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Stiff soles and Charcot

Discussion in 'Biomechanics, Sports and Foot orthoses' started by markjohconley, Dec 12, 2013.

  1. markjohconley

    markjohconley Well-Known Member


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    Am having a disagreemnent with an orthotist.
    He prescibes non-flexible soles with mid-foot rocker for plantar internal longitudinal arch ulcers.
    Most recent patient had > 60 degrees of dorsiflexion of hallux (passive).
    My most recent reply from him, to my query as to the use of inflexible soles and rocker was "they reduce plantar pressure".
    I am intending to forward my response to him.
    My thinking is; certainly inflexible soles and rocker bottoms DON'T reduce plantar pressure (use cam / aircast walkers for that), though they certainly would change the timing and position of the plantar pressure.
    Also wouldn't a inflexible sole (no flexion at all at forefoot region) inhibit the Windlass effect, increasing dorsiflexory moments on the metatarsals and thereby increase plantar pressure on the proximal ends of the metatarsals, tarsals?
    Please correct me and/or suggest more plausible explanation, thanks, mark
     
  2. Ros Kidd

    Ros Kidd Active Member

    Am I understanding you, the patient has a medial collapsed Charcot foot with ulceration?
    Ros
     
  3. markjohconley

    markjohconley Well-Known Member

    Yes Ros, the latest patient has a chronic plantar ulcer post Charcot neuroarthropic episode; I don't treat him; was asked to assess by the wound care nurse, mark
     
  4. Deka08

    Deka08 Active Member

    I may be speaking out of turn, or missing your point Mark, but why no TCC or cam walker?
    Is the non flexible insole a carbon fibre shank or a stiff accommodative device?
    If I understand you correctly I think you're right, in an unstabilised charcot, no support could cause further destruction and pressure through the wound.
    Boots and a stiff insole almost sounds like an poor imitation cast/cam walker.
     
  5. markjohconley

    markjohconley Well-Known Member

    Goodaye Derek,
    Apparently the stiff soled boots are his 'long-term' solution.
    I'm in full agreement any footwear could not reduce plantar pressure as do cast/cam walkers but since the patient / regular treating clinician have gone this path it's the effect of the stiff (inflexible at forefoot) footwear i'm really questioning,
    all the best and a merry xmas, mark
     
  6. Boots n all

    Boots n all Well-Known Member

    Charcot treatment for me is straight forward IMO.

    Custom boot to match the "new" shape of the foot with TCO and yes a rigid rocker sole.

    The combination will reduce the plantar pressure and improve gait, for some, and l cant speak for your client, greater use of ROM at the knee and hips and less waving of the arms to get moving and keep moving.

    The fulcrum of the rocker is very important, in the right location, less force/pressure will be required to go through from mid stance to propulsive.

    Also think for a moment, flextion will cause shear, as the shoe flexes the foot is then on the inside of a curve.

    In this manner we have kept a lot of charcot feet and their owners together!

    Edit; Do you or your Orthotist have any way to measure/ map pressure inside the shoe? otherwise it may well be a mute point, "In theory" doesnt mean you got it right.
     
  7. Boots n all

    Boots n all Well-Known Member

    These are Fscans of a diabetic, not charcot but they will serve the purpose.

    He lost a few toes before we saw him, the difference here the first scan (on the right) is of him in his original flexible shoe, the final scan(on the left) is of him in a new shoe with TCO and a stiff rocker sole, very big change, little force is now required at the forefoot to get the heel off the ground.
     

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  8. Ros Kidd

    Ros Kidd Active Member

    The immediate problem needs dealing with and that is to immobilise the pt in a TCC or similar until the temperatures are equal and the ulcer is healed. Very close monitoring for OM is required. I am assuming that this patient is being treated at a High Risk Foot Clinic. Charcot feet seem to be a law unto themselves and need an experienced orthotists working with the team. I would never of dreamt of second guessing our orthotists, when push comes to shove they certainly were the experts in this area.
    Ros
     
  9. Lab Guy

    Lab Guy Well-Known Member

    "Also wouldn't a inflexible sole (no flexion at all at forefoot region) inhibit the Windlass effect, increasing dorsiflexory moments on the metatarsals and thereby increase plantar pressure on the proximal ends of the metatarsals, tarsals?"

