just because it is asymptomatic. However, many researchers that are very well published in the podiatric literature may include this type of foot as one of their normals, as long as they are asymptomatic. Do we know that this foot will continue to be asymptomatic when they reach 45 or 55 years old? In other words, a lot of feet seem "normal" at age 25 because they are asymptomatic when, in fact, they may have significant mechanical pathologies that may cause painful syndromes to occur by the time they are 45 or 55 years old.

    Do we call a 25 year old with a blood pressure of 180/105 "normal", even though they haven't developed symptoms due to cardiovascular pathology? Do we call a 25 year old with a uric acid of 9.5 mg/100ml "normal" even though they haven't had their first acute gouty attack? Why then should we simply state, given our current state of knowledge, that if the individual hasn't had a significant injury to the foot or hasn't had foot pain that this should be the main inclusion criteria for normalcy, especially when they are in their twenties? Using the lack of symptoms as the main criteria for "normalcy" is, in my opinion, a very near-sighted method of trying to define the mechanical parameters that consitute a "normal foot".

    In addition, I don't believe that it wouldn't be accurate to state that the "normal foot" is simply "the foot in which the forces are below the threshold for tissue damage" since this definition does not take into account the wide variation of magnitudes of tissue stresses that will occur with athletic activities and the wide variation in body weights between individuals. Should the patient who has a equino-varus clubfoot that only can do a minimal amount of weightbearing activities but has no symptoms and no tissue damage due to the relative lack of weightbeaing activities be considered a "normal foot"? Should the patient that has an otherwise mechanically perfect foot but is running 200 miles per week and develops a metatarsal stress fracture be considered to have an abnormal foot just because they got injured? I don't think so.

    I believe that Mert Root was onto something in developing his criteria for normalcy over 30 years ago. Unfortunately, Mert didn't have access to the research and level of knowledge, during his creative years, to allow him to forge better definitions of what the normal foot should be. However, as far as I'm concerned, Mert Root's ideas regarding normalcy are probably the some of the best that I have seen in the medical literature thus far. It is high time that Root's Criteria for Normalcy are replaced by criteria that include dynamic parameters, and not just static parameters, to make them more appropriate to the functional realities of the constantly changing kinetics of the weightbearing foot.
  4. Atlas

    Atlas Well-Known Member

    I like it.

    But it infers that the bigger the amplitude the lower the insult?
  5. Cameron

    Cameron Well-Known Member

    Craig et al

    Whilst, Newton Rools, this is only a narrow interpretation of the universe and all who sail in her. The problem with mixing a skewed perspective such as a biomechanic's model as defined by universla laws with the wholeness of being is the sum of the parts will never equal the whole.

    People have from the beginning attemtped to make sense of their environment by use of the their bodies (or body parts). In a perfect balanced world idealisation becomes the measure of perfection and the concept there is a normal foot is like the Root pardigm, flawed. To follow this maxim would frustrate because nothing is ever shown to be consitent. Prescriptions are not always full proof and need tweeking. Non bespoke devices have the same results as bespoke orthoses etc, etc. I have said before, this baby, ie podiatric biomechnaics should have been thrown with the bath water.

    I think what we need to be aware of is the people who do not consult practitioners far outway those who do and hence we could as biomechnists and foot physicians be guilty of error in our blatant and biased extrapolations.

    Two good examples.

    If 90 % of the population have HAV, then HAV is normal. A few years back a colleague of mine George Rendall did a pilot retrospective on post HAV satisfaction rates and found something like 80% of the patients were delighted with the surgery and in that population when they measured the Hallux angle, there was a significant clinical presence of HAV in about 85%. Many explanations are possible but one unthinkable one would be functional anatomy may determine the hallux needs to adopt an everted, abducted and dorsiflexed position , au naturelle. Worth a thought.

    Pain and discomfort are more likey to predict disfunction. A foot within normal parameters (as defined by society) is a functioning kinetic machine and an abnormal foot, disfunctional.

    Hey, what do I know?
  6. LCG

    LCG Active Member

    I recently read an article by phillips

    Phillips,R.D.(2000) The Normal Foot. Journal of the American Podiatry Medical Association vol. 90. pp. 342-345

    This article has some intresting ideals and approaches to the interpretations of the "Normal foot".
    In summary phillips proposes 11 key criteria when determining or assesing the "normal" foot. Outlined below are some key arguements
    1.) The Normal foot should be defined in terms of societal demands. Ie a normal foot for the western shoed society may be considered abnormal for an unshoed society
    2.) The normal foot should be one that creates no adverse effects over a life time (reiterating previous comments)
    3.) Research must consider all aspects of the foot's function before taking a stand on one variable
    4.) All theories relating to normal must fit within grounded principles of biomechanics. If they fail to fit the new theory must adequately explain why
    5.) A theory explaining the normal positions and movements of any one individual should be applicable to all shapes and sizes of feet
    6.) A universal theory of foot function should include both static and dynamic functions of the foot (reiterating previous comments)

    The article is an interesting read for those wanting a historical overview of what has been considered the normal foot in medical literature.

