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I was looking through one of the articles posted in the Dannenberg articles post and found these quotes from
Functional hallux limitus: a review.
Durrant B, Chockalingam N.
J Am Podiatr Med Assoc. 2009 May-Jun;99(3):236-43. Review.
Quote:
The functional hallux limitus and sagittal plane facilitation
theory suggest that when adequate ROM is
available at the joint during nonweightbearing assessment,
but the hallux is unable to dorsiflex during
weightbearing activities, functional hallux limitus is
said to exist. The facilitation that occurs in order to
assist the smooth transition of weight from the point
of heel strike on one foot to heel strike of the contralateral
foot is thought to occur as soon as heel lift
commences.4 Fuller31 has further theorized on this by
suggesting that high tension will then be created in the
plantar fascia, causing a plantar flexion moment that
could prevent the hallux from dorsiflexing, should the
tension be sufficiently high in the plantar fascia to
counteract the dorsiflexion force that is occurring at
the hallux. In the nonweightbearing situation, there is
not enough tension in the plantar fascia to prevent
this motion from occurring.31 However, in a foot that
is maximally pronated, for example, at heel rise and
going into propulsion, the tension in the plantar fascia
may be so great that the opposing forces may not
be sufficient to cause the windlass mechanism (described
below) to function effectively.31
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
Quote:
Fuller31 offers a further possible theoretical explanation
for the differences between dynamic and static
function of the first MPJ. This explanation relates to
the function of the windlass mechanism linking kinetic
activity affecting the joint and uses the concepts of
Newtonian mechanics to explain differences in motion
at the first MPJ. Fuller’s explanation adds a further dimension
to the theoretical debate of the kinetics of
first MPJ motion, referring to free body diagrams and
force couples. However, this approach is limited and
does little to explain the function of the windlass
mechanism in relation to dynamic first MPJ motion. It
also does not address any of the issues concerning
forces acting as a result of muscle contraction, which
is likely to be the case during dynamic gait. Fuller’s
approach uses a model that is based on static motion
and therefore does not consider acceleration in the
model, a concept removed from what actually happens
during gait. The mechanical model referred to
here31 takes the foot out of the context of its usual environment,
and it is unclear how this is then applied
to the clinical situation of dynamic gait.
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
Last edited by efuller : 2nd April 2010 at 05:30 PM.
Reason: not finished yet
Re: Functional Hallux Limitus: A review And the windlass
Quote:
Originally Posted by efuller
Is this worth a letter to JAPMA?
Regards,
Eric
Eric:
Definitely is worth a letter. I'll coauthor it with you if you like.
__________________
Sincerely,
Kevin
**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
Re: Functional Hallux Limitus: A review And the windlass
Quote:
Originally Posted by efuller
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.
Eric,
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.
__________________ Science is the antidote to the poison of enthusiasm and superstition
Re: Functional Hallux Limitus: A review And the windlass
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
Quote:
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.
If you are saying that to define the windlass as active or effective if 1st met plantarflexion takes place and inactive or ineffective if it does'nt is fallacious then I'd agree entirely. That seems to be a new incarnation of the kinematic vs kinetic debate we've pretty much put to bed around the STJ (thought experiment 6 was it?).
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?
"The story so far: As usual, Ginger and I are engaged on our quest to find out what the hell is going on and save humanity from my nemesis, some bastard who is presumably responsible."
Re: Functional Hallux Limitus: A review And the windlass
Quote:
Originally Posted by Robertisaacs
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.)
Robert, I'm not quite sure what you are saying, or which side of the debate you are on. I agree that the last paragraph quoted from the is essentially saying that engineering dynamics does not exist. Podiatric biomechanics will not progress very far if people think dynamics doesn't exist. You can go into almost any college bookstore and get a text on dynamics.
Quote:
Originally Posted by Robertisaacs
If you are saying that to define the windlass as active or effective if 1st met plantarflexion takes place and inactive or ineffective if it does'nt is fallacious then I'd agree entirely. That seems to be a new incarnation of the kinematic vs kinetic debate we've pretty much put to bed around the STJ (thought experiment 6 was it?).
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 think you have touched on the problem. There is no real definition of an activated windlass. From reading some of the papers, and listening to the term being used it appears to be something like: In gait, an active windlass causes dorsiflexion of the hallux leading to first met plantar flexion and STJ supination. You can get those motions without forces present in the windalss. And you can have tension in the fascia creating STJ supination moments and a first met plantar flexion moment without seeing those motions. Is that an active windlass?
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?
Re: Functional Hallux Limitus: A review And the windlass
Quote:
I think you have touched on the problem. There is no real definition of an activated windlass. From reading some of the papers, and listening to the term being used it appears to be something like: In gait, an active windlass causes dorsiflexion of the hallux leading to first met plantar flexion and STJ supination. You can get those motions without forces present in the windalss. And you can have tension in the fascia creating STJ supination moments and a first met plantar flexion moment without seeing those motions. Is that an active windlass?
That, I think, is the point Simon was trying to make. It's certainly the point I was going for. Kinematics are a poor measure of kinetics.
Quote:
Robert, I'm not quite sure what you are saying, or which side of the debate you are on. I agree that the last paragraph quoted from the is essentially saying that engineering dynamics does not exist. Podiatric biomechanics will not progress very far if people think dynamics doesn't exist.
