I was looking through one of the articles posted in the Dannenberg articles post and found these quotes from
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Functional hallux limitus: a review.
Durrant B, Chockalingam N.
J Am Podiatr Med Assoc. 2009 May-Jun;99(3):236-43. Review.
The first sentence is a nice definition of functional hallux limitus.
The second sentence has nothing to do with the first or third sentences.
The third and fourth sentences accurately describes my attempts to explain why functional hallux limitus exists.
The last sentence has nothing to do with what I said in the article.
What bothers me about this paper and other stuff out there in sagittal plane facilitation theory is the notion of the windlass functioning effectively. Another way that it is described as the Windlass being activated.
What bothers me about this is that there is an assumption that the Windlass is supposed to work a certain way. They appear to be saying that the windlass "fails" when there is an absence of resupination.
The windlass is a passive structure that applies forces and moments within the foot. The windlass has many interrelated motions. When STJ motion and metatarsal plantar flexion are prevented then hallux dorsiflexion will be prevented. These internal forces are why the motion of the hallux motion is limited.
And later
They are dead wrong about force couples and free body diagrams not being able to explain the dynamic function of the windlass. Yes the model presented was a static model. However the same relationships will be present in the dynamic situation. Force is equal to mass x acceleration. Acceleration is dynamic analysis.
It is not hard at all to add in forces from muscles into the model. The windlass won't allow hallux dorsiflexion when there are high pronation moments at the STJ and high dorsiflexion moments on the metatarsal. All you have to do is know what kind of moment a particular muscle will create and this variable can be added into the model.
I would hate to have anyone quote this part of the article and say that free body diagram analysis doesn't work in dynamic situations. There is a whole field of inverse dynamics based on using free body diagrams to examine moments and forces and motions of structures.
There final sentence really bothers me. If you can't use force couple to explain why the hallux does not dorsiflex, how do they explain why it does not dorsiflex?
Is this worth a letter to JAPMA?
Regards,
Eric
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Windlass mechanism kinetics and 1st met compression
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Definitely is worth a letter. I'll coauthor it with you if you like.:drinks -
I agree. This concept that windlass mechanism can be adequately defined as a dichotomous variable: "activated" or "not activated", "effective" or "ineffective" is a fallacy and should not be being taught in this way. -
Related threads:
Threads tagged with functional hallux limitus
Threads tagged with windlass mechanism -
Fascinating debate. This seems to be a schism in the way people think of biomechanics. We all know that models will always be imperfect but the implication in the last paragraph seems to be that it is flawed to the degree that it is actually not applicable to dynamic function (that's my read of it at least.)
I would appreciate clarification on one point
However If you mean that that the windlass mechanism can NEVER be defined as inactive vs active I'm not sure I agree. What if, for example, the 1st MPJ is fused? Or what if even at maximal dorsiflexion there is not sufficient tension in the PF to create 1st met plantarflexion moment?
Surely in that case one could accurately define the windlass as being inactive?
Regards
Robert -
I'll have to read through Dannenberg papers to see if he defines what an active windlass is. Anybody know of any published definition of what an active windlass is?
Cheers,
Eric -
These differences in approach produce different ways of thinking. Most podiatrists I know DON'T understand the difference between kinetics and kinematics for example. This tends to lead to people lending too much importance to kinematics and the static weight bearing exam (for eg).
But I digress from the windlass. And this is shaping to be a good thread so I don't want to do that. -
Robert, excuse the tardy reply- I'm in Cyprus and the connection here is poor.
In addition to what Eric has already said re: kinematics and kinetics, it is important to remember that the plantar fascia doesn't insert only into the hallux. Now you may argue that the radius of the 1st metatarsal head is much larger than the others, but that does not mean that their is no windlass effect from the lesser metatarsals. So in your example of fused 1st metatarsophalangeal joint, I should still get windlass function through the others. The point is: what on earth does 'effective' windlass 'activation' mean??? -
Again I think this come from the jacks test, dorsiflex the 1st change in the arch height or not or increased force to cause change, the problem I´m having is how do we assess the windlass mechanism differences from patinet to patient and how do we discuss these differences.
Is it better to discuss plantarfexion moments or plantarflexion force of the 1st Metatarsal or 2nd or 3rd or 4th or 5th? -
Granted in the purest sense the lesser mets will also plantarflex. so there is windlass. Touche. But in terms of the frontal plane effect of the windlass (as in how much supination / pronation moment they exert) how significant are they. What with where they will increase GRF relative to the Sub talar axis and such.
Actually, I guess it depends where the axis runs through the mid tarsal joint at the base of the met (which is what is being pushed upward) rather than just the increased GRF won't it. Otherwise a jacks test in someone with an axis medial to the 1st met head would pronate the foot. In a very crude way, holding a pencil against my Skeleton with one end in the talus and moving it to show axial variation I have to have the axis leaving the foot Mid 3rd met to have the 2nd met cueiform joint entirely medial to the axis. A "typical" Axial shadow (as per biomechanics of the normal and abnormal foot;)) more or less bisects the 2nd met cuniform joint. Force directly on the axis = no pronation / supination moment.
I suppose its down to our old enemy, overextrapolation. In the purest sense a windlass effect could pronate the foot if it was all in the lesser mets. But we think of it as a supinator.
Regards
Robert -
Check out the auto-support thread where Simon worked it all through with me. Ive taken this from that thread where Mart was discussing the interpretation of windlass page 3 .
Auto-Support thread
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Theoretically I'd say for that to happen the axis would have to be properly medial to the Cuniform / navicular joint.
Empirically I'd say I can't remember ever seeing that, although I'll often not bother to do a jacks test on anyone that massively deviated.
Clinically I'd say that if somebody has that deviated an axis there will be such a massive 1st met dorsi moment from GRF that the (1st met) windlass would'nt stand much chance anyway.
I Suspect that a significant point here would be the degree of dorsi / plantar flexion available in each met, and the constraint mechanisms of each. Nice little study there. If I ever learn to warp time I might do that one.
Cheers
Robert -
Just to clarify, I've never seen anyone Pronate with jacks test. I've seen loads of people with Axis deviated medial to the navicular.
That is all. -
Jack, EA Naviculo-cuneiform fusion in the treatment of flatfoot. JBJS Vol 35-B 1953 p75-82
It's been a while since I read the paper and he may not have used pronation and supination explicitly. However, I do recall the motions described as being consistent with arch lowering and pronation. By the way the author is the Jack of Jack's test.
This article is also interesting in that one of Jack's students published an article 10 years later with a survey that said that over half of the patients who had the fusion were unhappy with the procedure. When I first read the paper, I think it was the first paper that mentioned that a particular treatment was ineffective. So much of the time we get stuff saying look at my great new procedure.
Cheers,
Eric -
Attached Files:
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If they do, I'll video it just for you ;) -
That would be great. Here is a photo of one of the patients that displayed this type of foot when she was younger than in this photo. If the medial column still has an arch with some stiffness left, then the lateral column will elevate with the Hubscher maneuver. If it is totally collapsed as in this photo, it will not likely elevate the lateral column.Attached Files:
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When I was doing the fellowship at CCPM, I was doing a teaching session with some students. One of the students showed internal rotation of the talus with Jack's test. I think it was right after I told them that the test should supinate the STJ.
Regards,
Eric
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Windlass mechanism kinetics and 1st met compression
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Pedar-x insoles for foot pressures analysis
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