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Foot orthoses & achilles tendonitis study protocol

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Simon Spooner, Oct 25, 2009.

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    This study protocol for a trial to examine the efficacy of customised foot orthoses in the treatment of Achilles tendinopathy has just been published:

    Now would seem a good time to comment, rather than picking fault with the study when it is completed!

    Anyone see any problems with this?
  2. Re: foot orthoses study protocol

    Starter for ten; wot no heel lift?

    Also, I'm just trying to think of the last time I had a patient with achilles tendinopathy where I used a medial heel skive...

    Although the authors are suggesting using two different thickness of polyprop for shell material based on body mass, this doesn't get around variation in the load-deformation characteristics of the foot orthoses that will inevitably be present in the study group. That is due to the unique nature of the foot orthoses surface topography, the load-deformation of the foot orthoses will also be unique to that device. Since foot orthoses are basically inert devices, they can only ever exert a direct kinetic effect on the foot. If foot orthoses "work" by altering the kinetics of the foot, then these load-deformation characteristics should be uniform across all of the study devices, otherwise we are effectively giving all of the participants in this group a "different dose" of orthoses reaction forces. Kind of like doing a drug trial and giving each subject a different dose of the drug.
  3. Lawrence Bevan

    Lawrence Bevan Active Member

    A heel lift has to be part of protocol - its always part of mine!! Bizarre.

    I have used a heel skive with achilles tendonopathy but the medially deviated axis "type" of foot is not often the sort of foot that presents to me with achilles tendonopathy. You?

    Are you suggesting that truth be told that in a study (or real world) all devices should be individually "calibrated"?

    This is though far better - to critique the design prior rather than retrospectively.
  4. I can't recall the last time I made a device for someone with achilles tendinopathy that didn't include a heel raise. Like you, I don't see too many of the kind of feet I use a medial heel skive for, presenting with achilles tendinopathy.

    I'm saying that if the effect of foot orthoses is via kinetic means, if we want to compare like with like with need to control the load-deformation characteristics of the orthoses within trials or use single case designs, because IMHO at the moment the trials being published are fundamentally flawed due to this problem. It gets worse as obviously one of the other major characteristics of foot orthoses that is likely to influence the kinetics is the 3-dimensional surface geometry at the foot-orthosis interface. Once again, when custom devices are employed, these are all different; so once again everyone in the study group is getting something different.

    Lets say we wanted to test the effects of drug X against a placebo in the treatment of achilles tendinopathy, would you give everyone in the drug group a different, unknown dose of the drug? Some people might get toxic levels while others might receive only homeopathic levels, but we have no way of knowing who received what level of the drug, just that all got "some". No, I wouldn't design a drug trial in this way- would you? So why are we doing this in orthoses research? At best, the current way of designing trials tests only the prescription protocol, not the devices per se.

    You almost need to do a couple of hundred single subject design studies and then some kind of meta-analysis on the data. Craig and I started to speak about this at the PFOLA conference a couple of years ago, I'm not sure I'm any closer to the answers, but this problem keeps on bugging me.
  5. One must make a choice in any orthosis research project on how to best accomplish getting the information desired, without introducing any biases. As we know, doing orthosis research is very difficult since orthoses prescriptions should be varied for patient foot type and body weight and activity to get maximum therapeutic effects. However, the very nature of customizing each orthosis for each study participant versus making the same orthosis for all participants causes study design problems due to the different mechanical characteristics that each type of study will have. I don't know the answer to the problem but I am excited to see Shannon, Karl, Hylton and company trying to tackle this important subject since Achilles tendinitis is a very common injury in my sports medicine practice and it would be nice to see how the individuals all respond to the different protocols.

    In regards to heel lifts, I generally hand out a heel lift at the first visit for my patients with Achilles tendinitis and if I make an orthosis I will more commonly put in a heel lift than a medial heel skive into the orthosis. Of course, a 4 mm medial heel skive is a form of heel lift so maybe it will have a similar effect??
  6. But even if we make all the devices for the participants using exactly the same protocol, the resultant devices will all have different mechanical properties due to variations in their 3-dimensional surface geometry. So we are stuck between a rock and a hard place; we can customise the prescription, but this means the orthoses will all be different; we can use a standardised protocol, but this means the orthoses will all be different.:bash:

    The root of the problem is the way in which we view levels of evidence and trying to apply "the gold standard" randomised placebo controlled trial to foot orthoses research.
  7. Simon:

    I totally agree. Certainly a paper that describes the inherent limitations of doing high evidence level foot orthosis research is badly needed within the peer-reviewed podiatric literature since there are many that believe that custom foot orthoses are just the same as non-custom foot orthoses. Of course, the insurance companies and governmental health bean-counters would love nothing more than to stop paying for any custom foot orthoses due to the perceived lack of high evidence level research that custom foot orthosis work better than non-custom foot orthoses.

