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The Effect of an Antipronation Foot Orthosis on Ankle and Subtalar Kinematics

Discussion in 'Biomechanics, Sports and Foot orthoses' started by NewsBot, Sep 12, 2012.

  1. NewsBot

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    The Effect of an Antipronation Foot Orthosis on Ankle and Subtalar Kinematics
    Liu, Anmin; Nester, Christopher James; Jones, Richard Keith; Lundgren, Paul; Lund-berg, Arne; Arndt, Antony; Wolf, Peter
    Medicine & Science in Sports & Exercise 10 September 2012
  2. full text anyone?

    I've been waiting for this one to come out for some time. I have to say on the basis of the abstract alone, I'm a little disappointed: which paradigm says the effects of foot orthoses occur only at the subtalar joint and are just kinematic in nature? I think it's pretty obvious that the kinetic effects of foot orthoses span multiple joints and that given the tri-planal motion available within the ankle mortice there will be potential for some kinematic effect here. A more interesting question is why some people show greater effect at one of the joints of the ankle complex than another?
  3. Unfortunately, the foot orthoses used were prefabricated orthoses.:confused:
  4. Rob Kidd

    Rob Kidd Well-Known Member

    Sorry to be difficult - but I am not being so............. Why are you disapointed that the orthoses used were prefabricated? When one of my staff (Karl Llandorf) did a comparative study (admittedly on a narrow range - heel pain), I seem to remember that they were just as effective. The questionis this: is there any hard evidence, from correctly conducted RCT's, that bespoke orthoses are more effective for any particular symptoms than prefabs? I could do with knowing - I am teaching full time next year! Rob
  5. Personally I'm not too bothered that the study in question used prefabricated devices (so long as we recognise the limitations of doing so). Kevin, Paul Scherer and I recently contributed to a paper which I believe will be published in November or December this year, within this paper I outline my thoughts on why over the counter devices may be perceived as being just as effective as custom foot orthoses.

    Here's a study as requested:
  6. CraigT

    CraigT Well-Known Member

    The effect of the foot orthoses was unsystematic- so the same orthosis has a different effect on different subjects. This is useful information. Now... will changing the orthoses have a different effect on the same subject???
  7. Rob:

    The reason I was somewhat disappointed about the use of prefab orthoses in this otherwise excellent study is that prefab orthoses are generally much more compressible, more deformable and they are all the same morphology when compared to custom foot orthoses made of, for example, polypropylene.

    If these relatively deformable identically-shaped orthoses are now applied to three individuals with low arch, medium arch and high arch feet, the low arch foot will have a relatively high magnitude of pressure in the medial longitudinal arch (MLA), the medial arch foot will have a medium magnitude of pressure in the MLA and the high arch foot may have minimal pressure in the MLA. Therefore, since the prefab orthoses do no all exert the same plantar pressures in the MLA of all foot shapes, we would expect non-systematic changes in foot kinetics and kinematics due to the highly variable changes in MLA plantar pressure changes with use of these orthoses.

    This is not to say that prefab orthoses are not helpful for many people, since I use them regularly, and find them sometimes very effective for my patients. However, I also routinely modify these prefab orthoses to more closely contour the MLA of my patients' feet since, after a quarter century of doing so, I know that they simply work better for the patient when I do so for them. Therefore, unless researchers account for the variable changes in contact pressures between the prefab orthosis and various regions of the plantar foot that would be expected with the use of such an in-shoe device in a number of subjects with non-identical foot morphology and foot function, they may not be able to adequately explain the results of their experiment.

    Hope this helps.:drinks
  8. Rob:

    In Landorf's study, all of the orthoses used were custom-molded to the foot. If insoles are custom-molded to the foot then, by definition, they are custom foot orthoses, not prefab foot orthoses.
  9. Rob:

    Here is another nicely done study comparing pre-made insoles to custom foot orthoses by a few of your own colleagues from Oz which show the superior therapeutic benefits of custom vs premade insoles.

  10. blinda

    blinda MVP

    I`d like a copy? Feel like I`m missing the party.....

    Thanks Kevin ;):drinks
  11. It really doesn't matter how deformable the devices are. The problem with foot orthoses research at present is that we should likely find the kinetic effect of all of the foot orthoses employed within a study to be unique to each subject, regardless of whether the devices employed were compliant or stiff, custom made or prefabricated foot orthoses. In other words, if we accept that foot orthoses “work” by altering the kinetics at the foot–orthosis interface, at present, each subject within the published trials is likely to be receiving a different kinetic “dose.” This is analogous to performing a drug trial in which each of the participants receives a different, unknown dose of the drug. Hardly surprising then when unsystematic results are reported. At best, the trials are a series of n=1 case studies; as are "real life" clinical cases.

