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Structure and function of the asymptomatic foot

Discussion in 'Biomechanics, Sports and Foot orthoses' started by NewsBot, Oct 31, 2012.

  1. NewsBot

    NewsBot The Admin that posts the news.


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    Foot type biomechanics part 1: Structure and function of the asymptomatic foot.
    Hillstrom HJ, Song J, Kraszewski AP, Hafer JF, Mootanah R, Dufour AB, Chow BS, Deland JT 3rd.
    Gait Posture. 2012 Oct 26.
    Foot Type Biomechanics Part 2: Are structure and anthropometrics related to function?
    Mootanah R, Song J, Lenhoff MW, Hafer JF, Backus SI, Gagnon D, Deland JT 3rd, Hillstrom HJ.
    Gait Posture. 2012 Oct 26
  2. efuller

    efuller MVP

    Well, I guess its good to show that asymptomatic feet can have different shapes. It is a lot harder to do a study that links measurements to pathology, but that's what I'm intereseted in.
  3. I'd like to read the full-texts, but this jumped out: "When walking speed was included, the adjusted R(2) increased to 45-77% but foot structure was no longer a factor."

    I'm not familiar with concept of r square providing a range? Unless, they are including a number of models within that.
  4. Griff

    Griff Moderator

    Emailed them both to you.
  5. OK, part 1, first read:

    They talk about foot-types being associated with pathologies, but despite their sample showing individuals with the 3 different foot-types, all subjects were asymptomatic. Which kind of begs the question of whether foot-type is a good predictor of pathology in the first place, don't you think?

    They categorise the subjects foot-type using a Root type classification; measuring angles presumably with skin markers and a goniometer:

    " planus: RCSP >/= 4 degree valgus OR FF-RF >/= 4 degree varus
    rectus: 0 degree </= RCSP </= 2 degree valgus AND 0 degree </= FF-RF </= 4 degree varus
    cavus: RCSP >/= 0 degree varus AND FF-RF >/= 1 degree valgus
    RCSP and FF-RF were measured with a 1 degree resolution goniometer."

    Yep, the goniometer may have a 1 degree resolution, but that doesn't mean you are reliably measuring to within a degree. I think most of us will realise that the error in measurement using this approach will be appreciably higher. Some of these subjects may have been put into the wrong foot-type subset due to error in the goniometric assessment process. Reliability of their other structural measures isn't really addressed either.

    They normalise arch height flexibility data using 0.4 x body weight; the 0.4 seems to be a guess, I'm not sure why they didn't just quantify the change in loading and normalise to this since they were using apparatus within the study which could have done this?

    Pressure platform problems have been described elsewhere, I won't go into detail here.

    They pooled right and left foot data, although they accounted for the potential covariances in their models, this type of pooling has previously been questioned- Craig?

    They point out the difference in mean age of the cavus foot-type group; could age differences confounded their results?

    No significant differences in arch height flexibility across the groups- could this be due to the manner in which the data were normalised (see above)?

    Not sure how they arrived at a minimally important clinical difference of 15%?

    They state: Although there were no differences across foot types, AHF was clinically interesting. Flexible pathologic feet may be treated with foot orthoses, but rigid feet may require surgical reconstruction."- Really?

    "In light of this information, the first hypothesis, measures of foot structure (MVI, AHIsitting, AHIstanding, and AHF) will be different across foot types, was accepted." Given that the feet were categorised by structure in the first place, I don't think this is too surprising. It shows that the Rootian protocol is sensitive enough to predict variation in these other structural measures or vice versa.

    The differences in the kinetic variables are interesting particularly when we view them in light of this statement: "From this data, AHF was not a function of foot type
    and there was an equal likelihood of having a flexible or stiff arch for planus, rectus, or cavus feet." The key being during dynamic function the loading applied to each foot-type will be different, so while the load/ deformation of the foot may be similar in magnitude following a sit to stand manoeuvre, during gait the loading pattern will be appreciably different in each foot-type and therefore the magnitude of the deformation each foot-type displays will be different; this has implications for the stress within specific tissues, within specific foot-types.

    Nice paper.
    I'll look at part 2 later.
  6. NewsBot

    NewsBot The Admin that posts the news.

    Kinematics and kinetics of normal and planovalgus feet during walking☆
    Prabhav Saraswat, Bruce A. MacWilliams, Roy B. Davis, Jacques L. D’Astous
    Gait & Posture; Article in Press

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