Welcome to the Podiatry Arena forums

You are currently viewing our podiatry forum as a guest which gives you limited access to view all podiatry discussions and access our other features. By joining our free global community of Podiatrists and other interested foot health care professionals you will have access to post podiatry topics (answer and ask questions), communicate privately with other members, upload content, view attachments, receive a weekly email update of new discussions, access other special features. Registered users do not get displayed the advertisements in posted messages. Registration is fast, simple and absolutely free so please, join our global Podiatry community today!

  1. Everything that you are ever going to want to know about running shoes: Running Shoes Boot Camp Online, for taking it to the next level? See here for more.
    Dismiss Notice
  2. Have you considered the Critical Thinking and Skeptical Boot Camp, for taking it to the next level? See here for more.
    Dismiss Notice
  3. Have you considered the Clinical Biomechanics Boot Camp Online, for taking it to the next level? See here for more.
    Dismiss Notice
Dismiss Notice
Have you considered the Clinical Biomechanics Boot Camp Online, for taking it to the next level? See here for more.
Dismiss Notice
Have you liked us on Facebook to get our updates? Please do. Click here for our Facebook page.
Dismiss Notice
Do you get the weekly newsletter that Podiatry Arena sends out to update everybody? If not, click here to organise this.

A rationale for midfoot orthotic control

Discussion in 'Biomechanics, Sports and Foot orthoses' started by David Smith, Feb 22, 2014.

  1. David Smith

    David Smith Well-Known Member


    Members do not see these Ads. Sign Up.
    THE RATIONALE FOR MIDFOOT ORTHOTIC CONTROL

    I believe and have believed for a long time that rear foot control is not the best way to balance and align the bio-mechanics of the foot and lower extremity. There is a retrograde effect of max pronation of the mid foot as well as the rear foot.

    The more the rear foot can pronate the more the range of pronation thoughout the foot structure. The more the Mid Tarsal Joint pronates (MTJ—middle of the foot, AKA "arch") the more allowable range of pronation at the rear foot, and as the rear foot pronates further, this allows the MTJ to open up further as well. This is the "retrograde" effect I'm speaking of.

    Because, the rear foot is being restricted by both a heel cup and possibly a rearfoot post (which is really an artificial means of "controlling" the foot). The MTJ may open up further, stressing the rear foot. That's why some orthotics can be so painful.

    (At the same time even with this restriction, the over all motion of pronation is limited/minimized and therefore one can feel positive benefits even if it's uncomfortable to wear.)

    When either the arch or rear foot is capable of pronating further, but is "restricted" in its motion rather than moving naturally, you have a controlled foot. While I am in the minority, I would rather "guide or assist" the foot movement naturally while limiting/minimizing the motion of both the arch and rear foot.

    In any footstep, the greatest range of pronation starts at the mid foot (after the foot has made full contact with the ground), therefore isn't it reasonable to address it first?


    Dave :D:D:D:dizzy::bash:
     
  2. davidh

    davidh Podiatry Arena Veteran

    I notice the word artificial in there Dave.
    I like a RF post. They work well for me and my patients - fashion shoes and football (soccer) boots are an exception of course.

    Coming back to artificial - that's what we walk on. The foot was never designed for concrete.
     
  3. David Smith

    David Smith Well-Known Member


    David please feel free to notice so much more, Give me a roasting -I'm just being a bit naughty,:butcher: you don't think I actually wrote this stuff do you?

    All the best Dave
     
  4. davidh

    davidh Podiatry Arena Veteran

    Do you know, I thought it was a bit strange...........:confused:

    So are you implying I found another hole in his argument?
    :D

    Cheers,

    Dave
     
  5. Actually, Simon Spooner and I gave a set of lectures at the Zaragoza seminar a few weeks ago where we addressed the midtarsal-midfoot joints and how foot orthoses work across these joint axes to improve symptoms and change gait function. Foot orthoses have much more potential to alter the biomechanics of the midtarsal and midfoot joints versus their ability to alter the biomechanics of the subtalar joint.
     
  6. Yep Zaragoza was probably the best conference I've ever attended. But lets pick up on your last sentence here, Kevin: "more potential" is an interesting comment; why should there be "more potential" for foot orthoses to alter biomechancal function at the midfoot? More potential, presumably than somewhere elsewhere, like the subtalar joint you mentioned?

    Thread title has a typo.
     
  7. Simon:

    Foot orthoses have more potential to affect midfoot/MTJ mechanics than STJ mechanics since foot orthoses cross the midfoot/MTJ, but do not cross the STJ.
     
