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Is forefoot varus posting an anachronism?

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Atlas, Jan 26, 2005.

  1. Atlas

    Atlas Well-Known Member


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    The obvious negatives are the detrimental impact on the windlass mechanism as the 1st ray is shoved into a relatively dorsi-flexed position.


    But does anybody use them, and if so, in what clinical circumstance?


    If (and we think we know why) forefoot varus posts are that detrimental, why was this addition persisted with for decades, and why did such devices presumably not exacerbate patient's symptoms?

    As clinicians, we may not know what component is working, but if something on the whole exacerbates our patient's condition, we swiftly either alter it, or dispense with the whole intervention avenue. In other words, if an orthotic device with a forefoot varus post was that terrible, the patient would have returned worse-off, forcing the clinician to change the prescription. :confused:
     
  2. Craig Payne

    Craig Payne Moderator

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    The only time in recent years I have used a forefoot varus or medial post is in those with a structural hallux limitus and I want to create some sort of rocker to facilitate motion.

    Yes, I used to use a lot of forefoot varus posts in the early days. Patients did seem to get better - also had some dramatic failures. Those that got better, I think, did so not because of the varus post, but despite it (ie the rearfoot post; etc was the reason for symptom reduction). In those days I used to think I knew what I was doing :eek: I just do not see the dramatic failures anymore... As I said in the thread on ESWT I used to use ESWT for plantar fasciitis in few years back, but just do not need to anymore as we have got that much better with our orthotics intervention (almost everyone routinely gets valgus forefoot posting for plantar fasciitis)

    When I first graduated I used to see a lot of forefoot varus and now I almost never see it. Either the human spieces has evolved since I graduated (where is Bob Kidd when you need him?) or I used to get it wrong.

    The students seem to see a lot of forefoot varus, but never when I am around :confused: .... don't figure :rolleyes: (I recall one student, Zac, who was so impressed with me as I could diagnose that a patient did not have a forefoot varus through the wall without even looking at them :cool: )

    Mert Root used to experiment a lot on this. The original "Root" orthotic was very much narrower than what we use today. Mert found by trial and error that back pain often developed if first ray plantarflexion was inhibited by the foot orthoses....

    We have data on a whole lot of subjects who did not need a forefoot varus post, but we gave them one anyway....we have rearfoot motion and plantar force/time data in these people with and without the post .... just have not yet analysed the data ...
     
    Last edited by a moderator: Jan 28, 2005
  3. Griff

    Griff Moderator

    Craig,

    Would you mind explaining your rationale for routinely issuing forefoot valgus posts for plantar heel pain?

    Is this in conjuction with a rearfoot varus post?

    Many thanks

    Ian.
     
  4. Craig Payne

    Craig Payne Moderator

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    We have shown that in those with plantar fasciitis, the forces needed to get the windlass established are higher - forefoot valgus posts (2-5 bars; reverse mortons extensions) reduce that force. The also induce the changes in the force/time curves I alluded to in this thread that are prospectively associated with a reduction in symptoms. Its nothing new - more and more have been changing their clinical practice to this based on experience. What is new is the research is catching up.
    Yes
     
  5. markjohconley

    markjohconley Well-Known Member

    forefoot varus posts for polysyndactyly of halluces

    greetings, i treat a family with modified forefoot varus posts, they have an autosomal dominant polysyndactyly / syndactyly bilateral / 1,2,3
    for the father a 4-2 varus with a plateaued 1st ray gives him relief from his 1st mpj pain, he maintains a dorsiflexion range of greater than 65 deg. bilaterally, i am looking at them right now, all the best, mark c
     
  6. Sean Millar

    Sean Millar Active Member

    activating the windlass

    Craig,
    in your clinical research, did you find or explore (aside from the forefoot valgus post/bar), other mechanical devices eg. met dome, cuboid padding that reduce the force needed to activate the windlass mechanism.
     
  7. Laurie Foley

    Laurie Foley Member

    Forefoot valgus posts for plantar heel pain

    From the following references:

    Bartold states in Sport Health 1997 10(3):18 “Plantar fasciitis is predominantly a mechanical injury and the basis for treatment…elimination of the inflammatory process by reducing tension on the plantar fascia and associated structures”
    Simon went on to describe a modified low Dye taping method which plantar flexes the first ray and/or everts the forefoot. .
    Bartold S. Conservative Management of Plantar Fasciitis Sport Health 1997:10(3):17-20 ,P 18 Rationale of Taping Procedure.
    1 reinforces the the PF both statically and dynamically
    2 Facilitates the action of PL which stabilises the First Ray
    3 Provides compression
    4 Plantar flexes the forefoot on the rearfoot, thereby increasing the calcaneal inclination angle
    5 Inverts the calcaneus beyond vertical
    6 Reduces the midtarsal joint oblique and long axis motion.

    Fuller E 2000 JAPMA The Windlass Mechanism of the Foot: A Mechanical Model to explain pathology. 90(1):35-46. . “Greater forces on the first metatarsal head and hallux will create greater tension on the medial slip of the PF” Fuller’s model predicts that there are two possible approaches to Tx of PF in the medial slip: Increase lateral forefoot loading and increased supination moment applied to the subtalar joint. Fuller refers to Kogler’s report regarding the use of lateral wedging (forefoot valgus wedging) to decrease tension on the PF .

