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Challenging the foundations of the clinical model of foot function

Discussion in 'Biomechanics, Sports and Foot orthoses' started by NewsBot, Jan 31, 2017.

  1. Jeff Root

    Jeff Root Well-Known Member

    Simon, thanks for catching this. What I meant to imply was that the angle of the plantarflexion of the talus relative to the plane of the floor is greater than the angle of plantarflexion of the distal segments due to MTJ dorsiflexion (mtj pronation). If we placed a subject in the neutral position prior to performing the navicular drop test and drew a line in the sagiattal plane that bisects the neck and head of the talus and through the navicular, medial cuneiform and the 1st met and then compared each of those segments after preforming the navicular drop, we would see that the line segment through the neck and head of the talus would form a more acute angle to the plane of the floor than the line segments through the navicular and the 1st met. This is because there would be relative dorsiflexion of the 1st met to the talus.

    My apologies if my hastily, poorly written and incorrect original wording was misleading and caused confusion. In my head I was thinking in terms of angles but I did not state that in my post.

    Simon, you said "To re-iterate, as I see you have since edited in your original post, you stated that". As I said before I did not edit my original post. When a post is edited the fact that it was edited is noted on the right hand side just below the post. If you go back and look at my original post that you took my quote from (post #626) you will see that there is no notation that the post was edited. I'm not sure why you would suggest that I edited my post when there is clear evidence that I did not.
     
  2. Jeff Root

    Jeff Root Well-Known Member

    Mike, in post #629 you wrote "I see you added relative to the ground after I made my point". Mike, I thought you were implying that I changed (edited) my post after you replied to it. If that wasn't what you meant then I'm sorry for my misinterpretation of what you wrote.
     

  3. All go Jeff maybe I could have written post numbers or quoted them to be clearer.

    Happy Easter
     
  4. efuller

    efuller MVP

    The criticism of saying that tissue stress is new is a valid one. I agree that it is an old idea. What is new with what I was proposing was a prescription writing protocol based on mechanical analysis of the chief complaint as opposed to foot deformities.


    Daryl wrote: "Your statement that the position of joints can explain pathology of the foot is a straw man argument if you mean that it can explain all pathology. " The position of a joint by itself cannot explain pathology. I don't think I said what you quoted. Can you give an example of the position of a joint will explain pathology. Sinus tarsi pain occurs when the STJ has high pronation moment and the STJ is at its end of range of motion. There are feet, that rest at the end of range of pronation that don't get sinus tarsi pain. If you look at just force in the sinus tarsi, you can explain sinus tarsi syndrome.

    "I learned that orientation of joint axes determines direction of motion. " Now there is something that should not be taught. The motion determines the axis, the axis does not determine the motion. Joint surfaces and ligaments can constrict motion so that it looks like it occurs about a fixed axis. That statement is the exact problem I have with how you use the term LMTJ axis.

    If I believe the world is flat and another person believes the world is round, how can we have a discussion about the shape of the world without being divisive? We can certainly have a friendly conversation about it, but one of us will be wrong about our deeply held beliefs because we believe opposite things. If we want to progress we should use science to figure out whether or not the Earth is flat.

    I believe there is no advantage to using subtalar joint neutral position. If someone believes differently than I do they should be able to list the advantages of neutral position. I've already given my argument that the prescirption writing protocol that has been passed down to us does not coherently use neutral position. If I believe that neutral position doesn't have any advantages then I should propose a new system that explains the existing observations. The new system should be called something different to avoid confusion.

    Daryl, thanks for taking the time to critique the article.

    Daryl, this is the exact criticism I have of neutral position theory. It is not predictive. It is a lot easier to make predictions with tissue stress than it is with neutral position related measurements. For example, I predict that feet with a more medially deviated STJ axis will be much more likely to get PT dysfunction. People with a laterally deviated STJ axis will be more likely to have peroneal tendonitis.

    For the diabetic population. Ulcer first toe. Predictions either a structural or functional hallux limitus will be present a vast majority of the time with first toe ulcers. I predict that a functional hallux limitus will lead to a structural hallux limitus. Of course I need to have a good repeatable definition of functional hallux limitus to prove this. I predict that it will be shown that functional hallux limitus will be shown to be related to high tension in the medial slip of the plantar fascia. Reduction of tension in the plantar fascia should reduce first toe pressures and allow the ulcer to heel.

    How do neutral position measurements predict where ulcers will occur. I will concede that a partially compensated varus will tend to cause ulcers under the lateral forefoot. However, the presence of a partially compensated varus can more easily be found with the maximum eversion height test than through the neutral position related measurements. Daryl, can you give an example of neutral position measurements help you treat diabetic ulcers?
     
