Anatomical Origin of Forefoot Varus Malalignment

Dear All,
It has been quite some time since i have been here, having moved onto pastures new, but there is something quite comforting about seeing the same arguments continue!! I see Brian is still trying to flog his Primus Metatarsus Supinatus Foot, and can understand Kevins continued frustration. In my fifteen years of clinical practice in Paediatrics I never came across a true forefoot varus, (Structural and neurological TEV both demonstrating both an inverted forefoot and rearfoot) Forefoot supinatus was certainly common. Having seen no further research that the supports the prevalence of this foot deformity i suggest it was about time it was put to bed!!
Always a pleasure!!
Tony Achilles

 

Lest anyone wonder, here is an excerpt from a piece I wrote for a journal on rothbarts foot. I could only find the draft so no references but it may be of interest to anyone wondering what we're talking about.

 

Welcome back Tony!

By the way, it was a pig....Spooner said it was!

Hope all is well.:drinks

 

Hello,
I have read with interest your article on Metatarsus primus supinatus, its etiology biomechanical impact and treatment on page 7 there is a table on percentage of patients with chronic pain and a correlation to you PM or otherwise known to you as rothbarts foot.
You say that as pronation increases (as measured by primus metatarsus supinatus- stj in neutral and wedge under the 1st mtp to resistance...as measured in mm, so does the amount of pain. However when you look at the table, all you have in fact found is the amount in percentage of each category...ie absent, mild, moderate and severe pronation (as you define it). I have a problem with that...and that is correlation does not infere causation.
The category from 14mm to 24mm- an increase in pronation - does not show an increase in MSK pain...it just shows that most patients fall into the mild pronation category.
Furthermore, I find it very difficult to believe that a foot with a high varus forefoot can be encouraged through proprieceptive training... the foot is reminded where it should be..and automatically makes the adjustment
I may be standing alone here, but you are going to have to come up with hard evidence to show that this works...and also while your at it...explain all this to those who do gait re-education with orthotics because I am sure they would be interested and you would be saving them a lot of hard work.
Just a thought

 

Another link to the "research website" in 5,4,3,2,1.....

 

Dear Peter,

Exactly which paper are you referring to (Name of Journal, Year of Publication)?

with regards,
Brian

 

Here are some interesting reviews of Brian Rothbart's book, Forever Free From Chronic Pain:

 

There are some rare people who do better with a forefoot varus extension. When standing, you can run your finger under their medial forefoot and if you could get your finger under the lateral forefoot it would be crushed. They also have no further range of motion available at their STJ in the direction of pronation.

Eric

 

Where's the shoe wear? Does he have range of motion to load the medial forefoot in stance. See my previous post. What are you treating? Design the othotic for that. Does he have genu valgum with lateral knee pain and increased knee pain with abduction of the tibia on the femur?

Eric

 

Phil,

I use this test quite a lot. Admittedly it is a static test but gives an idea about the relative dorsiflexion stiffness of the medial and lateral columns and how it affects the centre of pressure(which is how I personally like to think about what most people would describe as forefoot supinatus, ff valgus)

 

This is meant to be accompanied by a *.Pdf of a powerpoint presentation - if it is not there - someone tell me!


My apologies for being so tardy in getting a reply to Arena on my contentions about talar head torsion and its irrelevance in "so-called" forefoot varus. I have away from internet for perhaps a week, apart from stealing download at MacDonald's with a laptop balanced on my knee in their carpark......

My reply below is to address the issues raised at the point of the insertion of the Wikipedia page on “Neoteny” – I am not addressing the Rothbart stuff since.

This is not meant to be patronising – if it is, I apologise.

Now then, I thought the best way to deal with this was to post a short presentation, and talk you through it. This stuff is old, very old; sadly however, it seemed (seems?) to frequently miss the podiatric marketplace. For the life of me I have now forgotten where I obtained the talar neck angle pictures, but seem to think they were from the orthopaedic literature in perhaps 1990.

To be clear, there is no doubting that talar head torsion angle changes during ontogeny (ie an ontogenetic change [PLEASE, not ontological, this has connotations of the astrological arena, and we do not want to go there]). What there is doubt about, is what it is for. For this reason, I am trying to put into the greater context of talar ontongeny, and include also a description of the talar neck angle - you cannot separate the two for a complete story.

