Student with questions on forefoot varus and supinatus

Rob:

Thanks for that information. And since you don't have a clue how many journals I subscribe to and how much I read, then for you to suggest that I only read JAPMA does very little to increase the chance that I will take your comments seriously from now on.

I hope you enjoy your retirement from podiatric medicine.:drinks

 

I would suggest you get your university library to obtain a copy for you - that is their job. I have worked with university librarians for 35 years - they love to used and love to be able to demonstrate their abilities.

Who said anything about retirement from podiatric medicine - certainly not me. I simply have retired my position as A/Prof of anatomy. Rob

 

This is getting funny, if you don´t have a copy just say so.

I don´t work for a Uni any more and therefore can not get a copy - why don´t you just post up the article?

The journal does not exist the only response from search engines in a link to an old CV of your at UWA - there is not even a Abstract to be found.

Please , Post up the article.

 

With maximum eversion height you don't have to work in degrees. Maximum eversion height is the sine of the angle (or the height of the nail stuck in the cast).

Agreed that more research is needed.

Eric

 

In any area of knowledge you can have controversy.

There are many ways to gain understanding. One is to observe both sides of a debate and ask questions of those debating as is done here on the arena. You should also read many articles, play with feet, alter orthotics and sit and think about it. I learned a lot from modifying my own orthotics.

Eric

 

Degrees or trigonometry not withstanding, we still do not know the difference between a 1 degree post and a 3 degree post when it comes to the loading under the forefoot.

 

Nothing funny - I do not have a copy - too much paper in my office. Until a few years ago the APodC had *.PDF available at a price, but that seems to have gone. I have asked the Arena "Boss", Craig Payne to ask around his department for a copy - we will see. If all else fails, I will have a pre-publication version on my archives. Rob

 

Since my last comment, I have found a pre-publication version in my archives - no figures - sorry. Please bear in mind that this is 1997 - a very long time ago in scientific terms. And if and when someone finds the original, it will be posted up. Also, there was a follow up a few years later on supinatus; when I find it I will post it.

 

In the 1971 book Biomechanical Examination of the Foot (Root, Orien, Weed, Hughes) there is absolutely no mention of the plantar surface of the rearfoot that I can find. The technique for measuring the angle between the forefoot and the rearfoot uses only the rearfoot bisection as per page 72: “The rearfoot is represented by the bisection of the posterior surface of the calcaneus with the subtalar joint in its neutral position”. I know that Dr. Root used a perpendicular to the rearfoot bisection as his reference for the plantar plane or surface of the rearfoot, regardless of the actually anatomical contour or position of the plantar surface of the heel.

In the first paragraph of Robs article Forefoot Varus: Real or False he states: “The pedal condition of forefoot varus has been broadly defined as a situation that exists when, in the foot’s neutral position, the plantar plane of the forefoot is inverted when compared to the plantar plane of the calcaneus (Root, 1978; Seibel, 1988); this is illustrated in figure 1.” I think we now see why Rob has misinterpreted Root’s definition of forefoot varus. Unless you understood that Root used a perpendicular the rearfoot bisection to represent the plantar plane of the rearfoot, you would be left trying to guess what the plantar plane of the rearfoot was for each and every patient. I have never run across this issue before, but I guess Root wasn’t clear enough in defining the plantar surface of the rearfoot. I will attempt to find somewhere where he stated it, but I certain know that was how he determined the plantar surface of the rearfoot.

Jeff

 

Jeff:

Unfortunately, many, including Rob, seem to misinterpret your father's work and the vast majority of these people who don't take the time to properly study Dr. Root's work do not even come close to having your father's understanding of how the foot and lower extremity function during weightbearing activities. It is sad but I suppose this type of thing happens more than it should.

It is so good to have you here on Podiatry Arena giving those who never met or heard your father lecture a better idea of what this great man actually taught about the biomechanics of the foot and lower extremity and the treatment of foot and lower extremity pathologies:drinks.

 

In the book Normal and abnormal Function of the Foot (page 80), Root et al wrote:”In the normal foot, when the subtalar joint is held in a neutral position (neither pronated nor supinated), pronation of the midtarsal joint stops, and the forefoot locks against the rearfoot at a position in which the plantar surface of the forefoot and rearfoot are parallel to each other. If the forefoot locks at a position that is inverted in relation to the rearfoot, the abnormality is called forefoot varus. If the forefoot locks at a position everted in relation to the rearfoot, the abnormality is called forefoot valgus (see Vol.I).”

In their definition of forefoot varus and forefoot valgus, the authors clearly referenced Biomechanical Examination of the Foot (vol. I) which used the sagittal plane bisection of the heel and not the plantar surface of the rearfoot as the reference for the rearfoot. The also stated that the plantar surface of the forefoot and rearfoot are parallel in the "normal" foot. They did not consider forefoot varus or valgus to be present in a "normal" foot.

Restating the quote in the first paragraph of Robs article: “The pedal condition of forefoot varus has been broadly defined as a situation that exists when, in the foot’s neutral position, the plantar plane of the forefoot is inverted when compared to the plantar plane of the calcaneus (Root, 1978; Seibel, 1988)” I would have to argue that this is a clear misstatement of Root’s words and work. Root never said that the plantar plane of the calcaneus was used as a reference for the rearfoot. I think in retrospect Root, Orien and Weed could have been clearer, but I think that vast majority of individuals understood their intent when they referred to the plantar plane of the rearfoot. I’m actually very surprised that Rob has gone this long without understanding that but I'm thankful for the opportunity to help clarify it.

