Is forefoot varus posting an anachronism?

skives

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).

 

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.

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.

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.

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.

 

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

 

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

 

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.

 

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.

 

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.

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.

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.

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.

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.

 

Forefoot varus posts

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.

 

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?

 

How would you know it is a forefoot supinatus, and not a varus ? 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.

 

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.

 

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

 

orthotic picture

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

 

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 ??

 

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.

 

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.

 

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.

 

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

 

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


I think I'll be booking into Boot Camp this year!

 

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

 

Eh?!

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

 

Robyn,

I'm confused too.

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

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

Ian

 

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 scenariosne 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 Hoodigs:

 

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

 

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

 

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

 

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

 

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

 

Attached for interest

Ian

 

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

 

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

 

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.

 

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???

 

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 igs:

 

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 igs:

 

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?

 

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??