All,
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I'm keen to explore the concept of "auto-support" of the foot. My first introduction to this term was in Howard Dananberg's paper "gait style as an aetiology to chronic postural pain part 1"- too many years ago. As memory serves the mechanisms that are supposed to contribute to this are:
1. windlass mechanism
2. calcaneo-cubiod joint locking
3. locked wedge/ truss effect
Does anyone else think it might be time to re-examine these and moreover, the concept of auto-support per se?
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Starter for ten:
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Auto-support::cool:;):eek:
Attached Files:
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You got me. Laughed out loud! Just what I needed Prof. Kirby.:drinks
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I think that the intent was to imply that a well functioning windlass is likely to mittigate deforming forces acting though the foot generally. In addition if those forces became injurous (by causing structural overload) improving windlass would by implication be therapeutically helpful.
I agree that the premise may be flawed but it seems pausible and not neccessary undermined by your comment above.
Good subject :drinks
Martin
The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com -
Lets take a look at the definition of "auto-support" first. I'll need to go back to the original paper, which will take some literature review- anyone provide it? -
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I had not realized that this term was coined by Howard Dannenberg, I will try and dig out his paper unless someone has a scanned copy. Unfortunately it is doesn’t seem to be available digitally so will need scanning.
I was just thinking about why “autosupport” seems plausible to me.
Mostly I think because it has a mechanically pleasing aesthetic. I find the notion of evolution selecting for energy efficiency in gait as a major determinant for why things are the way they are appealing given alternatives.
Since we are largely attempting a reverse engineering exercise in creating theories to explain foot function and dysfunction it seems reasonable to look to that as a highly ranked clue.
I think it was you that introduced me to the notion of “mechanical intelligence” and this superficially seem to fit that moniker.
What I lack of course is evidence that windlass does improve energy efficiency, but it does seem intuitively probable. I think this was Dannebergs implied perhaps explicit premise but haven’t read his stuff for ages.
Would you let us know how your feet feel after walking backwards for 30 mins?
Don’t do this without supervision though.
Cheers
Martin
The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com -
Now you will have to spell this out for me . . . . . I have to admit that it has gone completely over my head :eek:
cheers (I think)
Martin
The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com -
Just Simon being himself.....with tongue in cheek....I'm sure no harm intended.
BTW, talk about rotational equilibrium.........hope that truck doesn't suddenly lose its "auto-support" of 4 x 4's and crush our budding auto mechanic.:D;) -
Morning! :morning:
Attached Files:
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Gait Style as an Etiology to Chronic Postural Pain part 1. functional hallux limitus.pdf
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Gait style as an etiology to chronic postural pain. Part 2.Postural compensatory process.pdf
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fair crack of the whip . . . . I could feel some incipient paranoia which is a bit of a hazard after smoking a bit too much podarena for one day.
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Thanks Sam got to have them on the computer now not paper copies.
Here some other articles for people who don´t have them.
1 eric about windlass and the other about high and low gear which explain cuboid-calcaneal compression.Attached Files:
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I´ve just done your little sideways, backwards walk.
What I considered that COP was very different to walking forwards and equilibrium is found in very different ways.
I beleive that Windlass is a none muscle support mechancism that helps in re supination. So auto-support may not be the best term as it indicates that the foot would collapse without windlass. But if you consider that it is an important mechancism which occurs without a direct brain influence ( ie auto) and windlass will support the Medial Longitudial arch ( MLA ) then the term works.
Without this automatic mechanism muscle function on the medial aspect of the Subtalar Joint Axis must be increased to have resupination. -
Supination = good; pronation = bad
Is this still believed? -
Pronation and Supination are both motion that are important its the stopping them that causes the problems ( to modify Craigs quotes on this subject)
But I still beleive resupination is an important mechanism. Do you think I´m wrong in thinking this ?
EDIT maybe it would be better not to say resupinated but to be going thru the motion of supination at from heel lift to toe-off in the gait cycle. -
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The above statement would only be correct when there is dorsiflexion of the 1st mtp joint and windlass. In negative windlass the foot and body drive the shank ? -
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Heres the quote you refer to
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If we were walking forward in a straight line on a flat level surface would it be most efficient for the support leg to be: a) internally rotating; b) externally rotating; or, C) not rotating in the transverse plane during the propulsive phase of walking? in other words would it better for the foot to be pronating, supinating or neither pronating nor supinating? -
Here´s my reasons.
1. Would allow the strongest plantarflexion muscles to have better propulsion effect ( gast,sol)
2. Greatest energy efficent in relation to muscle fatigue.
3 Body would travel in same direction as propulsion.
4 better use of vasoelastic effect of plantar foot muscle and fascia.
