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Sham orthosis

Discussion in 'Biomechanics, Sports and Foot orthoses' started by chonga@usq.edu.au, Dec 15, 2014.

  1. chonga@usq.edu.au

    chonga@usq.edu.au Welcome New Poster

    Members do not see these Ads. Sign Up.
    I am a new member and I speciliased in spatial sciences.
    My research is in the analysis of human motions
    I have been scratching my head over the term "sham orthosis"
    Could someone please tell me what is the word SHAM in sham orthosis mean?
    Thank you. albert
  2. Craig Payne

    Craig Payne Moderator

    A sham orthotic would be one that has no mechanical (kinetic or kinematic) or neurological effects, but somehow tricks the person wearing it into believing that it is a real foot orthotic --> that would make it a perfect "control", "sham" or "placebo" intervention in a clinical trial.

    eg look at some of discussion here: Custom made vs sham foot orthotics for achilles tendinopathy
  3. chonga@usq.edu.au

    chonga@usq.edu.au Welcome New Poster

    Hello Craig and Kevin,
    Thank you very much.
  4. The problem with a "sham" orthosis, is that, some researchers think that anything that isn't a custom molded plastic orthosis is a "sham orthosis". For example, in some studies, the "sham" orthosis used was a custom-molded foam orthosis that probably had significant kinetic and possibly kinematic effects on the study subjects that wore them. Is this the proper way to do a study? I don't think so.

    Any material placed into a shoe has a mechanical effect on the foot so that it is likely that a true "sham" orthosis is not like a placebo, in a drug trial, where no physiological effect should be detected. Rather, a "sham" orthosis should be a non-molded over-the-counter orthosis that does not fit the plantar aspect of the subject's foot well and is not customized in any way to the patient's foot. However, this "sham orthosis" will still produces some mechanical effects on the foot, regardless of what the researchers would like to believe.
  5. From another standpoint... a sham orthosis is one advertised as being "custom molded"
    to a model of the foot.

    Instead, the negative cast or digital image is matched up to an existing model pulled from a "library" of models and fabricated off of that.

    This is not a problem if it is presented for what it truly is...an arch support.

    If you want to assure that the orthosis is made from the cast of the patients foot, make sure to ask your lab to return the positive model to you with the orthotics.

    If the lab gives any pushback about returning the positive casts to you...red flag!
  6. And that, is impossible. Thus we are left with imperfect "sham" devices, which I should have no problem with provided the mechanical effects of these were thoroughly investigated and reported within the trials. In fact, loose the word "sham" and just compare two differing insole designs with known mechanical effects. Which would be an improvement on the current situation of using two different insole designs with unknown mechanical effects.

    The trouble with orthoses research is that some have tried to run with it, when really we are only at the learning to walk stage at the moment. We really can't skip the basic ground work and jump straight to the controlled trial, which is what has occurred here.
  7. If we know that an insole reduces peak pressure beneath the heel by 10%, what influence might this have on the joint moments at the joints of the rearfoot complex and the knee? Out of interest, what is roughy 10% difference in peak pressure in N/cm>2 as measured under the heel during walking in an average weight subject?
  8. I agree with Simon that to assume that an insole is a "sham orthosis" without first studying its kinematic and kinetic effects on subjects and/or on the central nervous system's control of locomotion patterns is not a positive way to move forward toward our understanding of the effects of foot orthoses on foot and lower extremity biomechanics. I don't so much have a problem with the term "sham orthosis" as long as this "sham orthosis" is first studied so that we can develop a baseline as to how this 'sham orthosis" affects the kinetics and kinematics of the foot and lower extremity.

    Simon is right in that we first need to do some basic research on how even simple insole designs (or what we may use as a "sham orthosis" in a research study) mechanically affect the foot and lower extremity, and how the central nervous system responds to these insole designs, before we rush forward and assume that putting a flexible, custom-molded foam insole inside a shoe of a subject produces no mechanical effect on the foot or lower extremity or on the central nervous system's control of locomotion patterns.
  9. Yet if we accept Craig's definition of what a sham orthosis should be:

    Then any orthosis which has demonstrable kinetic and kinematic effects is not a sham orthosis.

