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"Biomechanics Corner": Overpronation

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Robertisaacs, Oct 26, 2009.


  1. Members do not see these Ads. Sign Up.
    I am Grateful to the SCP and the "Podiatry Now" team for permission to reproduce this months "Biomechanics Corner" Column on Podiatry Arena.

    I'd hoped this months column would provoke a debate. I've had three emails regarding it already and I've not even had my copy yet (damn postal strike:mad:)

    This is the column as I submitted it.

     
  2. Ella Hurrell

    Ella Hurrell Active Member

    Re: Biomechanics Corner - Overpronation

    Robert

    Just wanted to say thank you for putting so eloquently what I have been banging on about for ages and can't get half my colleague to understand and move away from!:bang: I intend to ensure that as many pods, physios etc etc as I can find read, digest and NEVER again send me a referral with "overpronation" written as a diagnosis :pigs:- a thing most likely to see me turn an interesting shade of purple and start shouting at the piece of paper!:mad:

    Thank you - and I hope you haven't been bombarded with emails from those that haven't yet seen the light! :drinks
     
  3. Re: Biomechanics Corner - Overpronation

    Good luck with that! If you find a way PLEASE let me know how you did it!

    Its been very gratifying, 7 so far! Some in support, some thoughtful and some very anti!

    I consider all of them to be positive, because whether or not you happen to agree with my individual opinion (which is all it is) it means that 7 people have thought about their practice in sufficient depth to put pen to paper (or fingers to keyboard.

    Some of them make some excellent points. When I get time I'll post a few and answer them here. And if you are one of the stalwart reflective clinicians who wrote to me, bless your heart. I will get back to you if I've not already done so!

    Thanks
     
  4. Re: Biomechanics Corner - Overpronation

    Will these be published in the journal?
     
  5. Rich

    Rich Member

    Re: Biomechanics Corner - Overpronation

    Many years ago I was slightly offended when at a function I spoke at ,an orthopod asked if all Podiatrists belonged to the "save the pronated foot brigade'. Over -pronation against what given norm in relation to each individual. Do we keep looking for what we want to see (ie position over function) as it is easier to sell the concept to the patient or harder for some practitioners to understand the complexities that produce the forces that the foot/leg sustain during use and activity.
     
  6. Griff

    Griff Administrator

    Re: Biomechanics Corner - Overpronation

    Rich,

    What did said Orthopod quote as the 'given norm for each individual'?

    Ian
     
  7. Rich

    Rich Member

    Re: Biomechanics Corner - Overpronation

    the year was 1988 I was younger and details apart from what then was a perceived slur are foggy. His general gist was what is normal and why was pronation the root of all evils for lower limb pathology. Valid line actually and got me interested in other modalaties of treatment options
     
  8. Re: Biomechanics Corner - Overpronation

    a quite day feel like playing devils lawyer

    I´m not sure why this makes you froth etc While I get your point that Over is not the best word But if we take excessive or even too much which to me mean about the same thing. These can all be considered a bad thing especially when considering SALRE. Yes I agree that Pronation is normal and very important and that there is no such thing as the normal amount of pronation.

    But I think we tend to forget that the movement of Pronation will mean that the STJ axis medially deviates. Ie at the Talus adducts and plantarflexes during CKC this change in talus position will cause the STJ to medially deviate. ( A STJ internal pronation moment )

    Here a quote from Kevins paper.

    Subtalar Joint Axis Location and Rotational Equilibrium Theory of Foot Function
    Kevin A. Kirby, DPM, MS* J Am Podiatr Med Assoc 91(9): 465-487, 2001

    Right so as the STJ pronates there will be medial deviation of the axis. Which will mean that the external factors ligaments medial to the stj axis , muscles medial to the stj axis , GRFmedial to the stj axis , bone medial to the stj axis etc will all undergo increased force. The soft tissue will then require increase force to resupinate the foot.