  8. Re: A rationale for minfoot orthotic control

    Yeah, you got my interest with the words "balance and align"... For those following, Dave needs to expain here his choice of words "balance" and "align" since this suggests that an optimal "balance and "alignment" exist...

    All yours Smithy...
     
  9. Are you sure? There can be sides on an orthoses shell either side of the STJ axis... No?
     
  10. David Smith

    David Smith Well-Known Member

    Re: A rationale for minfoot orthotic control

    Let me make things more clear - go here
    http://www.drkiper.com/midfoot_orthotic_control.php


    Dave
     
  11. Dennis Kiper

    Dennis Kiper Active Member

    Optimal alignment and balance do exist in stance.
     
  12. When you say stance, do you mean static stance or the stance phase of gait? Regardless, if there is an optimal alignment in either of these states it will be unique to the individual and to the given environment. Optimal in terms of what?

    Anyway, back to the midfoot and foot orthoses.
     
  13. Since foot orthoses can only act directly mechanically inferior to the STJ axis, and cannot act direct mechanically superior to the STJ axis, it cannot act like most orthopedic braces that use a "three-point system" to modify the kinetics and kinematics of the joint being "braced" where both segments of the joint have external forces being exerted on them.

    However, since foot orthoses can act directly mechanically on both the rearfoot and forefoot, then foot orthoses are much more efficient at modifying midtarsal and midfoot joint kinetics and kinematics than they are STJ kinetics and kinematics due to their ability to exert external forces directly on both segments of the joint.

    This does not mean that foot orthoses cannot alter STJ moments, because they can in many instances cause significant changes in STJ moments, but their mechanical effect is not due to a "bracing" effect of the foot orthosis across the STJ axis.
     
  14. Dennis Kiper

    Dennis Kiper Active Member

    "When you say stance, do you mean static stance or the stance phase of gait? Regardless, if there is an optimal alignment in either of these states it will be unique to the individual and to the given environment. Optimal in terms of what? "

    optimal - definition of optimal by the Free Online Dictionary ...
    www.thefreedictionary.com/optimal‎
    TheFreeDictionary.com
    op•ti•mum n., pl. -ma mums, n. 1. the most favorable point, degree, or amount of something for obtaining a given result.

    In static stance--neither pronated nor supinated

    In dynamic stance--minimal pron/sup, prolonged stability of the forefoot and midfoot at heel off.--balance of the forefoot (mets 1-5 sharing the load) under full pronatory and wt bearing forces
     
  15. Griff

    Griff Moderator

    Dennis

    Are you suggesting that the 'optimal' position to be in during static stance is STJ neutral (i.e. neither pronated nor supinated)? Furthermore are you suggesting your orthoses will hold the foot in said position?
     
  16. Dennis Kiper

    Dennis Kiper Active Member

    Ian,

    see previous post
     
  17. "A given result"- what is the given result here? Metabolic efficiency; minimizing tissue stress; stability?


    Can you provide any evidence at all that the optimal position for the foot during static stance is neither pronated nor supinated? Why should this be the optimal position and for all subjects?

    What if I'm standing across an incline so that my left foot is higher up the slope than my right foot, is the optimal position for both feet the same in this situation?

    What about if I'm leaning on a bar, having a pint: my left foot is six inches anterior to my right foot and twelve inches lateral; my torso is learning at 30 degrees to the right and I'm leaning on the bar via my right elbow; my left hand contains 3/4 of a pint of liquid and is held with my upper arm extended at the shouder and my forearm bent 40 degress at the elbow- what is the optimal position for my feet during my static stance here?













    Oh, I forgot to tell you, I got one leg shorter than the other, the bar is on the beach and I'm wearing 6" stilletto's.

    Regarding your dynamic: when you say prolonged stability, how long is that exactly? Should the metatarsals all share the load equally and at all instances in time during the contact phase?

    You right, Griff...
    http://www.youtube.com/watch?v=aizCMO-mI1Q

    BTW the midfoot doesn't always move in a pronatory-supinatory manner, so it might be helpful if you define which segments you are talking about when you talk about pronation and supination.
     
  18. Griff

    Griff Moderator

    Dennis

    See previous decade
     
  19. :good: Now that is the funniest thing I've read in a long time :good:
     
  20. I get the three-point bracing effect about the vertical MTJ reference axis. How do we obtain a three point system about the medial-lateral and the anterior-posterior reference axes using foot orthoses? Are the third points from the upper of the shoe?
     
