Tag Archives: research

Foot Orthotic Dosing

The concept of foot orthotic dosing is something that has been bubbling away under the surface for a long time now, but for some reason, not a lot of noise gets made about it, or when noise is made about it, tends to get dismissed by those who want to protect the way they did things.

To introduce the concept, consider this hypothetical analogy: what if a really well conducted clinical trial was done on a very low dose of an anti-hypertensive drug and it shows that the drug does not work at that dose. Should that be used as evidence that the drug is not effective? Of course it shouldn’t, but that is exactly what is done with clinical trials of foot orthoses at low doses. As the methodology and analysis of that hypothetical drug trial was sound, should it be included in the systematic reviews and meta-analyses? It will meet all the textbook criteria to be included in a systematic review and meta-analysis, but, of course, it should not be included as the dose was low. To include it would probably be unethical as it would unreasonably bias the systematic review and meta-analysis in the direction of the drug not working (unless the review stratified the study results into different doses). It makes sense to exclude that study because of the low dose. So, why then is it acceptable to do exactly that in systematic reviews and meta-analyses of foot orthoses?

I will get to what a high dose versus low dose foot orthotic is shortly, but first, consider a hypothetical study that is going to be done in plantar heel pain/plantar fasciitis/plantar fasciopathy that one group is given foot orthotics and the other group is given a different intervention for comparison. This other group could be shock wave therapy or cortisone shots or manual therapy or homeopathy or magnesium supplements (currently the hot topic in plantar fasciitis support groups!). What sort of outcome might that study get? You may get very different results if you use a different dose of foot orthotic. A low dose type foot orthotic may not be much better than the other intervention. A high dose foot orthotic may be massively better than the other intervention (it also may not be, but I am being hypothetical to explain the concept); yet almost all foot orthotics that are used in clinical trials to date are mostly what I would call low dose foot orthotics.

Exactly what are high versus low dose foot orthotics? I consider it to be a high dose when the foot orthotic has the design features that are directed at the pathology present and a low dose when the design features are just generic. In the case of plantar fasciitis, I would consider a high dose foot orthotic to be one that inverts the rearfoot, everts the forefoot, is more rigid if the person is heavier, has a plantar fascial groove if the plantar fascia is prominent and has a short-term heel raise if the calf muscles are tight; ie the design features that have been shown to actually reduce the load in the plantar fascia (I can get into the rationale, thought processes and evidence underpinning these design features another time). When it comes to custom-made devices, a low dose foot orthotic would have a generic custom molded plastic shell with a heel post. When you look at all the clinical trials on plantar fasciitis, they all use a low dose type design that does not represent expert clinical practice. Not one of them uses what I consider a high dose device, which I consider represents good clinical practice – it is certainly what the clinical experts and thought leaders are doing clinically. So how fair are the clinical trials of foot orthoses in plantar fasciitis?

All the systematic reviews and meta-analyses of custom-made vs prefabricated foot orthoses and those of foot orthotics in plantar fasciitis conclude that there is no difference between custom made and premade and the effects sizes for plantar fasciitis are either none or small. All of the studies in those reviews used the low dose designs. How much information or guidance do those reviews really provide for clinical practice? None?

If you were to do a systematic review or meta-analysis on custom-made foot orthotics versus prefabricated foot orthotics, then you would have your standard textbook inclusion criteria (eg sample size, blinding, randomization, etc) to select the studies to include. However, surely, an appropriate inclusion criteria would also be something along the lines of the foot orthoses used in the studies are of the type and use that is commonly used in clinical practice by expert clinicians? For the custom made group, for example, did the studies include a plantar fascial groove if the plantar fascia was prominent (none of the studies I recall did that – and that may or may not be very important in plantar fasciitis); did they make the orthotic more rigid if the person was heavier (none did that either, most just use the same thickness of plastic for all); was there a first ray cut-out added if functional hallux limitus was present (none of them did that either); was the bulk of material in the device on the medial side of the highly variable subtalar joint axis if the rearfoot inversion moment needed to be reduced?; etc; in other words not one of the studies that used custom made foot orthotics used them in a way that they are typically and commonly used in clinical practice by expert clinicains, so they all should be excluded from the systematic reviews and meta-analyses.

