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STJ Pronation Not the Common Cause of Foot Problems

Discussion in 'Biomechanics, Sports and Foot orthoses' started by drsha, Mar 23, 2009.

  1. drsha

    drsha Banned

    I can understand your rigid resistance of the word rigid as per your definition.

    As an opposition to flexible, I have used rigid as the word that can be understood.

    Flexible would mean capable of going beyond verticale in FFTing and rigid means that at its end range of supination, the STJ is rigid in that direction and short of verticle.

    If you think in terms of rigidly resisting change or rigidly resisting advice, you may become more comfortable with my use of the word rigid.

    Finally, a moment does not produce motion because the structure that it is effecting is rigidly resisting that force becoming motion.

    I must ask the student or the professor both to compare the use of rigid in foot typing to the gold standard terminology that exists which would be:
    uncompensated rearfoot varus or partially compensated rearfoot varus which makes no sense to many.

    Please visit:
    www.podiatry-arena.com/podiatry-forum/showthread.php?t=28059 to get a sense of what I am saying.

    Dennis
     
  2. No my definition Dennis, THE definition. One cannot use a word and create ones own private definition for what it means.

    I do, however, understand what you mean now. There is an existing term for this in standard terminology. The name for something which moves to a smaller degree than expected and then is "rigidly resisted" would be "limited".

    Thanks for the clarification. One of the challenges in considering your work has always been that you use pre-existing terminology but create your own definitions. Its a profound obstacle. One of your other recent threads has so many of these that it is well nigh impossible to decipher what you're trying to say. Thats one reason most people don't bother.

    Anyway, I'm going to eat my car. Well, its the meal at the end of the day, you might call it dinner, but in the Isaacs household terminology we call it car. Its doormouse and cloud tonight!
     
  3. blinda

    blinda MVP

    The man has a point.
     
  4. drsha

    drsha Banned

    Robert:
    The problem that I have for changing my rigid types to limited is that the rigid type rigidly resists (or is limited) vertical and the stable foot types rigidly resists (or is limited) going beyond vertical.

    They are all limited.

    So until I find a better word, I must stick with rigid, stable, flexible and flat.

    Dennis
     
  5. efuller

    efuller MVP

    Damn Dennis, I know your system better than you do. Rigid was the word chosen (unfortunate choice) for when PERM is inverted relative to the leg in a non weight bearing measurement. That is the definition when using functional foot typing. The problem with this is that PERM ignores the effect of tibial varum. This concept was known and described by Root et al as a partially compensated rearfoot varus. I really don't see how calling it rigid is more clear and understandable.

    Also the reference to vertical makes no sense in terms of PERM because PERM is a non weight bearing measurement which may or may not be vertical. Now if you stand the person up and decide that you need to care about vertical then you need to add this concept to functional foot typing. But then it would just be a re-wording of Root paradigm. Then you could claim an improvement over Root et al for focusing on PERM rather than neutral. However, you can't claim that improvement until you do.

    Rigid stable and flexible are not good terms for description of the PERM position, because those terms don't describe a positional relationship. PERM classification is based on position.


    Eric
     
  6. drsha

    drsha Banned

    Yawn.

    Dennis
     
  7. David Smith

    David Smith Well-Known Member

    Dennis, Shall we hang our heads? Robert has such tolerant endurance that he shames us by example, shall we reciprocate and repay his forbearance with sensible well thought answers?

    Rigidly resisting does not describe or define anything unless it comes with your codicil. E.G. Well no e.g. Robert's already done the E.G.

    Is it rigid to GRF?
    Is it rigid to manually applied force?
    What force is it rigid to?
    How does the term describe the quality of the motion before it becomes rigid?
    So, in terms of the above and the orthotic design does it matter if the motion is compliant or stiff to the applied force before it becomes rigid?
    Does it matter which tissue is rigidly resisting the force applied?
    Does the term rigid imply anything other that stiffness to a certain applied force?
    Does rigidly resisting mean rigid at any position from max inversion to vertical?
    Vertical to what?
    How do you consider rigid at max inversion relative to rigid at 0.5dgs before vertical?
    Do they both/all get the same orthotic prescription? one might assume they do since there is only one foot type definition i.e. 'rigid rearfoot' to relate to a prescription parameter.

    The thing is that you need to answer all of these questions before 'rigid rearfoot' can mean anything useful to anyone you wish to communicate with.

    Therefore these terms are not useful for defining foot pathology or posture or to relate to an orthotic prescription or to communicate any of the above to a third party.

    Dave
     
  8. Attached is an image of a load/ deformation curve. Lets say the deformation in question is rearfoot pronation against an applied load. At what point is the rearfoot "rigid"?
     