Jeff

 

Thanks Kevin. I would like to take this opportunity to say how impressed I am with the impact that you have had on podiatry. Your contribution to the Podiatry Arena has had a profound influence on how people think. I know my father would have respected your challenge to conventional wisdom, including his own!

I was highly impressed by the volume of biomechanics related articles that you recently posted on the other thread on this forum. I can’t imagine how much time you spent reading, rereading, interpreting, scanning and posting all those articles, in addition to your own writing, lecturing, teaching and oh yea, running a private practice. I honestly don’t know how you do it, but it is obvious you get great personal satisfaction helping others. I know your efforts are greatly appreciated by many, including me!

Best regards,
Jeff

 

Here are two pictures that I use in lectures and articles to show what a rearfoot (calcaneal or heel) bisection is intended to represent. I tented the body of the calcaneus in one of my photos to emphasize the posterior calcaneal surface. The parabolic shape of the posterior surface of the calcaneus is palpated through the soft tissue in order to draw the bisection on the posterior surface of the patient’s heel. Note the everted relationship between the plantar aspect of the calcaneus and Root's rearfoot reference, the rearfoot bisection line. Root never intended the heel bisection to be perpendicular to the plantar surface of the calcaneus.

A Haglunds deformity, if present, should be included in the process of palpating the posterior surface of the heel. The key is to begin the process at the superior aspect or apex of the calcaneus and then simultaneous palpate both the medial and lateral borders of the calcaneus from superior to inferior only on the upper 2/3 of the heel as describe by Root. My intent here isn't to fully describe the rearfoot bisection technique, it is to point out the relationship between the rearfoot bisection and the plantar surface (plane?, not really) of the calcaneus, which in most cases, is an everted relationship.

Jeff

 

As so often seems to happen, the point has been missed in referring yet again to the original works of Root as if they were Dead Sea Scrolls, containing the meaning of life - they don't, and neither does Root 1/2. The point I am making is quite simply that it is the plantar planes of the forefoot and hind foot which are the issue (irrespective of whatever original definition may have been made). Yet in several places in Root 1 (sorry - gave my copy away 20 years ago) we are shown pictures of lines drawn beneath the forefoot and hindfoot - there may be no EXPLICIT use of this in the definition, but there is certainly an IMPLICIT one. I am signing out of this debate now - I have some real science to get on with - the follow up to the Australopithecus sediba foot paper (recently published in Science) is due out shortly. Rob

 

Rob,

I just went through every single page of Vol. I and in every drawing in the text that shows a line under and representing the plantar surface of the rearfoot, there is a bisection line drawn on the posterior aspect of the heel which is perpendicular to the line under the rearfoot. It can't get any clearer than that.

Jeff

 

Rob:

When an individual changes the definition of how a measurement should be made on a structural element of the body, the result will be a different set of values for that measurement. Dr. Root proposed the measurement methods for the human foot and lower extremity in the early 1970s which have been used for years not only by podiatrists, but also by biomechanists, physical therapists, chiropractors, and athletic trainers for years and in numerous scientific studies.

Then you come along and decided that Dr. Root couldn't be right because you somehow felt that is was better to measure the rounded and irregular surface of the plantar calcaneus as a planar object [when in fact its very rounded surface allows the human foot to invert and evert with relative ease during weightbearing activities]. You then wrote a paper saying that the deformities that Dr. Root claimed to exist could not exist because the posterior surface of the calcaneus should not be used but rather the plantar surface of the calcaneus should be used for the measurement instead?

You made that conclusion that the "very existence of the condition forefoot varus is in considerable doubt", not by taking the scientifically proper method of repeating Dr. Root's measurements using the definitions and measurement techniques he originally proposed to see if you could verify his findings or not. Rather you took the rather unusual method of changing the frame of reference of the measurement that Dr. Root originally proposed. Then you went on to make the statement "the methodology of diagnosis of "forefoot varus" is spurious" without seeming to understand that this measurement was always made by Dr. Root relative to a posterior calcaneal bisection and never to the plantar aspect of the calcaneus.

I have attached your paper below. I am glad that you reviewed our paper on the anterior axial radiographic projection that clearly showed that the average slope of the plantar calcaneus was 21 degrees from being parallel to the weightbearing surface of the plantar rearfoot (Kirby KA, Loendorf AJ, Gregorio R: Anterior axial projection of the foot. JAPMA, 78: 159-170, 1988). It is too bad that you couldn't make the next logical step after reading our paper and realize that your suggestion that the plantar aspect of the calcaneus should be used as a reference plane is fraught with even more errors than Root's method of using the posterior calcaneal bisection as a reference plane for measuring the forefoot to rearfoot relationship.

Sounds like you may want to update this paper since, in its current state, it is filled with somany innaccurate biomechanical assumptions that, in my opinion, undermine its validity and make it of little value for the modern podiatrist.

 

Talk about Circular! That is where I came in! The whole point of my postings was there was/is an implicit assumption that the calcaneal bisection line was perpendicular to the planter surface of the calcaneus. The is no such relationship. You yourself today showed exactly that. That is my only point - you yourself have made it. Rob

 

Seems this discussion has gone, well I´m not sure where it has gone.....