So what do the systematic reviews and meta-analyses tell us about the difference between custom made foot orthotics and prefabricated foot orthotics. Depends: if you have a superficial understanding and knowledge of foot orthotics then you accept what they say. If you have a deeper understanding of foot orthotics and appreciate the differences between low dose and high does custom-made foot orthotics, then the conclusion of the reviews is not valid as none of the studies that they included should have been included! That does not mean that if appropriate high dose custom-made designs were used that there may still be no difference (there may or may not be); what the evidence says to me is that we do not know, as no one has done the study.

The most recent meta-analysis of foot orthoses in plantar heel pain made the conclusion that:

Foot orthoses are not superior for improving pain and function compared with sham or other conservative treatment in patients with PHP.

Did it really show that? Of course, it did not come close to showing that. Look at all the studies that they included to reach that conclusion. They were all studies using a low dose design of foot orthotic. None one of the studies included actually used foot orthotics design features that have the high dose design that actually has been shown to reduce the load in the plantar fascia! The authors superficial understanding of foot orthotics led them to include studies that should have been rejected as the foot orthotics used were not of the design that an expert clinician/thought leaders would use in clinical practice.

Time for another analogy: in the early days of shockwave therapy for plantar fasciitis, the initial uncontrolled studies showed some pretty awesome results. Once control groups started to be added, the initial results were mixed. There was one very early controlled study that was particularly well done that showed that it was ineffective. I recall it being published and I was impressed with it and stuck up for it in some online discussions on it. At that time clinicians were screaming out that that study had fatal flaws – I was dismissive of them as they just did not like the results, as the results looked pretty sound to me – the methods were good and the analysis was appropriate etc. I could not get what they were on about. Now the early systematic reviews of shock wave therapy for heel pain were not that good for its use, most likely under the influence of that very well done study that showed it did not work. Over time, more controlled studies were done that showed it worked (a few showed it did not work); so up to the present day the most recent systematic reviews and meta-analyses generally conclude now that it is effective. What I failed to grasp years ago is what was making those clinicians crying foul over that early well done negative study – what the study did was use the shockwave at a low dose; it was used at a dose below what clinicians at the time were using in clinical practice. That is why they called it fatally flawed. That then raises the question about should it have been included in the systematic reviews and meta-analyses? With hindight, I don’t think it should have been. Can you see how it would have biased them in the direction of shock wave therapy not working? Compare that to the opening analogy above on that hypothetical low dose of an anti-hypertensive drug. This starts to raise all sorts of ethical issues. Should that low dose of shockwave study be included in the systematic reviews and meta-analyses? Then, why include foot orthotics at low dose studies?

Systematic reviews and meta-analyses are supposed to be one way of eliminating bias when interpreting the pool of literature on a topic. I think the above illustrates that this is clearly not the case at all.

Another way to address this could be when researchers present their foot orthotic studies at conferences, they should describe how they did the foot orthotics in the study and then ask for a show of hands from the audience as to how many do it that way clinically. I think they will be shocked to see how many don’t put their hands up. If most of the audience do not put up their hands, then whatever the results of the study, how useful is it going to be to inform clinical practice? Last week I did a webinar on this very topic. A week before I posted a note on Facebook that I was doing this, I mentioned the low dose anti-hypertensive analogy – it triggered quite a discussion on the whole topic. One comment posted has stuck in my mind and gnawed at me ever since:What happens at conferences: researchers present their research, telling clinicians how their work informs clinical practice; other researchers pat them on the back for an awesome job (I do know how much work goes into these studies); but the clinicians sit there rolling there eyes: “nope”. This is an oversimplified generalization but will continue until research is done that is translatable; that is the high dose foot orthoses used in studies are those that would be used by expert clinicians and thought leaders. If it is not useful to inform clinical practice, then whats the point? Research translation is not something to just pay lip service to.

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Craig Payne

University lecturer, runner, cynic, researcher, skeptic, forum admin, woo basher, clinician, rabble-rouser, blogger, dad. Follow me on Twitter, Facebook and Google+

But…but…it worked for me!