    As theorys relating to normal continue to evolve i think the biggest challenge will be alligning the clinical and research community together to embrace change, imperitive in maintaing the professions credibility.

    Luke Grainger
  7. C Bain

    C Bain Active Member

    A Thread of Pure Quality!!!

    Hi All,

    I know that this Thread is far from completed in discussion but I feel strongly compelled to complement the writers here, writing a professionally well thought out Thread couched in experience no doubt.

    The quality of the writing and the spirit of tolerance in the dealings here gives hope for the future of this Forum. To some who might question why pick a basic fundamental subject of 'Normality'? I say it is the first step in our understanding of our SUBJECT! Particularly when it is applied with such Enlightened Thinking of the most positive kind.

    A Thread worth returning to again and again when going stale I think! I never expected to read this level and standard of debate here!

    I never expected to return to the Metaphysical approach and understanding of 'Normality' when applied to the FOOT! Our 'Benefactor' is usually encouched and surrounded by a protective hedge of political correctness used by some to bolster possibly a psuedo-physics called P******y rather than leather? (It depends from where you look at it of course?).

    I do hope contributers will continue in the Spirit of Professionalism here as the subject develops further on the question of, "What actually is the NORMAL FOOT and why is it NORMAL?



    PS. No never mind this, back to what you have read and understood from above please!!! I really do appreciate something that has been written with quality and authority. Thank you all!!!

    PPS. No I'm not leaving you even if that is how it sounds on the proof reading? You're stuck with me!
  8. Tim VS

    Tim VS Active Member

    How about this thought from a self confessed 'rookie'. All feet are 'normal', it's the modern surfaces we walk on which 'aint! :)
  9. Nice article by Dr. Daryl Phillips.

    However, if we are discussing "what constitutes the normal foot", then I believe we have to include specific criteria that will describe what a normal foot is and/or is not. As I mentioned earlier, dynamic function is critical and I think, is the key to describing normal function. The bipedal human, because of certain design constraints, needs to walk with a certain movement pattern in order to be the most efficient mechanically.

    We could establish certain ranges for normalcy in gait kinematics first. For example, we may describe the normal kinematic pattern of the subtalar joint (STJ) by saying that the normal foot has 2-4 degrees of early stance phase pronation, undergoes no STJ pronation in late midstance, and begins to resupinate at late midstance to be normal. We could then say that for each phase of gait, the hip, knee, ankle, midtarsal joint and metatarsophalangeal joints, in addition to the STJ, must also have a range of kinematic patterns to be considered normal.

    Normal should then be understood to be not an ideal value but, rather, a range of values that would indicate normal function. This would be similar to a range of values for hematocrit or other serum/blood studies that are "within normal limits". A large study will be required to be able to establish these values. Hopefully, this will all be done in the not-so-distant future so that we can have some hard data to hang our hat on when we start discussing "normal feet" again.
  10. Cameron

    Cameron Well-Known Member


    Far be it from disagreeing with you, but I think we may have two separate aspects; the normal foot as in society; and the concept of a functioning foot model. The latter will always be reductionist, by virtue of it construction which is constrained by what we know. As you say in the near future we will know more and can refine the model. However with the reductionist approach the sum of the parts will never describe the whole. The painful foot would have a plethora of analysis from phenomenological through to biomechanical and provided we watch our extrapolations each can be true to itself but fail to describe the whole.

    If you catch my drift.

    Was over in your neck of the woods last month and had a fab time at Fisherman's .

  11. I believe that establishing normal ranges for structure and function of the human foot and lower extremity is very important for our profession and our patients. Having a lack of symptoms should not be considered the sole criteria for normalcy. As I mentioned earlier, this type of inclusion criteria (i.e. asymptomatic = normal) has been used by many kinematic studies that have been published by researchers within the last 20 years in both JAPMA and other scientific journals. Establishing these normal ranges for structure and function will have a huge effect on research in that it will narrow down the inclusion criteria for research subjects to include only individuals that are not only asymptomatic but also have a normal range of foot and lower extremity structure and function.
  12. Foot fan

    Foot fan Active Member

    NORMAL: Conforming to a standard; regular, usual, typical.
    At right angles, perpendicular (the Australian concise Oxford
    Dictionary 4th edition)

    Perhaps Root was closer to the truth than we realise? Maybe he meant to look at the foot based on the second definition and this has blended into the first. In order to define something as 'normal' by the first meaning, the standard has to be defined. Attempting to define this standard based on pathological presentations is futile as assumptions are all that will present - 'we think a 'normal' foot looks like this and yours doesn't so try this'. If we really want to know what a normal foot is, someone has to go out into the general community and find out. Measure the parameters of the population in terms of a population with no symptoms next to those with symptoms and establish a bell curve.

    If anything, finding out what normal really is should increase the inclusion criteria, not decrease it. 'Normal' in the sense of being typical probably doesn't exist in terms of the human body and if it does, the values will be very broad. Often, the only thing our feet have in common is some bones and a few muscles.

    Normal in the sense of being at right angles - that probably does exist but, as is being proven, probably isn't the way the human foot was designed to function.

