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Tissue Stress Theory: Just a Variation of Root Theory?

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Kevin Kirby, Aug 1, 2015.

  1. Rob Kidd

    Rob Kidd Well-Known Member

    Top of the trench? top of which trench? I may not have spent 50-60 hours a week in front of patients, but I did in front of cadavers.

    When I talk to my students about measurement (it happens in all branches of biology), some of which may best be described as goniometers, we talk about dimensions, ,and the error involved in their procurement. Now most of would employ a biologically recognisable reproducibility study. I have always favoured a two way analysis of variance without replication as it measures biological variation against measurement in a statistically valid manner. For the same reason I do not favour intraclass correlation coefficients - they do not consider the biology - at least to my way of thinking.

    When one is measuring a quantity where the (real) error is greater than that you are trying to measure - which is the case in most podiatric measurements, one needs to go home and think it through. The truth will always be the truth, no matter how you paint it. Rob
     
  2. Rob Kidd

    Rob Kidd Well-Known Member

    Top of the trench? top of which trench? I may not have spent 50-60 hours a week in front of patients, but I did in front of cadavers.

    When I talk to my students about measurement (it happens in all branches of biology), some of which may best be described as goniometers, we talk about dimensions, ,and the error involved in their procurement. Now most of would employ a biologically recognisable reproducibility study. I have always favoured a two way analysis of variance without replication as it measures biological variation against measurement in a statistically valid manner. For the same reason I do not favour intraclass correlation coefficients - they do not consider the biology - at least to my way of thinking.

    When one is measuring a quantity where the (real) error is greater than that you are trying to measure - which is the case in most podiatric measurements, one needs to go home and think it through. The truth will always be the truth, no matter how you paint it. Rob
     
  3. Rob Kidd

    Rob Kidd Well-Known Member

    I apologise for the double presentation - the evils are in my laptop tonight
     
  4. rdp1210

    rdp1210 Active Member

    I realize that I am first and foremost a clinician. I am heavily involved daily in the treatment of the diabetic foot, before, during and after the ulcer/infection. I realize that clinicians may think a little differently because we are making decisions daily, e.g. almost daily, to amputate or not to amputate. So if I come off as nonscientific to your viewpoint, I'm sorry. I realize that you never used the term "mental-midget" however your condescending tone to most people gives one the feeling that you consider your own intellect far superior to everyone else. This is purely an observation from someone who really doesn't know you (though when we get together we might find out that we are distantly related.)

    I am very cognizant of errors of measurement problems. I am doing a research study now where we are trying to overpower the errors of measurement with numbers of trials. I have pondered the errors of goniometry for 36 years as I have done them daily, constantly trying to compare what I did yesterday with what I'm doing today. You will be interested in a study that I will soon be publishing in which I showed statistical identity of two different populations, in measuring the forefoot to rearfoot deformity, using two different measuring tools (though the same person and technique) performed 25 years apart. I realize that it is intratester only, and that an intertester reliability would also be nice. I could discuss with you ad infinatum all the variables that are overlooked by almost all those that have published reliability studies on foot goniometry. That's why for years I have been calling the Root volume I book a concept book, not a technique book. I like the concepts, they give us a start, but as I have maintained, they are only a start and there are many details that are not well defined, thus leaving all who read to their own interpretations. I don't buy into the philosophy that we need to dumb down biomechanics by not taking any measurements. We need more, not fewer. The goal should be to take a 3D recon of any person's foot and simulate the gait pattern, thus being able to replicate the stresses that caused the injury or the deformity. Impossible? Only if you think it is.

    In the clinical world, we are constantly being asked to document, document, document. The more I can quantitate, the better I like it. We can talk all we want about the science of a neutral position, however I don't have a better clinical tool yet, even with McPoil/Hunt [MH] theory. Using only MH theory is a step backward or maybe sideways, but not a step forward. I thought that in my clinical lifetime, we would be far further ahead than we are today -- and so did Dr. Root and associates. Some would accuse me of not being progressive, yet progressive does not mean giving up ideas that have already been shown to be revelant and useful. If your goal is only to build a shoe insert, then maybe you don't need much, but if your goal is to learn as much as you can about each foot, then goniometric measurements must be added to all the other evaluation tools, as you search for etiology. As you read my 1992 paper, you should get the idea that identifying the position of the STJ axis is dependent on what position the subtalar joint is in. I have written an algorithm, using a stepwise vector transformation, for moving this axis in 3D. If any of your grad students want to contact me about testing the algorithm, I am looking for people to do so.

    Best wishes,
    Daryl

    my philosophy: Only if you are unafraid of truth will you find it.
     
  5. Rob Kidd

    Rob Kidd Well-Known Member



    I will write a full reply in the morning, but for now, no I do not have a copy of your paper or the one we talked about in a previous post (?1983?). I would be grateful for a *.PDF of each, and then we will talk, Rob
     
  6. Dennis Kiper

    Dennis Kiper Well-Known Member

    As I've stated many times on other threads on this blog alone, much of what we do is not amenable to empirical study.