    Attached Files:

  9. Here is another visual to help understand what Dave is talking about. This time its taken from Maitland and he is discussing the various gradings of mobilisations and manipulations. Note how the position the joint is taken into is dependent upon the force being applied, with manipulations taking the joint into a further range than the mobilisations (because the force applied by the manipulation is greater than the force applied in performing the mobilisation).

    Lets say we have 5 clinicians: clinician 1 (grade 1 on the image) is not very strong; clinician 2 (grade 2) is a bit stronger; clinician 3 (grade 3) is a bit stronger still; clinician 4 (grade 4) is even stronger still; clinician 5 is the strongest of all.

    If we asked these multiple clinicians (all of whom have different strengths in their hands and arms) to use their hands and arms to manually place the rearfoot into its end range of pronation position, then the end of range pronation position each achieved would be different depending on how much force they could apply to the rearfoot; the strongest (clinician 5 (grade 5)) would pronate the foot the most, then the next strongest (clinician 4), through to the weakest (clinician 1) who'd pronate the foot the least. Each clinician might say that when they applied the maximum force they were capable of producing the rearfoot was at its end of range of motion or erroneously say that the rearfoot was "rigid" at this position, but this position would vary across the individuals because they are all applying different amounts of force. This is why even with classification techniques like those promoted by Dennis there will be inter-observer reliability issues.

    Even with our strongest clinician (grade 5), when she takes the rearfoot to what she believes is it's end of range of motion, the rearfoot isn't "rigid", since if she could apply more force the rearfoot would displace further, it's just that she can't apply enough force to achieve this with her hands and arms. If she hit it with a hammer, it would displace further. And if she applied enough force she would rupture the restraining tissues and the joint would displace further with even minimal force. The joint is never "locked" nor "rigid". See the load/deformation curve I posted previously.
     

    Attached Files:

  10. BTW, you could use a hand-held dynamometer to standardise the loading applied by the clinicians, but this doesn't resolve all of the issues of reliability associated with the examination process Dennis advocates.
     
  11. drsha

    drsha Banned

    Simon:
    Once again, you (and Robert) are my Ph.D./Podiatrist professors.
    :good:

    Why can't we eliminate the banter that lives in between what we have to offer the science we all share passion for?

    In the strictest sense, Robert is correct in that the foot type for the foot that has an EROM of pronation that resists going to vertical should be called Limited.
    But then, the foot type that has an EROM of pronation that resists going beyond vertical would also be called Limited, confusing the student or the practitioners who choose to use the method.

    I chose "positions" instead of "degrees" in order to reduce the error rate inherent in The Rootian System where he chose to report degrees for STJ Neutral.

    Remember, at EROM, moments are driven into the equation and so, in your example of multiple practitioners, all would type the subject Rigid in that vertical was not reached by any of their everting forces, weak to strong.
    There is a bell curve of rigid types going from lets say 15 degrees away from vertical to one iota away from vertical (David's mention) but they would all be typed rigid and maybe one more than the other, the rules of treating the rigid rearfoot type would apply as a baseline for practitioners.

    It would then be up to each clinician to decide the level of customization to be applied within the rigid range making the treatment custom and not turnkey eventually developing an EBP of biomechanical care that rises above the current standards.

    The SERM Position of the rearfoot, an open chain measurement, relates to the closed chain position that the STJ will assume entering midstance and any additional positional change to that position must be coming from the plantar heel pad, the ankle joint, the midtarsal joint or some other influence exterrnal to the STJ. This defines locations and planes of treatment better than the current standards.

    Tibia varum is reflected in the transverse plane axis of the ankle and the osseous morphology of the mortise presents as a bony block that defines the SERM position as lets say 14 degrees inverted in one subject and lets say one degree inverted in another. Although they are both rigid types, the 14 degree will reflect a more classical set of characteristics for the rigid type and need more aggressive customization that the one degree rigid type which will reflect many of the characteristics of the stable type and require less customization. This is where FFTing takes tibia varum into account.
    Decisions on shell design, ORF's, MERF's, etc will be made by the practitioner foot typer.

    The beauty of the system is that all five of your evaluators come up with a rigid rearfoot functional foot type that gives closed chain information and an eventual intrapersonal sense of levels of care needed to apply, lets say tissue stress treatment to every patient typed rigid rearfoot FFT. Yet they all start with the same interpersonal diagnosis of Rigid RF FTT (more often than STJ Neutral, I hypothesize).

    So, with your collective help, I will re-define The Rigid Rearfoot Functional Foot Type as the rearfoot type that has a SERM Position that is Inverted from vertical and a SERM position that is limited in that it rigidly resists vertical in the PERM position.