  21. Dennis Kiper

    Dennis Kiper Active Member

    Simon:

    “Regarding your dynamic: when you say prolonged stability, how long is that exactly?” ( Do you want a precise amount of time or do you want that in % of stance phase?)--are you saying that you are aware of what segment I'm talking about, or do I need to define the segment? What segment do you think I'm talking about?

    Question to you—if I add 2 mg of fluid to that Rx, do you think it would speed up or slow down the prolonged state of stability?

    “Should the metatarsals all share the load equally and at all instances in time during the contact phase? “ --Are you asking to disregard the loading time and force or that every moment of the contact phase be the same?
     
  22. % of stance will do. I have no idea which segment you are talking about. I thought you were talking about the metatarsals? You probably need to define stability and the direction of stability too. Is mechanical stability a "good thing" in a dynamic system? How much stability is too much (percentages will do)?

    You are making the assumption that there is a state of stability in the dynamic foot- is there? Like I said you probably need to go back and define stability. But let's play along: I guess it depends where you insert the fluid and the difference this makes to the surface stiffness (Ksurf) in relation to the foot stiffness (Kfoot) and leg stiffness (Kleg). Effectively with any insole you are adding another "spring in series" to the foot/ leg spring mass system. What we do know is that the body attempts to modulates it's lower limb segmental stiffness in response to differences in Ksurf. This seems to be an attempt to maintain metaboic efficiency and displacement pathway of the centre of mass. Generally speaking increases in Ksurf result in decreases in Kleg, so if we assume stiffness is related to stability then if your increase in fluid results in an increase in Ksurf then in all likelyhood, it will result in a decrease in stiffness either in the foot or leg, but I'm hypothesising based on the available data. This is part of the CNS mediated influence of foot orthoses.

    Lets think about the direct mechanical effects of foot orthoses. Lets say we have a joint segment that is "neither pronated nor supinated". In this situation either a supinatory or pronatory force from the foot orthosis may bring about a change in position of the joint, thus we may conclude that the joint is unstable to both pronation and supination forces. While the joint is unstable in this position, the stress in all of the tissues which limit motion in either direction are probably at or near their net least (so this is the net least stress position of the joint- ignoring potential for cartilage compression). Now, lets take a joint that is "maximally pronated". A supinatory force may result in supination of the joint, so the joint could be said to be unstable in the supination direction. However, a pronatory force may not cause an further pronation, thus the joint could be said to be stable in the pronation direction. Yet, the tissues restraining the pronation will probably have their net highest stress, while the tissue which restrain supination motion probably have their net least stress. The same would be true in reverse if we placed the joint in maximal supination. So I hope you can see that we need to better define what we mean by stability. If the joints were stable in all directions, no movement would occur at the joints- not really what you want in a dynamic system. Lets say we have a joint at end of range pronation, you add extra fluid(????) and move the joint so that is now less pronated- is it more or less stable? The answer is obviousy less stable in the pronation direction, but probably more stable in the supination direction. I hope that you understand that.

    No, I understand that the loading beneath each metatarsal is not constant during gait, nor should it be; you seemed to be intimating that it was and should be, hence my question which you have not answered yet.

    Could I ask you to answer my questions prior to posing questions of your own please, otherwise we'll never move forward. Could you also differentiate the statements which I made from those of your own please otherwise it gets confusing for anyone following along.
     
  23. All,

    I don't really understand what Dennis is trying to say here, but for those following: attached are a few kinematic graphs for the talonavicular and calcaneocuboid joint kinematics during gait obtained from Nester's bone pin studies. For good measure, I've also attached the kinematic graphs for the cuboid-navicular articulation.

    Question: At which points during the stance phase are these joints demonstating "prolonged stabiity"?
     

    Attached Files:

  24. Dennis Kiper

    Dennis Kiper Active Member

    from your kinematic graphs, you asked: “
    Question: At which points during the stance phase are these joints demonstating "prolonged stabiity"? “

    First there is stability, then there is a “prolonged” stability. This is not a good question. It shows a lack of some understanding on your part as far as I'm concerned. When I spoke about a prolonged stability, first there id stability at midstance, then a prolonged stability at heel off (this is the point during the stance phase I'm referring to)

    Your graphs will not show a “prolonged stability”, because the forefoot on a traditional orthotic becomes unstable, just after midstance and just the moment before heel off (short but sweet). The instability then continues thru the moment of heel off and destabilizes (unlocks for you purehearts) to increase flexibility throughout the kinetic chain.

