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Prefabricated orthoses survey

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Simon Spooner, Sep 14, 2009.

  1. Members do not see these Ads. Sign Up.
    I'm planning a research project to investigate the morphological characteristics of prefabricated foot orthoses. At the moment I'm trying to identify the manufacturers contact details for as many prefabricated orthoses as possible. I should be grateful to any members of Podiatry Arena who can supply these details.

    Thanks in advance.
  2. In fact, let's throw this open a little wider in the hope to get some people involved who would normally shy away from research. Here's the first bit of the great Podiatry Arena prefabricated foot orthoses survey. What I want you to do is measure the height from the supporting surface to the highest point on the medial longitudinal arch section of a US size 10 (or the size that covers size US10 (i.e. large)) of a prefabricated device. Ideally using a calliper (these are available relatively cheap, e.g. http://cgi.ebay.co.uk/Electronic-Di...518c355d0e&_trksid=p3286.c0.m14#ht_2787wt_952 ) and report the results back here. You should list the manufacturer and "model" of the orthosis. i.e. SOS biomechanical "Project Step" size L (US 9 1/2 - 10 1/2) 15mm. Get the idea?

    Even if someone else has already submitted a measure for a certain type of devices, please submit your measure of the same device too- that way we'll see the inter-observer error. All devices should be new and unworn as they are prefabricated it should not matter whether you measure the left or the right device but just in case lets measure the right one of the pair (I just flipped a coin!)

    When you've measured the medial arch height, keep hold of the device, there will be more measurements to come!

    You should probably private message me the measurements in the first instance to keep it blind.
    Good luck!
  3. Phil Wells

    Phil Wells Active Member


    Just to throw something in the mix, I have noticed that some insoles that measure the same height at the medial edge of the shell are very different in arch profile - e.g. they are convex v's concave, the angle of inclination when viewed in the Frontal/ y axis is hugely different or the lateral arch height is higher = an effect on the medial arch height.
    This morphological difference is seen the casts we see here and consequently means that orthoses must reflect this accurately or cause medial arch irritation.

    Will this effect your research?
    The other option is to scan the dorsal surface of the shells and then compare them in a basic CAD system for deviation.


  4. Phil, You're absolutely right, and I am planning to do a much more intensive analysis than just measuring peak arch height. I just thought it was a nice opportunity to involve some of the community. Having said that, your response is the only one I've received to date, so it looks like I'll be doing it all myself anyway.
  5. Phil Wells

    Phil Wells Active Member


    If it helps I have access to lost of German insoles which I can give you measures for.


  6. you will have 3 from me tomorrow or friday. Depends on the wife bringing them home from her work. Im a tape then custom guy and I thought some Swedish/german prefabs might be intersting for you might be the same as Phils who knows.

    I know time waits for no man but you might have to wait for some measurments from me
    he he
  7. Good man, Michael. As Phil has intimated we a going to need to do more than just measure arch height. I have access to a 3d scanner and CAD, but most people won't have. I really would like this to be a global project and as such we could really do with some low-tech solutions. Obviously we can section the devices, but then they can't be used again and there is a financial implication for all. We could use profile gauges? Any other ideas?
  8. 1. Should we be deducting the lateral arch from the medial?

    2. How about profile volume? Put a tile cutter guide on the peak of the arch in the frontal plane then scan it and run it through some autocad type software to derive the volume, the volume medial of the midline and the volume medial to a "normal" sub talar axis.

    That might give us some intersting compasison data of where the bulk of the device lies...

  9. Phil Wells

    Phil Wells Active Member


    We re-engineer orthoses all the time by pressing the insole into a foam box then scanning them - only works with fairly rigid materials. If we have to do a more flexible device we cover them in clingfilm, rebate them in sand or build a wall around them, then pour in POP. Then we scan this etc.
    People could always do one of these and send in the foams?

    Could always ask for samples from the suppliers!

  10. I agree with the low tech solution so that it can be reproduced here, there and everywhere. As for what it depends a little on what the mission statement is for your study.

    Also do you want so called heat moldiable device such as formthotics ?
  11. Phil, that was Plan: A!

    Guys, I'm open to suggestions on this, originally I was going to get hold of as many devices as I could myself, scan them in and use the CAD. I was also going measure stiffness in medial and lateral arch section using my materials testing kit. I think a cheap profile gauge might be the way forward if everyone wants to play!


    But we will need to standardise the measurement points.
  12. I'm trying to think about some standardised measures, that would allow all to play along without a 3d sacanner.