I'm opining that there are two types of podiatrist. Those who use / believe in the usefulness of this type of modelling, and those that don't. There is no doubt in my mind that even a passing familiarity with this sort of thing changes the way you approach biomechanics on a day to day clinical level.
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.
"The story so far: As usual, Ginger and I are engaged on our quest to find out what the hell is going on and save humanity from my nemesis, some bastard who is presumably responsible."
Re: Functional Hallux Limitus: A review And the windlass
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???
__________________ Science is the antidote to the poison of enthusiasm and superstition
Re: Functional Hallux Limitus: A review And the windlass
Quote:
Originally Posted by Simon Spooner
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.
This point Simon and I have discussed a few times and Simon has had to keep reminding me all Metatarsal phalangeal (MTP) joints, it does take awhile to sink in some comes the fact that we seem to only discuss windlass and 1st MTP function and the other is that the jacks test is only on the 1st MTP joint which seems crazy when you consider what Simon wrote above.
Quote:
Originally Posted by Simon Spooner
The point is: what on earth does 'effective' windlass 'activation' mean???
I think I must own the record in the last year for someone discussing windlass for Eric to write what does effective or to engage windlass 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?
__________________
Michael Weber
The most common thing about common sense is it´s not very common.
Re: Functional Hallux Limitus: A review And the windlass
Quote:
excuse the tardy reply- I'm in Cyprus and the connection here is poor.
No excuse needed Simon. You should be enjoying the break instead of educating us!
Quote:
This point Simon and I have discussed a few times and Simon has had to keep reminding me all Metatarsal phalangeal (MTP) joints, it does take awhile to sink in some comes the fact that we seem to only discuss windlass and 1st MTP function and the other is that the jacks test is only on the 1st MTP joint which seems crazy when you consider what Simon wrote above.
Yeahbut...
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.
"The story so far: As usual, Ginger and I are engaged on our quest to find out what the hell is going on and save humanity from my nemesis, some bastard who is presumably responsible."
Re: Functional Hallux Limitus: A review And the windlass
Quote:
Originally Posted by Robertisaacs
No excuse needed Simon. You should be enjoying the break instead of educating us!
Yeahbut...
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
I would say that with 1st MTP joint dorsiflexion you can get STJ pronation.
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 .
Thats the classic example that I had as well. But if you read thru the post that Simon lead me thru yesterday it makes sense that the windlass mechanism can occur at any toe and cause differnt things to happen.
Try the experiement that Simon got me to do. Take off your shoes dosiflex each toe individually and see what happens at the subtalar joint. It may pronate or supinate the navicular may rise or drop and drift or nothing may happen depending on the position of the STJ axis.
You still have a windlass effect what ever happens.
__________________
Michael Weber
The most common thing about common sense is it´s not very common.
Re: Functional Hallux Limitus: A review And the windlass
Quote:
I would say that with 1st MTP joint dorsiflexion you can get STJ pronation.
Hypothetically, I'd say you're right.
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.
"The story so far: As usual, Ginger and I are engaged on our quest to find out what the hell is going on and save humanity from my nemesis, some bastard who is presumably responsible."
"The story so far: As usual, Ginger and I are engaged on our quest to find out what the hell is going on and save humanity from my nemesis, some bastard who is presumably responsible."
Re: Functional Hallux Limitus: A review And the windlass
Quote:
Originally Posted by Robertisaacs
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.
Pronation with the windlass has been reported in the literature.
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.
Re: Functional Hallux Limitus: A review And the windlass
Quote:
Originally Posted by efuller
Pronation with the windlass has been reported in the literature.
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
Here for everyones reading pleasure.
__________________
Michael Weber
The most common thing about common sense is it´s not very common.
Re: Functional Hallux Limitus: A review And the windlass
Quote:
Originally Posted by Robertisaacs
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.
I have had two patients, in 25 years of doing the Hubscher maneuver or Jack's test, pronate with hallux dorsiflexion...both children with severely medially deviated STJ axes between the ages of 6-14. Actually, in one, when I dorsiflexed the hallux, the lateral column actually raised off the ground. Wish I had a video of that one.
__________________
Sincerely,
Kevin
**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
Re: Functional Hallux Limitus: A review And the windlass
Quote:
I have had two patients, in 25 years of doing the Hubscher maneuver or Jack's test, pronate with hallux dorsiflexion...both children with severely medially deviated STJ axes between the ages of 6-14. Actually, in one, when I dorsiflexed the hallux, the lateral column actually raised off the ground. Wish I had a video of that one.
I have a few Kids in the Downs and CP clinic with crazy deviated axis, I'll have a go when I see them.
"The story so far: As usual, Ginger and I are engaged on our quest to find out what the hell is going on and save humanity from my nemesis, some bastard who is presumably responsible."
Re: Functional Hallux Limitus: A review And the windlass
Quote:
Originally Posted by Robertisaacs
I have a few Kids in the Downs and CP clinic with crazy deviated axis, I'll have a go when I see them.
If they do, I'll video it just for you
Robert:
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.
__________________
Sincerely,
Kevin
**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
Re: Functional Hallux Limitus: A review And the windlass
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.
Functional Hallux Limitus: A review And the windlass
) more or less bisects the 2nd met cuniform joint. Force directly on the axis = no pronation / supination moment. 
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