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RCT on foot orthotics for low back pain

Discussion in 'Biomechanics, Sports and Foot orthoses' started by NewsBot, Jan 18, 2013.

  1. NewsBot

    NewsBot The Admin that posts the news.


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    The short-term effect of custom-made foot orthoses in subjects with excessive foot pronation and lower back pain: A randomized, double-blinded, clinical trial
    Aurora Castro-Méndez, Pedro V Munuera, Manuel Albornoz-Cabello
    Prosthet Orthot Int January 17, 2013
  2. Admin2

    Admin2 Administrator Staff Member

  3. Anyone seen the full text of this?

    I'll be honest, I'm really surprised!
  4. davidh

    davidh Podiatry Arena Veteran

    Hi Rob,

    I can't make out if it's been published yet.

    What are you suprised about?
  5. That they were able to make placebo foot orthoses for a starter.:morning:
  6. Surprised because

    A: Thats a pretty substantial statistical certainty for a pretty small group

    B: One of my bugbears with the concept of orthotics for LBP has always been that the indiscriminate use (as in picking 50 people with LBP and "excessive pronation") presumes that the cause of the LBP is always weight bearing function. I'm no back specialist (Wedemeyer, where are you?) but I would imagine that LBP could have a spectrum of causes. Lots of driving. A bad mattress. Poor posture when seated at work. Injury. Being a lazy person who sits slouched on the sofa all day eating sugar puff sandwiches and watching Jeremy Kyle. Certain sports. Barefoot running :rolleyes:.

    We have no way of knowing how much of back pain is caused by what, but I think its probably safe to assume that if its one of the above, the orthotics won't have a great deal of impact on the pain of somebody who, for example, only leaves the house three times a week, or only gets the benefit of the orthoses for the 140 yards between their office chair and their car, and then the 20 yards from their car to their sofa.

    In a study like this, those people should have a tremendous drag factor on the results. Lets say, hypothetically, that 50% of back pain is caused by WB activity. That means of the 25 in the treatment group, only 12 had any real chance of genuine improvement caused by the orthotics, making it twice as hard to reach statistical significance.

    And yet, they did. Call me a cynic but my spider sense is tingling.
  7. davidh

    davidh Podiatry Arena Veteran

    In this case I wouldn't like to express surprise in either placebo orthotics design or statistical findings until I'd seen the whole paper.

    Not saying either of you are wrong BTW, although I think most of us could have a pretty good stab at a placebo orthosis if the actual effective orthosis is effective at holding the STJ in an approximation of neutral on a hard, flat surface, in stance. In other words most of us could make an orthosis which would allow calcaneovalgus to go unchecked.
  8. But would that make it a placebo orthotic ;)

    You were one of the people who introduced me to the notion that an orthotic does NOT hold the STJ in an approximation of neutral. Thats not what they're for.

    We still don't really understand all of how an orthoses work and unless we can confidently describe IN FULL the effects of any given device, we can't really make a placebo.

    For example, I could make a shaped, Non shank dependant device out of low density plasterzote and be reasonably confident it would not greatly alter the ORF. However nobody could tell you the effect that increasing the amount of the ground in contact with the foot would have on the exteroceptive feedback, and whether that would alter muscular patterns, because that would vary between patients, shoes, socks, and probably time of day, mood of the wearer. Nor could they quantify the hawthorn effect, nor the effect of the cushioning under the heel, nor the thermal effect... Etc etc etc.
  9. davidh

    davidh Podiatry Arena Veteran

    It may make it a placebo orthotic for the purposes of the researchers - we don't know, because we don't have all the data.

    An orthotic may hold the STJ in an approximation of neutral in stance........ just as it may reduce calcaneovalgus in stance.
  10. blinda

    blinda MVP

    Hmmm. How can it `hold` "the STJ in an approximation of neutral in stance......"
  11. Hold, (verb)- To keep from falling or moving.

    An insole cannot keep the sub talar joint from moving. In ANY position (much less sub talar neutral.)
  12. davidh

    davidh Podiatry Arena Veteran

    I believe we're moving into semantics now people, but looky here:

    To have and keep in one's grasp: held the reins tightly.
    b. To aim or direct; point: held a hose on the fire.
    c. To keep from falling or moving; support: a nail too small to hold the mirror; hold the horse steady; papers that were held together with staples.
    d. To sustain the pressure of: The old bridge can't hold much weight.

    (Defn of hold picked at random from Google)

    An orthotic with a medial heel wedged at, oh - I don't know - lets say 4 degrees varus;), will ensure that the orthotic itself will remain stable in the frontal plane when placed on a hard flat surface, such as a clinic or lab floor. If the material it's constructed from is stiff enough it will help to support the calcaneus in stance phase in something resembling vertical.