What does apple cider debunking, overpronation and cigarette smoking, Oscon supplements for Severs disease and vaccines causing autism have to do with each other?

^^^ that is the final slide in a video from my Critical Thinking Boot Camp. Anyone who blogs about science always get responses and comments with anecdotes about what was written with responses that it either does or does not apply to them. The science either ‘sucks’ or is the ‘greatest thing since sliced bread’ depending on the anecdote! It has now reached the point where I just delete that anecdotal comments on my posts as they contribute nothing of use to the topic under discussion. Steve Novella succinctly summed this up:

It is almost inevitable that whenever we post an article critical of the claims being made for a particular treatment, alternative philosophy, or alternative profession, someone in the comments will counter a careful examination of published scientific evidence with an anecdote. Their arguments boils down to, “It worked for me, so all of your scientific evidence and plausibility is irrelevant.”

In my other blog, I previously litigated all the issues around “anecdotes” and why useless treatment sometimes appear as though they did work. I don’t intend re-litigating the same issues here but develop them further with some examples I have dealt with recently. For background, I refer you to those two posts.

Health Benefits of Apple Cider
My first example comes from a blog post by Melinda Moyer following an article she wrote on the health benefit of apple cider. These three quotes sum up the issue:

After getting hate mail for debunking the health claims of apple cider vinegar, I’m explaining why I rely on science, not rumors.

Last month, I wrote my first Truth Serum column, “What Apple Cider Vinegar Can—and Can’t—Do for Your Health,” which explored what the science says about apple cider vinegar’s supposed health effects. I found that there isn’t much evidence ACV can cure colds, heal acne, help you lose weight, or alleviate heartburn—and that vinegar can sometimes be harmful.

Then came the angry emails and Facebook posts. Readers chided me for interviewing researchers and doctors rather than people who have actually been helped by apple cider vinegar. Others felt the evidence is irrelevant; vinegar works for them, so they’ll keep using it. A few implied that my writing was unbalanced and unfair.

I am sure you can see the issue …

“The Truth about Overpronation”
I and many others have written about the nonsense surrounding “overpronation” and no point litigating them here … again. To me the evidence is clear. The two most recent systematic reviews/meta-analyses show that it is only a small risk factor, but still statistically significant. I and others are forever dealing with what can only be called ‘clowns’ in social media who cherry pick the studies that show its not a risk factor and ignore those that show it is and then resort to the whole gambit of logical fallacies when called out on it. When the evidence is conflicted like that, you need to defer to what the formal systematic reviews and meta-analyses say (however my next blog post will be on how to bias a systematic review and meta-analysis!).

I only raise this now as a number of times recently I have seen this YouTube video used as “evidence” that “overpronation” is not a problem. Firstly, You Tube videos are not evidence of anything! Secondly, whenever you see “The Truth About…” in the title, there is typically less truth in the actual content. Thirdly, yes that video does show Haille Gebrselassie massively “overpronating”. He was a very good elite runner and almost never got an injury. It is held up as evidence that “overpronation” is not a problem and following on from that, foot orthotics can’t possibly work (Dunning-Kruger in full flight). So who are you going to believe? The anecdote or the preponderance of scientific evidence? I have been in exchanges several times in recent months on this one. What those using the anecdote (But…but…it worked for me!) fail to comprehend is that “overpronation” is a risk factor. It increases your risk or chances of getting a problem. So, of course, there are always going to be an example of people who “overpronate” and don’t get problems. That is NOT evidence. The analogy is that I do not think anyone will disagree that smoking is a risk factor for lung cancer. Just because there are anecdotes of people who smoke their whole lives and do not get lung cancer is NOT evidence that smoking is not a risk factor for lung cancer.