    This is true, because traditional orthotic technology is not scientifically quantifiable.
     
  7. Dennis Kiper

    Dennis Kiper Well-Known Member

    Firstly, there may or may not be a subtalar neutral position - but you will need to find a decent definition;

    I prefer the term ?optimal position?. This allows for a very slight variation in axial congruity, but close enough for best function.
     
  8. rdp1210

    rdp1210 Active Member


    And if you quit trying to make it quantifiable, it never will be.
    Daryl
     
  9. Daryl,

    None taken.

    I find "your positioning rather shallow in it's approach" too since you appear incapable of admitting that there are fundamental flaws in specific elements of Root's "criteria for normalcy" and thus the criteria when viewed as a whole is therefore fundamentally flawed due to the flaws within it's elements. But hey, I'm not going to lose sleep over your opinion when it comes to Root, you have placed your bias firmly on the table. Just remember that it was me that spotted the error in one of your equations in your STJ axis location paper and telephoned you to discuss it, all those years ago. But let's not get into the condescending- right, Daryl?

    I guess this was "too shallow" for you to respond too:


    As for your clinical "coal-face" argument with Rob Kidd, I do not see you applying this same argument to Jeff Root, who by professional training is a fireman- right? While he may spend his day running an orthotics lab these days, he certainly doesn't spend the hours in front of patients that you and I do. Despite this, I do not see you levelling the criticism to Jeff that you appear to be trying to apply to Bob.

    And Craig, Kiper is just going to de-rail the good discussion here as he attempts to sell his insoles. FFS.
     
  10. efuller

    efuller MVP

    Finding that theoretical position would not interest me. We deal with the foot in the position that is in and we have a hard time moving it from that position. If we found that position, would all pathology be reduced by trying to move it toward that position? The classic example here is the patient with peroneal tendonitis whose relaxed stance position is pronated from neutral. The damaged peroneal tendons get relief when we try to push the STJ away from the idealized neutral. Daryl, now it is your turn. Would this position interest you? Why or why not? How would finding this position change what you do clinically?

    I remember Chris Smith describing that feel. The interesting thing about that feel is that you can "feel it" only by grasping the foot distal to the midtarsal joint. One theory I have about that feel is that you are feeling the change in range of motion of the midtarsal jiont. The other theory that I have about that feel is that you are feeling the change in the direction of moment as your hand position moves from one side of the STJ axis to the other. I don't think this position would have any effect on ligament tension or joint compressive forces.

    Daryl, are you familiar with my windlass paper that came out about 15 years ago in JAPMA. In that paper I describe how you could predict hallux valgus. The mechanical model presented in that paper would predict that high loads on the first ray and hallux and a high pronation moment at the STJ would increase the likelihood of developing first MPJ pathology. So, we do have more than STJ axis position. I don't see how you can disagree with the theory that a medially deviated STJ axis will lead to posterior tibial dysfunction. The criticism that tissue stress can't be predictive just doesn't hold water. Conversely, the neutral position measurements are not predictive. Does a rearfoot varus invariably lead to bunions? Is it forefoot varus or forefoot valgus that leads to bunions?



    Your patient reminds me of a story. Kevin and I were lecturing at biomechanics summer school and I had taken volunteers from the audience to demonstrate the physical exam that I do applying tissue stress principles. This particular woman had a laterally deviated STJ axis. She was one of those tricky ones when you push medial to the axis you get peroneal contraction that makes it hard to find the axis. When she stood up she sat more pronated than you would expect. Then Kevin yells from the other side of the lecture hall "check her peroneal muscles". Kevin was a step ahead of me. Sure enough she was contracting her peroneal muscles in "relaxed" stance position. So, STJ axis theory was predictive. There are sources of pronation moment other than ground reaction force. I agree with you, when something doesn't make sense you do need to figure it out. In this case the peroneals were needed to keep the foot plantigrade in the presence of a supination moment from ground reaction force.


    Eric
     
  11. Dennis Kiper

    Dennis Kiper Well-Known Member

    And if you quit trying to make it quantifiable, it never will be.

    You don't have to quit, but you'll never find a scientifically quantifiable sol'n to traditional orthotic technology.

    Maybe Spooner will come up with a new idea:santa2:
     
  12. You the best Dennis. No-one can touch when it comes to selling ****. Now **** off and let the adults talk for a minute.
     
  13. drhunt1

    drhunt1 Well-Known Member

    How very British of you.
     
  14. Said the xenophobic "hunter" podiatrist from the corner, after being completely battered by the British podiatrist, Robert Isaacs in the "growing pains" thread: http://www.podiatry-arena.com/podiatry-forum/showthread.php?t=101275 Oh well, never mind... That dentist "hunter" who had to go into hiding after killing a defenseless lion with a cross-bow, is he a pal of yours, Drhunt1?:D What a prick.

