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Foot orthoses research: identifying limitations to improve translation to clinical knowledge and pra

Discussion in 'Biomechanics, Sports and Foot orthoses' started by NewsBot, Oct 28, 2016.

  1. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
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    Editorial
    Foot orthoses research: identifying limitations to improve translation to clinical knowledge and practice

    IBr J Sports Med doi:10.1136/bjsports-2016-096269 27 October 2016
    an B Griffiths, Simon K Spooner
     
  2. Admin2

    Admin2 Administrator Staff Member

  3. Ian Drakard

    Ian Drakard Active Member

    Good job. Any chance of a copy please?
     
  4. Petcu Daniel

    Petcu Daniel Active Member

    As the reaction force is a vector I think taking into consideration another of its characteristic which is "the direction", value could be added to the way in which foot orthoses exert their therapeutic effect. Because, supposing the magnitude, location and timing remain unchanged (only theoretically - just to highlight "direction" role) the reaction forces will remain constant but the moment created by the reaction force will be changed when its direction is modified. Of course, the moments created by reaction forces are influenced by the location, direction and magnitude. Even if the force reaction location is under the subtalar joint transverse plane projection, a pronatory or supinatory moment still could be created through the "direction" of reaction force vector modification.
    Daniel
     
  5. Agreed, but as the word count we where given here was ridiculously small, every word counted. I discussed this here: https://www.ncbi.nlm.nih.gov/pubmed/21084541

    Ian Drakard did you get a copy? If not send me your E-mail
     
  6. efuller

    efuller MVP

    It is a reaction force, so if the direction is changed, the motion will be changed. If you change the direction in the frontal plane, there will have to be some frontal plane acceleration of the body. On the other hand, the a direction change in the AP direction would cause an increase or decrease in the velocity of gait. I'm having a hard time imagining how an orthosis is going to change sagittal plane forces. There might be change in muscle activation, but I don't see how an orthosis changes sagittal plane direction of forces.
    Eric
     
  7. Net GRF will be a function of the surface angulation and the frictional co-efficients acting at the interface.
     
  8. Ian Drakard

    Ian Drakard Active Member

    Cheers Simon- got sorted :)
     
  9. ...and the direction and velocity of the motion and spatial location of the center of mass relative to the ground during the weightbearing activity.
     
  10. Petcu Daniel

    Petcu Daniel Active Member

    Indeed the article is discussing in great detail the problem of line of action of GRF (or direction) but the article is starting mentioning the same parameters of GRF vector : "Foot orthoses are believed to exert their therapeutic effects by modifying the location, magnitude, and timing of ground reaction forces (GRFs) acting on the plantar foot"! I believe mentioning "direction" could be of help as this could be, for example, an outcome in the evaluation of the orthoses.
    Daniel
     
  11. Petcu Daniel

    Petcu Daniel Active Member

    There is an article ( http://www.thefootjournal.com/article/S0958-2592(01)90713-8/abstract ) who shows that "alterations to the sagittal plane ground reaction force vector angle (GRF)" produced by functional foot orthoses "were small (<2.78 degrees) and warrant further research as no papers relating to this parameter of measurement with foot orthoses could be found."
    Daniel
     
  12. efuller

    efuller MVP

    The abstract says very little about how the vector angle changed. When I was in podiatry school one thing that was taught about orthoses was that they increased the propulsiveness of gait. I think this is one thing they got right. Winter's studies on joint power show that there is a trade off between ankle push and hip pull in making the trailing leg become the swing leg. If there was increased ankle push, you expect to see increased posterior to anterior shear from the ground applied to the foot. This would change the angle of the ground reactive force vector in gait. I wouldn't say that the orthosis is doing this directly. What the orthosis does is allow the ankle plantar flexors to contract more creating more ankle push. My theory is that the orthosis creates an environment where the foot is better able to withstand the stress of ankle push. Then the body chooses to use ankle push more. So, you may see a larger horizontal component of ground reaction force with orthoses, but is it really the orthotic that is causing that, or is it a change in muscle function?

    Eric
     
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