Is forefoot varus posting an anachronism?

[Atlas]

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:

[Craig Payne]

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 (http://www.podiatry-arena.com/podiatry-forum/showthread.php?t=58) 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 ...

[Ian]

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.

[Craig Payne]

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 (http://www.podiatry-arena.com/podiatry-forum/showthread.php?t=214) 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.Is this in conjuction with a rearfoot varus post? Yes

[markjohconley]

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

[Sean Millar]

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.

[Laurie Foley]

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.

[Craig Payne]

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 :( )

[Sean Millar]

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

[Laurie Foley]

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 ) :o

[Atlas]

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



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.

[Lawrence Bevan]

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

[Craig Payne]

earlier in this thread, I said:
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 ...
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...

[Lawrence Bevan]

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.

[Craig Payne]

What are the in-shoe parameters that indicate "stuffed up windlass" to you? 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. When you say hardly anyone needs a forefoot varus post why is that? Forefoot varus is rare.On a casted device how do you treat over-pronation secondary to RF varus?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. "functional hallux limitus"....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

[Lawrence Bevan]

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.

[Craig Payne]

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.

[Atlas]

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)



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.

[Lawrence Bevan]

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!

[yehuda]

: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

[Paul Harradine]

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

[Craig Payne]

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

Will respond to this: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 !!!!! 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!sorry i dont understand why one would pronate the foot more to treat xs stj pronation its like cooking a burnt chicken in order to make it taste better 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

[yehuda]

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
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

[Craig Payne]

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 which case you are not adding a forefoot varus post.how does a ff valgus cause a supinatus ?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 (http://www.podiatry-arena.com/podiatry-forum/showthread.php?t=25) 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.

[pgcarter]

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

[Atlas]

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.

[Craig Payne]

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.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...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??). 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.

[pgcarter]

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

[pgcarter]

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

[Bruce Williams]

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 :( )

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

[Bruce Williams]

I dont see the problem here

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.

All said in my personal opinion and well meant!
Lawrence

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

[Bruce Williams]

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


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.

[Bruce Williams]

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

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.

[Kevin Kirby]

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.

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.

[Kevin Kirby]

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

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???

[Bruce Williams]

Lawrence:

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.

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

[Kevin Kirby]

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

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.

[Bruce Williams]

Bruce:

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.



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

[Kevin Kirby]

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.

Bruce Williams

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: 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.

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.

[pgcarter]

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

[Lawrence Bevan]

Phil

I dont want to answer for Kevin but I think in his book he covers your point on arch lowering and skives and he "generally" advocates using varus forefoot posting to invert the cast/device to counter this where necessary. (which will also lower the lateral side of course).

[Kevin Kirby]

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.

The medial heel skive will exert a STJ supination moment regardless of how much sagittal plane and frontal plane motion is evident in the STJ during closed kinetic chain pronation.


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.

A radiographic study done by Don Green and coworkers quite a few years ago showed that there was little change in the calcaneal inclination angle with STJ pronation.


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.

I believe that you should do some more reading in my two books as to how I use the medial heel skive along with other orthosis modifications in order to accomplish my orthosis treatment goals (Kirby, Kevin A.: Foot and Lower Extremity Biomechanics: A Ten Year Collection of Precision Intricast Newsletters. Precision Intricast, Inc., Payson, Arizona, 1997.; Kirby, Kevin A.: Foot and Lower Extremity Biomechanics II: Precision Intricast Newsletters, 1997-2002. Precision Intricast, Inc., Payson, AZ, 2002. ) Yes, you are right, it is not about just the STJ, and I have never stated it is all about the STJ as you will also see when you read the last few paragraphs of my latest paper on STJ axis location and rotational equilibrium (Kirby KA: Subtalar joint axis location and rotational equilibrium theory of foot function. JAPMA, 91:465-488, 2001.



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

Again, I think you should read my books about the medial heel skive. I believe you will see that I have also noted these concerns in my fine tuning of the technique. When I wrote the original paper (Kirby, KA.: The medial heel skive technique: improving pronation control in foot orthoses. JAPMA, 82: 177-188, 1992) I had to keep it short for publication in JAPMA. Since then I have lectured and written on your concerns extensively.

Phill, you have good ideas and should consider and making the bold step to try to do research or write a paper to publish in JAPMA, for example. It is a lot of work but is a very satisfying accomplishment.

[Atlas]

A radiographic study done by Don Green and coworkers quite a few years ago showed that there was little change in the calcaneal inclination angle with STJ pronation.

Did they take into consideration, the sagittal plane position of the STJ axis in their sample?







The other issue with the skive may have been in relation to enthesopathies, associated with rearfoot pathomechanics. We want to oppose rearfoot pronatory torque on the one hand, but on the other, does the typical pathological medial tubercle prefer the straight edge of a skive, or the curved edge of a DC wedge?