    Back to the original question - why do orthoses work. Who knows? Do they actually do anything we thought they did in terms of controlling motion? Probably not. Does this mean we should throw the 'baby out with the water'? Definitely not. There is obviously some therapeutic benefit with orthoses and some credit for podiatric biomechanics, we just need to keep looking, possibly even broaden the search from where it has been focussed for the last 40 years.
  13. efuller

    efuller MVP

    Normal or when do we treat

    I might suggest a slightly different sense of normal. Abnormal is when it needs to be treated. If we can predict that someone with some measurement will probably have pathology later then that person should be treated. That child that comes in with massive genu valgum and a position of the STJ that has 90% of the weight bearing foot on the pronation side of the axis will have pathology. However does the foot that has 70% of the weight bearing foot on the pronation side of the axis need to be treated or should we wait until symptoms develop?
  14. Good to see you contributing in this forum, Eric.

    The problem with basing our definition of normality/abnormality on the requirement for treatment is that different disciplines and different physicians will have different thresholds for treatment of their patients and even different treatment methods. I believe that, initially, structural measurements including ranges of motion, intersegmental angular relationships and kinematic pattern of walking gait should be used to establish what "normal" is. The next step, as we become more sophisticated, will be to use kinetic data to establish normal ranges for external and internal forces acting on the structural components of the foot and lower extremity.
  15. Cameron

    Cameron Well-Known Member


    Just re-read Craig's original posting

    >"The normal foot is the foot in which the forces are below the threshold for tissue damage" (ie the tissue stress model) .... maybe all we are doing with foot orthoses when patients get better is simply altering the forces, so they are below that threshold (as stated above altering the position or motion is not correlated to symptom reduction).

    I would have to agree there. Well said.

    I suggest by maintianing middle range motion, end of range excess reduces repetative stress and strains and hence symptoms subside. Frontal plane deformities will respond better to posted shells but sagittal plane pathomechanics will be less likely to unless the heel is encouraged to re supinate during propulsion. .

  16. davidh

    davidh Podiatry Arena Veteran

    Hi all,

    "How about this thought from a self confessed 'rookie'. All feet are 'normal', it's the modern surfaces we walk on which 'aint! "

    This is the definition which I go along with, with some modifications (if thats ok TimVS?).

    Clearly, a foot in which the STJ is OA is not "normal". However, I contend that the plantarflexed 1st rays, ankle joint equinus's, lig laxities, claw toes etc etc are normal, or variations of normal, and only cause problems when footwear is worn, and when the foot is used to ambulate or stand on an alien surface (in terms of what the original design was meant for, which was a mixture of terrains). Today, our alien surfaces consist of concrete, and flat hard surfaces generally.

    You may argue that we have to wear footwear, and that we have, most of us, to live on concrete :eek: , and I agree, of course this is the case.

    I suggest we can, if we wish, extrapolate two facts from this.
    1. Footwear and hard, flat surfaces must be considered as part of the overall equation when looking at what is normal.

    2. Effective treatment of symptomatic feet is, perhaps unwittingly, directed at making them work more efficiently in footwear, on hard, flat surfaces.

    I do this second routinely, mostly with orthoses :) . But for most of my patients I believe all I'm doing is reversing the stresses and strains caused by normal (albeit in many cases, ageing) feet ambulating on abnormal (for them) surfaces.

  17. Cameron

    Cameron Well-Known Member


    > I suggest we can, if we wish, extrapolate two facts from this.
    1. Footwear and hard, flat surfaces must be considered as part of the
    overall equation when looking at what is normal.

    If shoes have not had an impact on foot form and function and they have been around for 7000 years then tarmacadem and concrete (circa 250 years) will be unlikely to alter the human foot. I would suspect.

    >2. Effective treatment of symptomatic feet is, perhaps unwittingly,
    directed at making them work more efficiently in footwear, on hard, flat

    I do this second routinely, mostly with orthoses :) . But for most of
    my patients I believe all I'm doing is reversing the stresses and
    strains caused by normal (albeit in many cases, ageing) feet ambulating on
    abnormal (for them) surfaces.

    Interesting the whole STJ Neutral theorem is based on Inman's flat surface walking. In viva, heel pitch and toe spring negate that as does the foot to inlay interface; inlay to insock interface and finally sole to terrain interface.

    Wish is was simple.

  18. davidh

    davidh Podiatry Arena Veteran

    Hi Cameron,
    I don't believe there has been any kind of permanent change in the human foot over 7000 years - caused by footwear, hard surfaces or anything else.
    Various changes certainly occur over one lifetime, which is what I mean when I talk about the effects of shoes/hard flat surfaces on feet, but the next generation will, in the main, start off with normal feet.

    As a sideline, for people in the UK, take a look at the exhibits in the Egyptian Room at the British Museum. There are some pretty hefty metatarsals in there - far thicker than the modern met.

    I surmise that these are due to the repeated gripping which the feet of the higher classes (those are the only ones in the exhibits I believe) had to do whilst riding a chariot barefoot/ shod in a sandal/ balancing, so that horses could be steered or arrows shot/spears thrown.
    This part is pure guesswork :eek: .