  5. rdp1210

    rdp1210 Active Member

    You're question is like trying to make stew with only one ingredient. STJ neutral alone, cannot predict. The same way an abnormal STJ axis is only one cause of abnormal STJ pronation. Please reread the part in Root's book on the etiologies (notice the plural) for hallux limitus. Abnormal pronation alone is only ONE cause of hallux limitus. Sorry I've got a 12 hour clinic day that I'm running to get started right now, so I will take more time later.
    Daryl
     
  6. scotfoot

    scotfoot Active Member

    In my opinion , any theory concerning the way in which the foot functions which does not take the initial and primary phases of the windlass mechanism into account , is of little value .

    Gerry
     
  7. rdp1210

    rdp1210 Active Member

    Who said I don't consider the windlass mechanism to be an important part of the entire picture of foot function? On another podiatry discussion site, Kevin gave out a problem on calculating the tension in the plantar fascia, assuming the foot looked like an isosceles triangle, and I was the only one that submitted the correct answer. Then I sent to him for his use in lectures the equation for calculating the tension when there were 3 different angles and side lengths for that triangle model.

    What I'm arguing is that some people on this arena argue you only need a tool box that is half-full. The arguments continue to be a circular rewrite of "The Blind-Men and the Elephant", everyone arguing for one point of view, no one willing to concede any value to anyone else's point of view, and no real learning occurring.

    Daryl
     
  8. scotfoot

    scotfoot Active Member

    Hi Daryl
    My comment was in no way specific to yourself or even to this thread . It applies to nearly all aspects of the study of the anatomy ,physiology, and biomechanics of the foot . In my opinion their are two distinct windlass phases during gait ,not one . Would you agree ?

    Gerry
     
  9. rdp1210

    rdp1210 Active Member

    I don't know if I've ever heard someone divide it into two phases. Sounds interesting. Please send me more of your views.
     
  10. scotfoot

    scotfoot Active Member

    Here is a link to the relevant thread . You can see that I started off tentatively but I have to say I am now pretty sure of my ground . I firmly believe that initial windlass phase is critical to the proper functioning of the foot .

    Cheers
    Gerry

    Windlass mechanism | Podiatry Arena

    https://podiatryarena.com › Forums › General › Biomechanics, Sports and Foot orthoses28 Feb 2018 - scotfoot Active Member. Members do not see these Ads. Sign Up. So during the gait cycle the windlass mechanism is engaged and reversed twice . Going from heel strike to heel strike we have windlass , reverse windlass , windlass and then reverse windlass at toe off . Yes ? GerrardFarrell Glasgow.
     
  11. efuller

    efuller MVP

    To continue your analogy. Neutral position is like a stone. You can make a stew, or soup, without using stones. I'm asking how does the stone add to the flavor of the stew/ soup.

    Or a different analogy. Using neutral position measurements is like a magician saying abracadabra before pulling a rabbit out of a hat. Abracadabra is not necessary for completing the trick. The audience likes it. The magician may even believe that it needs to be said.

    I'm asking for how the neutral position measurements adds to how you figure out what is going on. Say you have a diabetic with an ulcer under the first metatarsal head. The problem is high pressure under the first met head. How are neutral position measurements, and related treatments, addressing/ explaining that high pressure? You can pick another location for the ulcer if it makes it any easier.
     
  12. efuller

    efuller MVP

    Have you read the explanation of how abnormal pronation (how is that measured?) causes hallux limitus? It does not make any sense. (hypermobility? how is that measured? Hallux limitus, the problem is that joint is too stable and doesn't move. How does hypermobilitiy cause stability?
     
  13. Any chance we can keep that discussion in that thread?
     
  14. scotfoot

    scotfoot Active Member

    Not your site Simon . Craig's .
     
  15. Just a messy enough thread as it is... Anyway you Gerald , a dentist that for some reason has an obsession with the windlass mechanism (barefoot runner is my guess, or someone selling something to "strengthen" the plantar intrinsics), and Daryl- knock your socks off... Every thread you are involved in "Scotfoot" resolves to you talking to yourself... go ahead, kill this thread too.
     
    Last edited: Mar 30, 2018
  16. .
     