Cutting into the medial heel on the positive mould gives you the skive and adds a supinatory torque medial to the STJ axis. Phil's preference of adding plaster to the disto-lateral aspect of the heel, takes the device away and removes the pronatory torque lateral to the STJ axis. In view of the congruency/curvature of the DC wedge about the medial tubercle, this may be the device of choice...in theory.


And Kevin, most of the good people have gone into publication. For the sake of his patients and his students, a clinical animal like Phil is a rare commodity in this single-minded but necessary pursuit of evidence-based practice. In other words, the world gains a researcher, but his patients/students lose a clinician. To continue my generalising, many new graduates (in most allied health courses) come out with fantastic knowledge of sample-sizes and 'world's best practice'; but do they have the pragmatism, the grasp of concepts, the gut feel, the pattern recognition, to make it in the clinical setting? We need the research-based researchers at uni; but what is also needed and sadly becoming extinct, is the pure clinical animal.



Ron

[pgcarter]

Dear All,
Kevin, thanks for your response..and others of course.
I take your point that you have written lots of stuff that I haven't read and that you have thought about most of this stuff yourself. I don't really get how a medial or varus forefoot post would help, unless you are dealing with tib varum as well, or you do go for the normal foot is somewhat fore foot inverted etc.. there's certainly a lot of it around.
None of what I am saying is intended as an attempt to pick holes....or to try and "find the flaw" in your thoughts. I feel justified in saying what I do simply by clinical practice and the results that I seem to get by way of smiling patients....it may be that I am not doing what I think I am doing, there has been a fair bit of that going round in podiatry after all.

I do understand that the skive on the medial side of the STJ axis will exert a supinatory torque around the joint (as mostly a frontal plane oriented force).
I suppose I am suggesting that it may not always be the best place to apply the force, or the way to apply the least force for the same result. By same result I mean assymptomatic or enhanced function, not necessarily all patients pushed towards one definition of "correct" stance or position.
I do find I can keep the perceived force/alteration to a lower level (better patient tolerance) with less focussed shaping of plaster. Although I am quite happy to accept that skives often work and are frequently a perfectly acceptable option.
Thanks for your positve encouragement...I'd love to have the chance to do some research....but nobody wants to feed my kids while I do it so unless I win the lottery it probably won't happen.

Regards Phill Carter

[Kevin Kirby]

The other issue with the skive may have been in relation to enthesopathies, associated with rearfoot pathomechanics. We want to oppose rearfoot pronatory torque on the one hand, but on the other, does the typical pathological medial tubercle prefer the straight edge of a skive, or the curved edge of a DC wedge?


Cutting into the medial heel on the positive mould gives you the skive and adds a supinatory torque medial to the STJ axis. Phil's preference of adding plaster to the disto-lateral aspect of the heel, takes the device away and removes the pronatory torque lateral to the STJ axis. In view of the congruency/curvature of the DC wedge about the medial tubercle, this may be the device of choice...in theory.

Ron

Ron:

The medial heel skive does not have a flat or straight edge, unless it is done incorrectly. Perhaps you were not shown the proper method by which to perform the medial heel skive. I would suggest that you look closely at the paper I did 13 years ago on the medial heel skive so you will know how to do the technique correctly (Kirby, KA.: The medial heel skive technique: improving pronation control in foot orthoses. JAPMA, 82: 177-188, 1992).

As far as the "DC wedge" is concerned, adding extra plaster to the lateral heel of a positive cast of an orthosis to produce a varus-like heel shape was first introduced to me by Notty Bumbo, who previously taught at CCPM and made a lot of orthotics for Ron Valmassy, DPM. Notty first told me about his technique in 1992, soon after my medial heel skive paper came out. So the DC wedge is not something original, as far as I can see, since it has been used by others, though unpublished, for over 13 years.

Whether either technique is the "device of choice" is up to the practitioner to decide. In my hands, the medial heel skive is very effective at allowing precise control of the amount of STJ supination moment that an orthosis can offer.

[Craig Payne]

DC wedge Just a point of clarification - 'DC Wedge' is a trademark of The Orthotic Laboratory in Melbourne, Australia --- so is unlikely to be known outside Australia by many people.

[Kevin Kirby]

Dear All,
Kevin, thanks for your response..and others of course.
I take your point that you have written lots of stuff that I haven't read and that you have thought about most of this stuff yourself. I don't really get how a medial or varus forefoot post would help, unless you are dealing with tib varum as well, or you do go for the normal foot is somewhat fore foot inverted etc.. there's certainly a lot of it around.