    OK, so we have our prefab, we can identify the highest point of the medial longitudinal arch. Using an engineers/ woodwork square we can line it up with the medial edge of the orthosis at this high point and identify a point on the lateral edge of the device that intersects the perpendicular of the square. Place our profile gauges along this line and record the contour.

    The back of the heel cup section of the device is basically a semi-circle, we can find the centre of the heel cup using geometry. Thus: http://www.mathopenref.com/constcirclecenter.html

    I'd place the device upside down on a piece of thin card and draw around the "round bit at the back" of the orthosis and find the centre as indicated, then stick a needle vertically through the card to the mark the point on the orthosis.

    Pass a line from the centre of the heel cup to the highest point on the medial longitudinal arch and measure the profile along this line, now do the same with the point we identified above on the lateral edge of the orthosis. Does this make sense?
  13. Simon:

    I worry about trying to quantify the 3-D morphology of any orthosis just using a single measurement parameter. In order for the study to have more significant meaning for all of us, the various orthoses will need to be compared at equivalent areas on the respective orthoses. For example, an orthosis with a medial flange may have a higher medial arch height at its medial edge, but have a very low medial longitudinal arch height 10 mm lateral to this edge.

    In addition, I don't see how a study like this can be done by multiple testers so that it will have significant meaning without introducing a large amount of measurement error due to inter-tester inconsistencies. I think a better way to do this type of study, and involve a large number of Podiatry Arena consultants, is to have each of the participants in each country list the types of prefabricated orthoses available for purchase in their respective communities, and then have them purchase and send these insoles to one researcher who will then run all of these prefabricated insoles through the 3-D scanner. In that way, the expense (if any) of acquiring these insoles is minimized for each Podiatry Arena consultant and the inter-tester inconsistencies are eliminated.

    A subsequent study could involve testing the load-deformation characteristics of these same prefabricated orthoses with an Instrom machine placed at the central plantar heel, medial arch and lateral arch to test stiffness of all the devices. The people who sent in the insoles to you could be listed at the end of any paper as supplying the materials for the testing.

    Just my thoughts on the subject....
  14. Kevin,

    My original thoughts on this study were:
    1. Contact manufacturers of prefab insoles requesting a sample size 10 right foot.
    2. Scan in the insoles and use CAD analyses of shape variation.
    3. Measure stiffness of devices using material testing kit.

    I suspect this is what I (or someone!) will ultimately end up doing. I just thought there might be something here that was easy to assess that would get the members involved. I don't think Arena members will purchase prefabs and send them to me!

    I think it might be useful for all parties if there was an open-access database of this information that could be accessed freely by practitioners. Perhaps, this is just another of my pipe dreams.

    Perhaps, PFOLA would consider funding such a project, along with sponsorship from some of the key players?
  15. Simon:

    Sounds like a great study. Certainly couldn't hurt to ask and see if any of the members of Podiatry Arena could help you out with this one. I certainly could send you at least 4-5 insoles I use for my patients just so I could find out the results of the study at some later date.:drinks
  16. Sounds to me like Phil Wells may have done some of this already, perhaps we could pursued him to co-conspire with me or (someone) on this?;)
  17. To be honest, I think this approach is key to the foot orthosis consensus project, not just for prefabs, but for custom orthosis too. I'd like to see these kind of variables reported in all scientific studies of foot orthoses efficacy.

    "This is not my tale, it's in a book I read when a man said
    "Introducing one of life's brighter dreams""- Lets be other people: The wonderstuff

    The stuffies were obviously referring to the novel: Beautiful Losers by Leonard Cohen

    Best wishes,
  18. Phil Wells

    Phil Wells Active Member


    I have had to do a lot of what you have suggested as part of the formal Continuos Improvement schedules my company insist on. I have a great relationship with a large CAD/CAM company and may be able to persuade them to help -scanning, CAD work etc.
    Also I think I could swing a lot of samples - I already have 20 + as part of my R & D portfolio.
    Do you want to try and put something together for us to have a go at as a group?
    This seems like a really good piece of research that can only add value to both the medical and commercial sectors.


  19. Phil and all,
    What would we need to make this happen?
  20. Asher

    Asher Well-Known Member

    Hi Simon,

    Got me a digital vernier caliper yesterday. Don't have a scanner or any other fancy stuff but happy to contribute in some way. I have about 7 prefabs that I use.

  21. joejared

    joejared Active Member

    Within my own network, M-Tech Labs produces a small volume of prefab machined orthoses for some of the practices he serves, in addition to his normal production of custom foot orthoses. <40 pair a month.
  22. hi Simon Ive got the prefabs now.