Look at slide 1). These are the two angles, the neck angle and the head torsion angle. The position of the talus in the head torsion picture is known as the "trochlear head plane", defined by the late Pete Lisowski in his 1967 paper "Angular changes in the primate talus”, and further modified by myself in 1995, PhD thesis. You will find this angle measured with the talus in other positions, but for various reasons, these have validity problems. The neck angle of the human and gorilla specimen is shown in slide 2); the difference is obvious, with the gorilla being considerably wider.
Broadly, all apes have the same, wider angle than humans. This is shown in the greater context in slide 3); broadly, the presence or absence of a divergent first ray (and opposing hallux) correlates with a wide or narrow talar neck angle. However, you should note that there is no better correlation - there is no real relation between the degree of divergence with the degree of "wide neck angle", simply it is wide with divergence, or narrow with no divergence.

Slide 4) gives the adult values for humans and African apes, and slide 5) depicts the ontogenetic change in humans from newborn to adult. Slide 6) shows us that a similar direction of change, but with differing values occurs in apes, and slide 7) shows this graphically. The key issue to note is this: newborn humans have the same value as apes. Now take slide 7) and apply a pair of evolutionary scissor to it, and produce slide 8) - one can see a clear straight line relationship between the two. That is, humans have taken the ape value and extrapolated it further.

Now look at slide 9): Some of the many heterochronic models, courtesy of the late (and fabulous) Steve J Gould, curator of the Harvard museum. Put simply we are the product of three entities: are size (whatever that is), our shape (and whatever that is too), and our age (ie shape) at sexual maturity. To modified one of more of these entities brings about a change in morphology with respect to sexual maturity in some manner. This is known as heterochronic modelling and for one, I find it very difficult to get my head around. Broadly though, one can take into adult hood infantile characteristics, or the opposite. The former is known as "neoteny" (top left model) and was alluded to by Craig with his Wikipededia posting. This concept has often been suggested as a case for craniofacial remodelling in humans - though this is way outside what I know about. The later however, is what we are talking about in the talus, and indeed elsewhere in the foot, eg Manley-Buser, 1991. The talar neck angle takes the value of the ancestor and extrapolates it further - one the possibilities in "gerontomorphosis" - in this case peramorphosis, or peramorphic heterochrony (bottom left). That is, the acceleration of shape with respect to size and age.

So much for what, now for why. All evidence would suggest that talar neck angle reduction during human development is concerned with removing the divergent first ray; while this is likely to be a simplistic version of events, there is little doubt that it is broadly true. Now look at slide 11).: here we can see a comparison of adult values from the fossil record. Yes, I am aware of the ridiculously small sample sizes - but the trend is unmistakable - there is a reduction as one moves up the rock-record - classic gradualistic evolution. THUS, the same trend that is seen in ontogeny is also seen in phylogeny; while in the modern era one does not expect to see an exact replication, one does expect to see "shadows" and "reminders" of our evolutionary past, and this is a beautiful example.

Slide 12) would seem to complicate this - until one digs deeper into phylogeny. We did not always have a divergent first ray - only as a non-human primate. This very early change, from a narrow to wide angle is about MAKING a divergent first ray, a conversion process from the foot of a generic mammal to that of a primate. It is a very quick event - perhaps 2 weeks; the narrowing of the neck angle is far slower - perhaps 10-15 years, and is about removing the divergent first ray. As a working principle, those changes that are "evolutionary baggage", are very quick - blink and you miss them; those that are about you as a species, are much slower, often up and into adolescence.