I will not add a forefoot varus post, except on rare occasions to my orthoses. However, as stated earlier, I have recognized the "heel lift" effect of the medial heel skive soon after I started doing it about 15 years ago. To compensate for the slight heel lifting effect, I always advocate the use of minimal medial expansion plaster thickness and/or inverting the positive cast to increase medial longitudinal arch (MLA) of the orthosis when the medial heel skive is being used. In this way, both the medial heel skive and the increased MLA height work synergistically in increasing the subtalar joint (STJ) supination moment for the patient. If the medial heel skive alone is used, without an increase in MLA height of the orthosis, then the patient's MLA will collapse too much. If the MLA of the orthosis is increased alone, without the medial heel skive, then medial arch irritation is more likely to result. The medial heel skive and MLA height of the orthosis need to be adjusted together achieve an optimal increase in STJ supination moment. I have lectured and written on these concepts for the past decade.


None of what I am saying is intended as an attempt to pick holes....or to try and "find the flaw" in your thoughts. I feel justified in saying what I do simply by clinical practice and the results that I seem to get by way of smiling patients....it may be that I am not doing what I think I am doing, there has been a fair bit of that going round in podiatry after all.

Your clinical practice technique is identical to mine...making patients happy. And I really don't mind, Phill, if you do try to pick holes or find flaws in my thoughts, as long as your reasoning is valid and as long as basic physics and biological principles are not violated. I learn something new every day.


I do understand that the skive on the medial side of the STJ axis will exert a supinatory torque around the joint (as mostly a frontal plane oriented force).

Please, Phill, don't say "supinatory torque". Dr. John Weed told me over 15 years ago that "supinatory" is not a word. I believe he was right. In addition, "torque" is not standardly used now in biomechanics. The correct word is "moment". Supination moment instead of "supinatory torque", please.

I suppose I am suggesting that it may not always be the best place to apply the force, or the way to apply the least force for the same result. By same result I mean assymptomatic or enhanced function, not necessarily all patients pushed towards one definition of "correct" stance or position.
I do find I can keep the perceived force/alteration to a lower level (better patient tolerance) with less focussed shaping of plaster. Although I am quite happy to accept that skives often work and are frequently a perfectly acceptable option.

Have you ever seen a patient with posterior tibial dysfunction, Phill? I see at least 8-9 of these patients per month. Where is the plantar representation of the STJ axis located in these feet? (Kirby, KA: Methods for determination of positional variations in the subtalar joint axis. JAPMA, 77: 228-234, 1987). In a foot such as this, what location of the plantar foot has the greatest moment arm to produce a STJ supination moment? What percentage of the total surface area of the plantar foot is on the medial side of the STJ axis in the patient with Stage III posterior tibial dysfunction when compared to the foot that functions normally? I would suggest you make an approximation of this "percentage" surface area medial to the STJ axis in the PT dysfunction foot and normal foot and then get back to us on what you have found in a few feet. Then hypothesize on how this difference in STJ spatial location may affect the potential ability of the orthosis to cause a net increase in STJ supination moment in both types of feet. Also, next hypothesize on how you would change the design of the orthosis to compensate for this change in STJ axis location. Once you have done this, you are nearly halfway to a publishable paper, with hardly anytime lost to feed the children.


Thanks for your positve encouragement...I'd love to have the chance to do some research....but nobody wants to feed my kids while I do it so unless I win the lottery it probably won't happen.

Funny, I always thought that the increased academic recognition and increased knowledge that I obtained from my twenty years of research, writing, lectures and publications helped feed my children, now ages 22 and 17, and helped finance them through college.

If you say that you won't have the time to do something....then you likely won't make the time. If you want to do something, then you likely will find the time to do it. Feeding children and being active in research, writing and teaching are not mutually exclusive endeavors.

I hope at this early stage of your career as a podiatrist, Phill, that you haven't already resigned yourself to the possibility that you won't have adequate time to develop the great potential that you have to be a leader for your profession in biomechanics and foot orthosis therapy. It was not too long ago that I was nagging another former podiatry student of mine to start publishing his ideas. He now lectures nationally and internationally on biomechanics and his name is well-known. It all starts with the first published paper.

[Stanley]

I just signed on to this listserve. Hello everyone. From what I have read on this subject, i must be in the minority. I still use forefoot varus posting, and it still works great after 30 years. The conditions it is helpful includes: plantar fasciitis (especially when medial), Sinus tarsitis, posterior tibial shin splints, chondromalacia, pes anserine bursitis, and anterior innominate dysfunction when related to pronation.
If there is a forefoot supinatus, then I will decrease the post the next time I see the patient.
I think the problem occurs if the extrinsic pronatory factors are not eliminated.

[Atlas]

If there is a forefoot supinatus, then I will decrease the post the next time I see the patient.


I like this idea, and will try it; despite the consensus that the last thing you do is put a FF varus post on a supinatus. I am puzzled by the feet that's 1st MPJ is not plantar-grade in NCSP.

Do you use 1st ray cut outs in association with the FF varus post?