    Richie Dr. Douglas Richie, DPM for Podiatry Management Magazine. August, 2002
    "As Kogler’s work has shown, and from a simple understanding of the truss mechanism of the plantar fascia, the application of a medial post under the forefoot will actually increase strain in the plantar fascia for most foot types."

    Taping: Torg J,Pavlov H, Torg E, Overuse injuries in Sport :The Foot. Clinics in Podiatric Medicine and Surgery. 1987 4(4):939-968
    P 940-1 emphasizes Low Dye Strapping technique with plantar flexion of the first ray.
    Whitesel J., Newell S., The Physician and Sportsmedicine 1980 Modified Low-Dye Strapping 8(9):129-130. Empahsise plantar flexion of the first ray

    Consistently I have found that with the heel inverted and the toes dorsiflexed, palpation of the medial part of the PF reproduces the heel pain. WIth the same toe position and the first ray plantar flexed or if you like forefoot everted, palpation shows that there is less heel pain. I usually apply tape with the first ray plantar flexed ( to replicate my none weight bearing palpation) and acheve the same reasult. Hence my orthoses have a first ray cut out to lnatar flecx the first ray and or a reverse morton's pad (2-5) to help evert the forefoot.
     
  8. Craig Payne

    Craig Payne Moderator

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    Met domes and cuboid elevations also reduce the force to get the windlass established ..... working on the publication now (along with a lot of others..... problem is the students are back today for clinic :( )
     
  9. Sean Millar

    Sean Millar Active Member

    Plantar pressure and windlass

    A question that keeps begging to be asked, is does activating the windlass inrease or decrease the peak pressures under the 1st mpj?? :confused:
     
  10. Laurie Foley

    Laurie Foley Member

    Sean
    Maybe Craig can answer that one.
    Having said that,I assume that if planatar flexing the first ray allows the first mpj to go through its full range of motion, then pressures would be evenly distributed (ie within normal for that individual ) :eek:
     
  11. Atlas

    Atlas Well-Known Member



    Common sense tells me that good windlass activation must increase peak pressures under 1st MPJ. Windlass is associated with plantar-flexing 1st ray, which brings 1st met-head further 'into' the ground. Also if we think of an efficient windlass, we think of low force dorsi-flexing the hallux. Conversely, a high force dorsi-flexing the hallux would 'spread' the pressure between the 1st MPJ and plantar aspect of the distal phalanx of the hallux.

    But my advice would be to listen to Craig first.
     
  12. Lawrence Bevan

    Lawrence Bevan Active Member

    I dont see the problem here

    I think that yeah if you take a prefab and stick a varus wedge on it that is full width under the 1st ray you might get problems with 1 ray dorsiflexion in a lot of cases but NOT all. F-Scan has shown this to me.

    However if you take a NWB plaster cast of a foot and capture a large degree of forefoot inversion and dont balance it then you can get an orthotic that does diddly squat. Ive seen orthotics with higher lateral arches than medial arches because of this Rx mistake.

    If the posting is a gradually applied thing curving steadily to the talo-navicular area rather than an brupt curve under the 1st met and you utilise a 1st cut-out I dont find moderate varus ff posts giving any problems.

    When I 1st started using F-Scan I copied a protocal given to me by Bruce Williams who was taught it by Dananberg. This involved making a heat-moulded temporary device. This was moulded semi-weightbearing with the foot in "neutral" this almost always involved the foot inverted to the ground and had the net effect of capturing an inverted forefoot. The protocol called for the temporary device to be ground so ff to rf was "balanced" and thus I found in most cases I was grinding in a forefoot varus post. When used with a cutout under the 1st ray this almost always was great at sorting the signs of functional hallux limitus or problematic windlass. And NO the patient wasnt "laterally avoiding": the pressures under the 1st met increased, lateral forefoot pressure decreased, the COP line came more medial and force-time cuves became more classically shaped. I initially was confused and kept quiet as I used very little forefoot valgus posts such as the great and the good suggest are needed to facilitate the 1st ray function. Now Im telling everyone because ive realised I like shaking apples out of trees! I figure this whole line of thinking came from people "discovering" sagittal plane blockade with in-shoe pressure systems so if my in-shoe readings showed FHL gone with forefoot varus posts (+ cut-out) then we must be doing the same things but describing it in a different way. I dont care what an anatomist has shown with a cadaver foot Im dealing with dynamic data and patients with symptoms.

    Mert Root wouldnt worry about using ff varus posting but his devices were always very narrow and allowed good 1st ray function. So I feel the key is to support the arch or prevent MTJ pronation in some manner - a forefoot varus post or heel skive and allow the 1st ray to do what it desires to do - rotate as the body moves over the top of it. The simplest way to do this is with a 1st cut out, a more complicated way of doing this is a forefoot extension under 2-5 and even more complicated thing would be to call that a forefoot valgus post.

    All said in my personal opinion and well meant!
    Lawrence
     
  13. Craig Payne

    Craig Payne Moderator

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    earlier in this thread, I said:
    Just finished the preliminary number crunching.... looks as though a forefoot varus post in those who don't need one (pretty much everyone) has the effect of the rearfoot being more inverted at heel contact/early stance (which was surprising)....but no effect later in the stance phase. (this more inverted position may or may not have something to do with symptom relief when I used to use them a lot)

    When it came to the pressure and force/time data, the forefoot varus posts move many of the parameters in the direction of what we consider indicative of windlass function being stuffed up...(this finding may or may not have something to do with the miserable failures I sometime got when I used to use them a lot)

    ...will get it ready for publication soon...
     