  17. rdp1210

    rdp1210 Active Member

    Since you like to answer questions, with questions: Knowing where neutral position is helps me in judging what type of forefoot posting I want on my orthotic. I do extrinsic posting on diabetics, usually to the ends of the toes. Do I want to forefoot post to push the heel toward a vertical position, an inverted or everted position? It gives me a starting point. I also follow my patients, especially diabetics, closely to see what the response is. If a patient is standing with the heel vertical and they are at their pronation EROM, why would I want an orthotic to try to push their foot toward this position? How do I know if the vertical heel is at its EROM. Sorry, the asking the patient to lift the lateral side of the foot is not reliable. You would have to publish an actual paper on this concept. This would be especially unreliable with a diabetic. Now notice I said that the orthotic is pushing the foot toward the posted position -- the foot never can reach this position because the foot is pushing the orthotic into a deformed position -- the result is that the foot deforms less and the orthotic also deforms from its unweighted shape, and a point of equilibrium is reached between orthotic and foot. This is why no "neutral orthotic" can push the foot all the way to neutral position. Now this is one thing that I never heard Mert talk about.

    So do you use any type of forefoot posting (extrinsic or intrinsic)? What formula do you use? Can't say I really understood this in your February article. Also I'm not sure that I understood in the article when you advocate casting the foot with the STJ neutral and when you do not. I'll get back more with you about this.

    Daryl
     
  18. Daryl I don't deal a lot with the kind of patients you are discussing here, but with my limited understanding, ulceration in the diabetic foot is thought to be due to high vertical force impulses amd high shear components of GRF at the foot's interface. If we have a patient at risk of ulceration, for example beneath the 1st metatarsophalangeal joint, we don't need subtalar neutral to guide us in our orthoses design to offload that area of the foot, do we? Does Dave Armstrong worry about STJ neutral?

    I ask earnestly, how does STJ neutral relate to shear force components?
     
  19. efuller

    efuller MVP

    Daryl, I try really hard to answer all of your questions. I'm going split this response into two parts because I have comments on what you say and I want to answer your question. That said, you too often answer questions with questions. I'm ok with you calling me out when I don't answer your questions.

    I'm confused by what you wrote above. Are you more concerned about a vertical heel or neutral position. Why are you concerned about either?

    On your question of whether or not you want to push a foot toward end of range of motion. Say you had a first met head ulcer and you wanted to increase lateral forefoot load and the foot was at end of range of motion in the direction of pronation of the STJ. A forefoot valgus wedge could decrease load on the first met head and attempt to push the STJ in the direction of pronation. In this particular situation the problem is not the position of the STJ. There are other foot pathologies where you would want to push the opposite direction.

    Why wouldn't the direction you push be determined by the pathology and not where neutral or the heel bisection was?



    I will admit that there is a small subset of the population that just can't understand the instructions.

    How do you know this is not reliable. Have you tried it in clinic. It is far more reliable than forefoot to rearfoot measurement and other measurements that use heel bisections. How else are you going to know if your calculations that show that the heel should be able to evert 2 degrees are correct if you don't attempt to evert the foot and see if there are 2 degrees of motion available? If you calculated that there were 2 degrees of eversion available and you attemptetd to evert the foot and saw there was no eversion available, would you believe your measurements or what you see with your eyes?
     
  20. efuller

    efuller MVP

    I'm pretty sure that I mentioned that I use an intrinsic forefoot valgus post the same height as the maximum eversion height (MEH). I wish that someone with more time than I have could do a comparison of size of intrinsic post for people that have more than 3mm of eversion height. Maybe half height versus full height post. That is only for those with MEH greater than 3mm. I'm quite sure that the intrinsic post should not be greater than MEH. I've made that mistake enough times to know that you should not try to evert the foot farther than it can go.

    I did say in the article that casting position did not matter. I did mention medial arch height. If your semi weight bearing cast does not give you the standing medial arch height with finger pressure in the arch then you will have to do something to make the arch higher. (Cast SWB or neutral or carve the positive cast. )
     
  21. Dennis Kiper

    Dennis Kiper Active Member

    Kevin,

    All the issues you bring up that remain elusive to you, is because traditional orthotic technology is not as efficient to human biomechanics as it should be. Because it is mechanically inefficient, it is tissue inefficient.

    Neutral reafoot theory in my opinion pertains only to midstance. It does not address the mechanics of arch motion.. the technology model of human function doesn't start at the rearfoot, it starts at the midfoot.
    There is another technology (hydraulics) available, that utilizes principles of physics to improve bio-mechanical efficiency, mechanically. Gait scans record the data of foot function, accuracy and reliability of that data is best served with principles of physics.