But it seems to me that anyone reading this would be rather confused.

We have a few things ,

1. The inaccurate measurement from practitioner to practitioner of any rarefoot to forefoot relationship - which I think most will agree on.

2. What would the agreed definition of a FF Varus and FF Supinatus be, 1 as defined by Root et al ( Bolded above ) 2 would this be accepted in modern practice ? if not what would the way of finding a inverted forefoot and defining it - see point 4

3. We have one person saying that FF varus and FF supinatus does not exist but has used a very different measurement system to the original Root, ( I will look what we were taught on Monday - New Zealand School early 90´s )

4.Is it really that important ? in that perhaps it would be better to consider the position of the Forefoot against the cardinal body plane system and discuss this in terms of stiffness - ie an osseous deformity would be the highest stiffness v´s a soft tissue contracture , or use a x, y , z system the same as Nester et al to define forefoot position.

4a - which is I guess the point behind Eric´s Maximal eversion height test - it looks at stiffness and ROM when weightbearing.

4b. Simon - I do know that in the latest bone pin studies circa 2 years go they stuck EVA wedges onto feet forefoot and rearfoot Varus and Valgus and recorded the change in gait - it was unshod and I also know the 1st draft has been sent in but got sent back with lots of changes required no idea where it is at know or even what the results were or how many subjects were used.

Is that fair ? Comments ?

 

I never said that FF supinatus does not exist - but did say that FF Varus only exists as a rare, once in a blue moon (actually, I think I said 1/1*10^6) possibility. I wrote a paper about it in 2000 in the Australasian Journal - though perhaps this also was not read over the Pacific. I am heading back to real science now - Australopithecus sediba calls! Rob

 

Ok so it exists now we need a modern accepted way to look at FF varus FF supinatus.

Being a Podiatrist this is real to me and the study of Kinematics and Kinetics of the feet would be real science to me or I may as well just start prescribing a 1 orthotic fits all for my patients but I would rather discuss and investigate mechanics of the foot for better patient results and because I enjoy it most of the time.

 

Rob,

It's not a circular argument; you're just confused about what I'm trying to tell you. Please give my comments here their due respect and please try to understand the point I'm attempting to make. I think you owe me that much since you have written an article that I believe is a gross misinterpretation of Dr. Root’s technique and theory for determining the plantar surface of the rearfoot and I’m patiently and respectfully trying to point out why I believe you’re in error.

I never said, nor did Root et. al. that the bisection line on the heel was perpendicular to the plantar surface of the calcaneus. In fact, I posted a picture in this very thread of an actual calcaneus that showed that my posterior heel bisection line on the calcaneus is not perpendicular to the plantar surface of the calcaneus. You’re making the assumption that the terms "plantar surface of the rearfoot" and "plantar surface of the calcaneus" are synonymous. They are not. They are two related, but different anatomical features. This is a critical error!

The appearance of the plantar surface of the heel is influenced by the depth of the plantar fat pad and the other soft tissue covering the calcaneus. The plantar surface of the heel is typically convex. In some subjects it is much more rounded than in other subjects. You can't determine the plantar surface of the calcaneus or the posterior bisection of the heel from the plantar surface of the rearfoot (the bone and soft tissue combined).

Essentially what Root et. al. did was to define the plantar surface of the rearfoot as being perpendicular to the bisector of the posterior surface of the calcaneus, regardless of the actual shape or true anatomical contour of the plantar surface of heel in any given subject. You are welcome to criticize that assumption, but that is what they did.

Root et. al. never discussed any technique to measure or assess the plantar plane of the calcaneus, I assume because they found no reliable method to measure it. I remember my father lecturing about some patients who functioned excessively supinated having an altered or planed off lateral, plantar fat pad and that the plantar aspect of the heel could not be used to judge the position of the patient’s negative cast. Conversely, some patients who excessively pronate compress or plane off the medial, plantar fat pad of the heel.

One thing that helps prove my point is the technique for bisecting the heel of the negative cast that Dr. Root developed. He used the curve on the lateral side of the cast just inferior to the lateral malleolus as a reference for heel bisection. He did this because he did not feel one could use the posterior appearance of the posterior heel of the cast alone or the plantar surface of the heel, or just those two in combination. He felt the most reliable way to bisect the negative cast (except in subjects with gross obesity or edema) was to use the concavity of the curve just below the lateral malleolus which he felt was symmetrical with the curve above the malleolus when the STJ was in the neutral position. He believed that is was far less accurate to use the appearance of the posterior heel to bisect the negative cast since one could not palpate the calcaneus and that adaptation of the plantar fat pad made the plantar surface an unreliable reference. As a result, his primary anatomical reference for heel bisection was the lateral aspect of the negative cast (Neutral Position Casting Technique, page 30).

The drawings in vol. I are fairly simple. Some show the plantar aspect of the calcaneus and some do not. In those that do, one can see that the plantar surface of calcaneus is slightly everted relative to the bisection of the posterior heel. It wasn't the purpose of these drawings to show this relationship, but they show it none the less. I hope now I have made it clear to you and others how Root et. al. determined the “plantar surface of the rearfoot”.

