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Carbon fibre as a foot orthotic material

Discussion in 'Biomechanics, Sports and Foot orthoses' started by podtiger, Jul 25, 2011.

  1. podtiger

    podtiger Active Member

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    Hi all.
    This may just be a debate in my own head.
    I have a problem with the material carbon fibre for orthoses. It may just be blind prejudice but I don't feel it is necessary. I feel polyprop and eva is just fine for nearly all orthoses..
    Carbon fibre is a lighter material an perhaps is thinner but I never use it as a material. Am I selling myself short.
    I find some people come in asking for it as their oorthoses material but I can't see the point.
    Just wonering what other pods think?
  2. Re: The carbon fibre debate

    I concur.
  3. CraigT

    CraigT Well-Known Member

    Re: The carbon fibre debate

    I pretty much agree. I do use the carbon devices mainly for how thin they are rather than the weight- seem to fit better with football boots.
  4. CraigT

    CraigT Well-Known Member

    Re: The carbon fibre debate

    Having said that, I usually use polypro for an initial pair of devices as it can be adjusted very easily- I explain it is like a protoype for the carbon device.
  5. Admin2

    Admin2 Administrator Staff Member

  6. podtiger

    podtiger Active Member

    Thanks Craig T, Admin 2 and Simon.
    I agree Craig it may be useful in football boots because of it's thinness.
    I tend to use a thin polyprop material in football boots and so far have not had an issue. I do also have an issue in not being able to modify as easily as polyprop. Polyprop moulds so well as well. It's hard to beat in that respect and it is a great fit for plaster casts. I' not so sure carbon fibre has that same mouldable property.
    Thank you for thread admin 2:
    Related to previous discussion on issue

    Carbon fibre as an orthotic material
    Grinding orthotics made from carbon graphite composites

    It feels like there is an understanding in the community(in some quarters) that carbon fibre is a cutting edge material and it is the best material for orthoses. It must be because of the use of it in sports such as bike riding and tennis.
    I tell my patients that it is unnecessary and the material polyprop is strong light and very mouldable. That seems to work well.
  7. Ian Drakard

    Ian Drakard Active Member

    Re: The carbon fibre debate

    Hi Craig - you might find with the cadcam setup this changes. Use the same thickness poly as you wanted in carbon and add struts to increase stiffness where you need it
  8. RobinP

    RobinP Well-Known Member

    I can't imagine that the majority of us are seeing people for whom the extra grams of polyprop make a difference( and as Ian rightly pointed out, the CADCAM makes this strength to weight ratio arguement debatable).

    If you want something light use HD Pz
  9. For those that don't speak Isle of Man, that's high density plastazote.
  10. RobinP

    RobinP Well-Known Member

    Apologies to the deviants
  11. Griff

    Griff Moderator

    Hands up who has seen a triathlete who has requested a pair of carbon fibre orthoses which were the same colour as his bike?

    *raises hand*
  12. blinda

    blinda MVP

    Was just gonna ask that very question.
  13. That's just ****. Everyone knows they should choose green orthoses, since that is the colour which symbolises health.
  14. CraigT

    CraigT Well-Known Member

    What are a Triathlete's 2 favourite words used in the same sentence?
    Carbon and Fibre

    If they know it is available, they will want it...
  15. podtiger

    podtiger Active Member

    I'm predicting a surge in the buying of carbon fibre bikes in Australia after King Cadel's victory.
    Yellow lycra will be in high demand too.
  16. David Wedemeyer

    David Wedemeyer Well-Known Member

    You make it sound so wrong Ian :confused:

    When a patient can tolerate it, I prefer CF to poly. Especially when volume is an issue. I believe that they resist deformation longer based on observation both clinical and personal. Yes it is a difficult material to work with by hand but then that's what I pay the lab to do. One particular lab makes a proprietary composite blend that I wear myself. They offer pre-cut blanks of a very similar material that I have often used as a 'customized' device when the prescription calls for minor modifications that can be performed in house. It reminds me a bit of Carboplast but has a more natural flex to it.

    I bought a bike to match my orthoses FYI :D
  17. PodAus

    PodAus Active Member

    I find the thin CF composite is much easier to accommodate in footy / cycling / racing flats / motorsport / taekwondo (martial arts) footwear & boots.
    Also in many court shoes designs.

    Personal preference (developed from habit) often pre-determines the material selection of your next prescription.

    Is there anything wrong with CF?

    If I commonly use CF, should I have a 'problem' with poly??
  18. CraigT

    CraigT Well-Known Member

    Positives of CF as previously mentioned...
    Negatives- it is more expensive, harder on machinery to manufacture (grind etc), more difficult to adjust.