Now to the talar neck angle; slide 16) give the ape and human head torsion angles during growth, and these are depicted graphically in slide 17). after Pete Lisowski (1967). We see almost an equal-and-opposite story to the neck angle; both apes and humans get larger during ontogeny; and again, note that the newborn human has the same value as the adult ape. AND, in the same manner as previously, with the aid of a pair of evolutionary scissors, one can produce a straight line graph, though not quite so perfect as with the neck angle. So what does it mean? Slide 19 depicts the so-called midtarsal restraining mechanism - from Elftman (1960), Now before you shout at me, no one today is suggesting that this is entirely true, and the concept of the linear relationship between subtalar joint position, and midtarsal joint range of motion is ridiculous – never mind the decidedly subjective manner in which these bisection lines were achieved. However there is no doubt that the midtarsal joint (and I am not getting bogged down in axes here) has a lesser range while the subtalar joint is supinated, than that while the subtalar joint is fully pronated. The first time I saw this suggestion in the literature was in Eric Trincaus's PhD thesis of 1975 on Neanderthal feet- again, nothing new about it. Slide 20 depicts what Elftman's bisection lines (I use that word to avoid confusion with joint axes) would look like in the absence of the high degree of talar head torsion found in humans. That may well not be the whole story; whatever one feels about that explanation, one cannot argue with the simple fact that the talar neck-head-navicular occupy the apex of the long arch; by increasing torsion, one has increased the vertical dimension of bone at the arch-apex with little or no increase in bone substance; it seems we are back to beams again!

Slide 21 is back to the fossil record. With the same caveat and entered for the neck angle, one can see evidence for gradualist evolution here also.
So: what about so-called forefoot varus? I have made my thoughts clear on this in the past and have derided on more than one occasion for holding heretical views on the subject. As far as I am aware, there is no relationship between forefoot hindfoot alignment and talar head torsion. The last time I searched this, the definitive study stating this was by McPoil et at (1987):

They find no relationship. There may be others since supporting or refuting this, I do not know – though I have no doubt that it will be pointed out to me if there is.
Craig, as for your thoughts on the head torsion angle in clubfoot…… well, I would suggest that it is fanciful to suggest that ffvarus is a mild form of talipes – if it was, they would have to have the same aetiology – and I don’t think anyone has suggested that talipes is caused by anything to do with talar head torsion.
I still find it difficult to understand why anyone ever thought that a shape change in a bone that connects, indirectly even, with 3/5 of the forefoot, could be responsible for a relationship of the whole of the forefoot to the rearfoot; it is frankly, biologically naieve.

I do not wish to stir this pot yet again, but IMHO, apart from as a rare anatomical entity, forefoot varus is a fiction, a fiction perpetuated by an insistence to look at the posterior aspect of the calcaneus to define forefoot hindfoot relationship; that is, to use it as a proxy for the plantar plane of the calcaneus while there is no predictable relationship between the two. For anyone interested in my deeper thoughts on the subject, I have given a reference below – though was derided by some last time this conversation came up.

References:
Kidd RS (1995) Patterns of Morphological Variation in the Proximal Tarsus of Selected Human Groups, Apes and Fossils: a Morphometric Analysis. PhD thesis, The University of Western Australia

Kidd R (1997) Forefoot Varus: Real or False, Fact or Fantasy? Australasian Journal of Podiatric Medicine 31: 81-86

Lisowski FP (1967) Angular growth changes and comparisons in the primate talus.
Folia Primatologica 7: 81-97.

McPoil T, Cameron JA & Adrian MJ (1987) Anatomical Characteristics of the
Talus in Relation to Forefoot Deformities Journal of the American Podiatry
Association 77: 77-81

 

Below are my thoughts regarding the relationship between talar head torsion and the position of the embryological medial column of the foot. Much of this resulted from my embryological research (and please forgive my Freudian slip when I wrote ontological instead of ontogenetic) - looking at the developing embryo, specifically through Carnegie Stages 20-23.

Now, before I get started, I must state that what I am suggesting is theory. The only way to prove or disprove my theory would be to conduct a research study, difficult to do - both from a time line and funding (I doubt the drug industry would fund this type of research). The study would involve measuring the primus metatarsus supinatus angle (as I suggested to Cummings and his subsequent study at Georgia State University); then a postmortem study on those same feet, directing measuring the torsion in the talar neck and head; and then comparing those two measurements - using a large enough sample size to be statistically significant. Will such a study happen soon, I doubt it. Does it need to be done, absolutely!

However, the clinical implications of what I am suggesting has an exponential payoff when treating chronic musculoskeletal pain (an area of medicine that has captivated me for over 40 years). Which is exactly why I spend so much time talking about it.

Let me get started:

The question surrounding my embryological research was (and is): Exactly what are the cascading ontogenetic torsional events in the developing embryo's foot from approximately CS20 through the end of embryogenesis. Now all embryologists can eagerly explain the topographical changes and if you do a Google search, you will find many slides/photographs demonstrating and describing these changes. Succinctly put, the bottom of the feet go from a supinatus, heel to toe (e.g., both plantar surfaces facing one another) to the adult position (both plantar surfaces facing south, the head being north) - but what exactly is happening underneath the skin to allow this rather mind boggling changes?