Jeff

 

I would like to add my perspective on this subject since I was directly taught the technique of forefoot to rearfoot (FFRF) measurement by those individuals that created and promoted the technique at the California College of Podiatric Medicine (CCPM) including Mert Root and his students including John Weed, Ron Valmassy, Rich Blake, Chris Smith, Lester Jones, and William Sanner. Unfortunately, it seems since most of these individuals are either deceased or are not actively teaching biomechanics any more, I feel the obligation to report on what exactly was taught at CCPM by these men.

We were taught during my CCPM student years (1979-1983) that there was only one true calcaneal bisection and that this should be done by palpating the medial and lateral aspects of and then drawing a bisection of the posterior calcaneus. Contrary to the misinformation in Rob Kidd's paper, we were specifically taught to not use the plantar surface of the calcaneus to determine the FFRF relationship since this was not the calcaneal bisection. Therefore, FFRF relationship could only be determined by viewing the foot from posterior. This was done with the patient in the prone position. In fact, I never once heard Mert Root, John Weed or anyone else in the CCPM biomechanics department say anything about using the plantar surface of the calcaneus as a reference plane as Rob Kidd erroneously suggested in his paper. I don't know where he came up with this idea since I know for a fact it didn't come from my biomechanics professors at CCPM. They discouraged such ideas as being inaccurate methods of trying to determine FFRF relationship in the human foot.

John Weed taught us in our 2nd and 3rd year at CCPM and I got to know John very well during this time since I worked with him one summer helping him write a workbook of biomechanics problems for the 2nd year podiatry students, meeting him one day a week so he could check our work (I did the workbook with Kirk Koepsel, who was one of my classmates in the CCPM Class of 1983). Dr. Weed taught us that if we measured an inverted forefoot deformity with the subtalar joint (STJ) in neutral position and the "midtarsal joints maximally pronated" (i.e. the 4th and 5th metatarsal shafts loaded with a dorsiflexion force) that this inverted forefoot deformity would either be a forefoot varus or a forefoot supinatus deformity.

Dr. Weed claimed that the forefoot varus deformity was thought to be a structural and congenital deformity but I don't ever remember him talking about it being due to a talar head torsion as stated in a few references. I think by the time I got to CCPM that this idea that forefoot varus was caused by a talar head torsion was not being taught anymore since most in the department at that time probably thought this was unlikely to be the cause of it. Forefoot varus was thought to be fairly unusual but we would, on occasion see what we thought was a forefoot varus come into our clinic. I would imagine that only one in 100 feet we saw at the time was classified as a forefoot varus.

Dr. Weed claimed that forefoot supinatus was the much more common inverted forefoot deformity. He thought forefoot supinatus was due to excessive eversion of the calcaneus and the soft tissue adaptation that occurred within the ligaments and joints of the midtarsal and midfoot joints in response to the inversion force on the foot over time from ground reaction force but he didn't know which ligaments caused this "soft tissue adaptation" process. The problem was that, once a foot was determined to have an inverted forefoot deformity, Dr. Weed claimed that the only way to determine which of these feet had forefoot varus and which of these feet had a forefoot supinatus was to treat them over time with an anti-pronation orthosis to see which feet had a reduction in inverted FFRF relationship over time. He thought it would take at least two to three months of treatment with an anti-pronation orthosis to see such a change in the FFRF relationship of the foot.

There were problems with the whole process of determining FFRF relationship that I saw during my student years at CCPM but especially started noticing when I was the one and only Biomechanics Fellow at CCPM from 1984-1985. During my Biomechanics Fellowship I was teaching these FFRF measurement techniques to all the podiatry students at CCPM who were in their 2nd, 3rd and 4th years of instruction. In fact, Dr. Eric Fuller was one of my students that I helped teach these techniques to as a Biomechanics Fellow so I hope he can also chime in to see if I have remembered these events correctly since Eric followed up to do the Biomechanics Fellowship a few years after I completed the program.

What were the problems with the FFRF measurement technique that I saw during my student and Biomechanics Fellowship years?

1. The calcaneal bisection process was variable not only from one Biomechanics professor to another but even more so from one student to another. In fact, we, as students, would often play "stupid" and have one of our biomechanics professors come in a draw a heel bisection on a foot and then, when that professor wasn't looking, would erase that heel bisection line off the patient's heel and call another of our biomechanics professors to then draw another heel bisection to see how close they agree with each other. There were times that even our best biomechanics professors were 5 degrees apart in their heel bisection lines on the same foot. This was disturbing to me and many of my classmates since without an "accurate heel bisection line" then all the other rearfoot and forefoot measurements would be inaccurate.

2. The rotational position of the subtalar joint chosen as the one and true "neutral position" would be variable from one student to another student and from one biomechanics professor to another biomechanics professor. Some professors chose STJ neutral position as slightly more pronated than another professor which would greatly affect FFRF measurement.

3. The FFRF measurement seemed to change with the magnitude of loading force being used on the lateral column during the measurement procedure. As the loading force on the forefoot was increased, then the foot would have either an increased everted forefoot deformity or a decrease in inverted forefoot deformity which I believe occurred due to the greater lateral column loading force dorsiflexing the lateral column more than the medial column.

Even with these obvious problems in the FFRF measurement that I was taught and that I also taught to students for many years, any questions about the measurement technique accuracy was ignored at CCPM during this time since this was "just the way the test needs to be done". It was by me seeing such errors in the measurements I was making and teaching and due to their lack of correlation to many aspects of foot function that made me become excited about the idea that the subtalar joint axis could be estimated by palpating the plantar aspect of the foot.