    Last edited by a moderator: Jun 29, 2005
  19. Cameron

    Cameron Well-Known Member


    7000 years is not a long time in evolution so shoes and hard flat surfaces have not made a difference to feet. Ironmically hard surfaces may change the pattern of disease but merely as an exciting factor.

    As a sideline, for people in the UK, take a look at the exhibits in the Egyptian Room at the British Museum. There are some pretty hefty metatarsals in there - far thicker than the modern met.

    anidotal evidence.

    I surmise that these are due to the repeated gripping which the feet of the higher classes (those are the only ones in the exhibits I believe) had to do whilst riding a chariot barefoot/ shod in a sandal/ balancing, so that horses could be steered or arrows shot/spears thrown.
    This part is pure guesswork .

    The Egyptian Perod lasted centuries so it is difficult to relate a general pattern of travel to it. In any event it this would not be long enough to account for the genetic changes you suggest.

  20. davidh

    davidh Podiatry Arena Veteran

    Hi again Cameron,

    Are we talking at cross-purposes here?

    At no time have I ever suggested genetic changes to the foot :eek: .

    Indeed, I vehemently maintain that we do not see genetic changes in the feet of homo sap, and that the foot structure we know and love has probably remained largely unchanged for over a million years.

    How else can we explain Homo Erectus legbones that are a great match for our own (specimen Turkana Boy), or the partial foot of Homo Habilis (Oh8) which looks to me decidedly similar to modern feet?

    So, what I'm suggesting is:
    Our feet have not changed much (if at all) in perhaps a million years or so.
    Our modern terrain is not "natural" terrain for those feet.

    The description of the "normal" foot first appeared, as far as I can tell, in Grays Anatomy, at about the same time as Darwin was propounding his theory of evolution.
    I've done a little research on Gray, and could find nothing much. One thing though - he is not standing up to be counted in the evolutionary camp, which leads me to suspect (conject or whatever) that he may, when looking at feet (and how many did he sample to come up woith his defn of normal?), have tipped the balance towards the "in God's own image" camp.

  21. David Smith

    David Smith Well-Known Member

    Normal foot

    Getting back to lack of pathology being a criteria for the normal foot I have a friend who is 44yrs old. Very fit, runs long distance with the local running club, Martial arts and long distance swimming. He's about 5' 10" (178cm) and 88kg so not a light weight. As a biomechanist to see him run would make you cringe, feet at almost quater to three, fully plantargrade, and wide, knees abducted gait. All the propulsion coming from knee extension, he runs like a drunken frog. Yet he's amongst the fastest in his age group and has no pathology or pain at any time. I wouldn't dare add a pair of orthoses to this guys shoes even though everything about his posture scream abnormal, but its quite normal for him.

    Cheers Dave Smith
  22. Craig Payne

    Craig Payne Moderator

    David - I think that comes back to the point in my first message..... its the forces that do the actual damage to the tissues. Someone may have really bad foot and lower limb biomechanics based on what we would traditionally consider "bad" biomechanics, but does that really matter if the forces are below the threshold at which tissue damage occurs :confused: (also brings up some issues raised in the thread on elite athletes)
  23. David Smith

    David Smith Well-Known Member

    Normal foot


    I agree that force must cause injury and not motion but the two are difficult to seperate.

    "The concept of force is one of the most peculiar in all of physics, and has a fascinating history. It is, in one sense, the most viscerally immediate concept in classical mechanics, and seems to serve as the essential "agent of causality" in all interactions, and yet the ontological status of force has always been highly suspect. For example, we intuitively regard force as the cause of changes in motion, and imagine that those changes would not occur in the absence of the forces, but this causative aspect of force is an independent assumption that does not follow from any quantifiable definition, since we could equally well regard force as being caused by changes in motion, or even as merely a descriptive parameter with no independent ontological standing at all." Ref; Mathspages.com reflections on relativity, 3.2 Natural and Violent motions.

    In clinical practice one is not able to measure internal forces and the stress and strain on a particular tissue is unknown. But we may, from signs and symptoms, determine which structure has been damaged and conclude therefore that this structure has been the subject of excessive or abnormal loading ie loading outside the paramenters at which it can work without causing damage.
    From the motion of the foot and other parts that we observe one can make an educated guess at the origin of the external forces that may have caused the internal forces to become to high or applied for to long (in time).
    Whether or not the timing, Range, velocity or acceleration of the motion is abnormal may be difficult to quantify as others have suggested in this thread. Is it abnormal for a person with varus heel strike angle to pronate to the ground? I would say no its perfectly normal to do this but in the process the internal forces may be excessive. Therefore replacing some of the internal forces with external forces, EG orthoses, should reduce internal tissue loading to within normal or non pathological ranges and so reduce trauma.
    Is it normal for a person who jumped of a high building onto a concrete road to have broken a leg?
    Yes, because the forces would normaly be high enough to break the leg. Is it normal to have a broken leg? No. On the other hand if the same person jumped from the same height but landed in a deep tank of water, even though he may still hit the bottom, IE same range of motion, he is unlikely to break his leg. This is analogous of putting an interface, like an orthosis, between the foot and the ground it can reduce internal forces and trauma but not necessarily RoM.
    So I would conclude that it is very difficult to determine what is a normal foot in ambulation. Anatomicaly correct would be easy to define. While functionaly correct may be a better term to describe what we all imagine to be normal. Normal may be what works best for that person.

