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Ankle kinetics in snow boarding

Discussion in 'Biomechanics, Sports and Foot orthoses' started by David Smith, Mar 27, 2014.

  1. David Smith

    David Smith Well-Known Member


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    Hi guys

    I'm treating a guy who complains of severe plantar pain during activities,. The pain is especially intense, 11/10, snow boarding, which is his favourite pass time.
    Unfortunately this 40yr old guy has a terminal illness and only has a short life expectancy of a few months maybe a year. So he want to go snow boarding with his son as much as he can but the pain is to intense to do so.

    My diagnosis is popliteal artery entrapment syndrome. There is no pain that can be elicited by manual palpation or manipulation of the relevant tissues and joints.
    He finds that the pain is considerably less if he lossens the bindings on his snoe boarding boots, which are a soft type in comparison to the rigid type ski boots. However this of course leaves hime susceptible to ankle injuries.
    During snow boarding he often gets swelling in the upper shank above the boot top.
    He describes the pain as intense ache like cramp.

    He has been on chemotherapy for a long time but there does not seem to be signs of peripheral neuropathy.

    The DP pulse is strong and p[alpable but the Post tib pulse is non palpable.
    ABPI is 1.02 left and 1.2 left and doppler is triphasic on all pedal pulses other signs of circulation are good.

    The diff diagnosis is by SLR test and active pronation test, i.e. on Straight leg raise in supine laying position the DP pulse becomes weaker with hip flexion and dissapears at about 50dgs hip flexion. In the sitting position with knees extended the DP pulse dissapears with forced active pronation. I could not palpate the PT pulse so it was not possible to test it and it was too diffcult to reliably locate the pulse with doppler probe and manipulate the foot and leg at the same time.

    So after a bmech assess the most prominent feature was very lateral stj axes.

    After examining his snow board and boots and watching snow boarding action videos and instructional videos I came to the conclusion that most of the time there are considerable supination moments applied about the STJ. I.E. the feet are placed wide apart and toe out and so most forces are horizontal shear from lateral to medial as you push back and forth along the longitudeinal axis of the board.

    My reasoning is that with the constant lateral instability and high supination moments during snow boarding he will constantly be trying to evert / pronate the feet to maintain stability and so more than likely spend most of the time weight bearing on the medial aspect of the feet.

    This postion will also stress the PFascia and Abd Hallucis, if blood flow is already restricted by the pronation action as noted earlier in the test then additional tension in these plantar structures may also restrict circulation. Also there is the tight bindings which may further impinge on the circulation and finally there may be some mechanical pathology from the increased stress of the pronated foot and dorsiflexed 1st Ray.

    My solution is to design 2 pairs of orthoses - one for shoes one for snow boots and both with lateral posting in rear and forefoot with 1st MPJ/ray cut outs / grind outs. This will maitain lateral stability by increased orthotic forces causing increased applied pronation moments. This will reduce the requirement to use muscle forces to pronat the STJ. The CoP will move more laterally and the 1st Ray/MPJ c/o will further reduce dorsiflexion moments about the 1st Ray and so reduce PF and Abd Hall tensional stress.

    So that's what I've designed and ordered and he's going snowboarding next week. Any comments or thoughts appreciated here!

    So I've been searching for papers that study applied force vectors and magnitude about the foot and ankle when snow boarding but they seem a bit thin on the ground and the ones there are can only be got by suscription. So does anyone have such data or any papers they could share? It would be very helpful if you could pass them on to me for me to read and improve my knowledge and potential outcomes for this case.

    Regards Dave Smith :drinks

    PS I do already have this paper but not read it yet

    Biomechanical analysis in freestyle snowboarding:
    application of a full-body inertial measurement system
    and a bilateral insole measurement system
    Andreas Kru¨ger and Ju¨rgen Edelmann-Nusser
     
    Last edited: Mar 27, 2014
  2. Admin2

    Admin2 Administrator Staff Member

  3. Dave:

    My guess is that his legs are not receiving sufficient arterial perfusion during more aggressive physical activities that is causing intermittent claudication during snowboarding.

    If the posterior tibial arteries are occluded or severely restricted, then this would explain the cramping-like sensations in the legs and plantar feet with more aggressive physical exertion. You could have him try some low dose aspirin or talk to his family physician about using a medication such as Plavix which helps decrease the symptoms of intermittent claudication.

    Diagnosis and medical management of patients with intermittent claudication

    Effect of Aspirin Versus Clopidogrel on Walking Exercise Performance in Intermittent Claudication: A Double-Blind Randomized Multicenter Trial

    From your description, my impression is that this is not a biomechanical issue, but rather is an arterial inflow issue. I have treated many recreational and a few professional snowboarders over the past two decades and have never heard of symptoms such as you describe in this patient.
     
  4. David Smith

    David Smith Well-Known Member

    Kevin

    Thanks, ive been reading some of your posts on this thread
    http://www.podiatry-arena.com/podiatry-forum/showthread.php?t=1383
    from 2008/2009 which is mostly about orthoses for skiing and of course the requirement for skiing are very different than snowboarding but some principles can be applied and so is very useful. As you have expereince with snow boarding perhaps you could help further.

    What I note is that the snowboarder has a wide stance and this automatically results in horizontal forces at the foot/board interface that invert/supinate the STJ.

    so if someone has very lateral stj axes and valgus forefoot and so had their orthoses in the boots laterally posted, would this be detrimental to the snowboarding technique?