Oscon Supplements for Severs Disease
Another one that came up for was that I wrote elsewhere about Oscon supplements for Severs disease (calcaneal apophysitis). Oscon is a supplement with ingredients that are at their best,  are very very mildly anti-inflammatory. It is marketed specifically for Severs and Osgood-Schlatters, totally supported by testimonials on the website. Not one bit of research has shown that they work and the physiological mechanism that they could work by (very very mild anti-inflammatory) is certainly not specific to Severs and Osgood-Schlatters and there is no way that it could be. ‘Inflammation’ probably occurs in Severs and Osgood-Schlatters, but is not really seen as an important underpinning mechanism and certainly anti-inflammatory drugs are not used, nor recommended for their management. If the supplement “works” for Severs, then it “worked” because of the placebo effect, due to the natural history or anyone of the other seven reasons why ineffective treatments sometimes work. Try telling that to someone who used Oscon in their child and they got better. This was the response I got to what I wrote:

Sadly your report also has nothing to do with talking to people with first hand experience. My daughter is as a gymnast for 10 years, 6 years of which we’re at international level competing for Great Britain. She developed Severs at around 9 years old and it was awful, like watching a little old woman walk about. She had every treatment she could, physio, stretching, anti-inflammatories etc etc, nothing helped for 2 years, she had to ‘manage’ the times with intense pain. Someone in the gym mentioned Oscon and I ordered it, after looking it up on line and discovering it’s general use in the USA and also checking with British Gymnastics it was ‘safe’ from a competition/enhancement perspective. Within 1 WEEK she was 75% better, after 2 weeks it was 85% pain free and I couldn’t believe it. The last 15% was a privately paid for shoe insert made from a mould to support her foot. I told 2 other people about it and. Both had the same reaction for their children. Sadly this appears to be a word-of-mouth cire But there are plenty of discussion online to support what I’m saying. This is your first hand experience you should of had before writing your report

Placebo, natural history, etc. There is a reason that you should never rely on anecdotes. BUT, try telling that to those who have no idea about science, critical thinking and logical fallacies. Can you see the pattern that I am developing in this post?

Vaccines and Autism
Lastly, and clearly, vaccines do not cause autism spectrum disorder (ASD). The evidence is clear and strong. Despite that, the cranks still make stuff up, lie, spout conspiracy theories, refer to retracted, debunked, irrelevant and poorly done studies to support the claims and ignore the strength and the overwhelming number of the well-done studies that show it’s not the case. One of the criticisms of the “science” by the cranks is that they do not take into account the experiences of those parents who children first developed the ASD symptoms following the MMR vaccine….therefore the “science” is wrong (not quite the “But…but…it worked for me!” … but it is still the belief in the anecdote outweighs the science). How much weight should be given to those parents whose child developed autism following the MMR vaccine?

‘Fallacy Man” over at the Logic of Science blog did an awesome job of addressing this (strongly suggest you read it). Using mathematical probably and some modelling based on prevalence data, it looks like that on average 154 children a day in the USA will start showing the signs of ASD (or 1079 a week or 4623 a month). This means that 154 children will start showing the signs of ASD within 24 hrs of getting the MMR vaccine (or 1079 within a week; or 4623 within a month). Now try convincing that parents of those 154 or 1079 or 4623 that it was not the vaccine and would have happened by chance anyway is going to be an exercise in futility. From there, they then fall into the cesspool, conspiracy theories and made up stuff of the antivaccine movement, especially if they have predispositions to those characteristics. What they fail to see is that 154 children will first show the signs of ASD in the 24 hours before they get the MMR vaccine (or 1079 in the week before; or 4623 in the month before).

Surely it is obvious why the science has to outweigh the anecdote to get to the bottom of the problem. In this oversimplified example, the epidemiological research will look if there are statistically significantly more than the 154 children within 24 hrs (or within 1079 a week or within 4623 a month) who develop the symptoms of ASD following the MMR vaccine. That research has been done and there isn’t. What has happened though is the parents of the 154 (or 1079; or 4623) each year become a force to be reckoned with, even though they are misguided. Significant resources have to be diverted to countering the message coming from the cranks in that community. Resources that could be better spent finding the real cause and doing real things that actually do help.

Conclusion:
Hopefully, you can see where the ‘journey’ of this post has taken me. On my other blog, my tagline is “As always: I go where the evidence takes me until convinced otherwise…”. There is a reason for that and what I wrote above is that reason.

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Craig Payne

University lecturer, runner, cynic, researcher, skeptic, forum admin, woo basher, clinician, rabble-rouser, blogger, dad. Follow me on Twitter, Facebook and Google+