    You can't get a reliable prescription for tissue stress without addresing mechanical efficiency first. It's the technology that makes the difference in elevating biomechanical health. the science proves it, theory after al is still just theory
     
  22. Dennis Kiper

    Dennis Kiper Active Member

    The real challenge to the foundation of foot function is recognizing that biomechanical efficiency is balancing wt and pronatory forces thru all of stance (arch motion) by functional/mechanical alignment. With the mechanics of alignment, the proper proportionate amount of reduction (GRF) and balance is attained, otherwise a disproportionate amount of peak pressures, still contributes to the imbalance and pathology and associated tissue stress.

    Present day technology results of orthotic treatment have been inconsistent, as seen with numerous scientific papers and clinical trials comparing traditional prescription orthoses with all others. The comparisons are about the same in medical performance and mechanical factors that alter plantar pressures. And forget about long term analysis.

    We discuss axis of motion and motion along the axis yet gait scans cannot consistently or reliably allow us to accurately determine mechanical efficiency and function with traditional orthotic technology. After almost 70 years of theory and conjecture, podiatry has not looked at the real issue-technology based on principles of physics.

    Mechanically, it has been established, increasing joint axial congruity, increases lever arm efficiency. Joint stability is determined by anatomical/mechanical factors.

    A technology that is based on scientific principles makes it able to precisely measure data and gives us the tool to optimize bio-mechanical efficiency of the functional mechanics of a foot in all three planes.

    Increased accurate interpretation of bio-mechanical function leads to a higher predictability of outcome. Isn't it time for podiatry to enter the 21st century?
     
  23. Dennis Kiper

    Dennis Kiper Active Member

    Kevin
    I understand you don't want to hear from me, but it's unreasonable to test a healthy person? What about prevention? Isn't that worthwhile? Prevention of aging our biomechanical health faster. Isn't that worthwhile? Finding something to help and preserve our biomechanical health thoughout our lives starting as early as 8-10 yrs of age.
    Like learning to use a toothbrush as a toddler for our oral health.

    Testing a healthy person would be great to see what changes he might feel in a year. I can tell you from my experience, most of my runners came back and said they ran their PB or PR
    The mechanics changes instantly (I mean the increase in mechanical efficiency) the the bio part takes about a year.
     
  24. Dennis Kiper

    Dennis Kiper Active Member

    STJ dogma has its place for 20-30% of the population—it's not as efficient a technology as it should be. But for the 20-30% that need it (flat feet and anomalies) it's correct—but it's not as good as it should be (I obviously mean the clinical application) fot the other 70-80%. Root was a genius in my opinion for figuring what he's done. I couldn't believe how long it took me to recognize the couple errors he made.

    The harm is in professionals who should have the intersts of mankind ahead of personal intersts. Sometimes that has to change.
     
  25. Dennis Kiper

    Dennis Kiper Active Member

    Not better theory, better technology
     
  26. Dennis Kiper

    Dennis Kiper Active Member

    Kevin,
    Only technology will optimize the clinical practice of foot orthoses therapy
     
  27. Dennis Kiper

    Dennis Kiper Active Member

    Mike,

    There are many abnormal variations of the biomechanical foot, but the majority are normal in my opinion. They just vary in their ROM. The key is recognizing improving the mechanical efficiency of that variation.
     
  28. Dennis Kiper

    Dennis Kiper Active Member

    One of the problems I see with traditional orthoses is that
    interrupts the efficient transfer and fluidity of motion and momentum. In my opinion, kinematics needs laser measurements in order to see those changes.

    But present day tech (Tekscan) is excellent to measure GRF. When you recognize the value in being able to have accurate info, we would be able to recognize intrinsic function without the kinematics.
     
  29. Dennis Kiper

    Dennis Kiper Active Member

    Trevor,

    I agree and that's because I will continue to repeat that traditional tech is based on theory and conjecture.

    You,re trying to affect a mechanical model by external postings (like engineering outside of the foundation) insyead of engineering the intrinsic function of the mechanical model.
     
  30. Dennis Kiper

    Dennis Kiper Active Member

    The motion and forces of stance phase are too pwerful to "design" a structure to momentarily affect "moments".
    The construct of a "design" doesn't address the mechanics of arch motion starting at heel contact and ending with metatarsul lift off.

    I want to say again, this tech is not for the flat foot (subluxed), but the most common type of structured foot.
     
  31. Dennis Kiper

    Dennis Kiper Active Member

    If neutral means is the foot at it's "optimal position" then yes. Normally this refers to midstance, doesn't it? To me, the optimal position is the dynamic position throughout stance phase.

    e.g. at heel contact what biomechanical influence does traditional tech have? with HD tech--it reduces the impact force and reduces the speed of pronation, guiding the STJ into it's optimal pos at midstance--so that it never overpronates, but comes to rest at the moment of an equilibrium state of stability at midstance.
     
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