    I think the terms "sham" along with "placebo" have an implicit understanding in medicine. When one reads these words within clinical trials, one assumes that the interventions being applied are totally inert in terms of any known therapeutic effects. I think the use of this term in foot orthoses research is, at best, misleading to the reader who may not be familiar with the therapeutic effects of foot orthoses because by definition foot orthoses work by altering forces. Since anything that goes into a shoe alters forces, there is no such thing as a sham insole. Hence- loose the term and stop trying to pretend that the insoles are kinetically inert when they are not. They are not "sham's" nor "placebo's"; they are just another insole.
  10. A "placebo pill" does have physiological effects, but they are not significant compared to the drug being tested. In much the same way, I don't have a problem with the term "sham orthosis", as long as the orthosis effects have been tested previously and their kinetic and kinematic effects are minimal. However, I agree with you, Simon, that an even better idea would be to not use the term "sham orthosis" at all, and, instead, replace it with a term such as "control insole".
  11. I think we concur, Kevin. But for arguments sake I would say that within a study you would not use a placebo pill which has a physiological effect that is known to be therapeutically active on the condition of interest as this would not be classed as a placebo AKA "sham". Since kinetic change, is the therapeutically active "ingredient" in foot orthoses, you cannot call anything a sham nor placebo that you put into the shoe which changes kinetics, i.e., anything!

    I agree call it a "control insole" and have it as a required minimum standard to report the kinetic and kinematic influences of these within any trials in the same way that one has to make a written disclosure of ethical considerations prior to publication. That would be a move forward.
  12. I love a good argument. Doesn't a sugar pill have a physiological effect? Of course it does.....just a negligible physiological effect.;)
  13. But if you were looking into the effects of an active sugar pill on insulin levels versus a placebo pill, you wouldn't use a sugar pill as your placebo because that wouldn't constitute a placebo - right? Which is what is going on here: the active "pill" contains "kinetic change" and so does the "placebo". When sugar is the driver for the physiological effects being observed, having both the study pill and the placebo containing sugar is not the way forward, because the placebo is no longer a placebo nor "sham", it's a comparable drug with a different dose of active ingredient. Which I would wager is why some authors have tried to play the "it's the kinematics which cause the injury and the "sham" foot orthoses is only known to alter kinetics, then thats OK" card. Cobblers as we both know. In the drug research we can measure how much sugar is in the pills. The trouble with foot orthoses research, as it stands, is that everyone is getting the active pill, but we have no idea of the dose and they're all getting something different, so making comparison across or even within groups is pretty meaningless.

    Tell me I'm wrong, boss ;)
  14. Craig Payne

    Craig Payne Moderator

    Maybe the solution is not to call them "sham orthotics" and call them something like "foot orthotic shaped devices made with a very flimsy material".

    Then there would be not "foot orthotic" vs "sham orthotic", it would be a comparison between two different type of foot orthotics. Obviously the two will have different design features - one obviously designed to have a significant effect and one designed to have a minimal (or no) effect.

    In a perfect world, each subject in the study would have the response to the foot orthotics measured - then the publication can say that they compared orthotic A that had these design features and had this effect to orthotic B that had these design features and had this effect.
  15. We may have to agree to disagree on this. I think adding a 1 mm thick piece of flat foam inside of a shoe and calling it a "sham orthosis"would be analogous to giving a sugar pill and calling it "a placebo".

    The bottom line is, regardless of whether the insole used as a control in a study is called a "sham orthosis" or a "control insole", I believe we both agree that, in most research studies where a "sham orthosis" was used, the "sham orthosis" may very well have had a significant mechanical effect on the foot so should not have been called a "sham orthosis" in the first place.
  16. Lucy Hawkins

    Lucy Hawkins Active Member

    Presumably to compare results you need to use a standardised shoe as well, with a sole of known stiffness and shock attenuation, or at least declare it in your protocol.

    I'm quite sure that I walk differently in my walking shoes with a firm and stiff 'Vibram' sole with a pronounced rocker bottom and supporting upper than I do skipping around in my pumps with a sole only a few mm thick, slip on and can be folded in half between two fingers. My other shoes vary.

    Oh yes, and my socks as well, pop sock in the pumps and good comfey socks in the walking shoes. It can't make any difference can it.


  17. Craig Payne

    Craig Payne Moderator

    Not necessarily. The whole idea of "randomization" is that the two groups (or 3 or whatever) you get from the randomization process are the same in all characteristics. With regard to shoes, this means that each group will have equal numbers of good shoes, bad shoes, particular types of shoes etc. The only difference between the groups is the intervention under investigation.

    If you want to standardize shoes, then you going to have to standardize BMI, activity levels, height, etc etc - all these should be equally distributed between the two groups if the randomization is done properly.

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