    I concede that my choice of the word hold may not have been great.:eek:
  13. Foot orthoses are believed to exert their therapeutic effect on the human locomotor apparatus by altering the location, magnitude, and temporal patterns of ground reaction forces acting on the plantar foot during weightbearing activities. If you put a "placebo" foot orthosis in a shoe and it alters any of these, then it isn't a placebo foot orthosis, it's a foot orthosis.
  14. davidh

    davidh Podiatry Arena Veteran

    Yes, but we're discussing a specific study which may or may not be flawed.
    You are turning belief into fact. The two are not quite the same thing.
  15. how do foot orthoses exert their therapeutic effects, David?
  16. davidh

    davidh Podiatry Arena Veteran

    Off-topic, surely?

    I believe that on a hard and flat surface they allow the foot to work around subtalar joint neutral. I don't personally think there is much more to it than that. Ask me for proof of how orthotics work - I can't give it. In the same way neither can anyone else of course.

    Bearing in mind that although there is an implicit acceptance that our feet are designed to work on hard, flat surfaces (and barefoot running is one example of this), in fact there is no proof that they do so well. I'm talking about "normal" feet here of course. The normal foot is designed to work on a multitude of surfaces, flat and hard being one of them. What we think of as normal may not be so normal. Those feet may just be the one's which work better on hard and flat. Some feet don't work well on hard and flat at all. In my experience most feet work better on hard and flat if they are shod, usually with a small heel.

    It's why the barefoot running idea is such a nonsense, except when it's carried out on soft or undulating ground, where every footfall is different.
  17. No, exactly on topic. In order to design a placebo foot orthoses you need to know how foot orthoses exert their therapeutic effect so that you can be sure that your placebo foot orthoses exerts zero influence with regard to that effect. So, if we can all make placebo foot orthoses as you claimed, we first need to define how foot orthoses work.
  18. David, thanks for editing your post after I had already replied to it above. Most of the edit you made is "off-topic, surely". I've copied the extra edit below:

    I think one of the things we do have evidence for is that they don't usually exert their therapeutic effects in the manner in which you described above. How does your theory fit with data such as presented by Williams et al. 2003, for example? http://www.udel.edu/PT/davis/Inverted_orthoses_mechanics.pdf

    Can you point me to any evidence which supports your assertion that foot orthoses exert their therapeutic effects by "holding the subtalar joint in an approximation of neutral in stance"? Since that's clearly not how they worked in the study above.

    Here's a few other authors who have demonstrated that foot orthoses did not significantly alter rearfoot kinematics:
    e.g. Rodgers & Leveau, 1982; Blake and Ferguson, 1993; Brown et al, 1995; Nawoczenski et al., 1995; Nigg et al. 1997; Butler et al, 2003; Stackhouse et al, 2003; …etc

    Here's a few more author's that have shown that foot orthoses did alter rearfoot kinematics: Bates et al, 1979; Smith et al, 1986; Novick and Kelly, 1990; McCulloch et al, 1993; Stell & Buckley, 1998; Leung et al, 1998; Genova & Gross, 2000; Nester et al, 2001; Woodburn et al, 2003; etc. Although I'm fairly sure that none of them demonstrated that the "foot orthoses held the subtalar joint in an approximation of neutral in stance".

    Let's say a foot orthosis does change the position of the rearfoot such that it approximates subtalar neutral in stance; how did the foot orthosis achieve that kinematic change?

    Is it your assertion that any foot orthoses which do not hold the subtalar joint in neutral in stance, should be classified as placebo's?
  19. davidh

    davidh Podiatry Arena Veteran

    Our posts crossed. I obviously edited while you were posting.
    I looked t your linked reference. I got as far as 11 subjects:rolleyes:.

    I'll reply in more detail tomorrow.
  20. If you say so. Go ahead, read the paper. Given that you contend that foot orthoses exert their therapeutic effect via a kinematic change at the rearfoot, can you explain the difference in clinical outcomes observed between the types of orthoses employed within the study in light of the lack of kinematic differences achieved at the rearfoot between these orthoses, but significant difference in the kinetic effects? Indeed, can you explain to me how kinematic change at the rearfoot occurs in association with a foot orthosis?

    Provide any published studies, n=1 if you like, which support your contention that foot orthoses exert their therapeutic effect by "holding the subtalar joint in an approximation of neutral in stance"?