    Both the medial deviation and the attempt to resupinate ( lateral deviate the axis ) can lead to pathological complaints.

    Too much STJ pronation increased medial deiviation of STF axis more force applied during STJ pronation more force required during STJ resupination more pathological complains.

    Right I think I´m about to become a punching bag but here my statement Overpronation is a diagnosis as long at the person writing the statment understands what the cause to STJ pronation will be on the STJ axis location.
     
  9. Re: Biomechanics Corner - Overpronation

    Only if people write to the journal, which I would encourage anyone to do!

    Bless yew kind sir!:drinks. I'd hoped somebody would!

    I'm between patients (damn them:mad:) so i'll kick off with a quick one.


    What is the defining characteristic of "too much"? Is a matter of degrees or whether the foot has a pathology.

    Given that part of the point of notes is for the benefit of other professionals, if overpronation is a dx if the writer understands that it will cause a functional deviation of the axis, would it not be more accurate to write "functional deviation of the Sub talar axis"?

    Regards
     
  10. Griff

    Griff Administrator

    Re: Biomechanics Corner - Overpronation

    Hi Michael,

    I would have to disagree with this. In my opinion overpronation is not a diagnosis and should never be written (or spoken) as such. Even if it is terminology that a clinician is using and/or writing down - at best it can be described as an 'observation' rather than a diagnosis.

    Oxford Dictionary definition of diagnosis:

    Ian
     
  11. Re: Biomechanics Corner - Overpronation

    1 too much pronation = pain, familar history of problems tripping history

    2 To come back to with a question. How do you know the STJ axis is deviated ? How do you know that the deviation is the cause of the problems ? How do you measure the flow on effect of this deviation ? in Newton´s ?
     
  12. Ella Hurrell

    Ella Hurrell Active Member

    Re: Biomechanics Corner - Overpronation

    Yes, but that's the point - it can but doesn't necessarily.

    Yes, or maybe pathological deviation of the sub talar axis - but can't quite see that being confidently written on any referral :pigs:

    I have to agree - :bang:
     
    Last edited: Oct 29, 2009
  13. Re: Biomechanics Corner - Overpronation

    Therefore so is medially deviated axis an observation. Say we take PTTD Diagnosis, the casue we might write medial deviated STJ axis or STJ pronation or whatever it is still just an observation.


    I´m just playing the devil
     
  14. Griff

    Griff Administrator

    Re: Biomechanics Corner - Overpronation

    No. Think causation.

    As above - how do you know 'overpronation' is the cause of the problems (pain)?
     
  15. Griff

    Griff Administrator

    Re: Biomechanics Corner - Overpronation

    I agree - medially deviated STJ axis/STJ pronation moments are just observations also, and in your example the diagnosis is PTTD.

    What you said was that 'overpronation' was a diagnosis. It's not.
     
  16. Re: Biomechanics Corner - Overpronation

     
  17. Re: Biomechanics Corner - Overpronation

    If we agree then Robert and Ella would be wrong for writing functional deviation of the Sub talar axis an so would many people who think in the new school way of biomechanics and therefore when Robert sees ´medially deviated STJ axis ´on a form he should get just as red hulk like. ( But I guess he might smile if he read that)
     
  18. Ella Hurrell

    Ella Hurrell Active Member

    Re: Biomechanics Corner - Overpronation

    Fair point - I actually agree too - Diagnosis would be whatever condition it's leading to (PTTD to use your example).... although I did actually suggest pathological deviation, I concede that this is also an observation not diagnosis.:wacko:
     
  19. Re: Biomechanics Corner - Overpronation

    Alright then say that the head of the NHS Forms section is reading this Thread.

    They think we should have a cause or under lying pathology section on the form for referrals to Podiatrists.

    Standard name etc blah blah

    Diagnosis PTTD Cause excessive pronation/ overpronation

    How red Hulk are you guys now ?
     