    __________________

    I agree with David, the goal is to first get the ulcer healed using casting as David said and once it is healed, use a rigid sole with rocker. Accommodative orthotics with perhaps a double rocker if deformity is in the midfoot area/MTJ is beneficial to help off-load the plantar mid-foot. The goal is to restrict motion of the joints as much as possible.

    The windlass is not established at all in the Charcot foot; there is no resupination with collapse of the MTJ and possible fractures. The diabetic Charcot marches to a different drummer.

    The other consideration of course is surgery to remove the plantar prominence causing the ucler if rigid or resect the prominence and fuse the appropriate joints if there is mobility to prevent recurrence of this very challenging deformity.

    Steven
     
  10. markjohconley

    markjohconley Well-Known Member

    Thanks Boots
    Plantar pressure under the lesion not total plantar pressure, fair enough

    This point, wouldn't there be an increased dorsiflexory moment on the metatarsals with both a rocker bottom and an inflexible sole?


    Sorry Boots "on the inside of a curve" would you elaborate not sure what we're talking about here, thanks, mark
     
  11. markjohconley

    markjohconley Well-Known Member

    This is the bit i forgot!!!! thanks boots
     
  12. markjohconley

    markjohconley Well-Known Member

    Yes this latest patient is under a high risk foot clinic, mark
     
  13. markjohconley

    markjohconley Well-Known Member

    The other bit i forgot, thanks Steven
     
  14. Boots n all

    Boots n all Well-Known Member

    Easy way to explain.
    Put on your favorite old sports shoes, dont bend or flex any of your foot or your knees joints and feel the distance from your toe to the end of the runner, 10-15mm?

    Now bend everything you want including putting your foot into the extreme planta flextion, like a sprinter about to jump from the starting block, now check your toes distance from the end of your runner, 5-0mm from the end, its on the inside of the curve of the flexed sole a moment of shear action occurred at the forefoot.
     
  15. Phil Rees

    Phil Rees Active Member

    Mark,
    it would be helpful if you could describe the patients foot in a little more detail as it will be an important factor in the shoe sole design (Brodsky type would be helpful)
     
  16. efuller

    efuller MVP

    I'm not quite sure where the ulcer is. Plantar internal arch, is that the same as medial arch. For example plantar to talar head.

    There was a study out of Carville that did show that a rigid shoe, with no rocker, reduced plantar pressures on the hallux. It's kind of a behavioral thing. It's harder to plantar flex the ankle against the long lever arm. The placement of the rocker matters. There were some other studies that looked at rocker position and if I remember corrrectly ~ 60% of foot length (behind met heads was the optimal spot for hallux and forefoot pressure reduction. Now, if the ulcer is the middle of the foot then the rocker is not going to work. Those same studies showed increased pressure and duration of pressure on the heel with rocker bottom shoes. With the anterior rocker, just behind the met heads, as the ankle plantar flexes the whole shoe will rotate with the foot and the rear part of the shoe stays in contact with parts of the foot that are proximal to the met heads. If there is a charcot midfoot collapse deformity, then the rocker could reduce some of the deforming force creating a further dorsiflexion of the forefoot on the rearfoot. However, if the charcot foot has fused with the deformity then the rocker is not going to help the ucler under the talar head.

    On rigid shoes and the windlass. The windlass can unwind too. There are many feet where you can palpate a tight plantar fascia while standing on the rigid ground. The inside of the shoe should be the same thing as the ground. The windlass will still help resist forefoot dorsiflexion on the rearfoot even in a rigid shoe. However, if the talar head is on the ground, chances are the plantar fascia was ruptured and if it did heal it healed quite a bit longer.