    I think it would be very helpful for the Podiatry Arena community if you could also take the time to explain how effect size, power and beta error work. Using the paper in question as an example to demonstrate why, in your opinion, the sample size of n=11 discredits their findings would be really useful.
  21. davidh

    davidh Podiatry Arena Veteran

    No, exactly off topic. Post 16 in answer to this - "how do foot orthoses exert their therapeutic effects, David?".
  22. After you edited it, after I'd posted!! When I wrote that, your response consisted of:
    Nothing more or less. What kind of game are you trying to play here? Your attempted diversion not withstanding, just answer the questions.
  23. davidh

    davidh Podiatry Arena Veteran

    I have some statistical references I can quote right back at you - I'm sure.

    Do you understand diurnal variation?
    Ian Haslock was on the SCP's Referees Committee for a spell. Did you meet him?
    Big chap - visiting Prof at Durham Uni. Co-wrote the paper with Tony Unsworth on Diurnal variation....... It seems that living animal tissue moves around over a 24-hour period. The movement is not always linear. It can become looser or tighter. It can affect joint ROM. I did a little work on this, but the Prof's wrote an interesting paper. It should be available on google if you do a search.

    I know that statistics can be wrong. I know that small cohorts are not as trustworthy as big cohorts..........

    As I said, I'll pick this up tomorrow.
  24. davidh

    davidh Podiatry Arena Veteran

    Ok Simon,

    I gave you an explanation,

    I'm bailing out.

    I've told you how I think foot orthoses work. I think you are looking for an argument, not a discussion.

    Look somewhere else.
  25. Yes I do understand diurnal variation. Can you tell me how you differentiate this from within-day measurement error in a quantitative variable? Moreover, can you tell me what this has to do with the present debate?

    To quote you:

    It's not that simple, David. Anyway, differences in clinical outcomes, without differences in rearfoot kinematics... your thoughts in light of your conjecture regarding how foot orthoses exert their therapeutic effects? And how to make placebo foot orthoses.............
  26. I'm not looking for an argument, only a debate of the academic kind. But I am big enough to admit when I'm wrong and I do know when I'm out of my depth in an academic debate. Have a nice day.
  27. efuller

    efuller MVP

    I don'tbelieve that orthotics work by holding stj in neutral. I do want to know how their placebo orthotics differed from their treatment orthotics to get those results
  28. davidh

    davidh Podiatry Arena Veteran

    I offered an explanation of my post being altered. You chose to disbelieve me publicly. You demanded I offer proof of why I think orthoses work by allowing the foot to work around STJ neutral.

    Finally, you fail to realise the futility of a long debate arising out of limited data about a single paper (the abstract). We can't debate on this paper - we don't have all the data.

    I appreciate that you started another thread on stats, and I'm about to have a look at that now. Stay civil - I'll debate.
  29. I haven't demanded in bold anything from you. I asked if you could provide any evidence to support your assertion and provided evidence which I believed contradicted it; that's generally how debate works. I don't fail to realise anything with regard to this discussion, David. You did go back and edit your post after I'd replied. I pointed this out and you put this down to cross-posting, which I should have accepted, except you then proceeded to respond to my subsequent post by saying that you'd already answered that point, when at the time of my writing you hadn't. Try to come across as being less patronising and I'll debate too.
  30. davidh

    davidh Podiatry Arena Veteran


    I didn't say you demanded in bold. That was my emphasis. Ignoring for the time being the implicit insult in your post (26) I would rather not debate this until the full paper has been made available.

    I am happy to start a thread on why I think that foot orthotics work around STJ neutral. I'll also elaborate since the concept is rather too simplistic to encompass what foot orthotics do. You are welcome to join in if you wish.
  31. Like I said- patronising. I didn't demand anything, David; emphasised by you or not. Please show me where I used the words: "I demand"?
  32. Dananberg

    Dananberg Active Member

    There are certain types of medical conditions in which treatment analysis via placebo controlled trials just doesn't make sense. The use of foot orthotics in the management of LBP is one of these.

    However, the clinical nature of LBP suggests that most treatments are at best temporary, and that relapse of serious LBP occurs in 70+% of subjects within 12 months.

    In my 1999 outcome study on CFO's and lower back pain, we used pain assessment surveys and then followed at 3 months and then again at 12+ months. And, considering our test population was considered to be at medical endpoint with symptoms for greater than 5 years, there was considerable value in seeing a recurrence rate drop to 16% at the post 12 month period.

    There are times in which standard study measures are either inappropriate or impossible to apply, and using other methods which suggest outcome changes are often the best approaches to introduce evidence for treatments like the management of LBP with CFO's.