    Let's just stick to the plot and the facts, please... Too many good discussions are getting ruined by you two of late. I'd rather wait for the adults to talk than engage with either of you two any further, thanks. Goodbye Dennis and "Hunter". Carry on boys.... I'm sure it won't be too long until you both get yourselves banned from this site. Carry on, carry on....


    In the meantime, I look forward to learning from those with some wisdom, without your incessant interruptions...
     
  15. drhunt1

    drhunt1 Well-Known Member

    OT-When poster after poster from Jolly Ole, submit post after post that only confirms what my brother told me some time ago...a pattern certainly forms. I'm really good at "seeing" patterns, and am a pretty good judge of character. Your edited post is just further proof. It's not xenophobia...and that's a fact Jack.
     
  16. Dennis Kiper

    Dennis Kiper Well-Known Member

    Simon,

    You keep saying ?goodbye? but I see you?ve set aside this special time to humiliate yourself again.

    Listen up, just because you're bad at science, you can get help for your insecurities and neuroses.
     
  17. Rob Kidd

    Rob Kidd Well-Known Member

    And best wishes also
    Rob - your third cousin six times removed - perchance?
     
  18. To echo Simons sentiment, can we take it as given that Various people on this forum don't like each other very much, and try to stick to the actual subject matter? Whilst I enjoy seeing passionate people disagree violently, its only fun if its about the relevant subjects rather than just telling each other how stupid we think they are.


    I came here for an argument, this is just abuse!

    [​IMG]
    https://www.youtube.com/watch?v=kQFKtI6gn9Y
     
  19. drhunt1

    drhunt1 Well-Known Member

    Root loosely defined STJ neutral as 1/3 away from maximum pronation and 2/3's away from maximum supination. How about just defining STJ neutral as the position of the STJ during swing phase of gait...or the position it maintains when the athlete goes up for a rebound in BB, or jumps up to spike the volleyball? Having a definition, a starting point, as it were, aids in not only discussions, but in determing viable treatment strategies....or lack thereof. It is just a definition, therefore, it is just a starting point....as Dr. Orien rebutted in his letter to Kirby submitted to Podiatry Today. Of further interest, was Dr. Phillips' letter to the editor, which is available by accessing Kirby's article and scrolling down through the replies. He mentions personal attacks in his letter....and this is not the first time he has done so. Several posters here at PA would be best advised to carefully read Dr. Phillips' words.
     
  20. Eric and Colleagues:

    What do you do when you are waiting at the airport for your flight to take off to a country (S. Africa) which is halfway around the earth from you...go on Podiatry Arena!!

    My theory of why the "flat position within arc of rotation" of the subtalar joint (STJ) occurs is that this "flat position" mechanically indicates the point of maximal congruency of the posterior facets of the talo-calcaneal joint. During STJ pronation from neutral to maximally pronated, the anterior aspect of the posterior facet gaps slightly. During STJ pronation from neutral to maximally supinated, the posterior aspect of the posterior facet gaps posteriorly. In neutral, the posterior facet seems to be most congruent. At least that has been my observation at looking of a number of foot skeletons.

    I have noted that an examiner can only "feel" this "flat position" within the STJ range of motion when the forefoot is loaded plantarly, preferably at the lateral metatarsal heads. I believe this is because grasping the metatarsal heads distally gives the examiner a longer rigid lever arm away from the STJ in order to feel these subtle changes in direction of motion of the STJ. Try as I like, I simply can't feel this "flat position" within the STJ range of motion by only grasping the calcaneus. However, I can easily feel this "flat position" within the STJ range of motion as long as I load the lateral forefoot forcefully (at least 5 pounds of manual force) during examination.

    Why then does this "flat position" within the arc of curvature of STJ range of motion, which I believe indicates the STJ neutral position, occur? My theory is that these morphological adaptations within the facets of the talo-calcaneal joint occur during the years of weightbearing and growth (approximately ages 1 to 14) and is caused by the high intra-articular pressures within the articular facets of the STJ that occur during the late midstance phases of gait (i.e. the time during gait when the greatest STJ intra-articular pressures occur).

    Over the last 30+ years of examining subtalar joints, I have found that feet which stand closer to the maximally pronated position of the STJ in relaxed bipedal stance have STJ neutral positions that are close to a 1:3 pronation to supination ratio. I have also found that feet which stand closer to the neutral to supinated position of the STJ in relaxed bipedal stance have STJ neutral positions that are closer to a 1:1 pronation to supination ratio. In other words, the more pronated the foot the closer the "flat position" of the STJ range of motion is to the maximally pronated STJ rotational position and the more supinated the foot is, the closer the "flat position" of the STJ is to being halfway between the maximally pronated and maximally supinate position of the STJ.

    These are just my observations over three decades of examining tens of thousands of feet. Hopefully, someone will be able to research these theories further to see if the true answers to the mechanical nature of "subtalar joint neutral" can be made more clear.
     
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