Applicability of Modern Podiatric Theories to Athletics and Athletic Performance

as for the alignment yes...but ur kidding urself if you think you can 'correct' it all 100%

major problem in most cases is getting all this stuff in the boot. back to the originsal question ..it depends where the problme eminates from

abducted feet can come from many things, compensation for excessive STJ pronation and tight calf muscles is probably the most common that i see for ski boots..each case is individual, support foot best you can, punch out to allow the navicular not to bang on the shell and to support the soft tissue around it, lateral expansion if required, but this often encourages the foot to abduct further into the lateral side of the shell

then of course the somatec boots from fischer may be a consideration if applicable to the individual

My reference for the flange is in regular shoes. I think that navicular drift would mostly be a concern for people whose boots don't fit properly. A ski or snowboard boot is intended to hold the ankle and midfoot very securely. This tight fit should, on its own merit, prevent or at least reduce the drifting wouldn't you say? However, if there is enough room for navicular drift, either due to difficult to fit foot shape or bad buying decision, then it stands to reason that there would be enough room for a flange made of whatever material you like. That's just my analysis. What do you think?

I never said anything about expecting to correct to 100%. That said, I think it is a pods or bootfitters responsibility to do everything possible to get to 100%. Therefore, when fitting, every posible issue must be taken into account and, if necessary, accomodated or corrected to the highest degree possible. This is to provide comfort for the individual, a better skiing/boarding experience and, most importantly, to make their time safer. Injury prevention should be #1 in a fitters or pods mind. We're fortunate in that safety and performance go hand in hand on the mountain.

CEM: Yes I agree. I notice that many athletic problems in average people comes from lack of fitness and conditioning. Muscle imbalances, poor and uneven flexibility, especially in the posterior chain, seems to be the biggest culprit. I see it every day in the gym: guys with huge pecs and arms and weak backs, legs and shoulders who can't even touch their toes. Then they wonder why a hamstring tears or their rotator cuff gets destroyed...

CEM, fallscreek:

How would you fit ski boots to accomodate for tibial vara (or varum, whichever the case may be)?  Would you cant the boot to lessen the GRF on the lateral side of the foot?  If not corrected/accomodated for, wouldn't the extra force on the lateral side of the forefoot cause pronation of the STJ?  If this is the case, would it not cause internal rotation of the tibia as well, placing additional stress on the collateral ligaments of the knee, especially the MCL? 

I was thinking about how best to solve this situation, and my solution, assuming no other issues, would be to cant the boot the appropriate amount so that the GRF is even across the entire forefoot.  What do you guys think?

I ask because it seems that internal rotation of the tibia leads to a forward thrust of the pelvis, which leads to terrible posture, lumbar problems etc.

Is tibial vara not similar to genu vara?  Is genu vara just a more excessive version of tibial vara or is there some other reason there is a differentiation?


Also:

Would posting or wedging the FF in a rigid, bony FF varus still be a bad idea or does this only apply to a FF supinatus?

Super - to answer your 1st question yes but as an extreme worst case scenario obviously. to treat tib varum i would consider rearfoot posting or canting the device (fill in/narrow the gap between ski and ground).

in terms of GRF you are on the right track...think of a teeter-totter and think of there the middle balancing point is placed. if it is biased to one side the person on the shorter end is going to need to be much heavier than the person on the longer end (simple leaver stuff here). You can think of the foot in this way also with the placement of the STJ axis, if the stj axis is medially deviated then you are going to neeed to apply a larger force to supinate the foot than if it were normally positioned. 

if you cant the boot you are effectively applying a supination force to the foot (fat side in). to reduce how much pronation force is producing to 'compensate' for the angle of the tibia - a cant can be applied.

here is a pickle for your sandwich...i have just thought up this concept

There is evidence to suggest that pronation motion can not be controlled with orthotics, the studies that do only show a weak link. (kinematics)

There is evidence that orthotics can control kinetics (forces) i.e. the force of pronation etc 

There is evidence  that orthotics help pathologies.

The conclusion that has to be made is that orthotics control forces, and it is pretty common sense that forces are the cause of tissue dammage and that explains why orthotics work.

I know as boot fitters you dont normally see tissue dammage aka injuries. but you do attempt to 'align' and 'control' skiiers, which studies show to be ineffective. I know skiing is different to walking but i still think results would be similar.

I think if you aim to make the centre of pressure a more even position in the boot (i.e. balancing the forces), then there will be easier to roll from one edge to another.

Engineers on epicski here is your time to shine!




Your thoughts...

anyone?

Good to see that such an interesting discussion is occurring on foot biomechanics on this forum.  I have seen my name mentioned a few times, and yes, I guess I do not please everyone with my responses on Podiatry Arena.  However, after all these years of teaching foot and lower extremity biomechanics to clinicians, it is very good to see others so interested in the biomechanics of the human foot and lower extremity.

And, by the way, Superhero, you have some very interesting comments about podiatry and podiatrists. What is your training in foot and lower extremity biomechanics and foot orthosis therapy?

While the literature on running and walking biomechanics clearly show that foot orthoses can modify both the kinematics and kinetics of the foot and lower extremity, there is very little research on the orthosis effects on alpine skiing biomechanics.  During my biomechanics fellowship from 1984-1985, I worked with a few podiatry students that were advanced skiers and that wanted to do some foot orthosis research, but we were having difficulty determining how best to test how orthoses functioned to improving skiing performance.  Alpine skiing creates great difficulty for controlled studies due to the variability of downhill ski terrains.

So much of what foot orthoses do for the skier comes down to allowing the foot to transfer the forces coming from the rest of the lower extremity into changes in plantar forces coming from the bottom of the foot, to the bottom of the ski boot, to the binding and finally to the ski that allows for rapid changes in ski edge pressure.  Another factor is that foot orthoses increase the overall stiffness of the foot so that rotational motions of tibia can be more directly coupled to strong changes in medial-lateral center of pressure (CoP) movements on the bottom of the foot.  However, one must remember that alpine skiing is very different from walking and running and that one can not assume necessarily that what happens in walking and running with foot orthoses also happens when orthoses are added to the boots of an alpine skier.