  33. Howard,

    I concur, but would go further. The reality is that all trials involving foot orthoses are at best a series of single-subject case studies and that it is virtually impossible to make a placebo foot orthosis because anything you add to a patients shoe is likely to influence the kinetics at the foot's interface with it: by altering either the surface geometry, the load/ deformation characteristics or the frictional characteristics. Indeed, as Robert pointed out earlier in this thread, we cannot even rule out the change in thermal characteristics that a foot orthosis (or so called placebo/ sham foot orthosis) might have on the outcomes observed within clinical trials of foot orthoses. All that these trials provide are the effects in each individual, from a study in which each of the subjects have all been given a different dose of the "kinetic altering drug"; analogous to performing a placebo controlled trial of a new drug, but actually giving everyone in the trial a different dose of the active drug, with the control group generally receiving a lower dose than the treatment group- but this doesn't make it a placebo, it just means they received a lower dose of the active drug.
  34. Dananberg

    Dananberg Active Member


    And to make this more confusing, in migraine headache trials for Imitrix, there was a 28% positive response to placebo. Go figure that out! The only "care method" which I know of that responded to less than known placebo effect is magnet therapy. No surprise there!

    Sometimes, the best we can do is to alter conventional thinking by showing a positive change in outcomes over sufficient time periods. This is certainly a far cry from the "expert said so" methods all of medicine has used in the past. It is just a fact that not all methods of care can fall into the category in which placebo controlled trials can be used as the gold standard. Surgery is certainly one of these, as would be manual medicine and acupuncture. There are others. Perhaps, it will all come around to clinical judgement from as many of the evidence based sources as possible.

  35. This is why I dislike the rigid application of Sackett's hierarchy of evidence so much.
  36. David Wedemeyer

    David Wedemeyer Well-Known Member


    Robert you’re right on point as usual. Low back pain has myriad causes but typically the pain comes from two sources; the disc and the facet joints. I would add a third being primarily muscular and specifically the quadratus lumborum. Even the most accomplished clinician at times has trouble locating the precise etiology of a patient’s low back pain and often there is overlap.

    The problem in studies such as these I believe is in quantifying which subset of the low back pain spectrum the subject fall into. An example would be the acute overuse muscular strain versus say those with subacute degenerative disc disease experiencing a flare-up with attendant muscle pain. Two very different clinical types entirely.

    A better study design would be to include only mechanical low back pain patients, they do not appear to have made this distinction? The problem with acute mechanical low back pain is that most of it resolves on it's own over time and a good deal of the time it is traumatic. How is a CFO going to help that?

    I’d like to read the entire study if anyone has it please?

    No, not you Robert! :D
  37. David Wedemeyer

    David Wedemeyer Well-Known Member

    I would venture that the placebo effect also applies to issuing CFO's to patients. Almost every patient has an immediate and positive response to them, I've noticed even when they're very wrong for them. Their evaluation did state a short-term effect at 4 weeks. Follow-up over time would sort some of that out I agree.
  38. carolethecatlover

    carolethecatlover Active Member

    OK, lots of people got off the tract/track on this post.
    I have somewhere from my studies at Uni of Newcastle a study in which 'sham' orthoses were used.
    Two: stopping pronation stops LBP.
    OK: Causes of pronation?....Lots, but one of the main ones is LLD.
    So sometimes fixing up the pronation fixes the LLD, and relieves the pressure on the sacaral nerves.
    I 'fixed' 2 peoples LBP (and one was a box of chocolates pleased!) by putting a .5mm insole in the shorter leg. It was not intended to treat the LBP, but the LLD which generated a lot of callus on the longer leg. But a lifetime (50 years) of back pain disappeared within the day, and the patient was of an experimental mind and fiddled until he got the right thickness of insole.
    The second was just a guy at a party, I didn't even measure the LLD, I just told him about putting an insole in the aching side of the back. Again instant cure.
    I didn't intend to do this, it was totally random. But it made me think, and I am still thinking about it. I would love to talk to a back specialist MD about this.
    My objection to the study cited, was too many women.
  39. Griff

    Griff Moderator

    There are lots of studies that state they used a sham orthoses. Doesn't make it true (for the reasons Simon has already mentioned).

    That's a bit of a big shout....
  40. Craig Payne

    Craig Payne Moderator

    Just got the full paper. Looks like they did a pretty good job in this one.

    The stats look fine. I do not have a concern re sample size as effect sizes reported. They ticked all the boxes on what they reported and how they did the analysis.

    Here is the placebo used:
    Picture below:

    Attached Files:


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