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Orthotic materials

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Zac, Sep 26, 2013.

  1. Zac

    Zac Active Member

    Members do not see these Ads. Sign Up.
    Could someone tell me the difference between Superform & TL2100 & where you might use one over the other? Also is there an approximate guide on what thickness to use for a particular weight?
  2. Griff

    Griff Moderator

    In simple terms I think the characteristics of an orthosis shell should be chosen in the context of what you are trying to achieve clinically, and the load-deformation characteristics (stiffness) of the shell which may best achieve it. The shell material chosen, the thickness of said material (and of course the geometry of the device) will all be factors here. Spooner is your man for this stuff...
  3. Zac

    Zac Active Member

    Thanks Ian. Im prescribing a device for an older lady & her footwear requires a thin device. I feel a carbon fibre(CF)/Superform device would be best (given footwear requirements) & would like some "give/flexibility" in the device. I have used CF before but have seen on the script pad "Superform - semi-rigid/rigid/ultra-rigid" & "TL2100 - semi-rigid/rigid" & was wondering what Superform is (I gather it is a composite material) but whether Pods favour one over the other & if so, why. I intended to use a semi-rigid CF device but wanted some thoughts on Superfom.
  4. Spooner is on his way to Madrid to lecture on this kind of stuff. Terms like "rigid" "semi-rigid", "flexible" etc are pretty meaningless in this context since the geometry of the finished device will to a very great extent determine how the device responds to loading. I've always found "thickness to weight tables" amusing.
  5. Zac:

    Most podiatrists I know who do lots of foot orthoses use polypropylene rather than the composite orthosis materials. Polypropylene is more durable, has better rearfoot posts (they can be fused to shell so they will never shear off the plate), can be ground more easily (e.g. adding plantar fascial accommodations), and the compliance of the shell can be more easily modified by using thinner/thicker plate materials or packing material plantar to the medial/lateral longitudinal arches of the device, when compared to the composite materials. I haven't used a composite orthosis for 25 years.....and I don't think my patients have suffered any because of my choice.

    Hope this helps.:drinks
  6. efuller

    efuller MVP

    I agree with Kevin. The abilty of polypropylene to be ground to zero thickness and have surrounding shell not fracture really helps in fitting into difficult shoes. One reason that practitioners want a really thin shell is that that the thickness of the shell under the heel "lifts" the foot out of the shoe. With a poly shell, you can grind the underside of the heel so there is no lift.

  7. Zac

    Zac Active Member

    Thanks Kevin/Eric. i agree with all youve both said & I use polypropylene 99% of the time. BUT, what do you do when you have a lady that wears a fashion type shoe (& unprepared/unable to change footwear due to work requirements) & that is when she experiences pain? I have used the cobra type devices in the past but find they often do not sit well in the shoe. The idea of a very thin orthosis that was still able to provide adequate support seemed a better option.
  8. Well-made cobra style polypropylene foot orthoses with thin leather topcovers take up less room in ladies dress shoes than any graphite or laminate orthosis with orthosis shell material still left in the plantar heel.
  9. Zac

    Zac Active Member

    "Well made" is perhaps the issue. When you prescribe them Kevin due you request minimal lateral heel expansion? Are there any other modifications you request when prescribing?
  10. Zac:

    I don't use any changes to the heel cup of the orthosis with cobra style foot orthoses.
  11. BarryD

    BarryD Member

    Hi Zac,

    We use superform in our lab as a composite option, but I try to convince anyone requesting it to stick with poly.
    I agree with Kevin - Poly is better to work with and adjust.
    Despite some common misconceptions carbon fibre is not markedly lighter or better for low bulk orthoses.
    A well made poly device with a low bulk grind or cobra style should be fine.
  12. RobinP

    RobinP Well-Known Member

    Hi zac, it would seem that you have several of the best in the game telling you the same thing. Incidentally, I would agree wholeheartedly. Device geometry will determine stiffness as much, if not more than material properties.

    A carved polyp device with varying thickness along its shell can give a good combination of increased/decreased stiffness where required in addition to being made very thin directly under the heel. Do not forget, as well, that sending a typical shoe can give the cadcam technician some accurate dimension of the inside of the shoe in order to make it as well fitting to the shoe as possible.in fairness, the same can be done by traditional manufacture but the more accurate the fit to the shoe, the less the patient is likely to feel that she is being pushed out of the shoe. Note, however that a great fit to the shoe is not always a great fit to the foot.
    We then get into a whole other discussion as to the requirement of the shell to match the shape of the foot to be a successful orthotic device (it doesn't). But to go back to your original question, ian has the right of it. Shell geometry/topography will influence stiffness more than the choice of material so don't worry too much about the material.
    Edit: don't forget also that the shoe construction will greatly influence the stiffness, particularly if the material and geometry properties of the shell are such that the device becomes (a term I dislike really) shank dependant to a degree

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