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Foot orthoses length

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Simon Spooner, Nov 29, 2007.

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    Why do traditional orthotic shells end proximal to the MTPJ's?
  2. Re: Orthoses length

    Why do i think this is a trick question?

    Ok i'll bite

    Because traditional orthotic shells are primarily designed to exert force on the rear and midfoot. Unless you are using a forefoot modification to exert force under the mpjs extending the orthotic to this point will merely take up room in the shoe and if you extend the actual shell, affect the sag plane function.

    Interestingly all the orthotists i have ever worked with use only full length orthotics. Possibly to do with the fact that they tend to work in piedros or bespoke footwear.

    I pause with baited breath to have my head chewed off...

  3. Re: Orthoses length

    No trick, just wanted to know. So can you explain why orthoses that extend beyond the MPJ's would be less effective at exerting force at the midfoot/ rearfoot?

    I don't buy the sagittal plane thing see here:
  4. Craig Payne

    Craig Payne Moderator

    Re: Orthoses length

    It would not be a difficult to set up and experiment in which foot orthoses are made "too long" and measure function and comofrt in subjects; then repeat the measures with the orthoses shortened.
  5. Re: Orthoses length

    Nope. Only that the extended orthotics take up room and lots of our patients have shoes which don't have it to spare.
  6. Boots n all

    Boots n all Well-Known Member

    My answer to that question would be that not only do you have the “space” issues but despite how soft the extended material is, it is still going
    to add an extra element of stiffness to the shoe both through torsion and flexion moments that was not there to start with.

    The level of this effect is going be directly related to the material/substance used for the forefoot extension, Poron, EVA?

    As to how or why this lessens the effect of mid/rearfoot functional orthosis, l didnt know it did? but then again thats why l am here:)
    although l would imagine it would slow the flow midfoot to propulsive stage
    Last edited: Nov 29, 2007
  7. javier

    javier Senior Member

    The reason I was given when I asked the same question some years ago was to not interfere (or to facilitate) on MPJ dorsiflexion during propulsion phases.

  8. Cameron

    Cameron Well-Known Member


    Janvier wrote
    >The reason I was given when I asked the same question some years ago was to not interfere (or to facilitate) on MPJ dorsiflexion during propulsion phases.

    That was my understanding too and to illustrate this I would take the cast and draw a bisection line of the proximal phalanx of the great toe and fifth toe, proximally, then join a line across the broadest aspect to the metatarsal heads (defined by the medial and lateral prominences of the respective metatarsal heads). Where the lines intersect identifies the centre of the 1st and 5th heads respectively . The length of the orthosis should not extend distal to that point and finish proximal to the area otherwise it will interfere with the leverage function of the mpjs. Once heel lift takes place and weightbearing is over the met heads (mid propulsive phase) the traditonal 3/4 orthoses ceases to function (other than provide arch integrity). I have always used silicone props in conjunction with 'functional' foot orthoses to engage the lesser toes.

    Full length inlays of accommodative materials provide added comfort (if required) and most shoes should have approx. 3/16 " dead space to work with. At one point smaller sized functional foot orthoses were popular whereas now there seems greater acceptance of 'buttress style" foot orthoses (not sure why this is as there appears to be no physical advantage from the bulk). Some shoe manfacturers now claim to have shoe fittings suitable for foot orthoses, which to me seems rather an anathema since foot orthoses should fit the foot (and not the shoe), suffice anything the foot gets into the orthoses goes comfortably too.

    This may mirror the increased reliance practitioners put upon orthotic services, where minor adjustments made by the practitoner may negate product warrenty and therefore it is easier to have the supplied foot orthoses fitted to a larger shoe. (?)

    But hey. what do I know?
  9. Boots n all

    Boots n all Well-Known Member

    l think you will find that most people with an Orthosis in their shoe find there is slip/traslation at the back of the shoe due to a lack of "back height", those that state "Orthotic Friendly" are about 75mm deep as aposed to some products that are lucky to be 60mm depth at the back.
    The same can be said of some Orthosis when it comes to midfoot fit to say nothing of the inappropriate style choosen by the client:bash:
  10. Cameron

    Cameron Well-Known Member

    Boots n all

    >.....there is slip/traslation at the back of the shoe.

    As a mimimalist I would argue if the foot orthosis causes the heel to slip out of a standard shoe, then the bulk of the orthoses is at fault.

  11. Boots n all

    Boots n all Well-Known Member

    l would love to say that to some of the reffering Pods but l tend to break out in a rash at the thought of "tar & feathers":eek:
    Yes sometimes they are a bit high but sometimes the shoes they try to fit them into are far from right, its about balance, you cant spend $450+ on an Orthosis and try to make it work in a low cut $25 shoe:bash:
  12. Cameron

    Cameron Well-Known Member

    Boots n all

    Certainly sympathise.

