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A comparison of customised and prefabricated insoles to reduce risk factors for neuropathic diabetic

Discussion in 'Diabetic Foot & Wound Management' started by Admin2, Dec 5, 2012.

  1. Admin2

    Admin2 Administrator Staff Member

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    A comparison of customised and prefabricated insoles to reduce risk factors for neuropathic diabetic foot ulceration: a participant-blinded randomised controlled trial
    Joanne S Paton, Elizabeth A Stenhouse, Graham Bruce, Daniel Zahra and Ray B Jones
    Journal of Foot and Ankle Research 2012, 5:31 doi:10.1186/1757-1146-5-31
  2. davidh

    davidh Podiatry Arena Veteran

    Pointing out the obvious.......

    Here in the UK we see NHS "custom" orthoses made from easily-deformable, inexpensive and easily- machined EVA. I know the one's I see are custom - they have a little silver label underneath saying so:rolleyes:.

    True custom in the context of orthoses means just that. Made to a specification which will effect the best outcome for an individual patient. This may mean using materials other than EVA, of which there are many available. Most are much more expensive, to buy and to machine.

    This abstract doesn't mention what the custom orthoses were made from. I'm guessing EVA.
  3. Nowt wrong with EVA.

    But as you say the problem with this, as with all similar studies, is the old N=1 chestnut.

    Its like comparing a car to a lorry to see which will get you from A-B. They both will. Is the lorry more expensive? Yes. Will the car fit your sofa in it? No.
  4. davidh

    davidh Podiatry Arena Veteran

    I don't have a problem with EVA per se. I have a huge problem with it when it is used for every NHS "custom" foot orthotic I come across which has been requested by orthopaedics - or in a study such as this.

    I can't help but notice that looking at the spiffy prosthetics used by sprinters in this years Paralympics EVA is not much in evidence..........
  5. I suspect what Jo was trying to do here was to match the material characteristics of the custom devices to that of the prefabricated devices in an attempt to control the variables to an extent. Since:

    the custom insoles- "were constructed from a blue, medium density, 3 mm full length moulded ethylene vinyl acetate (EVA) base with a 6 mm full-length grey Poron® top cover."

    And the prefabricated devices-
    "consisted of a prefabricated full-length 3 mm medium EVA contoured shell covered in 6 mm Poron®"

    It seems to me she was trying to isolate the custom moulding as being the only difference between the two types. But Jo's a clever lady and I'm sure she can answer your questions herself.

    I think a major key to this study are those 6mm layers of poron. One of the main advantages of custom moulding over prefabricated devices in terms of pressure variable is in the degree of congruence between the device and the foot that can be achieved with customization. However when we have a 6mm thick poron foam on both the prefabricated and custom devices, coupled with a relative compliant outer-shell, both types of device are going to be congruent with the foot, hence the results reported here. If you removed the 6mm foam from the prefabricated device (the last time I looked, this particularly model and brand doesn't come with a 6mm poron top-cover as standard BTW) or used a stiffer outer shell, then I suspect the results may have been different. In essence, the prefabricated devices were not stock off the shelf devices and were customized for the purposes of this study.
  6. davidh

    davidh Podiatry Arena Veteran

    My point is that a true custom device would also incorporate a choice of shell material suitable to each patient, and, I would think, different thicknesses of poron, depending on the foot. Otherwise what is being compared are the same devices, but one has been custom-moulded.
  7. Indeed it would, but within the confines of a research study often it is better to attempt to control the variables so at least one question can be answered, in this case the question was something like: "how does custom moulding effect the variables measured." I think the title could be tighter in this regard. Perhaps, if you read Jo's full PhD thesis some greater detail of the rationale will be gleaned.

    In reality though, all that has been achieved here yet again is a series of 100+ single case study's.
  8. My problem with this study is that they concluded the following in the abstract:

    To me, this is a conclusion with an agenda....about saving money for an insurance company or for a governmental health-care agency, not about trying to "answer questions" regarding how a custom foot orthosis can very effectively be designed to reduce plantar pressures. By definition, a custom foot orthosis means that the foot orthosis can be customized very specifically to greatly reduce the pressure on plantar ulcers, not just molded to the arch of the foot.