[Stanley]

How would you know it is a forefoot supinatus, and not a varus :confused: ? They didn't give me a crystal ball when I graduated (maybe I was late with the tuition :) ). I use leather devices, and you can read what the foot is doing. If you see the first dropping, then make the correction.
What is really interesting is when you put the foot in neutral stance, I have yet to see the lateral side of the forefoot come off the ground.

As far as cut outs for the first, I visited Bruce Williams several weeks ago, and he gave me the course on sagittal plane theory. So I tried the first ray cutouts. Some patients liked it, and some wanted me to undo what I did. I am not sure how to predict the ones that will require it. But I have noticed if you see the first metatarsal dropping, you can go a little further with the grinding under the first metatarsal head.

One additional thing. If you are not posting under the metatarsal heads, then you really aren't forefoot posting. The reason is that the metatarsal heads are still in contact with the ground, so what have you really changed.

[Admin]

I have put this picture on the home page (http://www.podiatry-arena.com ):

http://www.podiatry-arena.com/images/orthoses.gif

Both are for the same patient (as part of a research project) .... comments?

[Stanley]

The orthotics look like a subortholen orthotic one has a first ray cut out and the other doesn't.
The first thing I would like to know is when the patient stands on it, does it change the forefoot to the ground position. If the forefoot to ground position is unchanged, then the forefoot post is non functional.

[Bruce Williams]

I have put this picture on the home page (http://www.podiatry-arena.com ):

http://www.podiatry-arena.com/images/orthoses.gif

Both are for the same patient (as part of a research project) .... comments?

I'm not sure if it's a 1st ray c/o or just that the medial column angle is much steeper. It does appear that there is a proximal/medial to distal / lateral taper to the distal edge of the device. It also looks like there is a heel skive in the RF, something appears different in the heel cup. Possibly a more varus posted heel, though it does not appear so from the blue posting, and the medial arch height appears not higher than the other device.
I would comment that the lateral aspect of the device at the FF appears to be very high on both devices. This can and will make it difficult for the medial column to fully establish stability no matter what modification you use along the medial colum. It could also be that the FF is valgus posted on both devices.
Bruce

[Lawrence Bevan]

Are they made from 2 casting methods - one standard method and one with the 1st MTP dorsiflexed?

[Admin]

They were both from the same cast - they were made by one lab, but they followed the protocol that they normally followed for one and then the protocol that is used by another lab!!!! A third one was made exactly the same as the right one, but incorporating a medial heel skive - subjects were measured to determine what predicted a response to each of the different design features --- results are pending.

[yehuda]

They were both from the same cast - they were made by one lab, but they followed the protocol that they normally followed for one and then the protocol that is used by another lab!!!! A third one was made exactly the same as the right one, but incorporating a medial heel skive - subjects were measured to determine what predicted a response to each of the different design features --- results are pending.

it seems that the orthotic on the left has less plaster arch fill on an int ff varus post as such the angle is much greated

am i right ??

[pgcarter]

How they arrived at the shapes becomes immaterial once the shape is under the foot.....the first met angle of plantar flexion is steeper under the left device...that's really all you can tell from this perspective. WWhether they used less fill or in fact ground the cast out doesn't matter....the shape and stiffness of the shape under the foot is what counts.


If the foot needs the increased angle to get the hallux freed up, the windlass engaged and the bones loading well then this will work better....if it does not need it you may get tolerance problems.....what do all the pathologocal subjects have to say about their symptom reduction?

Regards Phill.

[yehuda]

How they arrived at the shapes becomes immaterial once the shape is under the foot.....the first met angle of plantar flexion is steeper under the left device...that's really all you can tell from this perspective. WWhether they used less fill or in fact ground the cast out doesn't matter....the shape and stiffness of the shape under the foot is what counts.



Regards Phill.

I am sorry but I disagree, as a practitioner you must know what the consequenses are of the prescription you fill out as such if you ask for minimal plaster arch fill the result will be an orthotic which
1) has increased pressure under the arch (and therefore possibly more uncomfortable)
2) an orthotic that offers more control
3) an increased met angle allowing the windlass mechanism to operate better.
4) increased bulk in the shoe

regards Yehuda.

[Thomas Novella, DPM]

I think problems factoring in the decision to use an extrinsic forefoot varus post include:

-being sure the foot has a forefoot functioning in either compensated or uncompensated varus when it participates in the closed chain and

-being reasonably sure that posting the varus will help the complaint.

If I have a system who's alignment I want to tinker with, connected to a foot that I feel needs a forefoot varus post to put that system into the alignment I want, how did I make that decision?

First, I have to be sure tinkering with the alignment stands a high chance of helping the complaint and a low chance of hurting anything else.