  13. Re: Orthoses length

    Agreed. I would like to see a full length plate though- not just "a bit too long"
  14. Re: Orthoses length

    I have a pair of trainers on today, the thickness of the sockliner at the forefoot is 2-3mm, If I remove this and replace it with a full length orthoses made from 2mm material how will this effect the room in my shoe?

    Don't buy it. :pigs:
  15. Are these good things or bad things? Hint- see thread of post I linked previoulsy http://www.podiatry-arena.com/podiatry-forum/showthread.php?p=20460#post20460. BTW I wasn't talking about poron or eva, I was talking about polyprop or carbon fibre and the like
    Last edited: Nov 30, 2007
  16. Have you tried that in your 8 inch stilettos Simone?;)

    A good portion of our patients are elderly and its a sod of a job trying to get a 80 year old to wear trainers or decent shoes with a removable lining. They think that it makes them look old!:hammer:

  17. Boots n all

    Boots n all Well-Known Member

    Okay, Sorry Simon, l can only read what yout type?
    Polyprop or Carbon Fibre is a completly different topic, l dont know if you could call them " traditional orthotic shells " as you stated in the initial post but thats cool.

    "I have a pair of trainers on today, the thickness of the sockliner at the forefoot is 2-3mm, If I remove this and replace it with a full length orthoses made from 2mm material how will this effect the room in my shoe?"

    No l agree with you, you have changed nothing much in this case, pending the stiffness of the replacment compared to the original, if you replace it with Polyprop or Carbon Fibre it changes everything (excluding the space issue), especially if the shoe does not have enough "rocker" effect to the sole shape or you have bought a plate that does not match the contours of the shoes sole, heel height, toe pitch, thinking of those your 8 inch stilettos at the moment of course:)

    As l stated in my earlier reply, poron and EVA were given as a few examples, add
    Polyprop or Carbon Fibre to the examples and you have the same statement working just fine for your discussion

    "The level of this effect is going be directly related to the material/substance used for the forefoot extension, Poron, EVA?".......Add them here:cool:
  18. Me, I'm not a big fan of putting orthoses into the shoes of 80 year olds who are wearing inappropriate footwear. Regardless, my point remains. With appropriate footwear or a thin enough shell material, why should an orthotic shell end proximal to the MTPJ's? If the argument is that it will have a detrimental effect on the sagittal plane function of the foot, I should like to see the evidence. We do have some evidence that increasing forefoot stiffness of footwear will have a positive effect on selected activities. What evidence is there that increasing the forefoot stiffness of footwear has a detrimental effect?
  19. Shane Toohey

    Shane Toohey Active Member

    Hi all, especially Mr Toeslayer,

    I'd like to add some thoughts clinical/lab perspective and having been involved in this stuff for a while. There are just too many quotes to acknowledge that I'll just have to miss them all.

    So we're talking about the rigid shell extending beyond the 'normal' length of finishing just behind the met heads.

    I've got three real threads to outline.

    1. I have made them longer and to the end of the shoe.
    For sprinters I have made rigid full foot orthotic shells (called them RFFO's)
    These were made on casts taken with the forefoot dorsiflexed against the rearfoot. The amount of dorsiflexion was a variable. It was impossible to sprint in flat or low angled forefoot and an angle of 25-35 degrees seemed to work well - possibly enhancing performance if not at least improving stability. The higher the angle got the more difficult it was to walk with them. These devices were mostly made using real carbon shells with a thin soft EVA cover.

    2. From time to time we had a few clients ask for shells to be extended, so that they extended under the met heads in the form of Morton's extensions, Reverse Morton's, 2-4 extensions or with cutouts for particular met heads and extending under the rest. I don't think we were unique in doing that and we were rarely asked to remove the extensions.

    3. In my clinic, patients usually arrive with a couple of pairs of orthoses at least.
    One of the things I check on these old devices is the length which if long enough to interfere with dorsiflexion of the mpj's can be the cause of unresoved problems and the development of new ones either at the mpj itself or back at the bases of the mets. I have seen 1stmpj ROM improve more than 20% after wearing a shortened (from being 'too' long) device for a week. Often this was not the presenting problem.

    I'd say that you could extend many shell if you wanted to but would need to have some 'spring' or dorsiflexion angle built into it. Personally I like soft extensions if at all possible to keep devices more stable in shoes and so that I can add extra bits under the forefoot wherever I like very easily.

  20. Cameron

    Cameron Well-Known Member

    young Shane et al

    Absolutely no arguement from me and would suggest a "conditons apply" clause to specific managements. It would however be the exception rather than the rule, correct me if I am wrong.

    In a previous existance I taught the manufacture of foot prostheses and would set students the laboratory task of devising a foot prosthesis for post Symes amputation based on Root biomechanics. (Yes, I was once a devotee.) The best examples always included an distal extension of the three middle metatarsal plane with a moulded prosthetic toe block set to a pre-calculated angles to give the prosthetic extension, toe spring. Similar I think to what you are suggesting?