    Cheers Dave Smith
  24. davidh

    davidh Podiatry Arena Veteran

    Hi Dave,

    Would you say that what you're seeing with this chap is variation of normal, but compounded by running on a hard flat surface (I assume he is?).

    Would his gait would be different if he was running on a mixture of terrains, with some soft ground thrown in?

    Given his gait and running style, would the forces, (which are undoubtedly causing microtrauma in the lower limbs somewhere, and which are likely to cause symptoms at some stage in the future) be less if he ran on a mixture of terrains?

  25. David Smith

    David Smith Well-Known Member

    Normal foot


    No he runs on tarmac, grass and beach and he's always the same. However running on soft uneven surfaces undoubtedly reduces internal forces because the external forces are attenuated by the soft ground.
    It may be that in 10 years time his post tib will go ping but so far he shows no signs of trauma. If I hadn't known him since he was at school and he came into my clinic unknown he would be straight into a pair of orthoses because as you have said David I would assume he must be getting microtrauma that was building up trouble for the future. But why would he come to see me if he had no pain or problems with athletic performance.
    So as someone else said there may be lots of people out there with asymptomatic 'abnormal' gait but we never see them.

    Have good day Dave Smith
  26. Hello to all,

    Today I happen to have time to switch from my regular email to this Arena where I kept enjoying the discussion about normal feet, though it is already 3 AM here at the other side of the globe. And I still have some energy left to try my maiden entry in this Arena.

    As for the criteria for a normal foot, I was tempted at first to follow Graig in his concept of a normal foot functioning in a way that the loads (pressure or forces) on it are below the harming level or below the level where body tissues will break down, in this way keeping the functioning foot out of trouble. Anyway this definition compares well with the inclusion criterion of a trouble free foot as used by many biomechanicians, myself included, to create a so called "normal population". And for research purpose, where people affected with overuse injuries are compared with people with no injuries, this is somewhat the best, at least the most practicable criterion to use. This may explain its popularity with biomechanicians.

    But in the quest for the "normal foot" I can can also concur with Kevin when he objects to Graig's definition in the sense that people with clearly visible functional deviations (a hallux rigidus or an undeniable overpronation, to name only two) can hardly be seen as normal.

    Therefore, why not modulating Graig's definition with Kevin's remarks and considering a foot as normal not only when it is free from overuse injury or any other pathology (Graig's definition), but at the same time showing no anatomical and functional deviations we regularly see in patients who are affected with pain or injuries (Kevin's approach). The problem here is that we will have to determine the limit where these deviations should be considered as a real deviation, or when to consider hallux dorsiflexion lacking normal mobility, or where subtalar pronation starts to be considered exagerated.

    However, one way to establish these limits could be using data from epidemiologic studies and agreeing that the "red line" starts when a foot exceeds the median (50th percentile, or any other agreed on percentile) in a population who does suffer from any medical problem. For example, we could agree that subtalar pronation exceeding the median value found in a large population affected by chronical pain or injuries of the lower extremities, would be considered as abnormal and any feet displaying this abnormal pronation would be classified as not normal even when it is asymptomatic. This would marry the functional criterion from Graig with the more conceptual approach from Kevin and may offer an acceptable defintion of a normal foot.

    Well I just tried my best before my brains start displaying a normal behavior at this time of the day and force me to leave my screen and rest in a more prone position.

    Regards to all,
    Last edited: Jul 7, 2005
  27. pgcarter

    pgcarter Well-Known Member

    I sometimes think it is the use of the term normal itself which helps spark controversy and heat....the concept of the "normal " foot must surely be age adjusted if we mean "whatever most of the cohort have".
    On the other hand when we talk about non-pathological feet at any age couldn't we see it in terms of "the efficient foot" or similar rather than "normal" vs "abnormal".
    I do a fair bit of work in the over 80 age group and I am certain that the norm in this cohort involves some form of pathology.
    Not too many seem to remain unremodelled by the forces of gait and time...such a plastic thing the human body.
    Regards Phill
  28. I feel this is one of the most important threads to be discussed in this or any other podiatry forum, and the variations in the responses illustrate the width of the philosophical spectrum embraced by the practitioners in this field. I unfortunately think this topic is controversial because it pits the well being of the individual against the well-being of dogmatic tenets, and any attempt to jostle these tenets into one degree of pronation may receive an aggressive counter attack.

    That being said, regardless of how many degrees a certain joint "should" move, or how many degrees of varus a rearfoot "should" be posted, I believe a normal foot is one which successfully contributes to the individual's ability to maintain an asymptomatic equilibrium while engaging in necessary weight bearing activities. In addition, this normal foot should enable the individual to gradually adapt, under reasonably accelerating circumstances, to desired overuse activities within the obvious restrictions of their foot and body type. This is a lot of fancy verbiage for "common sense".