    Even though I have only read the abstract, I worry when the only two sentences of the conclusion of such a study both emphasize the lesser cost of prefabricated orthoses and make no mention of the fact that the "custom insoles" that they decided to use in their study may not, in fact, have been sufficiently customized to produce the pressure reduction results that has been clearly shown in other studies. Clearly, if these "custom insoles" had been truly customized that way that a good foot orthosis practitionere would do for their patients with pathologies caused by high plantar pressures, their results would likely been dramatically different.

    Here are a few references from my lecture on this subject which clearly show the potential pressure reduction characteristics of more effective custom foot orthoses:

    Custom orthoses most effective at reducing pain and all orthoses significantly reduced pressure under 1st and 2nd metatarsal heads in 12 RA subjects
    Hodge MC, Bach TM, Carter GM: Orthotic management of plantar pressure ad pain in rheumatoid arthritis. Clin Biom, 14:567-575, 1999.

    Both normal and RA subjects showed significant reductions in plantar pressures and loading forces during stance phase of gait
    Li CY, et al: Biomechanical evaluation of foot pressure and loading force during gait in RA patients with and without foot orthoses. Kurume Med J, 47:211-217, 2000.

    Orthoses caused 30% reduction in maximum peak pressure in 81 Type II diabetic patients
    Lobmann R, et al: Effects of preventative footwear on foot pressure as determined by pedobarography in diabetic patients: a prospective study. Diabet Med, 18:314-319, 2001.

    Peak pressure and pressure-time integral reduced in 34 adolescent Type I diabetic patients
    Duffin AC, Kidd R, Chan A, Donaghue KC: High plantar pressure and callus in diabetic adolescents. Incidence and treatment. JAPMA, 93:214-220, 2003.

    In 8 patients with plantar neuropathic ulcers that healed with custom orthoses, orthoses significantly reduced peak vertical pressure, reduced pressure/time integral and increased contact area versus the no-insole condition
    Raspovic A, et al: Effect of customized insoles on vertical plantar pressures in sites of previous neuropathic ulceration in the diabetic foot. Foot, 10:133-138, 2000.

    42 subjects with metatarsalgia, foot orthoses decreased metatarsal head pain and significantly decreased force impulse and peak pressure at metatarsal heads
    Postema K, Burm PE, Zande ME, Limbeek J: Primary metatarsalgia: the influence of a custom moulded insole and a rockerbar on plantar pressure. Pros Orth Int, 22:35-44, 1998.

    Prospective study of 151 subjects with cavus foot, subjects wearing custom foot orthoses after 3 months showed significant decreases in foot pain, increases in quality of life and showed 3 times more forefoot plantar pressure reduction when compared to sham insoles
    Burns J, Crosbie J, Ouvrier R, Hunt A: Effective orthotic therapy for the painful cavus foot. JAPMA, 96:205-211, 2006.
  9. Maybe Kevin, maybe. How many of those citations compared modified prefabs with custom devices as this study did? I don't think anyone is arguing that foot orthoses don't alter plantar-pressures, rather the argument being put forward here is that when two different types of device that are constructed of the same materials they used here are employed, then the custom moulding process makes little difference to the kinetic variables measured here.

    Perhaps that should be their conclusion?

    Maybe I'll contact Jo and ask her to contribute if she has the time.
  10. Exactly.

    The conclusion shouldn't have been all about cost of the devices since, you and I both know, that this study will now be used by insurance companies and governmental health-care agencies as further "proof" that "expensive" custom foot orthoses are no better than "inexpensive" prefabricated foot orthoses in treating very dangerous plantar neuropathic ulcers. Good for the patient? No. Good for the insurance companies and governmental health-care agencies? Yes in the short term, no in the long term.
  11. Agreed. I've sent Jo an e-mail, so maybe she'll comment.
  12. LuckyLisfranc

    LuckyLisfranc Well-Known Member

    Well, if this is what the 'custom' orthosis looked like - no wonder those were the conclusions....it looks exactly the same, if not worse than the prefab.


    Attached Files:

  13. jpaton

    jpaton Welcome New Poster

    Some interesting and valid points have been raised that I'm pleased to have the opportunity to respond to.

    The rationale behind the EVA and poron material selection was determined by the results of a bench top pilot study investigating 'The Physical Characteristics of Orthotic Materials used in the Manufacture of Orthosis for Patients with Diabetes' published in Foot and Ankle International 2007.