5 reduced compression stress in the medial or lateral knee joint.
thats what I got for now
1 more it would create a more efficent lever arm . ie motion travels straight over foot not across at an angle -
http://www.youtube.com/watch?v=e61uC-5s9VU&feature=related -
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Question 1 right foot-support veer of to the left. more efficient to pronate
Question 2 right foot support veer to the right more efficient to supinate.
I beleive this to be the case because of the mass of the body. If we want to change direction we get the COM of the body moving in that direction. It make no mechancial sense to accelerate the COM in one direction then stop it an accelerate it in the other. The body as a whole will take the easier path even if the foots motion path is not the easier path.
The foot is connected to the body is a signiture Ive seen somewhere on PA, maybe we forget that -
OK so now you have a range of propulsive strategies, one requiring pronation, one supination and one neither. Hmmm.
Now try this: take a weightbearing foot then take each digit in turn and dorsiflex it, like a Jacks test but not just the big toe (I call this the lesser digit dorsiflexion test when testing digits 2-5). What does the dorsiflexion of each toe do to the STJ in each case? -
OK so now you have a range of propulsive strategies, one requiring pronation, one supination and one neither. Hmmm, what does this tell us?
Now try this: take a weightbearing foot then take each digit in turn and dorsiflex it, like a Jacks test but not just the big toe (I call this the lesser digit dorsiflexion test when testing digits 2-5). What does the dorsiflexion of each toe do to the STJ in each case? -
so 1st dorsiflexion ( d) - supination
2nd d-supination but less
3rd d- supination but less again
4th d- no movement
5th d pronation.
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So does this mean that if I use a lateral propulsive strategy , i.e push off from metatarsal heads 2-5 my windlass mechanism will generate a net pronation moment?
Lets go back to veering off to the right. You said it would seem advantageous for me to veer off to the right with my right foot supinating-right? To this I'd add that it would also probably help to push-off obliquely through my lateral axis (low-gear axis). However in this situation my windlass mechanism through my low-gear axis may be generating a net pronation moment which is working against what my STJ wants to do. So how do we still achieve the preferred movement pathway? -
The body would cause the tibia to externally rotate. Which will then cause a Supination moment at the STJ which will then causee a lateral deviation of the the stj axis which will mean more of the 2-5 toe ( low gear) will be medial to the STJ axis which will mean now there is a greater windlass effect. This will also mean the the low gear toes will still be able to provide acceleration in the direction of movement to aid in propulsion to the right in this case.
hope that make sense. -
Now do the same analysis for veering off to the left using a "high gear" strategy. -
cheers
Martin
The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com -
idea 1 - the deviation of the stj axis is so medial that the insertion of the medial band of the plantar fascia is lateral to the stj axis which will mean a greater pronation moment.
idea 2 the medial deviation of the stj axis causes a FHnL which means there is no windlass.
idea 3 the pronation moment from the interal tibial rotation is greater than the windlass supination moment so pronation still occurs. ( this one is sending a few alarms bells off in my head but will put it ou there anyway) -
So, we have a hypothetical situation in which the windlass mechanism may result in increased foot pronation, pronation should result in loose packing of the midfoot- right? In this situation is the windlass adding to the foot's auto-support? -
simon,
However, the heel is raising at this point - ankle plantar flexion, which is not an element of "pure" pronation.
thoughts? -
Also if windlass doesnt have some form of protective function ie stabilising capacity of midfoot what better explaination might here be that fasciotomy see m to create problems in this region?
cheers
Martin -
[QUOTE I hope you can see that "windlass function" may not always = re-supination or even net supination moment.
Thats the thing that takes time. Normal thought windlass supination moment, but we must consider where in relation to the stj axis the pull comes from. you still have the windlass effect. nice ( only 7 years after not bad :D)
So, we have a hypothetical situation in which the windlass mechanism may result in increased foot pronation, pronation should result in loose packing of the midfoot- right? In this situation is the windlass adding to the foot's auto-support?[/QUOTE]
2 things in the pearls of biomechanics thread Blinda said something about negative windlass and tension of the PF. Here it is
As for the autosupport mechnism the correct answer is sometimes depending on the position of the STJ axis. -
becasue I think we have discussed that windlass can cause and change in STJ axis position. whether the axis moves laterally or medially will depend on the position that the stj axis is in when the 1st mtp begins its pull on the PF. -
Evolution seems to have imparted autosupport then irrespective of direction.
cheers
Martin
The St. James Foot Clinic
1749 Portage Ave.
Winnipeg
Manitoba
R3J 0E6
phone [204] 837 FOOT (3668)
fax [204] 774 9918
www.winnipegfootclinic.com
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