    The SDO does demonstrate a “prolonged—equilibrium state of stability)--
    Heel-off and release of vector force allows for supination of the rearfoot. The leg has moved into its post-vertical position. The forward progression of the rearfoot as it pivots onto the metatarsal heads and downward force at the forefoot, coupled with the weight bearing and pronatory forces of the MTJ complex, now displaces fluid back to the rearfoot, prolonging momentarily the equilibrium state of stability of the biomechanical cycle.

    Simon, you said:

    Y”ou are making the assumption that there is a state of stability in the dynamic foot- is there? Like I said you probably need to go back and define stability. But let's play along: I guess it depends where you insert the fluid “



    Simon, these are not compartmentalized orthotic bladders. They are a single container and a closed system. Fluid exchange is done with a new Rx/volume.--No wonder you're so confused!

    Define stability?--Com on, I'm at a loss for words on that one. Why don't you define stability and I'll see if I agree with you.

    Lets think about the direct mechanical effects of foot orthoses. Lets say we have a joint segment that is "neither pronated nor supinated". In this situation either a supinatory or pronatory force from the foot orthosis may bring about a change in position of the joint, thus we may conclude that the joint is unstable to both pronation and supination forces

    ----I agree if you're talking about a traditional fixed or semi-fixed orthotic. With the fluid orthotic there would be a hydrodynamic shift to accommodate the change in force and maintain the best balance under the circumstance.

    If the joints were stable in all directions, no movement would occur at the joints- not really what you want in a dynamic system.

    ---I disagree, there is ALWAYS at least a minimal amount of motion within the joint axis and thaT is exactly what I want in my dynamic system.

    Lets say we have a joint at end of range pronation, you add extra fluid(????) ---that depends if the foot is already at its optimal position.

    and move the joint so that is now less pronated- is it more or less stable? The answer is obviousy less stable in the pronation direction, but probably more stable in the supination direction.

    ---Now let's take it from the perspective that the foot is at the end of range of pronation on a fluid orthotic and ,but it is “LESS” than it's optimal position.
    If I add fluid to the volume—your answer is the exact opposite of what I expect in the pronation direction. Even if I don't add enough fluid, pronation direction is at least improved (minimized) a little more –so it's still a little more stable in the pronation direction.
    The 2nd part is correct, because if I need to supinate the foot further, I am getting closer to optimal position, therefore I'm getting more stable in the supination direction.--did I understand you correctly?


    No, I understand that the loading beneath each metatarsal is not constant during gait, nor should it be; you seemed to be intimating that it was and should be, hence my question which you have not answered yet.

    , --what do you mean by constant?

    “Should the metatarsals all share the load equally and at all instances in time during the contact phase? –

    The mets should share the the load as equally as bio mechanically possible, during the contact phase. The closer each met load peaks closer together near or at the same time in stance, I would expect to see some mets reduce in GRF and others to increase in GRF. I would also expect to see more effective balance in time and force between the hypermobile lat and med columns (when they're hypermobile) and the lesser ROM mets 2-4.
     
  25. I smell the familiar aroma of Snake Oil. Once one learns to recognize the characteristic odor of Snake Oil, it is much easier to recognize the next time it is brought out by those within our profession that are intellectually challenged.
     
  26. efuller

    efuller MVP

    this discussion reminds me of what Jack Morris said about the silicon dynamic orthotic when Marty Krinsky brought it to CCPM to get the faculty to try it. "it feels like you are stepping on a cow pie."
     
  27. Dennis, you are simply making sh!t up. "release of the force vector" -WTF? The midtarsal joints are never "locked" they are constantly moving during stance in response to the internal and external moments acting about them, the fact that they are in a constant state of kinematic change means that they are never stable, nor should they be- the graphs were not from feet with foot orthoses in-situ, they were from asymptomatic subjects.

    I've wasted enough time with you, your lack of understanding of modern biomechanics makes discussion impossible. Good luck with your future. The sad thing is, of all the people here, I probably have a use for your insoles- but not in their current incarnation.
     
  28. Dennis Kiper

    Dennis Kiper Active Member

    The last thing I need is some too highly emotional transgender cross-dresser in 6" stiletto heels. You are not suited for fluid technology, you're 10 years behind me in bio-mechanics.

    Good luck yourself
     
  29. Dennis:

    You may want to consider taking a night course in English since it appears from your difficulties in being able to write properly that English must not be your first language.

    Please let us all know how that night course goes. When you finish with the night course, then maybe you consider reading some biomechanics literature that has been published after 1980. You obviously are still living in the past.
     