    Please compare that to uncompensated rearfoot varus and partially compensated rearfoot varus (which by the way doesn't have one google response) of the current technology and for the sake of educating the masses, is IMHO, much more understandable.

    Finally, and this is why I was so upset with Craig delivering a STJ Axis position that was medially placed in his demonstration when clinically, it was clear to me that the rearfoot of his subject would FFT rigid is that if the SERM position of a STJ is rigid, the STJ Axis would characteristically be laterally deviated, if it was typed stable, the axis would tend to be in equilibrium and if it is Flexible, the axis would tend to be medially deviated.
    Once I began foot typing, it eliminated my need to measure the STJ Axis (which I never got the hang of doing any better than STJ Neutralling) as it was lacking in the tools and interpersonal reliability to generate valuable clinical information and generate valid and applicable evidence (i.e. the new Kirby STJ Axis article).

    I submit that FFTing is a better starting platform than our Rootian roots and better than Craig's demonstration where he was forced to become an actor and possibly most important, it does not have to be proceeded by a complaint.
    It can be used as a screening method, a predictor of future pathology or a baseline from which to apply, orthotic, muscle engine, surgical and non surgical or tissue stress treatment plans, monitor them and research them.

    Dennis
     
  12. David Smith

    David Smith Well-Known Member

    All the best Dave Smith
     
  13. Dave Smith. Like a boss

    I cannot add depth or scope to this well researched and intelligent answer. I could, however, have a stab a summarizing.

    This whole debate boils down to:-

    For me all of the foot typing systems, Scherer's, Shavelson's, the rootian concepts of forefoot / rearfoot valgus / varus, quadrastep, SNA, right down to the crudest of all, "flat feet" have the same appeal and the same flaw.

    The appeal is that they are all simple and as David eruditely points out, appeal to the unsophisitcated. They all give the appearance of quantifiable and measureable science to what is actually a very crude and generalised observation.

    The flaw is that where they all claim to be a reality, they actually only represent a reality. They all carry the assumption that what they represent (a foot type) is what is (a pathology or problem). And indeed that while all very quick to throw stones at the reliability and validity of everyone elses measurements, that THEIRS are valid. And theirs alone.

    Thus, the argument as to whether fft is a better system than root is sort of moot. Leave alone that there is not enough evidence either way, they're still both simply trying to represent a reality which in truth DOES NOT NEED TO BE SIMPLIFIED, because it is already simple.

    Find out which structure is bust. Find out what that structure does. Give an orthotic that will exert external force to reduce the demand for what that structure does. Is that not simple enough? Why do we need to come up with convoluted systems for working out which morphological variables predispose to which bust structures and treat the morphological variations in the hope that we have correctly predicted the internal bustness and the type of device which will reduce the stress in it? I just don't see the need. Why introduce the extra step?

    The problem, for me, is communicating to the unsophisticated that they don't NEED to simplify something which is already so simple.
     
  14. LuckyLisfranc

    LuckyLisfranc Well-Known Member

    F*ck me. There IS a second coming and his name is Robert.

    I have been dying for someone to say this for the last 10 years of reading these pointless, circular diatribes on orthotics.

    Admin, please copy this to the home page and put it in big bold font for eternity.

    Game over. Can we move on now?

    LL

    (PS. I think they invented a thing called basic orthopaedics a little while back which also encapsulates this outrageous concept)
     
  15. drsha

    drsha Banned



    Your personal suggestions and rigor and $10 would buy me a roll of quarters.

    Dennis
     
  16. You miss the point. What if "vertical" was the position within the joint range I have indicated on the image below?
     

    Attached Files:

  17. No they won't. See above. Clinicians 1 (grade1) and 2 (grade 2) would classify the rearfoot as "rigid" because they don't apply enough force with their manual examination to take the rearfoot to "vertical" whereas clinicians 3-5 (grade 3-5) would classify the rearfoot as something else because they do take the rearfoot beyond "vertical" during their manual examination by applying more force. Dave's assessment of 100% accuracy with qualitative grading was incorrect. There is still inter-obsever error in qualitative labelling hence we see poor inter observer-reliability when 3 clinicians attempted to qualitatively label STJ axial position as reported here: http://www.japmaonline.org/content/102/2/122.abstract.
     
  18. Jeff Root

    Jeff Root Well-Known Member

    Biomechanics is not just about orthoses. There have to be some structural norms in foot surgery on which to base surgical procedures. And ideally orthotic therapy should have a preventative component to it. So if the "if it ain’t broke, don't fix it" approach is the new gold standard, the price of gold just crashed! Sorry but it isn't point, set, match and I don’t hear the fat lady singing!