    Possible problems with Polypro id you are used to CF-is that the question?- You have to grind away more polypro to get a low bulk device... there is a skill in this.

    If you are looking at vacuum forming, and your model is spot on, I think CF is superior. The shell straight off the model will be closer to the finished product if it is out of the thinner CF.
    It is also faster to heat and cool which decreases manufacturing time compared to polypro.

    Just a couple of observations...
  19. MJJ

    MJJ Active Member

    Are you referring to Performance Rx? If so I have a sample of one somewhere it looks great if thickness and weight are a concern. Haven't tried it though.
  20. David Wedemeyer

    David Wedemeyer Well-Known Member

    No MJJ, I am referring to Superglass by Northwest Podiatric. It is a graphite/glass composite, it may be similar to what you're referring to I'm not sure.

    I've attempted working with TL-2100 before, not my finest hour but people with a lot more experience manufacturing may not feel the same way. Poly and graphite composites are much easier to work with and cost wise probably an even better choice. It comes down to preference I guess?
  21. pkarak

    pkarak Member

    Carbon fibre can be a great material for the right client. I am a sports podiatrist and affiliated with ketch orthotics lab. If you are confident with the script or if it is an external condition to the foot then be sure you won't be let down by carbon fibre. It s lighter thinner and if it has enough resin in it, then it has extremely good flex and response characteristics. It fits football boots really well . We use super form that is a form of carbon fibre with decent amount of resin so it's not brittle. This is something u have to watch carefully with carbon fibre.
    If you would like more info email Me at Paul@ktechorthoticlab.com.
    Paul Karak
  22. MJJ

    MJJ Active Member

    Performace Rx is "A nylon reinforced proprietary thermoplastic".
  23. David Wedemeyer

    David Wedemeyer Well-Known Member

    They're not owned by TOG are they?
  24. MJJ

    MJJ Active Member

    No, it's available from Paris Orthotics.
  25. mahone

    mahone Member

    Polypro is a joke vs Carbon Fibre in foot orthotics and most probably in all orthoses/
    Polypro softens during time, bottoms out, deforms, and its plasticity doesn't help much the patient.
    Carbon fibre is prob 100 % elastic, doesn't bottom out with time , doesn't change its shape during friction or high summer temperatures, doesn't make smelly shoes and many other things.
    It is indeed harder to work with it , until you get used to, but has no comparison. Its a pro material because of its final properties. Whoever does not agree with my post , I suggest to make himself one pair of orthotics, left foot polypro and right foot Carbon fibre. Same thing with other orthoses, and wear those for 4 months. See what happens :)
  26. markleigh

    markleigh Active Member

    Wow Mahone that's a big call that "polypro is a joke". I've used both materials very succesfully over the years. I prefer polypro. because I find it easier to adjust but I will use CF when indicated. I have never had a fracture/breakage with polypro over 20 years whereas I have seen CF fracture. I would think each has it's place.
  27. CraigT

    CraigT Well-Known Member

    Are we talking about the same material?
    I think if you are finding that polypropylene 'doesn't help much the patient' the problem probably lies more in your design...
    Carbon does not usually bottom out and deform- it cracks instead.
    How hot are we talking here? I am working in one of the hottest places on earth and it still does not approach the temprature required to cause polypropylene to change shape. I need an oven at 200C to do that. The carbon blend I use softens faster than the polypro I use.
    Neither carbon or poly 'makes smelly shoes'. EVA and absorbent top covers do that...

    Honestly... are you sure we are talking about the same material???
    Also- What type of carbon are you using?- there are many on the market...

    Agree. Although I have seen a couple of polypro orthos crack- and it was not due to the material, but due to how it was formed and ground in these particular cases.
  28. markleigh

    markleigh Active Member

    I'm sure there are plenty of other examples but Kevin Kirby often talks about his pair of polyprop. devices he has been wearing for the last 20+ years. I'd be guessing, but I think if he wasn't happy with polyprop. or thought there was something better, he might have changed them over.
  29. Ian Linane

    Ian Linane Well-Known Member

    Interesting little shindig here.
    Having, many years ago, made devices out of individual strips carbon fibre material (which I then had to vacuum resin on a mandril) I truly made some super slim and robust devices that did not bottom out or fracture. However, over time, the movement of the devices in the shoe would wear the anterior edges quite thin and make them vulnerable, and sharp!

    The carbon composites I used were great but could still pit when stones were in the shoe and were then vulnerable to cracking, depending where the pitting was. Equally there were some that would wear down with some people.