    Hopefully this research by Shannon Munteanu and company will help to support our combined clinical experience that custom foot orthoses have much greater potential to heal chronic foot and lower extremity injuries than do non-custom orthoses.
  8. The study in question is not comparing custom versus non-custom devices, so that question will not be answered here. My concern is that in the event of a "negative" outcome, i.e. no statistically significant difference between sham and custom foot orthoses, that the bean counters and media will conclude "custom foot orthoses aren't efficacious in the treatment of achilles tendon disorders". While we all know that the study is only testing one specific prescription protocol (a prescription protocol, it seems neither you, Lawrence or I regularly use in the treatment of achilles tendinopathy), as history shows, this tends to be ignored in favour of the eye-catching headline. :butcher:
  9. CraigT

    CraigT Well-Known Member

    I agree with all of the limitations that are mentioned above, but in fairness, they have made the effort to make the devices more custom than any other study that I have seen...
    If they have a pronated FPI, they get the medial heel skive, if neutral it is a basic shell, and if a supinated FPI they get a device to control supination as described in Josh Burns paper...
    The devices are made at a laboratory from slipper casts, so should be close to what many Podiatrists would prescribe... well at least closer than other studies that suggest they are investigating custom foot orthosis efficacy.
    For the record, I often use a medial heel skive of some description with achilles tendonosis patients.
    As for a heel lift- not always. If I get a good response from from low- dye strapping, and there is no limitation in dorsiflexion, I would tend not to use a heel raise unless acutely inflamed.
  10. DaVinci

    DaVinci Well-Known Member

    Agreed. The researchers have taken a big step here in at least trying to use custom foot orthoses in such away that it more closely mimics their use in clinical practice than we have seen in previous studies on so called "custom orthotics". We should be applauding that.

    However, this thread has raised some issues that the researchers are going to have to address if the research is going to be any use to us as clinicians.

    As it appears most of us tend to use heel raises in those with achilles tendonitis, are we going to believe the results of the study if they did not use them? Are those with tight calf muscles not going to respond to the foot orthotic, if a heel rasie was not used? Will this affect the overall outcomes?

    In my limited understanding of random trials, is that both groups should be treated exactly the same with the only difference being in the thing that is being researched, so this issue of a heel raise may not be important as I guess we assume that the number of short calf muscles is the same in each group.

    I do have an issue with the use of a medial heel skive in all those in the study with a pronated foot. Who actually does that in clinical practice? I only use them in a pronated foot if the pronatory forces are high and i don't use them in a pronated foot when those forces are low. Will that affect the results of the study? Will that affect our intrepretion of the results?

    Who uses foot orthotics in everyone with achilles tendonitis? All those that meet the criteria for the study are getting foot orthotics. I am much more selective as to who gets foot orthotics. Are you going to accept the results of this study if they do not get a result?

    I am pretty sure that the researchers will be somewhat dissmissive of these clinicians concerns, but how can they expect us to take the results seriously, let alone use them in our practice if they do not get addressed?
  11. pod29

    pod29 Active Member

    Hi all, here's my two cents worth if anyone is interested

    Much kudos needs to be given to those involved in the design and implementation of this study. Moreover, I think it is fantastic that they have published this protocol for public comment.

    As for the prescription variables..... In my opinion they are doing the right thing by giving foot orthoses to everyone who meets the critieria for inclusion in the study. As yet (to my knowledge) there is no evidence to suggest that people with an ankle equinus (or any foot type for that matter) will, or will not respond to foot orthoses therapy. BUT, this study may infact give us answers in this regard. I'm sure the authors have included a subset of anthropometric measures (age, height, weight, FPI, joint ROM etc) that they will be able to use to help determine why certain people in the study improve with foot orthses and why other participants may not. Giving the potential for an algorithm to determine who will be of benefit from foot orthoses in the treatment of Achilles tendonopathy. This would be similar to that of the paper by Natalie Collins, whereby she was able to predict subsets of the population that respond best to foot orthoses in the treatment of PFPS. For example they may be able to say that a particular foot type will respond favourably, or by age, gender, ankle ROM, duration of disease etc etc... the list goes on.

    You have to start somewhere if we want our profession to gain scientific evidence for our clinical reasoning. Whether this study gives us answers that we want to hear or not, it needs to be done. Otherwise we'll be thrown in the quackery basket with with chiropractors and homeopaths. The basic science and methodology of their project is excellent, I wish them good luck.

  12. Griff

    Griff Moderator

    Hi Luke,

    Could you point me in the direction of this article please?

  13. pod29

    pod29 Active Member

  14. pod29

    pod29 Active Member

    Vicenzino B, Collins N, Cleland J, McPoil T. A clinical prediction rule for identifying patients with patellofemoral pain who are likely to benefit from foot orthoses: a preliminary determination. Br J Sports Med. 2008 Dec 3

  15. Griff

    Griff Moderator

    Oh you meant the work by Bill Vicenzino and colleagues - sorry I got confused when you referred to Natalie Collins paper. Thanks for clarifying.

  16. Luke, you make a good point here. I guess this is why the drug industry develop population pharmacokinetic/ dynamic models of their drugs to help to control for these kind of factors within their trials by optimisation of sampling design. Perhaps we need similar models, so that we can better control the kinetic effects of foot orthoses within our trials.
  17. If we look at how drugs are researched and developed we may learn much.
    http://books.google.com/books?id=oq...age&q=pharmacokinetics in drug trials&f=false

    Scroll down to p.268-269 and replace the word "pharmacokinetics" with "kinetics" and "pharmacological" with "physiological" and we won't be a million miles away from what I think is required.
  18. pod29

    pod29 Active Member

    Thanks for the "light" reading Simon! A little out of my depth but very interesting all the same. I look forward to the day when we can model the exact surface geometry required to apply X amount of force to a particular region of the foot in order to achieve a truely customised orthosis. Even better, when this is easily applicable and accessable in clinical practice. That would be cool!:cool:

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