In 1984-1985, during my Biomechanics Fellowship, John Weed would come to CCPM one day a week to teach and meet with Ron Valmassy, who was our department chairman at the time. Since I respected Dr. Weed as being one of the intelligent, honest and thoughtful members of the Biomechanics faculty at the time, this one day a week was always a day I would allow time to try to speak to Dr. Weed for 5-10 minutes about questions I was having about biomechanics or orthosis treatment of patients since he seemed to have a good answer for all my questions.

One day in 1984, I cornered Dr. Weed in the hallway outside the MO Lab (Mechanical Orthopedics Lab) where we made foot orthoses for our patients at CCPM. One of the questions that I had for Dr. Weed that day was as follows:

"You have taught us that when we want to have extra pronation control from a foot orthosis that we can use such things as a deeper heel cup, a thicker orthosis plate, and a longer rearfoot post to try and control the patient's pronation, but how do you know which foot needs these features more than another foot?"

What Dr. Weed next described set me on a path of investigation for the last 28 years. Dr. Weed replied:

"What I do, Kevin, is to use my thumb to push up on the plantar heel of the patient while the patient is non-weightbearing. Normally pushing up on the center of the heel will produce inversion of the foot but in the foot that needs more pronation control features from the orthosis, you will find that you will need to push much more medial on their heel in order to produce that subtalar joint supination. I think this is due to the change in the subtalar joint axis in these feet that makes them so hard to supinate by pressing on the plantar heel."

I can still quite vividly remember that discussion, where exactly it took place in the hallway outside the MO lab at CCPM and how John Weed used his hands to press up on the palm of my hand to show me the technique he used in his own practice but had never previously discussed in any of his classes or any of our previous discussions.

After that, I immediately went out to try the technique that same afternoon on a patient and some students and, by the end of my Biomechanics Fellowship in June 1985, I had enough confidence in my development of the technique of palpating the whole plantar aspect of the foot (and not just the plantar heel as Dr. Weed showed me) that I felt confident that I could start thinking about writing up the technique for publication. The original paper on the technique that I wrote and submitted to JAPMA in 1986 (25 years ago now) was eventually published in May 1987 (Kirby KA: Methods for determination of positional variations in the subtalar joint axis. JAPMA, 77: 228-234, 1987).

I hope that this little history lesson gives you all a more accurate representation of the events that I experienced during my student and fellowship years during those exciting years of biomechanics learning and teaching at CCPM.

 

Mike,
I said that Root described the conditions you bolded above. The comments you bolded were me paraphrasing, not necessarily hard and fast quotes of Root's actual definitions. I get criticized by some people on here for quoting Dr. Root too much and for "not expressing my own opinion" and yet when I don't take the time to use actual quotes, it bites me in the ass! I can assure you I have my own opinions about my father's work, but here are a few quotes and definitions:

1. The rearfoot is represented by the bisection of the posterior surface of the calcaneus, with the subtalar joint in its neutral position. (Vol. I, pg. 72)
2. When the forefoot is inverted to the rearfoot , (the 1st metatarsal head is more dorsal than the 5th metatarsal head) this fixed relationship is called forefoot varus. (fig. 71) (Vol. I, pgs. 74-75) Jeff notes: figure 71 is a drawing showing hands holding a forefoot measuring device with the heel bisection used as a reference to measure an inverted forefoot condition.
3. In a foot with a fully pronated normal midtarsal joint and in which the subtalar joint is in its neutral position, the forefoot locks against the rearfoot at a position in which the plantar surface of the forefoot is parallel with the plantar surface of the rearfoot (see vol. I, page 70). Jeff notes: page 70 leads into the definition given in #1 above, so it is indisputable that Root always used the bisection of the posterior surface of the calcaneus as his only reference for the position of the "rearfoot" and used a perpendicular to the bisection to describe or represent the plantar plane of the rearfoot whenever he described the forefoot to rearfoot relationship or the rearfoot to leg relationship.
4. Soft tissue deformities, which hold the forefoot in a supinated position, are obvious if they occur at the oblique midtarsal joint axis. The forefoot is adducted, plantarflexed and slightly inverted, and midtarsal joint motion is restricted. However, when the forefoot is fixed in a supinated position about the longitudinal axis of the midtarsal joint, only the inversion component of supination is visually evident, and this deformity is very hard to differentiate from a true varus deformity of the forefoot (one plane osseous deformity). Restricted motion at the longitudinal midtarsal joint axis, producing asymmetry between the right and the left foot, helps to identify soft tissue tension as the etiology for the inverted forefoot position in this case. (Normal and Abnormal Function of the Foot, pages 43 and 46)

Mike, we see a lot of inverted forefoot conditions in which there is relative symmetry between the right and left foot. Although it is difficult to differentiate these from a true forefoot varus, it helps to look at how the rearfoot functions to get a clue. If the rearfoot is functioning fairly everted, and if the patient history indicates a change in function over time (i.e. bilateral adult acquired flatfoot) I tend to assume it is probably an acquired condition. I too tend to think a true structural forefoot varus is relatively uncommon, and that the majority of inverted forefoot conditions are probably acquired. Looking at the ratio casts that we receive at Root Lab with an inverted forefoot to rearfoot relationship, they are relatively small compared to those with and everted forefoot and I can attribute a fairly high percentage of those to casting errors in which the practitioner has inadvertently inverted the forefoot during the casting process. I see some practitioners who just don’t apply enough eversion force to full everted or maximally pronate the MTJ and the net result is an inverted forefoot and a false forefoot varus.