    For the last several years I have been very content with the Polypro devices that have come through and (admittedly I am not dealing with the elite athlete here) with the advent of cadcaming where devices can be successfully reinforced or thinned down I cannot see an advantage to CF for the average person.
  30. Griff

    Griff Moderator

    Strong comments. Financial interest perhaps... Which lab are you affiliated with Mahone?
  31. You don't know what you are talking about, Mahone. Polypropylene, when used correctly, is the most durable orthosis material available. I routinely see polypropylene orthoses of mine that are 10-20 years old that still have held their shape after daily use. In addition, even though I have seen many a carbon composite orthosis break, I have only had two out of 20,000+ polypropylene orthoses break, and one was when the patient's foot was run over by a truck tire....broke the orthosis, but not the patient's foot.

    I quit using carbon fiber orthoses years ago due to their inability to be adjusted and their breakage rate. I prefer plastazote #3 (high density plastazote) for distance runners and soccer players.
  32. Ian Drakard

    Ian Drakard Active Member

    Of all the points this was the one that made me laugh- can't say I've had any complaints about polyprop on this score!

    With some of the points there I felt it was a bit like saying carbon fibre is better because it doesn't increase your chance of being attacked by tigers. (probably) true but doesn't mean that polyprop does.
  33. simonf

    simonf Active Member

    I'd say poly prop was more durable than CF, CF doesnt like the bits of grit etc that find their way into shoes.
    A few years ago I had an elderly but veyr active country gent, I made him CF devices as they would fit best in his bespoke brogues. After about a year he phoned me to say they were broken. I replaced them for him with polyprop.
  34. mahone

    mahone Member

    It looks like I've touched a sensitive chord regarding polypro.
    Although the replies to my comment are fairly true "somehow".
    I didn't mean to upset anyone, I just express the feeling I had reading the posts. I did not advised anyone what to use or what to not, everyone does it accordingly with its own customers.
    PP doesn't crack, but it does bottom out in the way it is losing its strength with time and wear. Little by little. And it does it fast. After few months, more or less, is not 100% good anymore . It is easy to shape , no doubt about it, is a pleasure working with it and working with CF is sometime frustrating, mostly in deep heel cups. But it doesn't lose its strength, which I think is the most important characteristic. This is why people wear orthotics.
    I am not gonna compare a Chevy with a Mercedes but instead with a Honda or a Toyota. The same thing , the Chevy is a joke.
    For me, if there is a way to get the quality it doesn't matter how hard I have to work.
    The feeling at the end of work that I did something very good for someone is much more enjoyable than the comfort of melting PP .
  35. RobinP

    RobinP Well-Known Member

    I have, this week, replaced 2 carbon fibre devices due to fracture. I have replaced them with.........carbon fibre. Inexplicably, the patients still want them because they are higher tech material, despite my advice.

    I have, like Kevin had 2 polypropylene failures in 10 years, versus 2 carbon fibre failures in 1 week. No brainer
  36. mahone

    mahone Member

    CF doesn't melt so much as PP. When you get it out of the oven and you handle it from one end shall not collapse , may bend slowly down but not collapse. If it does, don't use that, it will crack. If you melt it properly , it won't crack. PP doesn't crack unless you force it to or maybe over cooked :).
  37. Mahone:

    Polypropylene is a molecule that can be spun into fabric, melted into various shapes and may also be made into custom foot orthoses. It is not proprietary molecule: it is made by numerous manufacturers, comes in stress-relieved and non-stress relieved varieties, is sometimes used as a copolymer with polyethylene and is very sensitive to being heated too much since this will make it lose some of its memory and allow it to bottom out more rapidly than normal.

    From your comments, either you are using an inferior grade polypropylene or whoever is making your orthoses doesn't know what they are doing. As I said before, the polypropylene orthoses I have used over the past quarter century don't "bottom out" after a "few months". They last for decades.

    I suggest, before you continue making uninformed statements, like:

    that you do a little reasearch, and ask others where they have their polypropylene foot orthoses made so you may better understand that not all polypropylene foot orthoses are the same. Once your ignorance about polypropylene orthoses improves, you will probably want to reconsider your "opinions".
  38. mahone

    mahone Member

    Some guy said I don't know what I am doing. Every day I learn something from somebody so maybe he is right. I wish I know everything. So for that , I can bet that less than 10 % of you use a thermometer inside the oven. Those 90 % who rely on the oven thermometer are mistaken. sic. :)
  39. RobinP

    RobinP Well-Known Member

    Thanks for that lesson in how to make an orthosis, as incomprehensible as it was.

    With reference to polyprop,

    Doesn't it?
  40. CraigT

    CraigT Well-Known Member

    What type of CF are you using? What are all of the other types that you have experimented with?
    There are lots on the market so it would be useful to clarify this.

    And judging from your description and experience, I think you need to change the type of Polypro you have been using...

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