  20. Re: Biomechanics Corner - Overpronation

    Nope. Never said that that should be the diagnosis;). I said that if you are writing overpronation on the basis that it causes a deviation of the axis, and that it is the deviation which causes the pathological forces, that you should write what you mean.

    I'd be puce if I didn't know that you were playing devils advocate. :rolleyes:

    To come back to what you said earlier (how fast is this thread moving?!)

    This is what I alluded to in the article because this is where the definition of overpronation becomes tautological and I think this tautology creates a fallacious logic loop which has misinformed a generation of biomechanics.

    We agree that we cannot define a threshold for a normal amount of pronation. So you define overpronation by enough pronation to cause pain.

    Its a given that most people in RSCP will be pronated more than neutral.

    Its a given that most people who come to see a podiatrist for a biomech assessment have pain.

    Therefore, we have pain, and we have pronation in most patients we see. So the diagnosis of overpronation becomes inevitable for any patients who are not pathologically supinated, simply because they have pain and pronation to some degree. :wacko:
    ======================================================
    To answer a point which came up in a few emails.

    We all see patients who come in with their nav's resting on the ground, their knees facing each etc etc. That is often pathological for assorted reasons including the axial position. Is this not "overpronated"?

    Well, kind of, however, is it good practice to refer to these as "overpronated"? When another clinician reads your notes how do they know that the feet were pes pancakeus as opposed to pronated a few degrees from neutral... but causing pain (as per the definition above).

    Does "overpronation" tell us that the rscp is thus, or does it reflect gait? Does it tell us the supination resistance? Whether the person is hypotonic or has ligamentous laxity; or both, or neither? Does it tell us if the deltoid ligament complex has been stretched? Does it tell us which structure is limiting the pronatory range, and when? Does it tell us the position of the foot at heel strike, mid stance or toe off? Does it tell us that the axis is functionally deviated because of the position of the joint within its range at a certain point or whether the whole bundle is deviated? Does it refer to the overall range or the amount of it which is used?

    It tells us nothing, save that there is A: pain and B: some unspecified degree of pronation beyond neutral. Which most patients have.

    Lets get down to cases and take two patients.

    One is a 6 year old with downs syndrome. They are hypotonic, have gross ligamentous laxity and excessive available range in the STJ and TC joints. When they stand their arch dissappears completely and the lateral side of their foot actually lifts from the ground.

    They, by conventional definition, are "overpronating".

    The other is 67 years old and has just had bunion surgery which stuffed up her windlass mechanism. As such the deltoid ligament has more to do to limit joint motion when they heel lift and has started to be a bit painful. Their feet operate in a range between 2 degrees from neutral and 8 degrees from neutral, even when in RSCP their arch is 13mm from the ground. But they are getting pain associated with pronation.

    They, by conventional definition, are also "overpronating".

    How can a term which covers such radically different pathological functions be even remotely informative or useful in notes?

    Kind regards
     
  21. Griff

    Griff Administrator

    Re: Biomechanics Corner - Overpronation

    Michael all of your posts are confusing me - I know you are playing devils advocate but I am not entirely sure of the point you are making/arguing?

    As for this:

    Rob let it go, but I'll say it again - think causation. How can one state the above confidently on a form? How does one not know that instead of the 'overpronation' causing the PTTD, that infact the PTTD did not cause the 'overpronation'?
     
  22. Re: Biomechanics Corner - Overpronation

    Pronation the movement does not always lead to pain. Pain the the bodies way of explaining that the movement of pronation andor attempting to stop it is too much...... therefore without taking out my goniometer Ive noted that I need to stop pronation for my tx plan because there is overpronation.
     
  23. Re: Biomechanics Corner - Overpronation

    Ian and Robert etc.

    I guess some of what I´m trying to argue is that ... if we can not say overpronation then we can not say medially deviated axis for many of the same reasons.

    I think that this is some of the main issues with people is that they read the 1st lines of the papers written on this stuff and think that what was excessive pronation now become Medially deviated axis and off they go which means that they are in this never never land where is just does not make sense.