Jeff

 

Why was the heel bisection line chosen to represent the rearfoot?

I vaguely recall an explanation (not sure whose) of why a vertical calcaneus was ideal. The explanation was when body weight comes down on to the top of the calcaneus, if the calcaneus is not aligned with the downward force from above it will tend to invert or evert further depending on the direction of the alignment. This is makes some sense visually in that you can draw the lines to make the force couples. However, this logic neglects the constraints of the subtalar joint. The STJ does behave like a hinge like axis and a better way to determine what motion will occur is to look at the location of center of pressure under the entire foot relative to the STJ axis and not just the heel.

I don't recall any other rationale for the use of the heel bisection to represent the rearfoot. Is the location of the heel bisection relevant for treatment or the prediction of pathology? I can see the use in a classification system that tries to differentiate feet. However, the forefoot to rearfoot classification system has a few flaws. I recall John Weed discussing the difference between a rigid and flexible forefoot valgus. That concept was sort of left hanging without any further explanation of why one foot would be rigid and one would be flexible. So, you can get the same measurement in two different feet that function quite differently. Is forefoot to rearfoot relationship measurement a good way to differentiate feet?

Eric

 

Eric,

The rearfoot bisection was created for and used within a system that attempted to enable practitioners to compare, contrast and evaluate both the structure and function of the foot. When you look at the absence of any real system prior to it, this was a substantial breakthrough in the clinical application of biomechanics.

I shot a few pictures of a pair of negative casts just before leaving the lab on Friday (see below). Notice the medial displacement and adduction of the talus relative to foot (clearly a medially deviated stj axis). The patient demonstrates a significantly inverted ff to rf relationship (likely a ff supinatus). The everted attitude of heel bisection is due to the inverted forefoot because the cast rests with the forefoot parallel to the counter top. I thought this pair of casts shows just how much information can quickly and easily be gained by looking at a negative cast and I think the heel bisection helps us appreciate this both structurally and functionally.

I could easily measure the everted angle of the bisection and this would correspond to the degree of forefoot inversion. When I communicate with a practitioner over the telephone, I can quantify the amount of forefoot inversion or the degree of eversion of the heel. This help both of us appreciate the relative severity of this patient's foot condition or "deformity" as compared to other patients. This is extremely helpful in developing an orthotic Rx. If I contrast this foot to a similar foot that has a perpendicular ff to rf relationship but is similar in all other respect, this information is critical to me, especially if I'm talking to the practitioner while they are still in possession of the casts and I haven’t had the luxury of seeing them yet (which happens frequently). I can have them describe this foot's characteristics, including the ff to rf relationship. This is critical for me at the lab if the practitioner wants my advice over the phone. And FYI, that is the doctor's bisection line but it appears that it would be very close to one of my own. Due to the photographic angle of distortion, you can't appreciate the angle of heel eversion in the transverse view but you can in the frontal plane shot.

Jeff

 

I think we have to look at what was implied as opposed to what was specifically said. They may have said that you should not use the plantar surface, but many things they did say was that the heel bisection represented the plantar surface. When I reviewed John Weed's lecture syllabus he would describe how you would need to invert or evert the cast a few degrees because of the measurements that you saw. For example, when you saw that a heel bisection was 2 degrees in stance and you calculated that the STJ was maximally pronated in that position then you should balance the heel bisection of your cast 2 degrees inverted. The implied logic is that the orthosis will support the bottom of the calcaneus in that position.

My recollection is that John Weed did teach the talar head torsion in class.

It is interesting to note that John Weed thought that forefoot to rearfoot could change over time.

Your recollections are quite similar to mine. When I started to teach as a fellow I had many of the same observations as well about forefoot to rearfoot. I remember Chris Smith worrying about the accuracy of the heel bisection. Otherwise there was a lot of disconnect between the accuracy problem and the acceptance of the measurement.

Another recolection from that time period. Jack Morris became department chair after Ron Valmassey stepped down around 1986. I remember students asking what caused bunions and his one word answer was supinatus. I was realizing later he was not referring to the condition we have been talking about, but he was referring to high amounts of ground reaction force under the medial forefoot.

I remeber looking back at John Weed's lecture sylabus that I would scribble notes in while he lectured. I scribbled in the margin exactly what you related above. You were fortunate enough and smart enough, and had enough experience to recognize the importance of this observation. I recognized the importance of that scribble in the margin only after reading your palpation of the axis article.

Eric

 

Eric,

When we manufacture an orthosis from a negative cast, we have to orient the cast in the frontal plane when we pour the cast and/or when we add the forefoot (balance) platform. Our default position is to correct the cast with the heel bisection vertical. If the practitioner wants to override that, they can instruct us to use a different position for correcting the cast. In an orthotic lab, the best way we have found to communicate this is with the use of forefoot and or rearfoot measurements that come directly from the heel bisection.

So yes, the heel bisection is extremely relevant for the treatment of pathology. How else might the lab orient the cast in the frontal plane other than randomly if it were not for heel bisections, and how else would the practitioner communicate their corrections to the lab? Heel bisections are pretty much universally used by labs to manufacture of orthoses.