Second, I have to be able to ken that a forefoot varus exists. So I put the rearfoot in the position I want, then I pronate the forefoot and see where it stops. If the plane that the met heads rest on at that moment is in varus to the heel bisection, I might have a functioning forefoot varus. Of course, if the foot has to pronate to absorb an equinus, the forefoot varus, and most likely, my lovely rearfoot position will go bye-bye (and your trusting patient will get a sesamoiditis, or worse). There are easy ways to tell if the equinus will pronate and obviate your efforts to supinate the foot. If anyone is interested or would like my input on that, let me know. If there's enough varum below the knee, I might be able to sneak medial posts in there anyway. Of course I'd start checking lateral ankle for stability, peroneal strength, and the possibility of impending peroneal damage if I get the patient started on a preemptive strengthening program.

Third, I establish that the alignment of the rearfoot I want will be pulled out of my nice position by a forefoot varus once plantigrade is achieved. In most cases this same forefoot varus will continue to do mischief at heel-off.

I have no business giving somebody an extrinsic ff varus post if I can't rationalize it will help them. There are many reasons to give this posting. Offhand, if the above criteria let me get this far, ...

I love giving ff varus posts (extrinsic from here on unless specified otherwise) for lateral midtarsal impingement or lateral ankle impingement in the presence of an uncompensated or minimally-compensated forefoot varus. These people obviously get no rearfoot post, or the forefoot post would have to magnify into sprained ankle city.

I agree with a previous poster that they can be magic for hallus limitus, as long as the inclusionary criteria are met.

Anterior tibial shin splints, and anterior tibial tendinitis ease up with appropriately-dispensed ff varus posts, as do posterior tibial tendinitis in youths (I don't give ff varus posts to individuals under 10-12 y.o., because I dont want to chance inhibiting their frontal plane derotation and perpetuate a forefoot varus. I don't think there is any research on ff varus posts perpetuating ff varus in the population, but I'd feel guilty doing it anyway, unless the child has a coalitional disorder like Apert's Syndrome).

I suppose most anything involving medial overload meeting the inclusionary criteria might benefit, so from here on in it's just the standard list and I don't want to get boringly pedagogic.

[yehuda]

[QUOTE=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[/QUOTE]

so if you had a +ve cast that showed 23 degrees fore foot varus how would you give it a valgus control

please define what you mean by a varus post are you talking only about extrinsic or even intrinsic

thanks

Yehuda

[Thomas Novella, DPM]

1/ I don't post to the cast, I post to the problem.
2/ If a problem requires a valgus post, and if the system allows a valgus post, I'll give one.
3/ I'm talking extrinsic.

TMN

[One Foot In The Grave]

OMG....I have just discovered the Earth indeed is not flat!!


I think I'll be booking into Boot Camp (http://www.podiatry-arena.com/podiatry-forum/showthread.php?t=393) this year!

[Robyn Elwell-Sutton]

Many of my patients with a "fore foot varus" and plantar fasciitis do not plantarflex the hallux at toe off and complain of discomfort in the newly issued orthotic. The addition of a poron shaft under th 1st MPJ ,along the hallux and tapering to zero mm at the end of the medial forefoot seems to reprogram this reflex action and brings immediately comfort and a more natural (no compensating) gait.
Robyn Hood

[Robertisaacs]

Many of my patients with a "fore foot varus" and plantar fasciitis do not plantarflex the hallux at toe off

Eh?!

The addition of a poron shaft under th 1st MPJ ,along the hallux and tapering to zero mm at the end of the medial forefoot seems to reprogram this reflex action

And again, Eh?!

I can't visualise what you're saying here. Are you talking about a shaft under the hallux tapering to nothing under the MPJ (as in a cloughy wedge)?

Not sure what you're driving at. Could you elucidate? What planterflexion at toe off? What reflex action? And what compensation does it prevent.

Confused of Kent

[Ian]

Robyn,

I'm confused too.

Many of my patients with a "fore foot varus"...

Are you referring to a true (bony) forefoot varus, or a soft tissue invertus (Supinatus)?

... do not plantarflex the hallux at toe off and complain of discomfort in the newly issued orthotic.

Do you mean plantarflex the MTPJ (i.e. dorsiflex the hallux) at toe off?

Ian

[Robyn Elwell-Sutton]

Ian,
Chicken and egg with the acquired flat foot. re bony v. soft tissue. Some regain motion- others do not. I am certain I am clinically seeing a true bony forefoot varus as I see it as 2 generations in a family and the child usually presents for treatment around puberty growth spurt.( Probably only around 10 % of cases). Two scenarios:one is a high STJ varus /high ROM and the midfoot "collapses on WB. I post 50/50 intrinsic/extrinsic and monitor to adjust the extrinsic post if ,over time I gain flexibility of the 1st ray - use mobilisation not just of foot but usually check out pelvic girdle movement/muscle tightness. Foot wear with the extended medial counter or (sports) the medial column "anti pronation block" is helpful adjunct . The other is the Tib.post./medial ligament deficits.
I check their stance on the orthotic at dispensing prior to top cover. If the fore foot (1st ray) remains dorsiflexed then I add the first ray shaft. This assists activating the dormant proprioception response. I use a cover that can subsequently be peeled back if needed.Without this feedback from the hallux they do not reengage intrinsic muscle function propulsion.
I am not on IT analysis and would love someone to check this. I work with physios.
Robyn Hood:pigs:

[Robyn Elwell-Sutton]

Confused of Kent
Re hallux plantar flexion - have a look (and feel) at the indentation on the sock liners of their shoes - there is usually a deep indentation from their plantar flexing their hallux for stability from midstance to the toe off phase and often clawing and medial rotation of the distal phalanx of the 2nd toes to assist this action. They have lost the ability to engage peroneus longus to plantar flex the 1st ray (because it is often in spasm) and to perform a single stance balance test with eyes shut , they will engage in an abnormal muscle firing pattern to avoid falling over. It is this pattern I attempt to break .

Robyn Hood

[Robertisaacs]

have a look (and feel) at the indentation on the sock liners of their shoes - there is usually a deep indentation

Yep.

from their plantar flexing their hallux for stability from midstance to the toe off phase

Whoa there, o hooded avenger of nottingham, thats a bold, bold leap! How do you know that the dent is caused by active planterflexion of the hallux from MS to TO, rather than passive planterflexion moments (ie joint stiffness, functional or otherwise) after toe off.

Also, you said, planterflex the hallux AT toe off. Which is it, mid stance to toe of or starting at toe off? Strikes me that increasing internal active Planterflexion moments in the 1st MPJ when the inertia of the body traveling forward over the foot and the gravity holding the foot down are creating such a huge external dorsiflexion moment is a bit... other!


They have lost the ability to engage peroneus longus to plantar flex the 1st ray

Will not actively trying to planterflex the toe in WB exert a dorsiflexion moment on the 1st ray? If I stand still and planterflex my hallux hard enough my 1st mpj leaves the ground and my 1st ray appears to dorsiflex.

Still unclear about where your shaft is going as well ;)

Kind regards

[pgcarter]

Isn't there an early paper by Green? that looked at the relationship of available dorsiflexion range at the first MPJ dependant on position of the 1st met shaft?....functional jamming as opposed to active plantarflexion, quite different things I would have thought?
regards Phill Carter

[Graham]

Isn't there an early paper by Green? that looked at the relationship of available dorsiflexion range at the first MPJ dependant on position of the 1st met shaft?

didn't they show for every 1deg of dorsiflexion of the first ray you lost 4deg of hallux extension at the mtpj?

[efuller]

Isn't there an early paper by Green? that looked at the relationship of available dorsiflexion range at the first MPJ dependant on position of the 1st met shaft?....functional jamming as opposed to active plantarflexion, quite different things I would have thought?
regards Phill Carter

Sherer and Rukis in JAPMA? I don't have time to look right now.
Eric

[Ian]

The authors present a quantitative analysis of the effect that first ray position has on motion of the first metatarsophalangeal joint. A goniometer was constructed to measure the degrees of first metatarsophalangeal joint dorsiflexion with the first ray in three positions: weightbearing resting position, dorsiflexed 4 mm from the weightbearing resting position, and dorsiflexed 8 mm from the weightbearing resting position. First metatarsophalangeal joint dorsiflexion decreased 19% as the first ray was moved from the weightbearing resting position to 4 mm dorsiflexed, 19.3% as the first ray was moved from 4 mm dorsiflexed to 8 mm dorsiflexed, and 34.7% as the first ray was moved from the weightbearing resting position to 8 mm dorsiflexed. The biomechanical significance of decreased first metatarsophalangeal joint dorsiflexion that results from first ray dorsiflexion is discussed, and proposed bases for the pathomechanics of hallux abducto valgus and hallux rigidus deformities are presented.


Attached for interest

Ian

[mgrig]

Hey,

A couple of questions...

1) have there been any papers produced which indicates prevalance of 'FF Varus vs Supinatus'? I know varus is rare but how rare???

2) what are your thoughts on channeled Varus posts?
e.g. a Dorsal extrinsic varus post which has a softer density fill (or no fill) under the 1st MPJ/toe. To me it seems like is an attempt to invert the forefoot while trying to facilitate sagital plane motion. Anyone use them? if so when?

Marc

[Craig Payne]

1) have there been any papers produced which indicates prevalance of 'FF Varus vs Supinatus'? I know varus is rare but how rare??? We got data that puts the prevalence of forefoot varus at 1.6% in a military population.

[Kevin Kirby]

1) have there been any papers produced which indicates prevalance of 'FF Varus vs Supinatus'? I know varus is rare but how rare???

Marc:

Forefoot varus will be very common in the practices of clinicians that evaluate the foot with the subtalar joint in a less pronated rotational position than other clinicians or that draw their heel bisections more everted than other clinicians. Unless we know how the evaluating clinician is bisecting the heel or how the clinician evaluates for subtalar joint neutral position, then attempting to discuss the prevalance of forefoot varus in the population is useless.

