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Asymmetrical heel lift

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Zac, Aug 15, 2013.

  1. Zac

    Zac Active Member


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    Could I have some advice on how to address asymmetrical heel lift. 20 year old male with left calf weakness (& reduced size) compared with right side. Appears to have a delayed heel raise on the left hand side. Im thinking how can I establish heel lift sooner on the left side (as well as him seeking further treatment from a Physio). He is working on strengthening the gastroc/soleus but I remember Craig P talking about using different density heel lifts to alter heel lift timing. Could someone give me some advice?
     
  2. Craig Payne

    Craig Payne Moderator

    Articles:
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  3. Get a clinical estimate of right and left sided leg stiffness (kleg) by performing a hopping test for each leg: have the subject hop on the spot for a known period e.g. 30 seconds:

    leg stiffness (kleg) approx= 40 x number of hops per second x body mass

    This will give you a rough estimate of left and right side leg stiffness, if you have access to a pressure mat or force plate you can measure it more accurately. With this knowledge you can then select materials with different stiffness characteristics (ksurf) with the aim of equalising the effective stiffness (Keff) for left and right sides. Most manufacturers should be able to provide material data sheeets to allow you access to the load/ deformation characteristics of the materials.

    The effective stiffness of the system is given by: Keff = (1 / kleg + 1 / ksurf) -1

    N.B. The body may be modulating leg stiffness during gait to compensate for limb length descrepancy, so check this first.
     
  4. phil

    phil Active Member

    Simon, I'm struggling with this concept.

    if leg stiffness = 40 x hops x body mass
    then more hops means stiffer leg?

    does this mean the stiffer side gets the softer heel raise?
     
  5. phil

    phil Active Member

    Simon, I'm struggling with this concept.

    if leg stiffness = 40 x hops x body mass
    then more hops means stiffer leg?

    does this mean the stiffer side gets the softer heel raise?
     
  6. Potentially.
     
  7. phil

    phil Active Member

    Potentially? If not, why not?

    How do you equalise effective leg stiffness otherwise?
     
  8. Because you need to ask yourself why are the legs functioning with asymmetrical stiffness in the first place? As I said, it may be due to a limb length difference; it may be due to available range of motion etc.

    If we assume that the body "wants symmetry" but we observe asymmetry then we might presume that the body has tried to equalise stiffness but failed, in which case putting the more compliant surface under the stiffer limb is potentially the right solution here. But, this assumes that the body will not modulate the Kleg in response to the change in Ksurf. However, in response to placing a more compliant surface under the stiffer limb the CNS may attempt to make the stifffer limb even stiffer with the converse occurring under the more compliant limb in response to a stiffer surface material. So it's not quite as simple as it superficially appears.
     
  9. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Asymmetrical heel lifts make no sense to me. In fact, any type of heel lift makes no sense to me.

    In a research project I did several years ago. the resulting data indicated that functional leg length differences are frequently a result of 'gravity drive' pronation. If you are dealing with a FLLD resulting from this, you should eliminate (address) the underlying cause of the 'gravity drive' pronation. By so doing, the FLLD will automatically be greatly reduced or eliminated.

    If, however, you are dealing with a true ALLD, use a full lift platform extending from the heel to the toes. Full lift platforms do not rotate the innominates anteriorly. (Heel lifts do rotated the innominates anteriorly - see citation below).

    Bottom line - determine the cause of the left calf weakness and treat that directly. Treating the symptom with a heel lift, in my opinion, should be avoided.

    Professor Rothbart

    Rothbart BA 2006. Relationship of Functional Leg-Length Discrepancy to Abnormal Pronation. Journal American Podiatric Medical Association;96(6):499-507
     
  10. Zac

    Zac Active Member

    Should have added sooner patient is otherwise a healthy male, no LLD, no evidence of weakness in triceps surae but there was a slight reduction in the circumference of the left triceps surae - measured approx 15 mm < right - unknown aetiology.

    I guess my initial posting was I thought enough detail as my thoughts were directed to one of Craig's bootcamps & his discussion of addressing asymmetric heel lift.
     
  11. Zac

    Zac Active Member

    Should have added sooner patient is otherwise a healthy male, no LLD, no evidence of weakness in triceps surae but there was a slight reduction in the circumference of the left triceps surae - measured approx 15 mm < right - unknown aetiology.

    I guess my initial posting was I thought enough detail as my thoughts were directed to one of Craig's bootcamps & his discussion of addressing asymmetric heel lift.
     
    Last edited: Aug 16, 2013
  12. Simon:

    Have there been any studies using the method you propose above of basing heel lift density on a hopping test? Or is this theoretical? Have you used this method with any success with walking patients or only with running patients? To me, using hopping in one place to estimate what happens during the biomechanics of running at different speeds is quite a stretch.
     
  13. Kevin, it is mainly the work of Claire Farley which has correlated running leg stiffness/ performance with hopping/ jumping tests. I don't have time to find all the refs right now as I'm on vacation, but here are couple.
    http://www.ncbi.nlm.nih.gov/pubmed/11224825
    http://www.jbiomech.com/article/S0021-9290(98)00170-5/abstract
    http://www.ncbi.nlm.nih.gov/pubmed/15320647

    You'll probably find the rest of them in the leg stiffness thread: http://www.podiatry-arena.com/podiatry-forum/showthread.php?t=46019

    As I understand it, leg stiffness doesn't change dramatically from oscillating up and down on the spot (i.e. hopping) to sprinting, what changes is the angle of attack of the leg as forward velocity increases.

    As I said, the hopping test provides a rough clinical estimate, to be more accurate you need to employ a force or pressure plate.

    I don't know of any studies using the asymetrical stiffness heel lift. I've employed it within a small series of patients (some walkers/ some runners) including a couple of elite rugby players with good clinical success to date.

    Remember that walking is more effectively modellled as a complaint bipedal spring mass system than the old inverted pendulum model- but we've discussed all of that before.
    http://rspb.royalsocietypublishing.org/content/273/1603/2861.full
     
  14. My only question is....Dr. Spooner.....why on Earth are you responding to me while you are on vacation!!! I thought I was the only one that was that obsessed.!!

    Have some nice time off with the family! And tell Grace "Great Job!" on all her cycling successes!:drinks
     
  15. One more post before I get into trouble. Grace says: "thanks Uncle Kevin"- she's racing at the British Championships next weekend.

    A thought for my holidays- leg stiffness appears to related to arch height in runners http://www.udel.edu/PT/davis/Williams_2004.pdf Arch height can influence the surface topographyof bespoke foot orthoses; surface topography of foot orthoses influences the load/deformation characteristics of the orthoses; higher medial longitudinal arch area in orthosis generally means a stiffer medial longitudinal arch area in the foot orthosis; in my experience cavus feet respond better to more compliant material selection for foot orthoses...

    When we use custom foot orthoses with left to right foot asymmetry in the height of the arch section of the devices we are employing asymetrically stiff foot orthoses. Hmmm.

    Got to go, I'm being prodded.
     
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