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Functional propulsive phase limb length discrepancy.

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Morgan, Aug 5, 2005.

  1. Morgan

    Morgan Member


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    Dear all
    Does anyone have some ideas as to how this problem may be solved?
    Patient: Left sided TEV, operated on as child. Left foot is shorter than right by approx. 2cm. Not bad foot posture for post-TEV. Good ROM. Triceps Surae all ok. Some ankle restriction bilat.(bony). Symptoms: thoraco-lumbar pain after walking or playing football. Force plate analysis indicates left foot reaching peak vertical forces at 500ms of 162N. Right foot at 500ms is only at 68N. Peak forces are reached far later. Result of this is a functional dicrepancy and thus asymetry in kenetic chain. This is obviously (or maybey not!) due to the shorter foot and thus the shorter lever mechanism during propulsion.

    Is there any way to increase the lever mechanism function of the left limb / foot using foot orthoses or modifying footwear?
    I have thought about making the left orthotic to web length and the right to met length, to try and get some leverage under the MTP joints during propulsion. (?) Any other thoughts?

    Thanks
     
  2. Bruce Williams

    Bruce Williams Well-Known Member

    Morgan;
    I find it interesting that your force plate measurements show pretty much what I see using in-shoe pressure analysis. I'll usually see a higher pressure on the short sided limb and faster accelerations on that side as well. The long sided limb will move more slowly and have lower heel contact pressures.

    First though you need to determine what the LLD (limb length difference) is exactly in inches or cm's. Use felt pads at the heel of 1/8" or 3mm thickness and keep adding until the pelvis equals out. You can check the PSIS as well right /left for balance. Make sure you check for any functional LLD as well... check the PSIS and ASIS and pelvis in Resting calcaneal stance position and then re-check when in Neutral calcaneal stance position ( i.e., have the patient roll their feet outwards - supinate them) and re-check. If the level of inbalance lessens in NCSP then figure in 1/8"-1/4" (3-6mm) of a functional LLD.

    Don't make your orthotic to sulcus length, not of polypropolyiene anyway. EVA or Leather/cork would be ok.

    If the LLD is 3/8" or less, then you can probaly put the lift in the shoe. Some pods won't go over 1/4" in the shoe, whatever works is how I feel. You can always add lift to the sole of their shoes too as necessary.

    I traditionally don't use flat lifts, I lift the heel in the majority of cases, but sometimes a flat lift is better, so long as the shoe has some rocker bottome properties to assist and not block sagittal plane progresssion.

    I hope this helps.
    Sincerely;
    Bruce Williams, D.P.M.
    tired and now back from vacation and work in Hot Orlando!!!!
     
    Last edited by a moderator: Aug 7, 2005
  3. Morgan

    Morgan Member

    Thanks for the reply

    Dear Bruce
    Thanks for your reply. I too have just returned from holidays, hence the delay in my response. I will try what you have suggested. I am glad someone else is getting the same readings with their force plate alanysis! I should have some motion to 'play with' in the rearfoot complex to carry out what you suggested. It sounds like a good idea. Thanks for your help. I will post a reply and let you know how I get on.
    Cheers
    Gafin :)
     
  4. dawesy

    dawesy Member

    Hi Morgan,

    I don't have access to force plate etc but i can however speak on very personal experience with a very similar problem....me!

    I too was born with TEV. I had two seperate operations around 23 years ago (am now 25) to surgically recorrect my right foot. My left foot is pretty normal, although slightly on the everted side of things (that is if we can define any foot as normal..... :p ). My right foot is approximately 2 shoe sizes smaller, and i have an LLD of around 2cm R<L. It is now a cavoid (as you would expect) structure, and quite rigid. An osseous ankle equinus is present. Due to a still reasonable degree of adduction and inversion, I walk with a low gear pushoff through the lesser metatarsal heads of my right foot.

    I have always been very active, and when i hit about 16, injuries including lumbar back pain became frequent.

    As i said i don't have access to force plates etc, but from just feeling what is going on, it is obvious to me midstance is very short. Not long after weight acceptance i feel myself already in propulsion, and spending a lot of time (relative to right stance phase) on my toes, possibly to minimise pelvic movements. I know i spend a lot more time on my left leg (and am constantly being asked why i limp whithout realising i am!!).

    It has been theorised that normal nutation of the back through biceps femoris has a role in bracing the back. For someone who spends little time on that limb, i know this is not occurring....could be one potential reason why lifts can be ineffective at fixing pain pain in candidates like you patient (an me!!). I have tried multiple lifts, full length being VERY ineffective as i found this made getting into propulsive phase difficult. 1cm+ lifts were very aggravating on my back, and i now use about 0.7 mm EVA (medium density) heel lift. This corrects me somewhat. However, as i mentioned, i feel there is a sagittal plane component, as i do not go through a normal propulsion, and have a low gear pushoff. I have found orthotics (EVA best as more rigid materials do not mix well with my rigid foot) to eradicate lesser metatarsal pain (low gear pushoff), as well as getting appropriate fitting shoes.....shoes that fit left foot, find flexion in the forefoot would be occurring closer to the toes of my right foot, rather than the met heads....another sagittal plane block.

    These raises, orthoses and appropriate shoes helped foot pain, however back pain still was there. I did however find this lessened with heel raise as this allowing me to flow more smoothly into propulsion. MY saviour has been all of this with good old physical therapy. I guess there is only so much we can do with a surgically reconstructed foot, and although the above helped, core stability exercises have found me getting back into doing such things as running on asphalt etc and pulling up well.

    No idea if any of this experience is helpful, but i know when i see patients with TEV i don't put all my eggs on the frontal plane basket (ie orthotics, neutal position etc). I think a lot is well treated taking sagital plane into consideration and also local therapy of the back.

    Interested to see how your patient goes and what treatment works for you.

    Good Luck!
     
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