    When is out next coffee date? On me this time.

    Hav a good one
  21. Cameron

    Cameron Well-Known Member


    Something which I have not seen discussed on the forum is when the use of balanced foot orthoses are contra-indicated because the physiological age of the joint. As I understood the situation as suggested in Root et al was there was a time when joints were no longer able to adjust to realignment (without further limitation of movement or osteoarthrosis) and at that point 'function foot prescriptions' were contra-indicated. This situation occurs as part of the normal aging process and was not uncommon in the thirty something group. Interesting aside the demographic is one to which foot orthotics are most frequently prescribed. Can we expect further foot morbididty as this demographic ages caused by foot orthotic intervention ?

    What say you?

  22. Bruce Williams

    Bruce Williams Well-Known Member

    could you elaborate on the above statements please? Possible post a picture or diagram.

    I'm a bit confused in your statement that you cast with the forefoot DF'd against the rearfoot. Can you describe this technique? It sounds like you are flattening the medial arch with this technique.

    You also describe a 25-35 degree angle of the forefoot. I'm trying to visualize all this but am a little slow tonite I guess?
  23. Shane Toohey

    Shane Toohey Active Member

    Mr Toeslayer,

    Definitely, as have regards to pass on from another of your comrades splattered around the globe. I had a chat with this one in Brisbane - just to get you thinking.
    I'm back from Adelaide next Sunday (9th), so perhaps later that week - the Friday?

    Strangely, I think there are ways of improving foot function aside from orthoses, including mobilising joints. Preferably this is done before the assesment and prescription of orthoses and I think this makes orthotic therapy more tolerable and effective. Also one can be very pragmatic about orthoses and for a benefit (like reduced pain or improved ability to increase ambulation, there is no reason not to modify prescriptions. There's not just one prescription per person dependent on some ancient rituals. As always, just my thoughts from practicing for too long!

    Hi Bruce, you said:

    Outside my skill level to do a diagram, I'm afraid, Bruce.
    Imagine if a cast was taken semi-weightbearing with the heel about 4cm off the ground but the forefoot in contact. Then round off the forefoot a bit more in the positive cast so that it has a very mild curve in the sagittal plane.
    This is a sprinting device and you definitely do not want the device to be high in the medial arch. We want to enhance movement in the sagittal plane and reduce movement in the frontal plane as beyond a certain amount occurring as part of a recoil any excess is a waste of time and energy.
    So you have a basic shell. There are more variables possible and one of these days perhaps it can all be researched.
    I hope this helps.

  24. Simon:

    This is based on the idea that shank independent materials, such as polypropylenes, acrylics and composites, have enough intrinsic stiffness so that if they extend past the metatarsophalangeal joints (MPJs) the orthosis shells would not only interfere with normal MPJ dorsiflexion but would also tend to produce uncomfortable excessive loading forces plantar to the MPJs during late midstance and propulsion. Of course, the shank dependent materials, such as EVA, plastazote, and cork, can easily extend past the MPJs since they do not possess the intrinsic stiffness that will prevent them from being deformed at the MPJs as the propulsive phase of gait occurs.
  25. Bruce Williams

    Bruce Williams Well-Known Member

    thanks for the reply, I understand much better now. Essentially you are pre-loading the mpj's for dorsiflexion transition from midstance toe-off.

    Will you add a 4mm heel post to the devices since you cast that way, or not?

    I'd be curious to see any research you have on those?

    Be well.
  26. Shane Toohey

    Shane Toohey Active Member

    Hi Bruce,

    I'd suggest that the dorsiflexion angle can be such as to cause acceleration in the sagittal plane. If it is too high you fall on your face - so somewhere there is an angle that you can just keep up with.

    Only got to an early stage in the research and can say that these devices enhanced velocity but it was harder to start.

    The casting angle was over 20 degrees and could be calibrated with an angled platform, and were obviously more than 4cm at the heel. Heel raises on the orthoses seemed logical up to a point to reduce the time taken for the heel to be dropping into weightbearing.

    I wouldn't mind taking this project up again sometime!

  27. Cameron

    Cameron Well-Known Member


    >Definitely, as have regards to pass on from another of your comrades splattered around the globe. I had a chat with this one in Brisbane - just to get you thinking.
    I'm back from Adelaide next Sunday (9th), so perhaps later that week - the Friday?

    Would you believe, I earn a modest living on Friday and seem to be busy up to the 20th. Will give you a ring tho' and arrange something.

    Meantime, I bet it was AC in Brisbane. That girl could do a tango with me anytime. :morning:

    .... and I would like to acknowledge the benefit of Yeastvite tablets and Senatigen Wine as a perfect combination for the older more discerning adult.

  28. Shane Toohey

    Shane Toohey Active Member

    It was AC, so that wasn't hard at all, Mr Toeslayer,

    We'll have to make it a WEDNESDAY!


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