    Jeff
     
  19. Norms are hard to find. Abnorms are a bit easier. ...
     
  20. Moreover, normal is a variable both within and between subjects. :morning:
     
  21. Here's where one of the other problems of inter-observer reliability and qualitative variables comes into play:

    Lets say we built a jig that could accurately place the rearfoot into any position. Lets say we set it up so a rearfoot is positioned 15 degrees inverted. We then ask a 100 clinicians if the rearfoot is inverted, vertical or everted. I'm guessing most should recognise that the rearfoot is inverted.

    Now we'll set the jig so the rearfoot is one degree everted from vertical. Lets take a hundred clinicians who don't know the position of the rearfoot (and can't guess by looking at the jig design) and ask them to decide whether the rearfoot is inverted, vertical or everted. There will undoubtedly be some who say it is inverted, some who say it is vertical and some who say it is everted. Some would "type the foot as rigid" and "apply the rules of treating the rigid rearfoot type" yet this would be erroneous.

    When we have categories, the areas around their borders become difficult to distinguish. It's pretty easy when it's 15 degrees from vertical; less so when it's only "one iota" from vertical. I said this several years ago. BTW, the above is a basic methodology for one of the studies you need to do, Dennis. Place a foot one degree inverted and see how many people say its inverted, how many say its vertical and how many say its everted...

    Further, lets say we have a subject that someone tests and finds the rearfoot "one iota" from the vertical and thus classifies it as a "rigid rearfoot type" and sets to treat it accordingly with the "rigid rearfoot type orthotic design" (whatever that is), when the patient comes back to pick up their devices the clinician decides to re-test the rearfoot but this time finds the rearfoot to be "two iotas" everted- should they scrap their original orthotics and start again due to within-subject between day variance in the assessment results? And there will be between-day variance even in the same subject.
     
  22. Jeff Root

    Jeff Root Well-Known Member

    But if you have a congenital, long and elevated 1st met and you decide to treat it surgically, you would need to know how much to shorten it and if and how much to plantarflex it. If you shorten the 1st met and leave it elevated, the patient is likely to get a transfer lesion sub 2nd that might be worse than the original chief complaint (i.e. bunion pain and or deformity). My point is, biomechanics needs to be utilized in both surgery and orthotic therapy. The interrelationship between structure and function is obvious and in osseous surgery you alter the structure and influence function. Hence you need to know how you should alter structure to produce the desired functional result. And if you have a poor surgical outcome, you can get your ass sued if your surgery isn’t biomechanically sound.

    Jeff
     
  23. But the reality is, they don't know; they make an educated guess. That's why sometimes it works and sometimes it doesn't. A good surgeon guesses rightish more times than they guess wrongish. But it's not a hard science, it's still guessing and every patient is a case study, n=1. Same with foot orthoses. The difference is with foot orthoses it's pretty easy to remove or add a little extra posting...

    BTW, I don't like the idea of "preventative orthotics" too much. It's a bit like giving people spectacles just in case their eyes get bad. If and when they do get problems, I'll design orthotics with what I believe are the correct design parameters to treat their condition; in the absence of strong predictors of pathologies it's hard to pre-empt. Would you randomly pick up any pair of spectacles from the optician and wear them just in guess you become long-sited?
     
  24. David Smith

    David Smith Well-Known Member

    Dennis

    I knew I shouldn't try reasonable argument with you its just a waste of time, you never answer a question directly or truthfully or straightforwardly or with any integrity. All you do is take a small piece of a sentence, quote it out of context and turn its meaning around to something that massages your ego and you imagine makes you look clever but Dennis I am afraid to inform you that you do, and could only ever, appear clever to a witless audience.

    All your answers are derisory even risible but especially your triumph and pleasure in extracting praise from my explanation that your system can only be 100% accurate with no error is proof indeed, if proof be needed, of that very fact and also indicates to any sensible reader that you are all the things that you need your target audience to be in order to be taken in by and believe such clownish and preposterous discourse.

    Dave Smith
     
  25. Jeff Root

    Jeff Root Well-Known Member

    No, but if I saw a child with gross pronation and a family history of **** for feet, I think it might be wise to treat the juvenile asymptomatic foot in spite of the lack of present symptoms. It is certainly easier to decide to treat in the more extreme cases. I certainly don’t advocate the use of orthoses unless there is reasonable justification.