    My brain may over heat here it´s very hard to argue for something that you don´t beleive in. I´ll continue but it may get more confusing and when the thread is done a might have to slip in a disclaimer " I don´t beleive what I argued for in this thread "
     
  24. Ella Hurrell

    Ella Hurrell Active Member

    Re: Biomechanics Corner - Overpronation

    No, I disagree, we can say it - so long (and perhaps this is harping on again) as it's recognised that this is also an OBSERVATION that is NOT necessarily a cause. The whole concept of causation is not clearly understood by many, evidently - just look at MMR/Autism, Swine Flu jabs/GBS....

    Exactly - you have just argued yourself around in a circle??!

    So give it up mate. Now. :mad:
     
  25. Re: Biomechanics Corner - Overpronation

    Ok Ella the observation and cause thing is covered we all agree

    I want you picture a classic pes planus foot type in RCSP Navicular close to the ground etc.

    Think 10 years ago you might have discribed in your journal "foot overpronated"

    Now think today what would you write in your Journal
     
  26. Re: Biomechanics Corner - Overpronation

    No DON'T! Whether or not the views expressed are that of the author, they are certainly very commonly held views! Without someone who will voice them, those who are following this thread but reluctant to post should be able to learn something from the exchange!

    Tell you what. Tomorrow I will argue FOR overpronation as a valid assessment observation and you can argue against;).

    Nah. Not buying. Overpronation can cover any of the factors I listed here

    and more.

    Leave alone that its tautological, it just does not give any useful information! Whereas "medially deviated axis" could refer to the position of the bundle of axis, or the position of the axis within the bundle, but it is a pretty open and shut observation. And if I see it in the NWB part of someone elses assessment I know that it refers to the position of the axial shadow with the foot in paralel plantar position.

    Regards
     
  27. Re: Biomechanics Corner - Overpronation

    Allright I see was Ella says later.......

    Medially deviated from what ? What is the normal position of the STJ axis ?

    Overpronated indicates a static position where the calc is everted talus .... etc this will also cause strain on the detoid ligament complex due to the change in position of the talus. calc navicular etc.

    No it does not but writing Medially deviated stj axis will not also.

    We can by using words like overpronated at toe off.
     
  28. Re: Biomechanics Corner - Overpronation

    Robert:

    You have created another beast of a thread....good job!:drinks

    There are many valuable lessons to be learned here in this thread. First of all, we must understand that "pes planus deformity" or "pes plano valgus deformity" or "pes valgus deformity" are acceptable diagnoses and are commonly used. I use them commonly in my charts since my charts need to read by insurance company representatives and non-podiatric health professionals who would not know what a "medially deviated subtalar joint axis" is. However, the term "overpronation" is not a diagnosis and should never be used as a diagnosis.

    One must remember when we speak of the subtalar joint (STJ) there are two very important parameters which are quite distinct from each other, but interrelated. The STJ axis spatial location is the 3D location of the STJ axis relative to the plantar foot (e.g. medially deviated, laterally deviated). On the other hand, the STJ rotational position refers to where the STJ is within its rotational motion (e.g. maximally pronated, neutral position, maximally supinated, 2 degrees from maximally pronated, etc). As the STJ rotates in a pronation direction, the STJ becomes more medially located relative to the plantar foot. As the STJ rotates in a supination direction, the STJ becomes more laterally located relative to the plantar foot.

    Therefore, when we see a child with a significant pes plano valgus deformity, their STJ will be maximally pronated in stance (i.e. STJ rotational position) and their STJ axis will be medially deviated (i.e. STJ spatial location). Both of these STJ parameters should be noted by the clinician since they tell us where the STJ is within its range of motion during stance and where the STJ axis lies in space so that we can make an estimate of which of the structural components within their foot and lower extremity will be subjected to possibly pathological levels of stresses during weightbearing activities.