  14. Lawrence Bevan

    Lawrence Bevan Active Member

    forefoot varus posts

    What are the in-shoe parameters that indicate "stuffed up windlass" to you?

    I have found a "forefoot" varus post can often move the COP line medially, increase pressure under the 1st mtp relative to 2/3 mtp, make F/t curves become more "m" shaped and symmetrical. Is that windlass stuffed up? From what Ive been told from other users of FScan who are attempting to improve sagittal plane function these would be positive signs signifying less "functional hallux limitus". Bear in mind the posting would be used in conjunction with a cut-out under the 1st ray and relatively small posts.

    When you say hardly anyone needs a forefoot varus post why is that? On a casted device how do you treat over-pronation secondary to RF varus? I seem to remember reading in Kevin Kirby's book his opinion on orthotics to deal with "over-pronation" were relatively ineffective unless inverted to some degree and he advocates the use of varus posting to increase support (not Blake inverted devices but traditional posting). Paraphrasing and some over-simplification of course, Kevin will no doubt slap me down here.

    I know your probably thinking - "looking through the lenses of the old paradigm" but no just saying what i have found with use of an in-shoe system clinically.
     
  15. Craig Payne

    Craig Payne Moderator

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    This is still work in progress, but we have done a number of things to inhibit and enhance windlass function and compare pressue and force/time parameters. At this stage indicators of inhibited windlass fucntion include delays in timing of the heel and forefoot peak forces; delayed heel unloading ---- we still got no clear picture of what happens in forefoot - still working on that one.
    Forefoot varus is rare.
    With a rearfoot varus post - the amount of posting is determined by the amount of force needed - stopped worrying about the angle of rearfoot varus a while back.
    ...this may deserve its own thread, but we stopped thinking in terms of FHL lately - we working on the model/hypothesis that FHL is a and/or of 2 very distinct entities - a high force to get the windlass established and/or a delay in onset of windlass action --> both clinically have the characteristics we previously ascribed to FHL
     
    Last edited: Feb 22, 2005
  16. Lawrence Bevan

    Lawrence Bevan Active Member

    Forefoot varus posts

    I guess you would be using very flexible materials so that the orthotic bends in the middle? With your varus rearfoot post this would give you a inverted heel cup and a distal edge bending to make contact with the supporting surface.

    I have seen pre-fab devices such as the "Interpod" which have a "varus rearfoot post" incorporated in them i.e. an inverted heelseat/cup. But the distal edge is flat on the supporting surface. To get this shape with a casted device would require a forefoot varus post done intrinsically to the cast. Forefoot varus posts are not just for forefoot varus (if it exists or is measurable)

    I know I sound like a old hander stood here with a bucket of plaster, pack of nails and an angle finder but it is the case that more rigid materials (e.g. 4.5mm poly, 2.5mm TL2100) rock up and down with only a varus rearfoot post and no forefoot post.

    I think its all about how hard you push on the medial side of the foot. A forefoot post that "balances" the orthotic ie does not allow it to rock will push harder than a varus rearfoot post that does allow it to rock. Therefore in my method of semi-weightbearing forming a device and adding 2-3 degrees of forefoot posting ground in + 1st ray c/o equals the same as 4-6 degrees varus rearfoot posting.
     
  17. Craig Payne

    Craig Payne Moderator

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    We moved on from doing it that way a while back. The evidence is getting clearer - we usually don't use rigid devices as much as in the past - the RCT's are showing that outcomes are the same. We commonly have forefoot valgus posts assocated with the varus rearfoot post - as that is what is needed to change the parameters that have been shown to be prospectively related to better outcomes (I will post thread here soon with the hard data).

    The profession is way to hung up on positions, angles and motion when the research is showing that altering these are not associated with outcomes. Forces, not motion damage tissues. Alteration of the forces is associated with the better outcomes. You don't have to alter motion, positions or angles (though you can) to alter the forces.
     
  18. Atlas

    Atlas Well-Known Member


    Is that a relative forefoot valgus incorporated in the device?


    A device that inverts the rearfoot significantly, thats distal edge is flat surely pronates the midfoot?


    Keep shaking those trees Lawrence. BTW, you should start an 'old hander's (aka casting) thread.
     
    Last edited by a moderator: Feb 23, 2005
  19. Lawrence Bevan

    Lawrence Bevan Active Member

    Forefoot varus posts

    For forefoot valgus posts am I to read 2-5 extensions such as 3mm EVA/korex? Are u also using pre-fabs predominantly?

    I hardly ever measure any positional morphology just make an attempt to identify it, after all if its not FnHL but a high force opposing the windlass or late engaging why is that happening?

    I agree that the orthotic is a means of applying a force to the sole of the foot to alter foot and therefore lower extremity moments. But measuring that is probably even harder!
     
  20. yehuda

    yehuda Active Member

    :confused: :confused:

    I make my own orthoses and often see casts with humungous ff varus (>>15 degrees) and you would treat this with a ff valgus post !!!!!


    sorry i dont understand why one would pronate the foor more to treat xs stj pronation its like cooking a burnt chicken in order to make it taste better . :D

    please explain i would love to know the rational behind this method of rx
     
  21. Craig, I wonder if you could possibly supply the RCT refs showing outcomes are the same for rigid and non-rigid appliances which you quote. In the context of this statement, what outcomes are you referring to, changes in forces, motion, symptoms etc.