    Eric
     
  17. efuller

    efuller MVP

    The dorsiflexiory moment on the metatarsals comes from ground reaction force plantar to the metatarsals.

    Without a rocker bottom, in gait after heel lift, the other leg is in swing phase, the entire body weight will be on the metatarsal heads. You can't get much more dorsiflexion moment from the ground than in this situation.

    Now, when you add a rocker, in gait, when the heel of the shoe lifts off of the ground, the heel of the foot remains in contact with the shoe. The total force on the entire foot is going to be determined by body weight. If you shift some weight to the heel, then it has to reduce somewhere else. In this case the pressure under the forefoot reduces as the pressure under the heel increases.

    Eric
     
  18. markjohconley

    markjohconley Well-Known Member

    Goodaye Phil, I was attempting to ask a general question re. use of rocker bottom inflexible footwear for Charcot-type midfoot ulcerations. The last patient was the last of a group that I have been asked to 'look at' in the wound clinic. Good point I should've, all the best, mark
     
  19. markjohconley

    markjohconley Well-Known Member

    Thanks Eric, excellent opinion. However, I don't doubt you, but this is difficult for me to comprehend. How would the rearfoot, after heel off, even though still in contact with the shoe, have any ground reaction force? all the best, mark
     
  20. efuller

    efuller MVP

    There is a difference between the heel of the shoe and heel of the foot. As the heel of the shoe lifts off of the ground the heel of the foot is still in contact with the shoe. Ok, it's not ground reaction force, but shoe reaction force. The foot is in contact with the shoe and not the ground. Force from some object has to resist the pull of gravity toward the center of the Earth. If it doesn't you will accelerate toward the center of the Earth.

    It's like standing on a piece of plywood about the same size as your foot. Under the plywood 3cm diameter rod running from medial to lateral under the shafts of the metatarsals. As you attempt to plantar flex your ankle, the center of pressure under your foot will move anteriorly. When the center of pressure of contact between your foot and the board is anterior to the rod, the piece of plywood will rotate. As it rotates, the heel will still be in contact. When the anterior edge of the board hits the ground, further attempt to plantar flex the ankle will lift the heel of the foot off of the board.

    Eric
     
  21. markjohconley

    markjohconley Well-Known Member

    Thanks Eric, that's straight-forward, like a childrens playground see-saw. After the rocker section of the sole lifts off, with an inflexible sole, would the GRF be transferred, via the sole, from the toes to the metatarsal heads / remainder of plantar foot?, mark
     
  22. efuller

    efuller MVP

    I'm not quite clear on what you mean by rocker section of the sole. Some orthotists talk about posterior rockers versus anterior rockers. The typical rocker used to decrease pressure on the met heads will be flat on the posterior half of the shoe and then curve, or angle, upward starting about 60-70% of the shoe length (just behind the met heads. Which part of the shoe are you asking about?
     
  23. markjohconley

    markjohconley Well-Known Member

    This bit, where your 'rod' would be. I didn't realise how difficult I am to understand, a few posts this thread have queried my use of English. It always was my worst subject, my first choice for university (1972) was Veterinary Science, missed it by 3/500 marks thanks to my poor English result. Don't worry any more, very good of you to attempt to educate me, I'm 'barking up the wrong tree' with this one, all the best and merry Xmas, mark
     
  24. markjohconley

    markjohconley Well-Known Member

    Goodaye Boots forgot to ask if the patient was Fscanned with the new shoe with TCO and NO rocker and flexible sole at metatarso-phalangeal joint region? Would like to see that, mark
     
  25. Boots n all

    Boots n all Well-Known Member

    No Mark, been there done that and learn the difference very quickly, from my experience, flexible sole for a foot that is not flexible just creates more force than if they had a rigid rocker sole.

    We do all that we can to make the shoe as close to what we think will be the end results before the client arrives and prepare to make changes as needed.

    Have you ever noticed clients that come in wearing AFO with a rigid sole plate and no rocker sole, they tend to break the foot plate... no rocker = too much force, not that different to your Charcot foot client?
     
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