    Dave
     
  5. Dave:

    The snowboarding stance is only a little wider than a normal standing stance in distance between the feet. I don't think that this creates excessive subtalar joint supination moments in most snowboarders. Snowboard orthoses, if necessary, should support the midfoot/midtarsal joint and prevent any excessive subtalar joint supination or pronation moments. Of course, if their foot structure encourages excessive external STJ supination moments, then a slight valgus rearfoot and forefoot wedge may help stability and help lessen peroneal muscle fatigue.

    http://blog.storeyourboard.com/2013/10/how-to-set-your-snowboard-stance.html
     
  6. björn

    björn Active Member

    Hi David,

    You write and know more from technical, podiatric knowledge perspective than I, however I have snowboarded for about 18 years and would say I'm reasonably competent (never raced, but can take on most runs on any mountain - but not in that annoying way where people snowplough down black runs to say they did it!! haha)

    How competent is this guy as a snowboarder- probably quite good at 40 if its his favourite thing, but fatiguing unfortunately due to his illness :(?
    How old are these boots ? Have they been bought prior to onset of pain? Has this happened in more than one pair of boots?
    HOw new are the bindings? What type are they?

    A lot of questions I know but much like different types of athletic shoes affect a runner, they certainly do similar in snowboarding.
    I at one point bought and sold three pairs of boots which were giving me claudication-style pain in the plantar aspect of both feet. It was intense - to where I would stop riding, loosen boots and get back out there after a break. In the end, I got a pair where it stopped happening - though my toes would freeze off, and hope some new ones now don't take me back to the bad old days of cramping soreness whilst maybe alleviating the coldness too!

    Bindings have to be tight - but the location of them can be signficant in claudication symptoms also.

    Without knowing what you know and whether you've asked all these questions already, I would try different boots - and one thing worth considering is a hard-boot set up (like racers use in slalom - but a little more like a ski-boot is an easier explanation) though there are other short comings - such as difficulty walking and then applying pressure elsewhere.

    Another thing worth noting is that these symptoms were always worse at the beginning of a season for me - because no matter how fit I was, I just wasn't yet conditioned to riding a snowboard, so my guess is that this patient was not hitting the powder during his chemo sessions so may be lacking some condition also??

    I hope this helps you and look forward to reading of a pleasant outcome in what is a horrific situation I would never wish upon anyone.
     
  7. David Smith

    David Smith Well-Known Member

    Very good thanks Bjorn, I'll get back ASAP

    regards Dave Smith
     
  8. David Smith

    David Smith Well-Known Member

    Bjorn

    His boots are two years old, the binding type is strap and ratchet, he did have the pain before buying the new boot, which is one reason for changing the boots but the pain did not change.

    Dave
     
  9. efuller

    efuller MVP

    I've never snow boarded, but I will assume that steering is somewhat like skiing. In order to steer with an edge you have change the location of center of pressure between rider and ski. When you shift the center of pressure toward an edge, the the wider ends will contact the snow and the middle portion will not. The weight in the middle will cause the board to curve and thus create the situation where a turn can be carved with the edge of the board.

    So, to engage an edge the person has to shift their center of pressure either forward or back depending on which edge they want to engage. Shifting their center of pressure is straight out of the old Hicks article. Anterior tibial shifts weight posterior, Achilles tendon shifts it anterior. Shifting of center of pressure could also be done with the leg in a more rigid boot. Flexing the knee would pressure on the anterior aspect of the boot and if the boot was rigidly attached to the board that would also tend to put pressure on the edge.

    I would imagine there is a lot of physics that is similar to a cat always landing on its feet. One end of the body twists one direction while the half of the body twists the other direction, but that is not so much related to the feet.

    So, thinking about this guys problem. It sounds more vascular from your description. However, thinking about the physics of the sport is entertaining.

    Eric
     
  10. amz135

    amz135 Welcome New Poster

    Again I'm coming from a snowboarder/skier experience and a previous snowboard boot fitter.

    I'd definitely look at the boots more - the size in particular, length and width. The other source of cramping sensation is from boots too big. He's had the boots for 2 years, which means the padding inside would have broken down more. If the boots are on the big side then the foot is swimming around and his intrinsic muscles are overworking to stabilise the foot which is another cause of cramping.

    When fitting snowboard boots, they should be fitted so that the toes are touching the end of the boot when stood upright (knees straight), then when knees are flexed the toes will come away from the end. This is something a little unnerving for snowboarders that have never owned new boots before but in my experience is a lot longer lasting fit. Likewise different boots are different widths, ask a boot fitter for advice as my knowledge is outdated now.

    A stiffer boot is also another option I have used. Also a heel raise if calf length is reduced as this reduces the forefoot pressure.

    I understand that his medical history does indicate this could be what's causing the problems but I have come across the above complaint in healthy individuals as well and thought I'd share what I did to resolve the problem.

    Let me know if this was any help.
     
  11. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
    1
    Three-dimensional lower extremity joint loading in a carved ski and snowboard turn: a pilot study.
    Klous M, Müller E, Schwameder H.
    Comput Math Methods Med. 2014;2014:340272
     
  12. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
    1
    Differences in injury distribution in professional and recreational snowboarding
    Ehrnthaller C, Kusche H, Gebhard F
    Open Access Journal of Sports Medicine » Volume 6
     
  13. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
    1
    Strength Asymmetry Between Front and Rear Leg in Elite Snowboard Athletes.
    Vernillo, Gianluca PhD; Pisoni, Cesare MS; Thiebat, Gabriele MD
    Clinical Journal of Sport Medicine: April 02, 2015
     
  14. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
    1
    Simultaneous bilateral snowboarder's fractures in a young woman: a rare entity.
    Barai A et al
    N Z Med J. 2017 Jun 16;130(1457):79-83.
     
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