This is where my research starts. I first looked at the embryological columns of the foot, lateral and medial. I suggest that the ontogenetic torsional events of the lateral column follow the frontal plane ontogenetic events of the posterior aspect of the calcaneus. That is, as the posterior cartilaginous surface of the calcaneus torsionally unwinds from its structural valgus (in Podiatry terms) or supinatus (in Embryological terms), the entire lateral column of the foot follows. And as the torsion in the neck and head of the talus unwind from their structural valgus, it takes with it the entire medial column of the foot.

These series of events would follow the timing that all embryologists basically agree to. That is, the ontogenetic timing of the torsional changes seen in the developing embryo start centrally and then proceed peripherally. When it comes to the foot, this implies that first the calcaneus unwinds (on the frontal plane) and then the talar head (on the frontal plane).

My theory fits in very nicely with what we are seeing topographically in the developing embryo. Now I will not repeat the previous discussion about the three basic abnormal embryological foot structures that could result when the torsional ontogenetic events (that I have suggested) are prematurely interrupted. However, it was the clinical data that I accumulated over the years that led to the above theoretical model (which explains nicely what I see clinically).


Basically, what all this comes down to is: Rob, I must respectfully disagree with you on one point. That is, I believe that the frontal plane ontogenetic torsional events (in the talar bone) occurring in late embryogenesis has a direct relationship with the alignment of the medial column of the foot (which involves only the first ray, not the entire forefoot).

Brian

 

Yes can you answer this question Brian?

Phil I was taught that forefoot varus is an osseous frontal plane deformity while a supinatus is solely via musculotendinous influence; tendoachilles. I imagine that others will have a lot to say about this.

I think this works best when there is available range of motion in pronation (to quote Eric) at the STJ and a flexible midfoot?

I cannot recall using a varus forefoot post in some time myself. Would this be more appropriate at the end range of pronation Eric with no eversion available at the STJ, as in a rigid forefoot varus?

Oh look; root principles and terminology still apply today. Imagine that?

 

Actually, the available range of motion is at the MTJ. To use Root terminology, the calcaneal eversion causes supination of the long axis of the MTJ. To use tissue stress, the rearfoot eversion increases the load on the medial forefoot and decreases the load on the lateral forefoot. This low load on the lateral forefoot does not move the MTJ into the piont in its range of motion where the stiffness increases. (When you grab a non weight bearing foot and plantar flex the forefoot on the rearfoot, you can then dorsiflex the forefoot on the rearfoot. As you move from a plantar flexed position to a dorsiflexed position there will be some range of motion before the ligaments become tight. As the ligaments have increasing tension there will be increasing stiffness in the joint. It is important to look at range of motion and stiffness.)

Sometimes, you can put a wedge comfortably under the lateral forefoot and see no motion of the STJ. This indicates to me that the ROM is at the MTJ and not the STJ. Especially when you ask them to evert, they contract their peroneal muscles and you see no calcaneal eversion.

Yes. I learned this from one of my earliest patients who still ranks as one of the most dramatic reactions that I ever got after giving a patient a pair of orthotics. He was depressed and in chronic pain after having a calcaneal fracture that fused his forefoot in varus. He had a bagfull of orthotics. He came back as one of the happiest people that I've ever seen. Many of those orthoses looked to have a forefoot varus intrinsic post as Root principles would recommend. A forefoot varus extension out under the metatarsal heads was the key to the success. I always had a problem with the idea of an intrinsic forefoot varus post, that ends proximal to the metatarsal heads, working in gait.

Maybe Brian is on to something....For people who have had calcaneal fractures that had the forefoot fused in varus.

If it worked once it work again... right?

Eric

 

The only difference is that Rothbart would charge the patient 20,000 Euros for that varus forefoot extension.......and only he is capable of making the correct amount of forefoot varus extension.

 

Nonono. An orthotic merely supports the foot. The PCI "corrects the deformity". Proprioception you know. So presumably the PCI would un-varus the forefoot. or something.

 

Mr. Rothbart, you are a JOKE