    I've had individuals report to my office with warts, for example, who have a frank pes plano valgus, who've successfully and asymptomatically run marathons, because they took on the order of a decade to gradually increase their training to let their systems adapt. Not infrequently will such patients report with disdain about podiatrists who insisted they have orthoses simply because their feet were flat. Sometimes they bring their orthoses in, sometimes they are beautiful Root-type orthoses. Often these patients report usage of the orthoses coincided with onset of first-time lower back or knee pain, only worsening during orthotic usage, which abated to utter asymptomatology as soon as the orthoses were discontinued. If the system is in an asymptomatic equilibrium, and has been so for many years, I see no reason in the interests of the patient to change it. If anyone knows of any articles which have been published in medical journals which statistically substantiate that orthoses prevent bunions, patellofemoral problems or back problems (I said prevent, not treat), would you kindly cite these articles? I and many future patients will appreciate these data.
    Last edited: Aug 2, 2005
  29. DrLCT2

    DrLCT2 Member

    The "Normal Foot"

    Unfortunately, Root's "Biophysical Criteria for Normalcy" (established and published in the late 1960’s) represent a rather "idealized" or "perfect" foot type that rarely exists, rather than being a true reflection of the foot type that prevails.

    Studies conducted on thousands of feet at the Biomechanical Engineering & Shoe Research Laboratory over the past 30 years indicate that a generalized "varus foot type" is, in fact, the most frequent structure of the human foot noted off-weight bearing; and therefore, "varus foot types" need to be considered the norm.

    The analysis of more than a hundred still-born fetuses indicate that "varus foot types" are inherent and residual from our classical in-utero position within our mothers' wombs when our feet and lower extremities are tucked-up and inverted considerably. There is nothing genetically that programs feet telling them it will be best if the plantar surfaces (the soles) of the feet end-up parallel to the horizontal plane and ground supporting surfaces of modern man's hard, flat surfaces (floors, pavement, etc.) once we’re out of the womb and become ambulatory.

    This just doesn't happen; and Tim VS has it somewhat right when he proposes in his June 23rd, 2005 posting that "modern society's surfaces are abnormal". In fact, modern man’s hard, flat surfaces have become the common pathological denominator to which all feet (regardless of their morphology) must ultimately compensate, conform to, and function on.

    Extensive studies conducted at our Laboratory reveal that most (and we do mean "almost all") people have about four (4) degrees of rearfoot/subtalar joint varus; and more than ninety-five (95%) percent of the general population have an additional four (4) to eight (8) degrees of forefoot varus/supinatus. This additional amount of forefoot "deviation" is in excess of the usual finding of four (4) degrees of rearfoot varus - with both the rearfoot and forefoot "deviations" being residual from in-utero positioning.

    Not to confuse the issue, but rather for the sake of completeness, our studies also indicate that a "forefoot valgus foot type" is also found in less than 4% of the population.

    The "ideal" foot type depicted by Root, et al. in their "Biophysical Criteria for Normalcy" is, in fact, a highly unusual set of circumstances for which there are actually very few clinical examples and is recognized in less than 1% of the population.

    Interestingly enough, Dr. Root and his biomechanical pioneering colleagues made the correct observation relative to the frequency of occurrence of their "ideal foot" when they stated in their same book, "Biomechanical Examination of the Foot, Volume 1", that "such ideal relationships are seldom seen clinically”; and yet, most podiatrists, orthopedists, physical therapists, biomechanists, pedorthotists, and others adopted this ideal set of criteria as the standard of normalcy to which all feet have been (and in many disciplines still are) evaluated, measured, and compared.

    Orthotics work, at least initially, by effecting changes in positions, motions, and functions of the feet and lower extremities - whether the prescription is correct or not. In this regard, one could simply place Kleenex tissues inside a person's shoes (we've actually done this at our Laboratory) and effect change and resolution of symptoms, albeit temporary, as a result of altering pathological forces.

    In the meantime, it's our belief that the inherent forefoot positions (be they forefoot varus/supinatus [recognized in more than 95% of the population] or forefoot valgus [noted in less than 4% of the population] are the real culprits causing excessive pronation or excessive supination respectively; and therefore, it's the forefoot that really needs to be addressed, compensated, and controlled by treatment efforts.

    In our opinion, the four plus or minus (4 +/-) degrees of rearfoot varus that almost all people possess should not be touched; thereby, allowing the rearfoot to act as an effective shock absorber when the foot first comes in contact with the ground at the contact phase of gait.

    As Tim VS humbly suggested in his June 23rd posting on this site, and Dr. Herman R. Tax wrote in his 1930’s book "Podopediatrics", and reiterated by Tax in his response to a Jane Brody "Health" column published in "The New York Times" in 1985; and again in Tax's answer to Richard Staheli, M.D. in "the Journal of Current Podiatric Medicine" in 1987 – Tax said: "The human foot is not suitable for use on modern man's hard, flat surfaces without modification of the surface.".