    I think we not only get ‘too hung up on positions, angles and motions’ but also on the idea that one thing is ‘wrong’ and another thing ‘right’. Rearfoot varus posts (if on the medial side of the axis) will reduce pronatory moments across the STJ. This in turn may 'reduce' the effect of the ‘reverse windlass’ which can be one of the courses of a FnHL. A forefoot valgus post may help to ensure medial COF progression and so aid in first ray propulsion. By its very construction it may also allow for the first ray to plantarflex (reduce dorsiflexion 1st ray moments if you'd rather), essential again for first ray propulsion and windlass. All makes sense, as does balancing a Root prescription with a 25% ‘creep’ (effectively a first ray cut out and a 2-5 'shell bar’, obtained by the varus post and 2-4 scoop). Some people will need different amounts of angles added, extensions and cut outs to obtain these results. Is your research demonstrating another way of doing the same old thing? Did your varus post comparisons have a 1st ray cut out or 25% first ray section? Sorry Craig, lots of questions, but that's what good research always brings!

    Also, What was your sample? For example, I’ve spoken to Eric Fuller in the past and he doesn’t forefoot valgus post a maximally pronated foot in stance. This is a fair percentage of my patients. I have tried forefoot valgus posting this foot type and assessed using video analysis and in-shoe F-Scan. I would not have let the patients walk out with these appliances.

    I eagerly await your research.

    Paul Harradine
     
  22. Craig Payne

    Craig Payne Moderator

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    Paul & Lawrence - get back to you later -- bit busy at moment (...deadlines looming!).

    Will respond to this:
    Are you sure its a forefoot varus? It more likely to be a forefoot supinatus, in which case a varus post is the last thing needed!
    Who said they pronate the foot more? Pronation is a motion. Motion don't damage tissues. Forefoot valgus posting/2-5 bars etc lower the force to establish the windlass mechanism (we have shown its higher in those with a supinatus) --> more efficient first ray planatarflexion --> etc etc
     
  23. yehuda

    yehuda Active Member

    excuse my ignorance but why ? surely if you int post you allow the ff to drop (in a flexible foot) and therefore slowly get rid of the supinatus (in 15 years of practice i have seen patients improve there ff varus with an int post ff )

    how does a ff valgus cause a supinatus ? i can not picture the mechanics if you could referr me to appropriate papers it would be appreciated.


    thanks


    yehuda
     
    Last edited by a moderator: Feb 24, 2005
  24. Craig Payne

    Craig Payne Moderator

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    ..in which case you are not adding a forefoot varus post.
    It dosen't.

    BTW - a forefoot supinatus is NOT caused by a rearfoot pronating past vertical (just analysed that data yesterday --- need to do more as conference abstract deadlines looming -get back to you later)

    Brain teaser:
    Under Root theory the defined normal alignment, the plantar plane of the forefoot should be perpendicular to the posterior calcaneal bisection. How many of those feet that we call "normal" or "ideal" alignment started life as a forefoot valgus, but became a supinatus (relative to the valgus position) - so are in this defined normal alginment, despite being a supinatus..... think about it.
     
  25. pgcarter

    pgcarter Well-Known Member

    All very interesting...and high tech... Try this?
    Grab a mobile foot that pronates a little much and for too long in gait and has plantarfasciitis pain.
    1. Put it in T-N congruence (STJ neutral assumed)
    2.Dorsiflex the 1 st met shaft as much as you can and check the tension in the plantar fascia.
    3. Now plantarflex the 1st met shaft as much as you can and check the tension in the plantarfascia.
    When you P/F the 1st met the distance between the calc tubercle and the 1st mpj decreases.
    4. If "heel spur" enthesopathy and plantarfasciitis are traction related injuries or tensile stress damage then this is what you want to do.
    5. In order to maximally plantarflex most 1st met shafts in gait then a posterior focussed high point under the navicular with the steepest possible angle of descent under the met shaft assissted by a forefoot valgus post (and usually increased lateral column support by grinding out the cuboid to some extent) is the most effective way to decrease the linear distance between the calc med tubercle and the 1st MPJ during stance.
    In many feet you can feel the change from soft tissue structures being the load bearers to the bones being the load bearers during propulsion...(when a successful MTJ lock has been facilitated by what you have done} have a look at foot prints in sand and see the relative depth positioning of various parts of the foot and what parts are load bearing.
    Not very scientific....but it works.
    Regards Phill Carter
     
  26. Atlas

    Atlas Well-Known Member

    In view of the sense that you have made Phill,

    1. What do you make of PF grooves. Surely they get the line between A (insertion) and B (origin) shorter. As you are no doubt aware, a straight line between 2 points is shorter than a curved line. Shorter in this instance equals less tensile stress.

    2. What do you make of devices (DC wedges) and their components (skives) that push into or near the medial tubercle? Where the plantar-fascial problem is near its origin (enthesopathy), should we avoid them? Or if such a force is bearable to the patient, do these devices/components 'straighten the line between A and B?'. I remember you making a good point about what a skive does to the arch in relative terms, and accordingly, a skive may remove the need for a groove (in my mind??).




    Thanks.
     
  27. Craig Payne

    Craig Payne Moderator

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    Its another one of those....that we not published yet, BUT plantar fasical grooves do lower the force to establish the windlass mechanism (and we also know that this is associated with better outcomes).