    Jeff
     
  26. Jeff, I missed this first time around. First we need to show that a congenital, long and elevated 1st met causes pain and dysfunction before we start hacking pieces off of it to make it shorter- right? Just like we need to show that a foot that doesn't stand with a bisection of the heel that is vertical results in pain and dysfunction before we start making orthosis to try to hold the heel vertical during standing- right?
     
  27. Jeff Root

    Jeff Root Well-Known Member

    Interesting comment from a letter on PM News yesterday with respect to scope of practice. "In Israel, the DPM is recognized by the Ministry of Health by law but the Europeans here practice non-surgically and also call themselves podiatrists. It is disconcerting, to say the least, when a non-medically trained professional who cannot write a prescription advertises that he treats diabetic foot problems. Or, when the non-surgically trained European advertises that he is a podiatrist who treats bunions". full letter at: http://www.podiatrym.com/letters2.cfm?id=54098&start=1

    What I find so interesting is that where podiatry is a non-surgical specialty, there seems to be more of an interest in biomechanics.

    Jeff
     
  28. Your presumption being that family history predicts foot problems. Now we're on to my PhD subject- cool. I haven't really thought too much about this since '97. So, lets take two parents one has a positive family history of say "sh!t foot", while the other parent has a negative family history of "sh!t foot". What is the probability that the offspring will have "sh!t foot"?

    P.S. My father in-law has glaucoma and puts about 8 million different drops in his eyes daily. Glaucoma has a familial link. Should I have my daughter start putting the drops in her eyes now, aged 7?
     
  29. If I made a system in which a prescription was made based on the car a patient drives, the system would be 100% accurate. That would not make it a good system...

    Thats the point here. If you're going to base a prescription system on measurements or ranges those measurements / ranges have to be reliable, repeatable etc. Having a system which may have that repeatability is only useful if the repeated result leads to a prescription with a repeatedly better outcome. If one cannot produce evidence that it does, one has to be able to make a jolly good argument for why it should.

    Here we all agree!

    Jeff, I think we all agree that sometimes it is advisable to treat in the absence of symptoms. The question is how we set our "threshold of significance" for what patterns we consider likely enough to cause symptoms to justify treatment. Its how strong the strong predictors Simon mentioned were. Some people are a little too hair trigger for my liking, others too reserved. I suspect thats true of you and Simon both.
     
  30. If all you got is hammer (Birmingham screwdriver) , everything looks like a nail.
     
  31. Indeed, and what one needs to show is that a positive family history is a better predictor of the pathology than is age, gender, etc... amongst others.
     
  32. Jeff Root

    Jeff Root Well-Known Member

    There is no right or wrong answer when it comes to treating feet in this example. As for glaucoma, I don't know the potential side effects of the treatment. As for orthoses, they are a class one medical device in the U.S. and as such, are considered relatively safe. First do no harm, so given the relative safe nature of orthoses, I believe we can be more comfortable treating even if the odds of the child having sh!t for feet is not as high as we might like. I would examine the child and if they demonstrate characteristics of the parent with sh!t for feet (i.e. MTJ hypermobility or generalized ligamentous laxity, a congenital long 1st met, or some other characteristic associated with the parents symptoms/condition) then I would use that information in making the decision.

    Jeff
     
  33. But it doesn't mean orthoses can't create problems that didn't previously exist, and it doesn't mean that the child will get **** feet- right Jeff?

    We're on the same page Jeff, but there are other fish to fry here. Nice to have you contributing again, BTW.
     
  34. Jeff Root

    Jeff Root Well-Known Member

    So using tissue stress, how do you know when your orthoses will create other problems? If you take the stress off one component, how do you know it won't cause stress to another component?

    Jeff
     
  35. You don't; you use educated guesses to hope that they won't. To paraphrase what I said before: a good orthotic prescribing podiatrist guesses rightish more times than they guess wrongish. But it's not a hard science, it's still guessing and every patient is a case study, n=1. End of Story. Anyone who says otherwise is a liar. But a sound knowledge of Newtonian mechanics probably helps.

    Ask me about prescribing orthoses using a Root protocol Jeff...
     
  36. Not true. Of those who say otherwise, some are liars, the rest are mistaken.

    There is a difference.
     
  37. K, yet all are naive but happy.
     
  38. drsha

    drsha Banned

    So your practice a la Sackett n=1.

    You use educated guesses.

    You guess rightish more than wrongish.

    Bit its not hard science? It's not? I thought you had all that evidence and drawings and the subtalar joint axis and tissue stress ans N=1 for you?

    and

    A sound knowledge of Newtonian mechanics probably helps?

    Not very convincing or as powerful as you preach to me?

    I'm confised.

    let's change the topic here.

    I thught that someone would have by now:

    Dennis
     
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