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A New Classification of Foot Structures Based on Foot Embryogenesis

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Brian A. Rothbart, Nov 29, 2019.

  1. Brian A. Rothbart

    Brian A. Rothbart Active Member


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    Below I outlined a classification of genetic foot structures based on the normal embryogenesis of the foot. It was started on another discussion. But the implications of this foot classification system are potentially so far reaching, that I decided to open a new discussion revolving around this one topic.

    Looking at the embryogenesis of the lower extremity, the ontogenetic (torsional) development of the lower limb axiomatically occurs centrally to distally.

    • At week 3pf, the lower limb bud sits at right angles to the rump of the embryo. The soles of the feet and posterior compartments of the leg and thigh face cephalad.
    • Week 8pf, the limb bud is rotating 90 degrees around its longitudinal axis. This places the soles of the feet and posterior surfaces of the thigh and leg facing one another.
    • At this point, the thigh and leg continue to unwind (the process of decentralization), so that by 10pf only the feet remains in supinatus (soles facing one another).
    This is where my 1-4 classification fits in:

    At approximately week 10pf the talus migrates to sit on top of the calcaneus.

    These two bones then begin to unwind around their longitudinal axis

    • The ontogenetic (torsional) unwinding (saggital plane) of the cuboid determines the adult position of the lateral column of the foot.
    • The ontogenetic unwinding of the talus determines the adult position of the medial column of the foot.

    Clubfoot Deformity: the ontogenetic unwinding of the entire lateral column of the foot ends prematurely.

    PreClinical Clubfoot Deformity: The cuboid completes its ontogenetic development but the calcaneus and talus remain in supinatus

    Primus Metatarsus Supinatus foot structure: The calcaneus completes its' ontogenetic development, but the talus remains in supinatus (and along with it, the entire medial column of the foot).

    Plantargrade foot: The talus completes its' ontogenetic development

    This is a very abbreviated presentation on how my foot classification fits into the process of embryogenesis. If you would like to expand this discussion, I would be very pleased to do so.
     
  2. Brian A. Rothbart

    Brian A. Rothbart Active Member

    This Ontogenic-Phylogenic Calcaneal Model (that I proposed a number of years ago) is based on my clinical research which entailed the discovery of a previously unrecognized inherited foot structure, the PreClinical Clubfoot Deformity.

    The hallmark of this foot structure is the structural twist (supinatus) in the posterior aspect of the calcaneus. This is the same structural twist found in the fossilized calcaneus of the H.naledi (dated approximately 2 million years ago).

    The PreClinical Foot Structure is:
    • The most common foot structure in our population today is the PreClinical Clubfoot Structure/Deformity.
    The least common is the Plantargrade Foot Structure (the calcaneus and talus no longer retain any supinatus/axial plane structural twist).
    I opine that the homo sapien foot is still very early in its anthropological evolution, evolving from the bipedal dysfunctional PreClinical Clubfoot structure towards the very stable bipedal plantargrade foot structure."
     
  3. Brian A. Rothbart

    Brian A. Rothbart Active Member

    PreClinical Clubfoot Deformity (PCFD)

    In 2002, I published a paper in the Journal of Bodywork and Movement Therapy describing a previously unrecognized embryological foot structure, the PreClinical Clubfoot Deformity, which occurs when the talus and calcaneus do not complete their normal ontogenetic development (e.g., Calcaneal and Talar Supinatus).

    Clinically, Calcaneal and Talar Supinatus maintains the calcaneus and entire medial column of the foot in supinatus, observed as an elevated and inverted calcaneus, first metatarsal and hallux when the foot is placed into its anatomical neutral position, e.g., subtalar joint congruity.

    PreClinical Clubfoot Deformity is one of the most common causes of abnormal pronation. This occurs because gravity forces the stance phase foot to rotate inward and downward until the elevated and inverted calcaneus, first metatarsal and hallux rest on the ground (referred to as Gravity Drive Pronation)

    The definition of abnormal pronation does not refer to the amount of pronation. Abnormal pronation refers to the timing of pronation. That is, the foot is pronating when it should be supinating, e.g., it has escaped Hip Drive Pronation and becomes engaged in Gravity Drive Pronation.

    Differential Diagnosis

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

    Cummings GS, Higbie EJ 1997. A weight bering method for determining forefoot posting for orthotic fabrication. Physio Research International, 2(1). Whurr Publishers Ltd.
     
  4. Brian A. Rothbart

    Brian A. Rothbart Active Member

    Dr Kidd in 1997 published a paper which examined in detail forefoot varus to see if evidence existed to support or refute its existence, its supposed aetiology and the basis for its diagnosis.

    The essential conclusions of his work was that the accepted aetiology was without foundation anywhere in the literature and that the methodology used in establishing its presence, and thus reach a diagnosis, is fundamentally flawed.