  30. Dennis Kiper

    Dennis Kiper Active Member

    You think the site should adequately explain my technology to you as well as the lay public, NO! You've already taken excerpts from the site, either mocked or denigrated it. Of course you don't agree with it, Using words like “propaganda”, “peddle” --that's real classy. So far, you're lashing at me and this techniology from reading my web site, and it's not familiar technology to you, applied to biomechanics. That's why there's a published article, and it's evidenced based..

    Telling me I'm “making **** up”--are you freakin nuts? I don't need to make anything up—you don't understand the science meld with biomechanics, and this is your science”: ““But how would it change the shape of the cast if you pronated the foot say 2 degrees, 5 degrees or 10 degrees from neutral? Moreover, when the person stands, there is going to be whole lot more than 10 pounds of force to the forefoot distal to the MTJ- right? “

    You don't recognize that a shift of 2 5 or 10 degrees or a force of 8lbs and 10lbs (when casting) will alter joint axis? AND you're just guessing, let alone not knowing exactly how much force you're applying (what you don't realize is that the correct adjustment for the planes of motion may be less than 1 degree and shifting it up to 10 degrees???--real science—real nice!-----and you think this is an accurate way to make a functional orthotic????? no wonder you're dizzy with real science. You're too batty about all your little theories.


    “This does not mean that foot orthoses cannot alter STJ moments, because they can in many instances cause significant changes in STJ moments, but their mechanical effect is not due to a "bracing" effect of the foot orthosis across the STJ axis. “

    Sincerely,

    Kevin


    You seem intersted in the STJ moments and mechanical effects (where you don't know the outcome)—how come you never said anything about fluid being displaced at heel contact to fill the arch and forefoot? (where I do know the outcome), and it isn't a “bracing” effect, it's a hydraulic effect.

    I'm glad you told me about meeting Dr Krinsky (we met around “88) and trying the SDO yourself. Unfortunately I know how Marty worked—he just threw a pile of crap against the wall and waited to see what stuck. When I got involved, I argued with him that there's too much to know how this works and what to expect and how to adjust it. I told him to do more follow up and support. He felt it would be insulting to try and educate this technology to his colleagues (he was WRONG!)Everyone of you failed (I blame Marty for that). It's taken me years to figure it out, especially after he died. It took thousands of cases to have the experience it took to understand how to make it work. I couldn't discuss it with him and you certainly wouldn't have been of any help.



    Maybe that's your problem, it just sounds too easy. There's a learning curve even with your biomechanical background.—You do remember this?--it is very painful for many podiatrists who are currently "comfortable" with their version of reality to change their "belief system". --Kevin Kirby


    Simon asked “when you say prolonged stability, how long is that exactly? “

    The real answer is that how long exactly, doesn't matter. What matters is that the forefoot and MTJ are stable at a point in stance phase (heel off) that a trad orthotic is becoming Unstable. That's what's important to me, not exactly how long. And I can see that biomechanical event and result taking place on a scan, both dynamically and statically (when we average out the stance time).

    You know in fact in all this time, not one person has addressed anything from the article. I presume it's because other than arbitrarily calling it “hogwash” you really can't refute it.


    Originally Posted by Jeff Root
    That's not the question. The question is how can you maintain the stj in neutral while applying a strong pronation force to the forefoot in an effort to get more pronation at the mtj?


    I appreciate that this may have not been the original question, Kevin has given his response to this already, but I'm interested to know the answer to the question I subsequently posed: viz. what difference does it make whether the subtalar joint is maintained in neutral during casting or not to the shape of the cast? Remember, all we are capturing during casting is an initial shape.
    All of you with the same problem, keep guessing, make a bunch of casts—chances are you can't even duplicate one cast to the other. And if all of you try to do it with the same pt—wanna bet there will be differences in each cast?--Not with fluid technology. I can interpret the Rx based on the outcome of the pt's biomechanics (think I'm making that up?)
    And if I have a Rx, then I can duplicate that Rx 10000 times, PRECISELY the same way each time.
     
  31. Dennis Kiper

    Dennis Kiper Active Member

    SPOONER

    I guess it depends where you insert the fluid and the difference this makes to the surface stiffness (Ksurf) in relation to the foot stiffness (Kfoot) and leg stiffness (Kleg). Effectively with any insole you are adding another "spring in series" to the foot/ leg spring mass system.


    TOTALLY INCORRECT.

    the only "spring in series" a good orthotic should provide is the proper biomechanical spring of the kinetic chain.

    Unlike the static performance of your traditional technology, fluid is displaced and guides the foot without bracing it.
     
    Last edited: Feb 27, 2014
  32. Dennis Kiper

    Dennis Kiper Active Member

    It doesn't just "bounce" the foot along
     
Loading...

Share This Page