    Medium density EVA formed the base of the insole, because it not only offered a high degree of control but also demonstrated reasonable dampening characteristics. Poron 4000 (6mm) was used to cover the device because it achieved the highest possible score for dampening impact load within the pilot study. Clinically and ethically, I felt comfortable that materials selected would be suitable and safe for use by the high risk neuropathic individuals in the RCT irrespective of differing activity levels, life style considerations, foot types and plantar pressure patterns.

    It was important to me that the pre-fab and custom-made insoles were controlled for materials for the reasons Simon described, to maximise robustness of the study design and also to ensure the trial could remain single blind to limit patient bias (so the patients could not tell which insole they had).

    I agree that with the observation that 6mm poron may have diluted the custom design features incorporated within the shell. However this was a pragmatic randomised controlled trial and it is common practice to cover the insoles of diabetic neuropathic patients with a material with dampening characteristics to help reduce plantar pressures. It is important to note that this trial focused on reducing plantar pressures in neuropathic patients to aid ulcer prevention, and was not concerned with altering gait kinematics.

    I would also like to draw attention to the findings that the custom made insoles was significantly more effective at reducing forefoot pressure time integral and remained so for the 6-month follow up. Whilst the conclusion correctly reports on the primary outcome measure peak pressure, on which the trial was powered and is associated with ulcer development, I would hope that this secondary significant finding is of interest to clinicians and would warrant further investigation/discussion.

    In response to Kevins concerns regarding the emphasis on cost within the conclusion. Within the conclusion and the rest of the paper I am careful not to generalise beyond the custom made insoles within the trial and emphasis that prefabricated insoles should only be used when clinically appropriate. However I also believe that practice should be informed by research and cost is an important clinical consideration. I also believe that where it is clinically appropriate to do so neuropathic patients do benefit from being prescribed the cheaper prefabricated insoles not only because they can be issued in a timely manner (off the shelf) of particular importance when dealing with a patient coming out of a TCC post ulceration for example and for whom waiting for an insole to be custom made can be the difference between remaining intact or reulcerating, but also because the insole is likely to replaced more frequently. I am often appalled to find patients struggling to manage with just one pair of insoles or continuing to wear insoles that have past their best before date because of cost constraints cited by the prescribing clinician.

    I would suggest that other stakeholders (government bodies and alike) are unlikely to use this trial in isolation as a lever a cost cut, but rather that treatment recommendations (made by NICE in the UK for example) should and would be based on evidence from carefully conducted systematic reviews of the literature authored by experts in the area.
  14. Lucky:

    Like I said, insurance companies and the governmental authorities who control the purse strings of health care expenditures will surely use this study to show that "custom" foot orthoses are no better than prefab foot orthoses at treating neuropathic ulcers. The poor patients who need true custom foot orthoses from an experienced foot health professional in order to heal their ulcers are the ones who will ultimately suffer because of this.
  15. jpaton

    jpaton Welcome New Poster

    With due respect I think you may have missed the point. The two trial insoles were in fact purposely fabricated to look the same so that the participants remained blind to the intervention allocation.

    The custom made insole in the photo was chosen for the photo to demonstrate that exact point and as such did not contain some of the more overt custom design features ie 1st ray cut out, medial heel skive, increased arch height you eagle eyed enthusiasts would have preferred to see.
  16. davidh

    davidh Podiatry Arena Veteran

    Hi jpaton,

    Thanks for coming back with more details.

    You said:
    "The rationale behind the EVA and poron material selection was determined by the results of a bench top pilot study investigating 'The Physical Characteristics of Orthotic Materials used in the Manufacture of Orthosis for Patients with Diabetes' published in Foot and Ankle International 2007. "

    I haven't seen this paper, but I'm quite confident in stating that the EVA orthotics I see on a regular basis do not retain the physical characteristics of a block of EVA once they have been machined.

    Just to be clear - I'm questioning the rationale for using EVA as a universal shell material - as it is already in many NHS establishments up and down the country.
  17. Hi Jo, and thanks for coming out to play in the road.

    I think that Your study, in the context in which you've explained it, has great value. The problem here is our old enemy, woolly terminology.

    What exactly is a Custom made insole? In this study its an orthotic cast from EVA and covered in 6mm poron. Is that all you have in your toolbox? I bet its not! I bet you use lots of different materials, gels, covers and suchlike. I bet you sometimes use thinner or thicker poron. So is this really a study comparing custom made insoles to pre fab insoles? I'd argue not.