[mgrig]

Thanks Craig and Kevin.

Kevin, I can understand where you are coming from. I work for a lab, and I would say (roughly) 10-20% of Rx have some form of varus posting (intrinsic or extrinsic).

For the life of me and cant seem to work out why? Are that many people behind the times???

[Robyn Elwell-Sutton]

We got data that puts the prevalence of forefoot varus at 1.6% in a military population.

Perhaps people with true forefoot varus have such foot discomfoot they never contemplate joining the armed forces. You would have to look at the initial presenting cohort in a year of conscription.Perhaps if you put out a plea for all those who find standing still in a queue to come forward, you might get a very difference incidence??
Robyn Hood :pigs:

[Robyn Elwell-Sutton]

Yep.



Whoa there, o hooded avenger of nottingham, thats a bold, bold leap! How do you know that the dent is caused by active planterflexion of the hallux from MS to TO, rather than passive planterflexion moments (ie joint stiffness, functional or otherwise) after toe off.

Also, you said, planterflex the hallux AT toe off. Which is it, mid stance to toe of or starting at toe off? Strikes me that increasing internal active Planterflexion moments in the 1st MPJ when the inertia of the body traveling forward over the foot and the gravity holding the foot down are creating such a huge external dorsiflexion moment is a bit... other!




Will not actively trying to planterflex the toe in WB exert a dorsiflexion moment on the 1st ray? If I stand still and planterflex my hallux hard enough my 1st mpj leaves the ground and my 1st ray appears to dorsiflex.

Still unclear about where your shaft is going as well ;)

Kind regards


On top of the medial shell or preferably the full length mouded full length insole - commencing at the sulcus , along the plantar hallux and tapering beyond it - usually about 3mm max and semi compressible e.g PPT. I am attempting to activate a (primitive) reflex response used by children in early gait when unsteady.

I would prefer to describe these "varus" feet as either: rigid dorsiflexed 1st ray; flexible dorsiflexed 1st ray; dorsiflexed hallux ; metarsus varus (not adducto varus) plus the various hallux pathologies - because it leads me to the pathological process and hence the treatment . That way there is no ideological or terminological confusion between us and other professions who use the terms in reverse.

Robyn Hood :pigs:

[mgrig]

Hey guys,

Sorry to dig up an old thread again, but one question still bugs me...

What are your thoughts of Extrinsic FF varus posting that has the 1st cut out? i.e. 2-5 only

If we are speaking in terms of STJ axis position wouldnt the force be applied too far lateral? (in most cases)

does anyone on here use this method of posting? if so why?

[Sam Randall]

Something similar is used quite alot; it is known by a variety of names..

Kinetic wedge, reverse mortons extension, 1st ray cut out, 2-5 bar.

Have a look at the beginning of this thread (mentions of it there) and I'm sure admin will be along shortly with a list of links to related topics... (drum roll: cue admin)

I've used FF varus posting rarely. I had a marathon runner in once c/o knee pain. Been to a few people and had tests and nothing much showing up.. Dx: Chondromalacia Patellae

O/e he had marked tibial varum, limited rearfoot eversion and a supinated and pretty rigid foot with a fully inverted fore foot in stance where the medial column hardly touched the ground.

During both walking and running, he was internally rotating the leg really quickly around midstance phase. The fixed inverted rearfoot poition, tibial varum and rigid foot type meant the only way he could get his medial column loading was to internally rotate the leg in that fast flicking way. It was my idea that this transverse plane motion could be causing the knee pain, so I tried some forefoot varus wedging and asked him to try it now and again on the shorter runs. The knee pain reduced significantly.

In this (rare?!) case, and ? in the spirit of tissue stress thinking, forefoot varus wedging seemed reasonable to me??

[mgrig]

Sam,

i can see how valgus posts or similar (rev Mortons, kin wedges 1st ray out etc) they all work around everting the forefoot which is going to facilitate windlass etc...

ff varus posting with 1st out seems like a totally different kettle of fish... you are trying to encourage 1st met function whilst supinating the rest of the forefoot...

i am guessing the goal is to reduce calc eversion, but if you think about it in terms of STJ axis postion there would be many better places to apply such a force depending of how far medially it is deviated.

[Sam Randall]

I was aware of the slight conceptual difference between the two, but I wouldn't be surprised if they both behaved very similarly.. there would be only so high you could go with a ff varus posting + first ray cut out before it turned into something resembling a poorly placed met dome, and how high would you need that inclination to go to get the desired effect... what would the desired effect be...? It seems the important part of this modification is the 1st ray cut out.

It's my understanding that FF intrinsic varus posting is used to "balance the rearfoot" in an old fashioned type device. This works under the assumption that the foot should be operating around STN, so i guess you'd be right that the goal is reduced Calc eversion. But now we have been enlightened SALRE and tissue stress principles this appears to be incorrect. Which means your last point is also correct.. But, even with a laterally deviated STJ axis... how much of a significant supinatory moment could you get from a forefoot 2-5 varus wedge...??