    You may say that at least the orthoses are standardised when we perform a study using prefabricated devices. Be cognisant though that foot orthoses work by altering kinetics at the foot-orthosis interface and that they can only directly do this by: a) altering the surface topography at the foot-orthoses interface b) altering the load/ deformation characteristics at the foot- orthoses interface c) altering the frictional characteristics at the foot-orthosis interface. Together, these three characteristics are the orthoses prescription variables. Thus, if the subjects within a trial use different size versions of the prefabricated device, they may be getting a different prescription in terms of at least some of these variables.
  12. You can't have it both ways Prof. Kirby- it's my understanding that the "sham" devices in the Burns study were constructed in the same manner to those employed within the Landorf study. i.e., they were custom molded; viz. they were custom foot orthoses ;):drinks
  13. So you are saying that the stiffness of a foot orthosis has no mechanical effect on the foot, Dr. Spooner?
  14. No. I'm saying that the kinetic effect of a foot orthosis is unique to the individual wearing it regardless of whether the device is relatively stiff or compliant. When are we all coming to the biomechanics summit in the mountains?
  15. So, two foot orthoses are made with the same morphology, one being highly deformable (i.e. less stiff) and the other one being much less deformable (i.e. more stiff). Are you saying then that the deformability (i.e. stiffness) of these two orthoses will have no difference in their mechanical effects on the foot? What were you really trying to say when you wrote this?

  16. Sorry, Dr. Spooner, you are wrong. The study by Burns et al used a "sham insoles made from flat, nonsupportive, 3-mm latex foam, a material shown to be
    least effective at reducing pressure." The study by Landorf et al used the following protocol:

    However, I need to also correct myself, two of the devices used by Landorf et al were custom molded, one was prefab.
  17. What I'm saying is that if we have two different feet, that belong to two different people and they walk in your two different types of devices, the kinetic change that occurs will be unique to the individual regardless of whether the device is stiff or compliant. Your original post seemed to me to intimate that this inter-subject variability in the kinetic effect of foot orthoses would only occur in compliant prefabricated devices, when in reality it will occur in any kind of device.

    Place me in your stiff devices and record the kinetics as I walk; now place you in the same devices and record kinetics- different twixt me and thee, right?

    Now place me in your compliant devices and record kinetics as I walk; now place you in the same devices and record kinetics- different twixt me and thee, right? Different within me in the two types of device too; different in you in the two types of device too.

    But, it doesn't matter whether the devices are complaint or stiff, custom or prefabricated, the kinetic effects will be different in me and you. It's the inter-subject variation in the same devices I was referring to. Now, stop pretending you don't understand and get that meeting organised at the cabin. I could do with some California dreaming (Spooner is across the lake and Reno is just down the road).
  18. Simon:

    Thanks for better explaining yourself. That is what I wanted since you are ....... da man.:drinks
  19. I stand corrected (just as Mert would have wanted it). ;)
  20. As I recall, and again I'm happy to be corrected, Josh commented on this and stated that plantar pressures were altered by the "sham" orthoses. Reality is: you can't put an insole in a shoe and expect it to be inert in terms of kinetics. Anyway, back to the plot: I know they stuck a lot of bone pins in those feet over in Sweden: midfoot kinematics paper?
  21. We'll need to work on that. However, I'm afraid that all of the seminar registrants would rather be hiking, fishing, exploring old gold mines and riding mountain bikes rather than discussing midfoot kinematics.;)
  22. I still want to do that paper on rotational equilibrium across the midtarsal and midfoot joints that I originally planned on doing about 10 years ago.:drinks
  23. Ian Linane

    Ian Linane Well-Known Member

    "However, I'm afraid that all of the seminar registrants would rather be hiking, fishing, exploring old gold mines and riding mountain bikes rather than discussing midfoot kinematics."

    oooooh, field trips as well!! I can see the paper coming out from this.

    "The carrying of 10lbs of gold in the pocket and its impact on the kinetics of foot function over rough terrain in minimalist footwear as opposed to barefoot or military boots whilst avoiding snakes or snake oilsmen"
  24. Never found any gold, but lots of quartz.

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