Jeff

 

I think the point that I understood was that the posterior calcaneal bisection represented the whole calcaneus as a reference, including the medial, lateral, dorsal and plantar aspects. However, the plantar aspect of the calcaneus was not used to determine the forefoot to rearfoot to rearfoot relationship, at least that I ever saw.

Maybe he taught it and I just thought it wasn't important so I don't remember it? I honestly can't remember this specifically being emphasized...it was 30 years ago!

It wasn't just John that said that. I remember having discussions about this with Chris Smith, Ron Valmassy, Jack Morris and John Weed about this phenomenon which they thought was a reduction in forefoot supinatus over time. Many of the podiatric surgeons who started using the subtalar arthroereisis procedure at CCPM during the mid 1980s also noted that, over time, the child's forefoot to rearfoot relationship would evert to a less inverted position and change quite dramatically over a 6-12 month period. Now that would be a great study!

Chris Smith drew his heel bisection lines the most inverted and Ron Valmassy drew his heel bisections lines the most everted from what I could see. Sometime the two of them were nearly 4-5 degrees apart in bisections on the same foot. Other times they were nearly identical to each other with their heel bisections. Go figure!

Now, in retrospect, thinking back to those days when I was still in my 20s, those were fabulous times for learning. Since the Biomechanics Fellowship is now extinct we will be like the dinosaurs pretty soon, Eric. Not having a Biomechanics Fellowship program will be a bad thing for the future of podiatric biomechanics here in the States, I am afraid. In the future, who are going to be the teachers of this fascinating and important subject here in the States..... people like Ed Glaser and Dennis Shavelson? I think I'm going to have nightmares about this possible scenario.

 

Two other alternatives. 1 tell the lab to put a nail that extends "X" mm plantarly from the 5th met head when an intrinsic forefoot valgus post is wanted. Have the practitioner ask for a medial arch height at the navicular of "x" mm. Does your lab regularly add medial arch fill to orthotics with a large amount of forefoot varus that are balanced to vertical? A lot of labs do. I wonder how they decide how much fill to add. There is not much guidance from the heel bisection. Or for that matter how much fill is added when there is a request for an inverted cast technique.

Jeff, I realize that for you to communicate with practioners you have to use terminology that they understand. My hope is, at some point the podiatry world will move away from heel bisections.


The first pair of orthotics made for me had an everted appearing heel cup even though the heel bisection line was perpendicular. This shape happened because of how the lateral expansion was added. Those casts were made by a 4th year student when I was a third year student. I later took those same casts and added a medial heel skive and eventually made orthotics that were more comfortable.

Eric

 

Eric,

If you put a nail in the 5th met head X mm, it will move the heel bisection Y degrees in the direction of eversion. It accomplishes the same thing mechanically with the cast, but by using a different method of measurement. If you want to evert the heel bisection Y degrees, you will need to put a nail in the 5th met head X mm. If you end up with the same result (an identically balanced cast), then I'm not sure what the point of using mm instead of degree is. But how does the practitioner know how many mm to make the nail?

We have some practitioners who dictate the height of the MLA or the MLA at some point (i.e. their mark on the navicular). Most don't. The amount of MLA filler is a variable on our Rx that the practitioner can control. It is one of a number of variables that the lab or the practitioner can alter, depending on the amount, location or nature of force/control desired.

Jeff

 

How does the practitioner decide what the forefoot to rearfoot relationship is? Or how does the practitioner decide what the forefoot to rearfoot relationship should be given that there is huge error in the measurement and that the measurement changes over time.

This is why I think we should look at maximum eversion height. And then use the the mm measurement. Then once we put the nail in the 5th met head we can then choose how we want to shape the heel (skive).

Eric

 

Eric,

The practitioner doesn't have to decide what the forefoot to rearfoot relationship is, it is created (captured) in their negative cast by maximally pronating the midtarsal joint. Regardless of how accurate or inaccurate the practitioner might be in actually bisecting the heel, what is important is that they capture the plantar, non-weightbearing contour of the foot with the STJ in the neutral position (+ or - 2 degrees) and with the MTJ fully pronated. This should create an acceptable cast for manufacturing a functional orthosis.

I think that one of the most valuable things that Dr. Root discovered was his casting technique and position. He felt a plus or minus two degree error in positioning of the STJ was clinically acceptable in most cases, but he felt it was imperative that the MTJ be maximally pronated. Why? Because in most feet the plantar contour doesn't change radically when you are plus or minus two degrees from the neutral position. However, a few degrees of change in the position of the MTJ can have a much greater impact on the plantar contour of the foot.

The maximally pronated or what Root referred to (but did not coin the term) as locked position of the MTJ seems to help us improve stability of the foot as a whole with an orthosis. The further one gets away from the neutral position of the STJ or from fully pronating the MTJ, the less accurate and effective the cast becomes for making a functional orthosis (exceptions to this exist in cases of certain pathology).

I have found that some practitioners are very accurate and consistent at heel bisection and some are not. Our lab will override inaccurate heel bisections unless the practitioner specifically instructs us to use their bisection lines (it's their option). That increases consistency significantly and allows us to accept greater responsibility for both the comfort and therapeutic results of our products.