Kind regards,

Sam

[mgrig]

Makes sense to me Sam,

part of my role at the lab i work for is to interpret orthotics prescriptions, and this style of Rx would pop up quite frequently from more than one customer. It always makes me scratch my head and wonder!

[Peter1234]

[QUOTE=

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[/QUOTE]

Hi Craig,

can you please point to the article you wrote where you explain this lowering of force to establish the windlass mech.

Peter

[Craig Payne]

can you please point to the article you wrote where you explain this lowering of force to establish the windlass mech. Sorry, its only in abstract form from a confernece. Its on a long list of publications that I need to get to.

But try this: Do Jacks test. Put felt under first ray to simulate forefoot varus post. Do jacks test again.

[Peter1234]

Hi Craig,

i did have a go myself - not very efffective!! From how I understand biomech a ff varus post (including the 1st ray) should make make the jacks test more difficult. Although it may be argued that it may change COP more laterally! In any case 1st mtpj function is reduced.

However it is a ff valgus post with a cut out to the 1st mtpj that I am querying: HOW will that decrease the amount of force needed to initiate the windlass? Surely the force needed is the same with either orthoses, however the amount of motion that is needed to produce the same windlass effect may be different - such as in a forefoot varus. Surely - force is the result of time over resistance?

Peter

[Peter1234]

Craig -

it's just that you said that you treat plantar fasciitis with forefoot valgus posting (didn't you?)

thanks,

Peter:boxing:

[Craig Payne]

it's just that you said that you treat plantar fasciitis with forefoot valgus posting (didn't you?) Routinely. Its still in conference abstract form, but we showed that in those with plantar fasciitis, that the force to dorsiflex the hallux (ie jack test) is higher. If you elevate the lateral forefoot the force to dorsiflex the hallux goes down ... simple tissue stress stuff.

[Peter1234]

Hi Craig,

thanks very much. Looking forward to it!!!

Peter

[joejared]

I have put this picture on the home page (http://www.podiatry-arena.com ):

http://www.podiatry-arena.com/images/orthoses.gif

Both are for the same patient (as part of a research project) .... comments?

Well, the left looks MASSish, more likely to immobilize the midtarsal joints than the right and looks like it has less fill. In comparison to the right, it's definitely more aggressive and intuition suggests you're asking us to compare mass posted devices with neutral.

[efuller]

Hi Craig,

i did have a go myself - not very efffective!! From how I understand biomech a ff varus post (including the 1st ray) should make make the jacks test more difficult. Although it may be argued that it may change COP more laterally! In any case 1st mtpj function is reduced.

However it is a ff valgus post with a cut out to the 1st mtpj that I am querying: HOW will that decrease the amount of force needed to initiate the windlass? Surely the force needed is the same with either orthoses, however the amount of motion that is needed to produce the same windlass effect may be different - such as in a forefoot varus. Surely - force is the result of time over resistance?

Peter

The windlass mechanism helps stiffen the first ray in the direction of dorsiflexion of the ray. It does this by creating an internal plantar flexion moment of the first metatarsal. Tension in the windlass will also tend to increase supination moment at the STJ in most feet. (see my paper in JAPMA on the Windlass from 1999 or 2000 for pictures.) So, the windlass prevents both first ray dorsiflexion and STJ pronation.

What you are doing with a forefoot varus wedge is to attempt to supinate the STJ by increasing force on the medial column. (Increased force on medial forefoot and less force on the lateral forefoot will tend to move the center of pressure more medial.) This will simultaneously increase the external dorsiflexion moment on the first ray and decrease the pronation moment on the STJ. The problem is, most of the time, it will increase the dorsiflexion moment on the ray more than it will decrease the pronation moment on the STJ.

With first ray dorsiflexion, the distance between the hallux and the calcaneal attachement of the fascia will increase. This will tend to increase tension in the fascia and other structures attached to the base of the proximal phanlanx. These distal to proximal forces on the phalanx will create a plantar flexion moment on the hallux that will make it more difficult for you, the clinician, to grab that toe and dorsiflex it.


I hope this helps,

Eric

[efuller]

Well, the left looks MASSish, more likely to immobilize the midtarsal joints than the right and looks like it has less fill. In comparison to the right, it's definitely more aggressive and intuition suggests you're asking us to compare mass posted devices with neutral.

The medial anterior edge is much more proximal on the left. Some would call that a first ray cutout. Agree the arch height looks higher on the left. I would give it a more aggressive rather than a much more aggressive.

I have a problem with the term immobilize the MTJ. I don't think a piece of plastic under the foot can immobilize the MTJ. A better term might be resist plantar flexion of the rearfoot, if that is what you mean.

Cheers,

Eric