    Try this - get a foot and push up in the arch on a prominent bit of the plantar fascia ... then try and dorsiflex the hallux ---- see how hard it is? - wonder what the orthotic might be doing to that process if it pushes on a prominent plantar fascia.

    We also found that the groove did not always work, as it was often in the wrong place. Hold a foot at 90 degrees - dorsiflex the hallux - note where the plantar fascia is prominent --> thats where the groove should be. I have been grinding a lot of deep and very anterior plantar fasical grooves into orthostics lately...
    Problematic. At the end of the day if the force needed to supinate a foot is high, you need to incorporate design features into the orthoses to overcome that force. With insertional plantar fasciitis/enthesopathy, as you allude to, the pain is in the area where those design features put most of their force ---- so it has to be a compromise.
     
  28. pgcarter

    pgcarter Well-Known Member

    Dear Atlas and others,
    My 2c on p/f grooves is that if you need one your orthosis is the wrong shape. In 5 yrs of prescribing and making devices as a podiatrist and 15yrs before that solving problems in fitting ski boots I have never prescribed or needed to insert a P/F groove. If the angle of descent of the 1st met is steep enough (and from posterior enough) impingement won't occur....I think anyway...and practice seems to bear me out.
    The skive as Kevin Kirby describes it in his earlier writing is something that I have issues with and the whole STJ axis line and torque thing I basically agree with but 1st ray function does over ride this at times I think.
    Particularly in respect to P/F of the 1st met....if you elevate the lateral side of the forefoot which by Kevins reckoning should pronate the foot, what you can get is facilitated p/f of the 1st met which actually helps supinate the STJ.

    I don't for a moment think I have this all figured out but I also think that the DC wedge concept of adding plaster to the plantar lateral heel rather than cutting it off the plantar medial heel has the effect of maintaining a greater relative height difference between the plantar surface of the heel and the navicular when you put the foot on it.

    This in turn contributes a component of resistance to pronation in the saggital plane not just the frontal plane, among other things.

    As far as position of the calc tubercle goes even though it is called the medial tubercle it is still a fair bit lateral and posterior to the navicular and base of 1st met, so I think you can do a fair bit of work with an orthosis plantar to the more anterior "neck" of calc and the navicular.

    And yes maybe the shortest difference between two points is a straight line but (no sarcasm or rudeness intended) I don't see too many straight lines in feet. Clearly the medial slip of the plantar fascia is able to follow some curves when it is not under too much tension and I think if you really get the 1st met p/f'ed then you have got the tension off it, which means it will tolerate impingement better and allow d/f of the hallux with less difficulty.

    I hope this makes some kind of sense to you.
    Regards Phill Carter
     
  29. pgcarter

    pgcarter Well-Known Member

    I suspect that what Craig is saying about large anterior P/F grooves is similar to me saying get that angle of descent steep enough....either way you have got bulk out of the orthosis under the medial plantarfascial slip and facilitated 1st ray plantarflexion....thats where I like to go back to Root and say that IF we achieve this 1st ray P/f then we have achieved resupination of STJ probably which is helping MTJ lock, propulsion with a rigid lever and greater foot efficiency......all of which helps to reduce loads of different symptoms.
    Regards Phill
     
  30. Bruce Williams

    Bruce Williams Well-Known Member

    Forefoot Varus Posting

    Craig;
    Could you expound on this please? You know of my interest in Metapads that extend to under the cuboid from the podiatry list serve.
    Also, I would suggest that you consider a small study, maybe with me, that looks at changing the casting position of the foot, modified Root method.
    In other words, instead of maximally pronating the 5th ray while the foot is in STJ neutral, and while plantarflexing the medial column - you should instead plantarflex the 5th ray / lateral column as well.
    I think you will see, as did I, that the ability of the 1st ray to plantarflex becomes very limited in this position, as opposed to when the lateral column is maximally pronated and the medial column seems at times to have no end in ability to plantarflex.
    I think you will also find that the need for reverse moton's extension will be greatly limited as well with this new technique.
    I am finding great results w/ a very limited metatarsal pad utilizing my Amfit scanner. I remove the pad from under the 1st met and also the 5th met, and extend it to the apex of the tarsal arch for support of both the navicular and cuboid. This seems to "fill" the transmetatarsal arch, while providing an intrinsic varus post in most patients. The varus post is only 2-4 though.
    I see so much less need for drastic use of heel lifts utilizing these modifications w/ plaster or scanner. LLD seems to resolve or drastically decrease, as would be expected if the MTJ were indeed in its most stable and supinated position instead of allowed to pronate at the lateral aspect.
    To me it just seems appropriate to position the midtarsal joint in its most stable position this way, instead of maximally pronating the lateral column, and automatically destabilizing the MTJ as we have all been taught thru the years.
    Looking forward to your response(s)! ;-)
    Sincerely;
    Bruce Williams, D.P.M.
    Indiana, USA
     
  31. Bruce Williams

    Bruce Williams Well-Known Member

    Lawrence;
    Thanks for the shout out on the temporary device protocol.
    You are indeed correct, and I was wrong I think to feel that there was no FF varus intrinsic posting in my temporary device.
    What I was not able to describe due to ignorance, was the difference in the casting techniques and eventual orthotic positions. I was essentially getting the same results, but using different techniques.
    Now using the AMFIT scanner, I see exactly what I was doing with the temp devices. I also noticed this about a year before switching to the AMFIT scanner, when I changed my plaster casting technique as described. That then truly mimiced as much as possible the partial wbing temporary casting that I was using with the temps.
    Thanks for posting your opinion. And in the future, please do not ever hesitate to privateley, or openely disagree or dispute my opinion. I am ever a student of podiatric biomechanics and will never cease to be 'til in the grave! ;-)
    Sincerely;

