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Functional Hallux Limitus: A review And the windlass

Discussion in 'Biomechanics, Sports and Foot orthoses' started by efuller, Apr 3, 2010.

  1. efuller

    efuller MVP

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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.

    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?


    Last edited: Apr 3, 2010
  2. Eric:

    Definitely is worth a letter. I'll coauthor it with you if you like.:drinks
  3. 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.
  4. Admin2

    Admin2 Administrator Staff Member

  5. 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

    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?

  6. efuller

    efuller MVP

    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.

    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?


  7. 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.

    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.
  8. 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???
  9. 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.

    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?
  10. No excuse needed Simon. You should be enjoying the break instead of educating us!


    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.

  11. 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 .

    Auto-Support thread

  12. 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.

  13. 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.
  14. efuller

    efuller MVP

    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.


  15. Here for everyones reading pleasure.

    Attached Files:

  16. 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.
  17. 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 ;)
  18. 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.

    Attached Files:

  19. efuller

    efuller MVP

    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.



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