    However, there are cases, such as in patients with high degrees of rearfoot varus deformity, limited range of STJ motion and metatarsus adductus deformity, where things are not so clear. In these feet during standing, their calcaneus will be inverted but also their STJ will be maximally pronated. These feet, even though not common, may experience supination instability and peroneal tendon pathologies even though they are maximally pronated at the STJ (or as some would say, "overpronated").

    The biomechanical cause for their STJ supination instability and peroneal tendon pathologies are not due to "overpronation" but rather due to their more lateral STJ spatial location since the plantar calcaneus is so medial to the STJ axis (i.e. calcaneus is so inverted) and Achilles tendon insertion is so medial to the STJ axis. In these feet, they are both maximally pronated at the STJ and experience "oversupination" pathologies of supination instability and peroneal tendinopathy. This is why it is so important for the more advanced clinician to fully understand the kinetic effects of STJ axis spatial location and how both the external STJ moments from ground reaction force and internal STJ moments from joint compression and central nervous system controlled muscular activity all interact together to produce both motion and stability at the STJ.
     
  29. Re: Biomechanics Corner - Overpronation

    Fair comment. My assessment form actually has lil pictures of feet upon which I draw the position of the axial shadow when the foot is in parallel plantar. A simple descriptive of "medially deviated axis" is not particularly informative.

    Overpronated is any position where the calc is everted? That means ANY pronation is OVER pronation. It does not tell me anything which does not apply to 90% or more patients.

    Anyway you said earlier that "too much pronation = pain,". Which is it, pronation in the presence of pain or everted calc? And how can it be a meaningful observation if everyone has such radically different ideas of what it means?

    Is that not what the deltoid ligament is there for? What happens to ligaments upon which no strain is placed?


    Nope. Because this patient

    Could be described as overpronated at toe off, as could this one

    And they are nothing alike.

    Mid stance overpronation could cover anything from a stiff arthritic foot with a pronatory range of 6 degree and DCIS through the aforementioned massively hypermobile downs kiddie, and indeed a CP kiddie with a tight Triceps Surae and a massive amount of escape pronation.

    They could all have pain in the presence of pronation.

    They all pronate (overpronate).

    Yet they are radically different problems with radically different causes and require radically different management!

    Regards
     
  30. Re: Biomechanics Corner - Overpronation

    Call me baron Frankenstein. I cobbled it together from bits of many dead threads then stuck a bolt of lightening through it. Hey presto, the monster lurches off toward the village leaving me with a slight concern as to whether I put the knees on the right way around.;)

    Its slightly peripheral, but I thought I'd poke this little gem in from a UK podiatrist website

    So supinators are overpronators too! But in disguise...

    [​IMG]
    Acme Supinator kit

    Cheers
     
  31. Re: Biomechanics Corner - Overpronation

    Sorry put the over in when I should have said just Pronated

    So Overpronation should mean pain.

    In this case Ive never put a degree on it. I even said pronation was required and important.

    So again overpronation pain
    normal pronation no pain.

    The little old lady who has only 6 degrees of pronation to much for her Overproantion.

    Pes planus navicular on the ground type foot no pain not overpronated no pain.

    so to some up pronation is not bad overproantion is because is causes pain.
     
  32. Re: Biomechanics Corner - Overpronation

    I was going to ask Ella this if she gave me the answer I was hoping for but since Kevin has come here Ive got a question.....

    Pes planus foot type Can the stj axis be lateral ?

    I remember Eric saying that he has a Pes planus foot type and when you were doing some experiment using his feet you discovered that he has a Lateral STJ axis. He posted something along that line in the last few months.can find the post.

    I also had a student with this this year. Pes planus in midstance, lateral stj axis low supination resistance test results.

    The reason I bring this up is that it is important that people should not always assume pes planus medial axis 99 % of the time they will be correct but 1% no .
     
  33. Re: Biomechanics Corner - Overpronation

    So a foot which is so far into pronation that it only weightbears on the medial border of the foot, if it causes no pain, is NOT overpronated.