    Bruce Williams, D.P.M.
    Indiana, USA
     
  32. Bruce Williams

    Bruce Williams Well-Known Member


    Paul;
    Ultimately it may be a difference in the way that you cast the patient in nwbing neutral. Especially if you found that many of these patients did not improve in function on F-scan w/ valgus FF posts.
    Eric Fuller likes to think that he sees a different patient population from me and many of the rest of us. I don't just don't see how that can be true.
    Also, just because someone is standing in a maximally pronated position at the lateral column, does not mean that they don't have availability of supinatory position at that lateral column. What I mean is that if you were to position them maximally supinated at the lateral column while casting nwbing neutral, I think you would find much less FF varus in your casts and patients.
    My opinion.
    Sincerely;
    Bruce Williams, D.P.M.
     
  33. Bruce Williams

    Bruce Williams Well-Known Member

    Yehuda;
    Think about the forefoot in 2 columns. The lateral column of the 4th and 5th digits and metatarsal, and the medial column of the 1-3rd digits and mets and cuneiforms. Appreciate that these 2 segments of the foot can and will move independetly of each other. Imagine a patient with a flexible pes valgus and a forefoot that spreads tremendously medially and laterally when they stand.
    Now if you put this patients foot in neutral STJ position and then attempt to plantarflex both the 1st and 5th rays, you will find that you can put these rays in the same plane below the level of teh mets 2-4. You will find a large increase in the transmetatarsal arch area as well, where we usually put a metapad.
    Now, if the lateral column can and will maximally pronate/dorsiflex at contact, then this destabilizes the MTJ and allows the cuboid and navicular to rotated away from each other. This in turn destabilizes the medial column into midstance and allows the medial column to maximally dorsiflex/supinate (supinatus) as well. over the years the foot will take on this position potentially to the point of it being a more fixed type varus positon, though rarely.
    But, if you can position the lateral column so it does not have to maximally pronate/dorsiflex or only does so for a short time before midstance progresses and then it can begin to stablilize in a better position plantarflexed /supinated due to the position of the casted orthotic, then the navicular and cuboid will be able to position themselves in more stabilly and keep the medial column from dorsiflexing/supinating so much or for too long.
    This will facilitate sagittal plane motion and stop FnHL in its tracks, and keep the MTJ from chronically dorsiflexing the FF on the RF and prolonging and worsening AJ equinus.
    my 2 cents.
    Bruce Williams, D.P.M.
     
  34. Lawrence:

    No slapping necessary, Lawrence. When treating symptoms due to excessive subtalar joint (STJ) pronation moments, then something must be done to add STJ supination moment and/or to decrease STJ pronation moment to the foot so that symptoms will improve. This may involve multiple orthosis modifications including the following:

    1. Inverting the positive cast or orthosis
    2. Adding a medial heel skive
    3. Blake inverted orthosis modifications
    4. Increasing the stiffness of the orthosis plate
    5. Decreasing the medial expansion plaster thickness
    6. Increasing the length and durometer of the rearfoot post

    The problem with adding STJ supination moments to the foot to improve pronation related symptoms is that, during late midstance, the patient may start to experience symptoms due to supination instability of the STJ. For example, the patient may complain that they are "walking on the lateral side of their foot", "feel as if they are going to turn their ankle" and they will often show decreased stride length and increased late midstance pronation.

    Many times a forefoot valgus forefoot extension or 2-5 forefoot extension or a 4-5 forefoot extension are necessary to optimize the function of the foot if these signs or symptoms occur. These wedges increase the ground reaction force (GRF) plantar to the lateral metatarsal heads in late midstance, increase the STJ pronation moment in late midstance that, if done with the right amount, will actually increase the supination of the STJ in late midstance and propulsion and increase the stride length. This somewhat paradoxical effect is likely related to the necessity for the gastrocnemius and soleus to have a GRF lateral to the STJ axis during late midstance and propulsion to resist the STJ supination moment and optimize their propulsive function so that they can exert increasing magnitudes of contractile activity in late midstance without causing lateral ankle instability.

    The above thoughts are mentally catalogued within a paper that I have planned to write for the past seven years now but haven't found time to do so. I hope, however, that this allows you to see that just looking at the STJ axis in a static situation does not always explain the dynamic effects of STJ axis location on the bipedal human during walking or other locomotor activities.
     
  35. Phill,

    I just love it when someone says that they have "issues" with the medial heel skive technique. Finally, I sense a challenge!

    Plantar fascial accommodations are a necessary part of many foot orthoses. Needing to add a plantar fascial accommodation to an orthosis does not necessarily mean that the orthoses are "the wrong shape". It just means that the medial band of the central component of the plantar aponeurosis is "bowstringing away" from the contours of the plantar medial longitudinal arch more than initially expected and the orthosis needs a modification to eliminate compression irritation to the plantar aponeurosis. After 20 years of practice and over 10,000 pairs of orthoses that I have made for patients, I still can't reliably predict which feet will always need a plantar fascial accommodation.