Jeff

 

For the past five or so years, at Precision Intricast Orthotic Lab, we have decided that the best way for our podiatrists to order frontal plane cast balancing is to simply have them instruct the lab on how many degrees of intrinsic forefoot valgus or forefoot varus correction they want to build in to the cast. In that way, we have essentially eliminated the problem of using heel bisections on negative casts, which we all know to have significant inter-examiner errors. In other words, we just have the podiatrist indicate to us how many degrees he or she wants the plantar plane of the forefoot to be inverted or everted to the ground when we build their patient's orthoses.

I believe this frontal plane cast balancing reference, which we have been using for some time now, goes along well with what Eric is saying about telling the lab how to balance the forefoot, rather than the rearfoot. Since we have been using this method of frontal plane cast balancing reference, my patients' orthoses seem to be more consistent and accurate even though it did take some time for me, and the other podiatrists who use the lab, to "change gears" initially on how we order orthoses. Now, this method is "second nature" to me and I prefer this method compared to the old method, except in a few circumstances.

Jeff, you may consider using this system in your own lab since it eliminates the podiatrist having to draw a heel bisection and/or you having to draw a heel bisection or guess if you should use your or their heel bisection or not. Even though your lab is probably one of the most accurate in the world at this type of stuff, I think it would simplify things for both you and your podiatrist-clients.

 

Kevin,
We have done since I first got involved with the lab back on the 1970's. It just isn't our default or primary method for positioning the corrected cast. The problem is, the practitioner still needs to know how inverted or everted the forefoot of the cast is, and or how much of it should be corrected in the cast. Although we have our standard techniques, we have a fair number of practitioners who like to do things differently. Our job is to fill the Rx they way they want it done, not the way we think it should be done. As a result, I have no problem with your suggestion if that’s how the practitioner wants us to do it.

Jeff

 

The practitioner actually should decide what the forefoot to rearfoot relationship is. Some use the technique of "removing the supinatus" where the first ray is plantarflexed during casting. That is one way that a practitioner can alter the forefoot to rearfoot to get what they want. If the practitioner doesn't care what the forefoot to rearfoot relationship is he can still create an acceptable cast for creating an orthotic, but it may not necessarily be the best orthotic. I can personally attest to the fact that when the intrinsic forefoot valgus post is too large the orthotic can hurt. So the practitioner should decide on the amount of intrinsic forefoot valgus post before the cast is sent to the lab.

Eric

 

Eric,

Even if the practitioner decides how much intrinsic forefoot posting to use, it may still be too little or too much. It is a judgment call based on a clinical assessment and not an exact science.

You criticize heel bisections as being unreliable but the technique you describe could have an error factor that is even greater than heel bisections. Has anyone done a study on the reliability of your suggested method of intrinsic posting? If so, then this could be compared to the reliability of intrinsic posting using bisection of the negative cast.

You have been a vocal critic of some of Root’s techniques because you claim they are unreliable but you seem to be advocating a technique that to the best of my knowledge, is totally untested. This seems hypocritical. If the justification for abandoning Root's method is poor reliability, then isn’t it necessary to have a more reliable and proven method to replace it?

Jeff

 

My rationale for abandonment of Root's method is not only based on reliability, but also on the logic for the choice of measurements to alter the orthotic. So, you get the forefoot to rearfoot relationship in neutral position in the cast. Then you place that orthotic under a foot that is standing at or near maximally pronated, ie not neutral. In that position of the STJ the forefoot to rearfoot relationship will be much more valgus than in neutral position. So, it doesn't make sense to use the orthotics "balance the deformity" rationale for making an orthotic. Root et al. were definitely on to something, but the logic is not complete.

I'm not advocating for the complete abandonment either. The concept of a partially compensated varus and the use of intrinsic forefoot valgus posts are two things that I think are quite valuable.

I'll admit that there will be some measurement error in the maximum eversion height. There was a cadaver study on tension in the plantar fascia from forefoot valgus wedges. So there is some evidence that adding a forefoot valgus wedge can reduce stress in structures. There should be some rationale for choosing the height. And if you get the wrong height you can change it. When I was a studnent, when we had an orthotic that didn't work, we often redid the orthotic using the same methods. If it didn't work the first time, why would it work the second time. Using tissue stress you can have some idea of how to alter the orthotic when it doesn't work the first time.

Eric

 

Because Kevin and Ian are always givng me papers......


Ian txt me we need to have that xmas drink :santa:

 

Many thanks for posting that. I know it seems ridiculous, but one loses hard copy of what one has published. This was pre the *.PDF era.

Rob

 

The existence, or not, of forefoot varum is definitively and unequivocably answered if one simply reviews their Embryology 101! Apparently, this course has been forgotten/ignored by many of my Podiatric compeers.

• Succinctly, Forefoot varum exists only as part of the Clubfoot deformity. Other than postnatal trauma/bone pathology, it cannot (based on the normal embryological development of the foot) exist on its' own.

You can access a paper on this subject in ResearchGate.

Rearfoot supinatus (in conjunction with a supinatus of the entire medial column of the foot) does exist and is termed the PreClinical Clubfoot Deformity (Rothbart 2002). In this foot deformity, the calcaneal supinatus is observed in the posterior surface of the heel bone. What fascinates/titillates me is that the fossil record has unearthed a calcaneus with this structural twist (S.aureus?)

• Rothbart BA, 2002. Medial Column Foot Systems: An Innovative Tool for Improving Posture. Journal of Bodywork and Movement Therapies (6)1:37-46