The effect of customised and sham foot orthoses on plantar pressures

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The effect of customised and sham foot orthoses on plantar pressures
Chris J McCormick, Daniel B Bonannod and Karl B Landorf
Journal of Foot and Ankle Research 2013, 6:19

 

Not before time. Congratulations to the authors. I've been saying this for some time now, but to reiterate: you cannot put something into a shoe and expect it to be "biomechanically inert".

 

agreed

what would you have as a control type group to test devices ?

or just use the sham device but not that there will be changes ?

 

I believe the authors of this study did expect their "sham insole" to be biomechanically inert or "to provide minimal structural support for the foot."

http://www.formthotics.com/images/s..._Foot_Orthoses_to_Treat_Plantar_Fasciitis.pdf

Here is where we discussed this paper on Podiatry Arena.

http://www.podiatry-arena.com/podia... orthoses plantar fasciitis: randomised trial

Very interesting!

 

Yep, interesting that I made this comment regarding the Landorf study at it's time of publication in 2006: http://www.podiatry-arena.com/podiatry-forum/showpost.php?p=11883&postcount=18

 

Simon:

Is a fooot a long foot?

 

Yep, but not as long as a foooot. I'd already spotted that but since it was back in 2006, I was only 12 years old then.

 

It's difficult, Mike. I guess the best you can do is to minimise the influence that the control orthoses have upon the variable of interest; quantify the kinetic effects of all of the foot orthoses employed within a study and attempt to standardise the kinetic dose across subjects within the treatment and then the control groups.

 

The term sham foot orthosis is oxymoronic(is that even a word?)

We have all had patients who have been "cured" of their plantar fasciitis by the most ridiculously flimsy insoles.

Like anything internally or externally with respect to the footwear/foot orthoses, they have effects and cannot be discounted

Kinetic quantification of some sort is required but it has to be footwear/foot orthoses combined, not just the foot orthosis

 

One idea would be to use a flat material that has the same durometer as the shoe midsole as a sham insole. In that way, there would be minimum change in plantar foot pressures.

Another option would be to use an over-the-counter insole that is readily available, not modified and is of a construction that isn't so high in the medial arch that flatfooted subjects would experience discomfort with it. This would at least serve as a baseline control insole that is readily available to the public to compare in biomechanical effects to a more customized, form-fit orthosis such as would be made by a podiatrist, pedorthist etc.

I didn't like the "sham insole" in the Landorf et al study (Landorf KB, Keenan AM, Herbert RD: Effectiveness of foot orthoses to treat plantar fasciitis. A
randomized trial. Arch Intern Med, 166:1305-1310, 2006) since the sham insole was " fabricated by molding 6-mm, soft (120 kg/m3) ethyl vinyl acetate foam
over an unmodified cast of the foot." In other words, not only was 6 mm of cushioning material added under the heel of the foot, but it also was custom molded to the contours of the plantar foot. Certainly this "sham insole" used in the 2006 Landorf et al study was more of a custom-molded soft foot orthosis than a "sham insole" in its biomechanical effects on the foot.

My opinion above about the 6 mm EVA custom molded orthosis not being a "sham insole", which I expressed publicly on Podiatry Arena at the time of the 2006 study, certainly is now confirmed by the more recent research performed by McCormick et al which shows that the "sham insole" was quite effective at reducing peak pressures under the heel (McCormick CJ, Bonannod DB, Landorf KB: The effect of customised and sham foot orthoses on plantar pressures. J Foot Ankle Res, 6:19, 2013.) It would have made more sense to me to perform the 2013 study before the 2006 study so that better conclusions about the effectiveness of custom foot orthoses could have been drawn from the 2006 study.