    Brings us back to the tautology does'nt it. Pain + any pronation = overpronation.
     
  34. Ella Hurrell

    Ella Hurrell Active Member

    Re: Biomechanics Corner - Overpronation

    Why would I need to describe it any differently to your description? - pes planus foot type in RCSP with navicular close to the floor. This is a perfectly adequate description of a foot that all readers of said journal would understand. What it doesn't do is encourage (for want of a better term) the "myth" that all pronation is bad. I don't disagree that we need some clearer terms to describe and record this type of foot, that wasn't my issue - it is more that pronation is often demonised by many professionals of many disciplines and I have a hard time explaining to patients that I will not be providing "arch supports" in order to "fix" their pronation.

    Fair point - I apologise for sounding so blunt. I have terrible issues with turning purple and blood pressure rising when discussing this subject. My comment's intention was not to quash debate, but the ranting of a frustrated podiatrist who is unable to express her point particularly eloquantly. Step in Prof Kirby.....

    Bravo - I can only aspire to explain things in such a way, but is pretty much what I meant (with a whole lot of extra!):drinks
     
  35. Re: Biomechanics Corner - Overpronation

    I feel your pain. I get that.

    Perhaps there is not enough blood to your brain due to bad posture. You must be hyperpronating. Proprioceptive insoles will fix that you know. ;)

    Personally I tend to dislike the use of "pes planus" as well. I find that many people fail to distinguish between a hypermobile foot which flattens on the floor, a fixed supinatus, a foot where the forefoot has dorsiflexed and become fixed or a foot where the mid tarsal joint has become hugely arthritic and filled up the gap. But thats a different column ;).

    What IS the definition of pes planus BTW? Does it distinguish between a fixed flat foot (one which is flat in NWB) and a hypermobile flat foot which pancakes under load?

    Cheers
     
  36. Re: Biomechanics Corner - Overpronation

    Yes it does and we have come a cyclone of full circles.

    Overpronation hate it as a term it´s crap and should be not be used in any way in relation to Podiatric biomechanics.

    But we have also discussed well that Medial deviated axis should be used in an appropriate manor.

    I also hope Kevin or Eric will come and explain the lateral deviated stj axis in a pes planus foot type which Eric said he has if my memory is holding up.

    I think this is a good place for me to say good night from him...

    it been fun even if Ella got a bit mad
     
  37. Ella Hurrell

    Ella Hurrell Active Member

    Re: Biomechanics Corner - Overpronation

    I think I like you again now :D

    Even if you are a cheeky so-and-so :drinks
    :craig:
     
  38. Re: Biomechanics Corner - Overpronation

    I have never seen the STJ be lateral at the forefoot in a pes planus deformity but have seen it to be lateral at the rearfoot in a small number of pes planus deformities. In other words, the STJ axis is more adducted than normal in many cases of pes planus deformities, but are medially positioned at the forefoot and laterally positioned at the rearfoot in only a small number of cases.

    Hope this makes sense.
     
  39. cpoc103

    cpoc103 Active Member

    Re: Biomechanics Corner - Overpronation

    Ian having just read this thread, I agree fully, yes over/hyperpronation what ever we call it is not a DX, but yes is the pronation not from PTTD or other structure/s??
    Now I'll play devils advocate Michael you are also correct that hyperpronation will cause a lot of pathology in the foot and possible other structures, but we cannot call that a DX, the DX is whatever structure/ pathology is occuring, as for Ella I dont think we will ever get other Health professions to use any other terminology than what they are used to. Having worked in the NHS alongside physios, orthopods and other health staffs you get to know we all use differing terminology for the same things, but a lot of them just dont know enough about lower limb mechanics!!

    Col.
     
  40. Re: Biomechanics Corner - Overpronation

    hey col.

    What is hyper pronation? ;)

    How are YOU defining it?

    Cheers
     
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