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Predictors of overuse and foot/leg injuries

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Dean Hartley, Dec 21, 2009.

  1. Dean Hartley

    Dean Hartley Active Member


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    Hello all.

    The old way of thinking would lead us to believe that a pronated foot type is an accurate predictor of injury. Obviously it is not as clear cut as this. However I was after some info, or nudging in the right direction of where to look to determine what are the most likely predictors of foot/leg injury that we know of.

    Do we have enough research to know this?

    For example, if we were to take a group of middle aged workers, who stood on their feet for 8 hours a day, which of these people would be more at risk of developing symptoms?
    Is it those with a hard resup test? A functional hallux limitus? laterally deviated STJ? negative lunge test? BMI over 25?

    I understand there are loads of variables, but what biomechanical findings would we consider to be important when assessing these people and to determine if they were more 'at risk' of developing foot/leg pain.

    Any input would be appreciated.

    regards,
    Dean
     
  2. Griff

    Griff Moderator

    Dean,

    To my knowledge the only factor of those you mentioned which is predictive of pathology is the lunge test (Pope, Herbert & Kirwan, 1998).

    Ian
     
  3. Craig Payne

    Craig Payne Moderator

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    Foot pronation has not been shown to be a predictive factor in the vast majority of studies that have looked at it.
     
  4. Dean and Ian:

    Predictive is not a good word to use in this context since it implies certainty. How about saying, instead, that an abnormal lunge test is a risk factor for the development of certain injuries. Or you could say that an abnormal lunge test is associated with the development of certain injuries. However, you can't say an abnormal lunge test is "predictive" of certain pathologies since not all patients with an abnormal lunge test will develop any specific pathology.

    By the way, a pronated Foot Posture Index was found to be a risk factor in the development of medial tibial stress syndrome (Yates B, White S: The incidence and risk factors in the development of medial tibial stress syndrome among naval recruits. Am J Sp Med, 32:772-780, 2004).
     
  5. Admin2

    Admin2 Administrator Staff Member

  6. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    Yes, but it was only increased the risk by a small amount. Almost all of the other ~30 or so studies that have looked at foot pronation did not find an increased risk for injury in those with a pronated foot (one even found a pronated foot was protective of injury)
     
  7. Small is not the same as none.:drinks

    Here is another study that found a correlation between navicular drop and medial tibial stress syndrome.

     
  8. Here is another study that found that foot pronation (navicular drop) was a risk factor for the development of patellofemoral syndrome.

     
  9. Griff

    Griff Moderator

    Kevin,

    You're right - predictive is possibly a poor choice of words, and 'increased risk factor' may be better; however I took this verbatum from the abstract of the paper (attached):

    "Survival analysis indicated that ankle dorsiflexion range was a strong predictor of injury (p=0.03)."

    Ian
     

    Attached Files:

  10. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    And what about all the other studies that showed a pronated foot was not a risk factor for patellofemoral pain:
    Cross-sectional: - Powers et al (2002);Dierks et al (2008)
    Prospective: - Thijs et al (2008); Hetsroni et al (2006); Youri et al (2007); Nakhaee et al (2008)

    My 2 cross-sectionals and 4 prospectives trump your 1 prospective! :santa:
     
  11. Dean Hartley

    Dean Hartley Active Member

    Agreed.

    Craig, if I was to present you with a group of 100 people who carry out the same work activities (lets say a mixture of standing and walking) over an 8 hour period would you be able determine which of the workers were at greater risk of developing overuse injuries or painful legs/feet?

    Im not asking if you could distincively say that x amount of people will suffer from this condition in x amount of time. However do you think you could group these people into who were say 'at-risk' or 'not at-risk'. Does all the research we have enable us to have more of informed decision, rather than the old way of saying "you have flat feet, so you will have problems"?

    If you believe this could be done, what are the 'risk factors' you would be basing it on?

    Regards,
     
  12. I'll spend another five minutes on the internet and come up with a few more prospective studies. Looks like we can at least say that now a few studies do show a correlation between foot pronation and certain injuries.:drinks
     
  13. efuller

    efuller MVP

    When thinking in terms of tissue stress, your measurement variable should be compared to a specific pathology. For example, a medially deviated STJ axis, or a difficult resupination test would theoretically be associated with posterior tibial dysfunction. Whereas a laterally positioned STJ axis and easy supination resistance would theoretically be more likely to be associated with peroneal tendonitis. Posterior tibial tendonitis and peroneal tendonitis are both foot/leg pain. If you did a study looking at foot/leg pain and axis position you might not find andy correlation. However, if you looked at the individual pathologies you might have significant findings.

    Cheers,

    Eric
     
  14. Genetics and enviromential factors about the only things that I can think of which may effect with any degree.
     
  15. Predictive modelling is a fantastic topic. The problem with many of the correlational studies which have been performed is that they only attempt to fit to a linear model (y= mx +c, where m = slope of line and c = constant intercept value). So, lets say we have a poor linear fit between two variables (as Kevin said small r square is not zero r square), what this tells us is that the relationship between the two variables does not fit the linear model well. It does not tell us whether or not the data fits another function, for example quadratic, cubic etc. As far as I am aware this non-linear modelling has rarely been attempted within the literature pertaining to foot pronation as a predictor. Rather the data is tested against a linear model and if it doesn't fit well, the authors report that pronation is not a predictor of y; this isn't the correct conclusion to draw. The correct conclusion in such circumstances is that the relationship between pronation and y is poorly defined by the linear model.

    Another problem is that of measurement scale. Lets say we measure pronation in degrees and use that as an independent variable and model it against a dependent variable using a linear model and find a poor fit to the model. By performing a scale transform on the data, for example taking logs of the degree data we may induce a better fit of the data to the linear model. If memory serves, this is the transform performed for monofilaments in order to derive a linear fit, so it's not 10g, it's log10g that is predictive.

    Multivariate models are better than bivariate models as we can begin to unravel the co-dependency between variables, but common sense needs to be employed and where necessary new variables created. For example I've seen models that include both height, weight, and BMI as independent variables- there is obviously co-dependency here. So, why was this not addressed?

    When reporting predictive models the 95% confidence intervals should also be reported along with the line of best fit, that way the clinical usefulness may be better established, lets say we have a model which predicts hallux abductus angle but the confidence intervals are +/- 10 degrees- how clinically useful is this model?

    Risk can be established from predictive models along with the probability of the model reporting a false positive or negative.

    Other factors of importance include the way in which outliers are dealt with in the data set.
    There are whole books written on this topic, I'll find some references if I get time.

    Hope this helps.
     
  16. Here is another prospective study that shows an increase in overuse injuries in triathletes with more supinated foot types.

     
  17. Here is yet another prospective study that shows an increase in overuse injury in indoor football players with more supinated/high arched feet.

     
  18. So, after doing a few minutes of scouring the internet I have found that:

    1. There are a number of clinical tests that show an association with injuries to the foot and lower extremity.

    2. Foot pronation has been shown to be a risk factor in a number of studies for certain injuries.

    3. High arched feet have also been shown to be a risk factor in certain athletic injuries.

    Anyone want to take some more time to find other risk factors associated with foot and lower extremity injuries?
     
  19. Dean Hartley

    Dean Hartley Active Member

    Increased BMI is a risk factor

     
  20. Craig Payne

    Craig Payne Moderator

    Articles:
    6
    You can not determine risk from a cross-sectional study. Only correlations can be determined from cross-sectional designs.
     
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