    Doctor Tax continued, "The human foot is still in a period of transition toward efficient upright bipedal weight-bearing and locomotion, and that man's modern technological environment has evolved more rapidly than human foot structure - so that flat, unyielding surfaces tend to put the contoured and inverted foot at a functional disadvantage. To apply the inner border of the foot to such walking surfaces, most people must pronate their feet excessively. In most cases, the foot cannot recover from this pronated position in order to act as the necessary rigid lever it must become for proper toe-off during locomotion.”

    Doctor Tax concluded that "This represents the basic cause of most future foot problems; and therefore, orthotics or the soles of shoes must be constructed in ways that neutralize excessive pronation as much as possible to prevent future foot disability.”

    Many (we're tempted to say most) practitioners tend to concentrate their treatment efforts toward controlling excessive rearfoot/STJ motion, by addressing the rearfoot itself with medial rearfoot posts or rearfoot skives on their orthotics. Some running shoe manufacturers (most notably Asics, and in recent years Nike, New Balance, and other) have also concentrated on the rearfoot by including rearfoot posts of dual-density midsole materials on the medial aspects of the heels of their shoes. This is not the least bit surprising since excessive pronation is most noticeable by observing heel evertion, positive Helbain's signs, lateral heel flaring, etc., on weight bearing and with dynamic functioning.

    The forefoot, however, is really where it’s at; and where we need to focus our attention!
    Last edited: Aug 15, 2005
  30. davidh

    davidh Podiatry Arena Veteran


    Pretty much what I've been saying for the last three years on various forums.

    You may also like to add to your reasoning the fact that hominids homo erectus (although now recognised as an evolutionary "dead-end" and not a forerunner of homo sap), and homo habilis both exhibit strong characteristics of modern osseous morphology, yet 1.6 million years ago there were certainly no roads, concrete or pavements.

    Quote."In fact, modern man’s hard, flat surfaces have become the common pathological denominator to which all feet (regardless of their morphology) must ultimately compensate, conform to, and function on."

    Nicely put, and for me this encapsulates the essence of what we try to do in pod biomech.
    We try to provide an interface for the foot to work efficiently on our hard, flat surfaces.

  31. Peter

    Peter Well-Known Member

    I thought Tax wrote his book ( 1st Edition) in 1980?

    Furthermore. I don't think many Pods would entirely disagree that modern terrain ie unyielding and flat is in itself pathomechanical.
  32. davidh

    davidh Podiatry Arena Veteran

    Hello Peter,
    I can't comment on Tax unfortunately.
    I can however comment on flat surfaces and pod biomech.

    If the majority of pods (I believe that is what you are saying) believe that the hard flat surfaces we walk on are responsible for biomech dysfunction (which I certainly do), how come we still regard Equinus as a "condition"?
    Or Forefoot Varus?
    Or any of the other biomech "conditions" which depend on an alien ( to our morphology) surface to produce symptomology?

    How come we still use hard flat surfaces as a reference point when describing those conditions?

    I don't think we evolved for life on a hard flat surface.
    Thats why I liked the previous post. DrLCT2 has presented some evidence which suggests strongly that in fact this is the case. If you want to approach this from fossil evidence, I've given the two specimens to look at.
    The casts are in the Anthropology Dept at the Uni of Durham, near to where you are I think.

  33. Ian Linane

    Ian Linane Well-Known Member


    If we take the view that a varus foot is a norm and that forefoot supinatus in its various levels (within reason) is a variation of normal, that must react to a uniformly flat and uniformly hard surface, then do we have to reconsider the issue of what we call over pronation.

    Perhaps what we call over pronation is simply the normal, increased range of movement of a varied foot to the above surface.

    Because this surface is generally continuous this normal potential for increased rom becomes a consistent action where as, on a surface with slight undulation where each step has a different demand for foot conformity, there may be moments of increased and decreased rom at the STJ at any given step or series of steps. ( Let alone considering the ability of the 1st and 5th rays to adapt independently of each other and the other rays).

    When you think about how capable the foot is for conformity then you cannot seriously consider that it was suited to walk always on a uniformly flat and uniformly hard surface.

    Is there really any time when our foot ever functions in its capacity to be a mobile on our modern surface?

    It would seem that in shaping our environment we have made it suitable for wheels and furniture to sit on but possibly hostile to a multi-adapting foot.

    I have often tried to observe how it feels to walk on undulating surfaces - such as grass. One thing that, and it might be my peculiarity, I have noticed is that because the 1st and 5th rays may often be in very different levels on that surface, the platform for propulsion becomes mets and toes 2-4. This seems to make some sense to me.