    Kidd R 1997. Forefoot Varus - Real or False, Fact or Fantasy. Australian Jour Pod Med; 31(3).

    I presented my 1-4 foot classification for Dr Kidd's critique. Specifically, to see if he would comment on my methodology as he did on forefoot varus.

    His comment regarding the medial and lateral columns during embryogenesis was:

    "Since the talus and calcaneus are respectively the hindmost component of the medial and lateral columns it is enticing to make the leap to them dragging along the two columns"

    Basically, he did not repudiate my methodology.

    Intelligent comments are welcomed.
     
  5. Rob Kidd

    Rob Kidd Well-Known Member

    ********************************************************************************************************************

    FROM ROB:

    What I actually said is (in part), this:

    "You have made some woefully simplistic assumptions, some of which are simply wrong.

    For instance, your statement that at the "10pf the talus migrates to sit on top of the calcaneus", is simply not true. I refer you to pages 26 & 67 of Freddy Wood Jones' text "Structure and Function as seen in the Foot", you will see quite clearly that the talus lies medially to a laterally positioned calcaneus. And, as is found in the reptilian model - but not in any (adult) primates, the fibulares (calcaneus) is articulated with the fibula. What not occurs is a translation of the calcaneus from being lateral, to being medial (ish), to eventually being positioned beneath the talus - the talus does not translate - it is locked in the ankle mortice from a very early stage.

    Since the talus and calcaneus are respectively the hindmost component of the medial and lateral columns it is enticing to make the leap to them dragging along the two columns - this is likely to be a simplistic explanation of their development.

    Whatever may be compelling to believe, there is no evidence at all that any prehuman specimens is the fossil record are direct descendants or antecedants of any other."


    On the separate issue of "Forefoot Varus" my point was that while there is no doubt that talar head torsion takes place from about 20' to 40' of valgus torsion, the point has been missed. There is NO correlation between this process and forefoot-hindfoot relationship. A decent review of the literature tells us this quite clearly, including, but far from exclusively, in JAPMA. What is being expressed by the talar head torsion is the evolutionary process of peramorphic heterochrony, where a structure transcend the ancestral state and extends it even further. Pete Lisowski's work of ?1967 demonstrates this quite clearly. 1967! that is about a decade before Root II was published.

    I do not have a copy of the published paper - and we are pre-dating the usual archiving systems. However, I do have a copy of the words - I have attached it.

    Rob
     

    Attached Files:

  6. Brian A. Rothbart

    Brian A. Rothbart Active Member

    From Brian

    Let's agree to limit our discussion on the 1-4 Classification system that I have presented.

    This classification is based on the normal foot embryogenesis: the ontogenetic growth of the cuboid, calcaneus and talus. The embyological record is somewhat thin when it comes to a careful examination of the foot has it goes from supinatus to plantargrade. In my model I have suggested that the ontogenesis of the cuboid carries with it the lateral column of the foot. And the ontogenesis of the talus carries with it the medial column of the foot. To my knowledge, no embryological textbook expands on this subject. However, it is a very compelling and plausible model. Examine the changes in the foot position during Carnegie stages 17 -23. How does the foot progress from this total supinatus towards the plantargrade foot, if not from the unwinding of the cuboid, calcaneal and talar bones?

    The medial column of the foot encompasses the talus, navicular, medial cuneiform (medial part only), 1st metatarsal and adjoining phalanges and hallux. I devised a protocol for measuring talar supinatus (PMSv) which was undertaken at Georgia University (published in 1997). Basically Cummings and Higbie found this protocol reliable (both intrarater and interrater) for indirectly measuring talar supinatus. I linked the PMSv to the 4 foot structures which can be viewed here.

    The model of these foot structures are very consistent with what one sees clinically:
    • The PreClinical Clubfoot Deformity, due to its' calcaneal and talar supinatus, should engage gravity drive pronation at heel contact through heel lift. This is exactly what we see when examining extrapolated treadmill frames.
    • Whereas the Primus Metatarsus Supinatus foot structure, due to its' talar supinatus, should engage gravity pronation at midstance (not at heel contact). Again, this is exactly what we see when examining extrapolated treadmill frames.
    Cummings GS, Higbie EJ 1997. A weight bearing method for determining forefoot posting for orthotic fabrication. Physio Research Intern, Vol 2(1):42-50.
     
  7. Brian A. Rothbart

    Brian A. Rothbart Active Member

    Well, it appears that my esteem compeer Rob has no further objection or comment to make in this discussion, which is enlightening since he was so erudite in his critique of forefoot varus.

    However, be that as it may, are there any human embryologists on this forum who can offer their educated opinion on this classification? Specifically as it dovetails into normal foot embryogenesis as we currently understand it.
     
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