    HOWEVER what this study does do, and very well I might add, is compare standard last to custom last shapes for a very specific design of orthotic (EVA with 6mm poron). Thats a useful piece of information! Very useful actually. But its not a truly custom made orthotic (IMHO).

    With due respect I think you may have missed the point. The two trial insoles were in fact purposely fabricated to look the same so that the participants remained blind to the intervention allocation.
    I believe that this is your intention, and I believe that this is how it SHOULD be used. However I fear that you may be a little naive in thinking this. Dynamite was invented to move mountains out of the way for railroads and such, but it took very little time before it started being used to kill people. You have to think not of what SHOULD be inferred into your study but what COULD be inferred from your study. The last line of your abstract is the part people will read and remember. What you MEANT may have been that if you're making an EVA and Poron full length cast, Pre fab can be just as effective as cast. But what people will take from it, if they want to, is that Prefabricated orthoses are just as effective as custom orthoses and thus, should be used.
    I suspect Kevin understands your point very well. HIS point is not what the study actually says, but how it will be used! Abused I should perhaps say. You can speak with authority on what you meant, what you found, and what you wrote Jo. But you can't speak for what other people will use your research for.

    Kipling had it right
    "If you can bear to hear the truth you've spoken, Twisted by knaves to make a trap
    for fools"

    The truth you've spoken is a good truth. A well written, thoughtfully designed and relevant truth. What I suspect Kevin is speaking of is how it might be "twisted by knaves", and thats something he is very experienced in seeing.

    Apologies Kevin, for presuming to put words in your mouth. But I share your concerns.
  18. Whoa there.

    Easy on the NHS fella. I can't speak for all NHS depts (neither can you) but I think the inference that this is the "nhs way" is a little harsh. I know some IPPs who only have one tool in their box, but its not fair to extrapolate that onto more than those individuals. How many NHS trusts do you know, up and down the country, who ONLY use EVA as a material? Bear in mind that just because the patients YOU'VE SEEN have all had one type of insole, doesn't mean thats the only type which gets issued. Perhaps all the ones who were issued poly devices are all tickedy boo and thus don't need to come see you ;-).
  19. Robert:

    You hit the nail squarely on the head with this post.:good:
  20. Changing the conclusion of the abstract from:


    ...would have been much more helpful to the patients throughout the world who suffer from peripheral neuropathy and have limb-threatening plantar ulcers that need treatment with custom foot orthoses.
  21. davidh

    davidh Podiatry Arena Veteran

    Hi Rob,

    I see more EVA "custom" orthotics than I see either true custom or pre-fab orthotics.
    Agreed, most of the orthotics I see in practice are from patients based in and around the Midlands. Some that I see are from pods in PP.
    But I also see claimants from up and down the country, from Newcastle to Plymouth, as part of my medlegal practice.

    These claimants were, by and large, fit and healthy before their accidents or clin neg. They have never been near a polypro or carbon-fibre device.
    Most have been through NHS surgery before seeing me. Most of them bring their NHS "custom" orthotics to show me. They are invariably machined from EVA, and either collapse when weight is placed on them, or are too thick to fit into a shoe.
    The orthotics are made, fitted and supplied by Orthotists, who work as part of the overall Orthopaedic team. Orthopods tend to listen to them. In all the cases seen so far, where orthopaedic surgery has been involved Podiatry and podiatrists were not involved in any of the orthotic-fitting process.

    I am aware that the Orthotists orthotics (not just foot orthotics) and prosthetics budgets are no longer ring-fenced (protected) in the NHS, and I can see that is one reason why a cheap substitute for a true custom foot orthosis is made. Sticking a custom label on the underside of an EVA device is not just a bit of harmless deception though - some orthopods now actually think that:
    a) Custom foot orthoses should cost no more than £150.00 in total (I've seen this in writing)
    b) Their patient has tried custom foot orthoses and they dont or didn't work.
  22. davidh

    davidh Podiatry Arena Veteran

    I looked for this thread this morning and it's gone - already:confused:.

    Anyway, I wanted to add to this part of Jo's post that NICE rely to a greater or lesser degree on the Cochrane database for their information.

    I think we have to acknowledge the possibility that Cochrane may not be totally impartial.
    See what the BMJ printed here.

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