  34. DrLCT2

    DrLCT2 Member

    Tax's Book

    Hi Peter,

    I gave the Herman Tax book I had, "Podopediatrics" to my son, Ross, when he was a student at the California College. Ross is now a 2nd year Podiatric Surgical Resident at Kaiser San Francisco. I'll ask Ross to check the date it was published; however, I'm sure it's an old edition as I inherited the book from my Uncle, James Brown -a Chiropodist, who died in 1961 when I was a junior in high school, but who inspired me to go into the profession when he was alive. Now I've dated myself! :)

    It's interesting how some of the old stuff is still pretty useful in this day-and-age!
  35. DrLCT2

    DrLCT2 Member

    Right On, DavidH

    Hi David,

    Right On! ! !

    Which forums have you presented your ideas at? Audiences of mine haven't been all that receptive to the idea. I think it's so simple that it flys in the face of intellectualization which is a pretty good pastime for some; and, in itself, an avoidance of sorts. :)

  36. DrLCT2

    DrLCT2 Member

  37. While the feet of the human population today ambulates more on hard and flat surfaces than it ever has, and while I readily acknowledge that many of the pathologies that we treat are due to individuals walking on these surfaces, I don't think that it serves us much as a profession to solely focus on this idea alone.

    Foot pathology is multifactorial, and is not just due to individuals walking on hard, flat surfaces. Factors such as body weight, type and intensity of physical activity, shoewear preferences, and mechanical characteristics of the structural components foot and lower extremity are just a few of the significant influences that affect foot pathology in humans. There are millions of individuals that develop no pathology when walking on hard and flat surfaces throughout their lives and there are plenty of individuals who have never walked on flat surfaces that have foot pathology. In addition, there are many individuals who suffer serious injuries to their feet and/or lower extremities when they walk on irregularities in the ground and, for example, sprain their ankles or fall.

    Therefore, to suggest that most of the ills of feet in today's society is due to ambulating predominantly on hard, flat and unyielding surfaces, is purely speculative, quite misleading and does not paint an adequate picture of the multifactorial causation of pathology in the human foot.
  38. Ian Linane

    Ian Linane Well-Known Member

    Hi Kevin

    I agree that there can be no doubt that many multifactorial influences contribute to pathology and I'm not aware of either myself or David H suggesting differently. Our contention has been that the definition of normal so frequently assumed is as per Root yet the evidence of this is virtually negligable so why base a whole science on it and all that follows. Considering that the root type foot view is virtually negliable yet so readily assumed - could this not be the epitomy of speculation disguised as science?

    Further to our contention is the view that a varus foot type could generally be considered more of a norm (with exceptions). It is the relation of this more natural foot type to the unnatural surface on which it ambulates that excacerbates (is that spelt right?!) the various forces.

    In addition we contend that it is time to recognise and admit that the role of podiatric measurements in relation to this is generally an inaccurate and unnecessary process in assessment.

    If you take this view of the foot then biomechanics can become a much simpler clinical skill, more readily and easily applied.

    Essentially working with the foot (however it presents, it is normal to that person) to balance it in relation to the unnatural surface.

    All very briefly put Im afraid.

  39. Cameron

    Cameron Well-Known Member


    It is interesting to follow the theme and particularly where it appears hard flat surfaces have been cited as the reason for increased incidence of foot problems. By implication there should be a close association between foot morbidity and the introduction of sidewalks. These of course are a comparatively new concept and would have followed the horse and horseless carriage. Commuting to work in urban areas within the 20th century relies less on perambulation than this oversimplification of causation would imply.

    Something, which has been overlooked, involves the foot types of Romans living in Britain two thousand years ago. It appears from sandal analysis, Romans had wearmarks consistent with contemporary foot types. The human foot has not changed in 2000 years.

    Permambution is an interesting phenomenon it itself and crazes for walking can be traced back to Victorian times. Often these were extreme events such as hiking and distance walking. Two aspects have been well documented, being able to walk faster than a chaperone meant many courting couples could enjoy relative privacy and 'Muscular Christianity, meant extreme sport was seen as a wholesome activity. This was especially encouraged by companies eager to supply their products, which were often advertised falsely as being efficacious. The Bunion Derby was and still is a major event with a walk across America. In the beginning this was sponsored by the Scholl Company and every effort was taken to advertise their products in local papers and civic events in the towns the competitors passed through. This might infer people had sore feet, or need for foot care but equally it may just have been a marketing ploy to create the impression foot comfort could be improved. During the thirties between the Great Depression and the beginning of the Second World War, marathon events of all types overtook the Western World as Physical Culture caught on and again many of these were heavily sponsored by footwear and corn care industries.

    It may be if there is now an epidemic in foot morbidity it is more likely because we live longer, do less physical activity and have unhealthy diets as opposed to walking on hard surfaces. Life always has its irony and those who indulge in extreme sport may be unaware shoes (and foot othses) are no real prevention to osteoarthroses.

    What say you?

  40. Peter

    Peter Well-Known Member

    Did Mert Root apply his criteria for mechanical normalcy to the present day surface of hard, flat terrain. If so, surely he was near the mark, given the understanding and knowledge of his day?

    Furthermore, we can alter the forces that the ground applies to the foot, rather than alter the ground.

    I always thought the Romans laid flat ( sorry Cameron, slightly convex) roads to aid vehicles with wheels and less so for ambulating soldiers.

    But what do I know! :confused:

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