    See my note that I just wrote to Lawrence Bevan on why sometimes adding a lateral forefoot wedge may increase STJ supination in gait. This is not contradictory to earlier writings of mine.

    The DC wedge is another form of an inverted heel orthosis similar to the medial heel skive and Blake inverted orthosis techniques. Understanding how these modifications work is much more important than how the inverted heel modification is actually accomplished. I don't think you will find any reasonable explanation for why these modifications work within the medical literature until my and Don Green's chapter was published in 1992 where we discussed and illustrated how I thought the Blake inverted orthosis was different from the Root type orthosis (Kirby KA, Green DR: Evaluation and Nonoperative Management of Pes Valgus, pp. 295-327, in DeValentine, S.(ed), Foot and Ankle Disorders in Children. Churchill-Livingstone, New York, 1992). Before this time, podiatrists were taught to make vertically balanced foot orthoses for nearly every pathology. We have certainly come a long way in the past 15 years.

    The medial heel skive modification can be extended anteriorly on the positive cast. Dr. Richard Blake has been using a modification he calls the "extended Kirby skive' for over the past ten years which involves this exact modification (Blake, R.L., Ferguson, H.: "The inverted orthotic technique: its role in clinical biomechanics.", pp. 465-497, in Valmassy, R.L.(editor), Clinical Biomechanics of the Lower Extremities, Mosby-Year Book, St. Louis, 1996). Rich was one of my instructors when he did the Biomechanics Fellowship and I made Blake orthoses for him in my student years at CCPM in 1982-1983. Seeing the mechanical effects of the Blake inverted orthosis first hand was very instrumental in me inventing the medial heel skive technique in 1990.

    Now, Phill, what exactly are the issues that you have with the medial heel skive technique???
     
  36. Bruce Williams

    Bruce Williams Well-Known Member

    Kevin;
    Actually, if the forefoot extensions mentioned above works appropriately, the GRF's will be less under the lateral met's, 4-5 and increased under the metatarsals, 1 specifically, and also 2-3.
    Ideally the foot should be toeing off thru the 1st mpj/hallux in late propulsion / toe off. This requires a supinated positon of the STJ as you point out, but to achieve that the GRF's under the metatarsals must equalize or bet greater under the medial mets in late midstance.
    Increasing the pronation moment in the foot at this stage of foot function is deceptive in its description. The foot may actually be pronating positionally, but the Center of Force should be moving medially at this time, not languishing under the lateral metatarsal heads, as they should technically be preparing to lift off the ground at this time.
    An increase in pronation moment does not necessarily mean an increase in GRF's plantar to the lateral metatarsal heads.
    Respectfully;
    Bruce Williams
     
  37. Bruce:

    So good to have discussions with you, Bruce, in another forum. I hope that all is well.

    The location of the center of pressure (CoP) relative to the subtalar joint (STJ) axis spatial location will determine whether the moments caused by ground reaction force (GRF) are of a supination or pronation direction (assuming a vertical GRF vector). Therefore, when I add a pad under the lateral metatarsal heads, the GRF will increase lateral to the STJ axis which will, in turn, cause a more lateral location of the CoP and, all other things being equal, will cause an increase in STJ pronation moment.

    Unfortunately, whether the foot actually pronates or supinates when the lateral forefoot wedge is added is not just due to the effects of GRF but also due to any changes in internal forces such as changing contractile activity and temporal pattens of the extrinsic muscles of the foot.

    For example, lets say a 3 mm korex addition is added to the orthosis plantar to the 4th and 5th metatarsal heads so that 1.0 Nm of STJ pronation moment is added to the foot from GRF (i.e. external force) in late midstance. Now, if the internal forces on the STJ are unchanged at this time in gait, then the STJ will pronate in late midstance due to the increase in STJ pronation moment. However, if the posterior tibial muscle contracts more forcefully at late midstance so that 2.0 Nm of STJ supination moment occurs as a result when the 3 mm korex pad is added to the orthosis, then the foot will not pronate but will, instead, supinate at the STJ when the pad is added to the foot (Kirby, KA.: Rotational equilibrium across the subtalar joint axis. JAPMA, 79: 1-14, 1989). If this seemingly paradoxical result occurs then it is likely due to a proprioceptive effect mediated by the central nervous system whereby the muscle recruitment patterns are changed by the lateral forefoot wedge.

    Otherwise, I don't really understand some of your posting since I never said that an increase in STJ pronation moment would mean an increase in GRF under the lateral metatarsal heads. Therefore, so that we understand each other, and the others trying to read along understand us, we must be sure to separate the effects of GRF on the forefoot that cause STJ pronation or supination moments from the effects of STJ pronation and supination motion on the distribution of GRF on the plantar forefoot. These are two very different things and are not always related or dependent on each other.
     