    The big question is have you decided the path you want to follow.

    A pod arena type or the more science based with Phil and you getting all the devices and using the CAD etc. I dont mind finding the supplies names for you or buying them from the wifes work and send to you if Phil or you does not have them already

    let me know I can also look for other supplies in Sweden for you as well.
  23. Phil Wells

    Phil Wells Active Member


    I am talking to the CAD company to see whether they can help and then we can decide whats the best way to go.

  24. Arjen

    Arjen Active Member


    As you develop a study protocol, I wonder if it suggests a standard technique for measuring stiffness that could be applied to my thread on CAD/CAM F/O stiffness?
  25. Arjen,
    As the study protocol is developed, I am sure that any technique we employ for measuring orthoses stiffness will be applicable to both prefabricated and custom foot orthoses, as will our analyses of surface geometry.
  26. Phil Wells

    Phil Wells Active Member


    I am not sure as to the relevance of orthoses stiffness as it is so dependant on factors that are outside the control of the lab or practitioner.
    Some of these variables include shoe interface (different shoes making the insole shank dependant), walking surface, fatigue, dehydration, mood (possibly) etc.
    These variables can change as the day progresses or function is changed due to activity.
    I think the best we can do is to try and define a common term and subjective test that everyone understands for the insole - something better than the practitioner flexing it between their hands or pressing down on the arch.

  27. duplicate post
  28. Phil,
    I tend to believe that orthoses stiffness is a significant variable in the efficacy of foot orthoses. It is true that in the "real-world" variation in shoe gear and surface environment and the other factors you listed will impact with the stiffness of the device, but no more so than these factors impact with the geometry of the device. I firmly believe that we can do so much better than the "bendy-bendy" test.
  29. joejared

    joejared Active Member

    So, a pressure sensor and a dial indicator and what have you got? Something similar to a Rockwell hardness test, except in the range of plastics, testing for flexibility at the arch peak, and clamped perhaps half way, and testing for tensile strength applying pressure at the heel center. Something as simple as a digital depth gauge and pressure measurement would be pretty easy to manufacture and mass produce, at least for me. Come to think of it, my customers might want a quantifiable definition as well. What I'm thinking is touch down, zero depth gauge, deflect a constant amount, noting pressure applied. While I doubt it would be used constantly in a production environment, it'd be easy enough to make a dozen prototypes for those interested for future research. One note, for plastics with memory (retention to the original shape), pressure will remain constant over time. For heat moldable devices, I'd expect pressure to drop.
    Last edited: Sep 23, 2009
  30. Phil Wells

    Phil Wells Active Member

    Joe and Simon

    I agree that stiffness is a significant variable but without a meaningful test, and it being placed in to context i.e. caveats on extrinsic variables that will effect the starting point of the orthoses stiffness, then it would be too subjective to ever be part of the prescription process.
    Even though Joe has some simple testing methodology ideas, I am sure that most people would not find this information useful to the prescription process.
    My bias in this thread is that as a manufacturer of orthoses for practitioners, I find that individuals vary on what flexible, semi flexible and rigid actually should 'feel' like in their patients insole and will return the orthoses for alteration. This is costly for me and for the practitioner and I would like to document something more quantifiable.

    I think we all agree it needs defining but some additional practitioner input may be helpful to ensre that any research we undertake creates real benefits.


  31. joejared

    joejared Active Member

    I thought in the context of my post that I doubted it would ever be a production tool, but rather a research tool. In one such extrinsic design, the forefoot extrinsic post can be pulled behind a first metatarsal cutout, dramatically strengthening the device, while allowing for full mobility of the first metatarsal.

    Old school, often the practitioner would suggest one of many thicknesses of plastic, or tell the lab technician what they want in terms of flexibility. Cad Cam simply provides for more resolution in meeting the practitioner's request. It still comes down to tolerances from a machining perspective, and accounting for minor variances in design. There's probably already enough data in my customer's databases to plot a non-linear regression with a reasonable standard deviation to have a starting point on thickness based on patient weight.

    It's worth researching, if only to improve on what the patient receives.
  32. Hey Simon.

    Where are you at Ive borrowed these prefabs. Should I return them for a later time?
    Are you still after more so I can contact my Swedish supplies?
    Or will you publish a list of what devices you have and people around the world can see if they have different ones and add to the list.

    Just wondering as I´m sending a order to a supplier who maybe able to get many differnt types for you

    let me know and I can ask

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