  38. Bruce Williams

    Bruce Williams Well-Known Member

    Kevin;
    You wrote, "These wedges increase the ground reaction force (GRF) plantar to the lateral metatarsal heads in late midstance, increase the STJ pronation moment in late midstance that, if done with the right amount, will actually increase the supination of the STJ in late midstance and propulsion and increase the stride length. "

    You did emphasize a relationship, causal I think, between an increase in GRF's under the lateral metatarsals and an increase in a pronation moment, as stated above.
    I most definitely agree with you that GRF's are not the only cause of pronation or supination of the foot.
    You mention the increase in the contraction of the PT muscle as a result of a pad under the lateral metatarsals. While this may certainly occur, it will be much more likely that the Peroneus longus will have a more prominent effect due to the placement of this pad, than the PT tendon. They will neither work as well singularly as they will combined.
    But, if there is no stablilty of the MTJ inherent in the orthotic device and attributed more due to the position of the FF extension you mention, then neither muscle will be facilitate properly, and there will never be an effective force to supinate the STJ.
    This may sound contrary to what I've posted twice or thrice today, but if you read into my posts more closely you'll see what I mean. If there is no inherent positional lateral column stability by allowing it to plantarflex / supinate to maximal position, then you must, in most cases, add a reverse morton's extension of some form to allow more room for the medial column to plantarflex, as it will not reach its end range of plantarflexory motion so long as the lateral column is maximally pronated.
    The orthotics effect on the MTJ and lateral column must be taken into account as well, as you say, "due to any changes in internal forces such as changing contractile activity and temporal pattens of the extrinsic muscles of the foot."
    Finally, you said, "Therefore, so that we understand each other, and the others trying to read along understand us, we must be sure to separate the effects of GRF on the forefoot that cause STJ pronation or supination moments from the effects of STJ pronation and supination motion on the distribution of GRF on the plantar forefoot. These are two very different things and are not always related or dependent on each other."
    I respectfully disagree. These forces from the ground and within the foots articular surfaces adn the tension of the ligamentous structures and tendons will always effect both the position of the STJ, MTJ, AJ and all other osseous structures within the foot and ankle, etc. As well, the position of these anatomical structures will have a huge effect on the GRF's on the foot. They are forever related and intertwined and will never be torn asunder.

    Not sure if that clears things up for you Kevin. I hope you and your family are well too.
    Nite.
    Bruce Williams
     
  39. Bruce:

    Let me try to clarify my statement a little more. If there is no muscle force to resist it and the STJ is not maximally pronated, then an increase in GRF acting lateral to the STJ on the metatarsal heads will cause STJ pronation motion since a STJ pronation moment is produced by this GRF.

    However, this is very different from saying that the foot is supinated by, for example, the posterior tibial muscle which, in turn, causes an increase in GRF on the lateral metatarsal heads.

    In the first case, a change in GRF on the forefoot causes a moment that causes a motion. In the second case, moment causes a motion that causes a change in GRF on the forefoot.

    When you state:
    I really don't know why we are now talking about tension in ligaments and tendons since even though these factors are always important, these factors are not germane to our current discussion. The discussion is regarding the difference between STJ motion causing a change in distribution of GRF on the forefoot and a change in distribution of GRF on the forefoot causing a change in STJ moments. Yes they are interrelated, but these are really two very different things and must be separated so there may be adequate clarity to enable meaningful discussion of the mechanical interrelationships of motion, moments and ground reaction forces in the foot.
     
  40. pgcarter

    pgcarter Well-Known Member

    Hi Kevin,
    The "issues" I have arise from use of said modification in practice over time and stem from consideration of the variation of the component of motion in each plane that forms STJ pronation and "forefoot dorsiflexion" as is so often seen in the mobile foot type.
    If a foot has a higher component of sagittal plane motion and a lower component of frontal plane motion then a skive is likely to exert less influence.

    When you look at pronated feet on XRAY do you ever see a foot that has maintained the "calcaneal inclination angle" this collapse of the calc anteriorly occurs in a plane and position largely uninfluenced by a medial skive.

    The position of a skive is by definition quite medial and by definition focusses force rather than diffuses force, it tries to work by force rather than by changing the spatial postional relationships of multiple joints of the foot as can be achieved with shaping of devices in more complex and individually specific ways. And yes perhaps everything can be reduced to torques and levers and forces but I'm also sure that what goes on here is not just about torques around the STJ, there is more to it and I think that 1st ray plantarflexion and stabilization is part of it, as is lateral column function as an integral part of how a foot functions as a rigid lever and delivers propulsion through loaded bones rather than stressed soft tissue. And all these things happen slightly differently for every foot you ever deal with, although there are some fairly common threads.

    Rather than focus force I work very hard to ablate/spread/decrease peak loads while giving any given foot a stable position to make excursions from rather than a postion to hold it in.

    What I think changes over time based on clinical experience and it is very difficult to try to explain what I try to achieve with feet. Yes this is both a reason and a cop out for not staying up all night writing and thinking.

    Specifically with a skive : if you cut the medial heel off a plaster foot as per your instructions as part of making an orthosis, then mold your plastic over it and machine it off the fllowing occurs.
    1. By cutting the medial heel off the plaster you have changed the relative height support that results under the T-N joint region in the resulting orthosis.

    2. When you put the foot on top of the orthosis the medial plantar surface of the heel has been lifted further from the floor than it otherwise would have been, but the region of the orthosis under the T-N joint has not been or anywhere else for that matter. So relative "midfoot lift" has been decreased.

    3. The loss of height differential between the plantar surface of the heel of the foot and the T-N joint opens more available space for the foot to "collapse" onto the surface of the orthosis.
    Feet with the range of motion available in the sagittal plane at any of the possible joints will then do this....the nett result in my humble opinion is less stable than it otherwise would have been had you increased the support under the T-N joint by adding plaster to the plantar lateral heel rather than cutting it off the medial side.

    Easier to demonstrate than explain...I hope this gives you some glimpse of what I mean

    Regards Phill Carter
     
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