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Occam's Razon or the Law of Parsimony

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Brian A. Rothbart, Nov 3, 2021.

  1. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member


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    Over the years I have read many posts on this forum, discussing biomechanics in terms of moments, vectors etc, and in all humility, with great difficulty. Sometimes I find those discussions so convoluted that it gave me a headache trying to follow the train of thought. Could it be that we are overcomplicating our understanding of biomechanics?

    Nearly 700 hundred ago, a philosopher by the name of William Ockham presented a theory called the Law of Parsimony, which suggests that the simpliest explanation is often the most correct one. That is, given two competing theories, the simpler explanation is to be preferred.

    This has been my mantra during nearly 50 years of research in biomechanics and posturology. I see abnormal pronation, its definition and its impact on postural aberrations in a very simple linear fashion, one that even a child could understand. Not so complicated that it takes a PhD or DPM to discern.

    I would be interested in hearing your thoughts.
     
  2. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Example Occams Razor.jpg


    Any similarity to our discussions on Biomechanics?
     
  3. efuller

    efuller MVP

    A great read for you would be Thomas Khun's on the nature of scientific revolutions. He talks about paradigms as well as Occam's razor (to bad you can't change typo's in thread titles). A paradigm is a way of viewing the accumulated knowledge of a field of study. People use, wittingly, or unwittingly, these paradigms to organize their thoughts on a particular subject. Kuhn describes how the adherents of one paradigm have difficulty in understanding other paradigms because it conflicts with their view of the world.

    When I was teaching, the students were exposed to both neutral position biomechanics and the force and moments biomechanics that I was teaching. Many students thought what I was teaching was much simpler and straight forward. Brian, if you could open up your mind to new ideas, you might be able to understand them. Attempts to explain motion, or lack of motion, without forces and moments leave one with explanations that are too simplistic to be useful.

    Eric
     
  4. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Thanks for the heads up. Will take a look at Thomas Khun's The Structure of Scientific Revolutions.

    Perhaps my view that embryology holds the key in understanding gravity drive (abnormal) pronation is what one would consider a "divergent paradigm shift" Just food for thought.
     
  5. scotfoot

    scotfoot Well-Known Member

    Occam's razor right enough .

    Habitually shod feet are only about 50% -60% as strong as nature intended . When we move about this weakness means other stuff has to help to fill in .

    If you strengthen the feet of runners you get 50% less injuries .

    Strengthening the foot is a good place to start for all musculoskeletal problems involving the leg, hips and feet . You can add in other treatments which can also help but, in my opinion, there is no excuse for ignoring core weakness in the foot which will almost always be present .

    Plantar fasciitis ? IMO double toe flexor strength whilst keeping strain off PF . Strengthening the intrinsic by hoping about on the affected side will not give the PF much rest !

    Re selling stuff on Pod Arena .
    If you want to sell a product on the internet you advertise where all of your potential customers can see it . You don't post on a professional site because it will get you nowhere . You post on a professional site if you believe you having something to say that needs saying .
     
  6. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    The question is: If the foot muscles are weak (a symptom), what causes that weakness. Treat the cause, not the symptoms.

    Your statement regarding selling product(s) on this forum, needs clarification. Specifically, who is selling what?
     
  7. scotfoot

    scotfoot Well-Known Member

    Modern footwear
    Me
     
  8. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Below is a summation of my divergent paradigm shift

    A New Classification of Foot Structures Based on Foot Embryology is proposed?

    Basically I have proposed a new 1-4 classification of inherited foot structures based on foot embryogenesis:
    • 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
     
  9. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    I agree. This forum is to discuss ideas, not sell products.
     
  10. scotfoot

    scotfoot Well-Known Member

    Occam's razor , you said it . At least from the point of view of preventing running related injuries, keeping it simple works for most, strengthen the foot . Do that and the shoes don't seem to matter much statistically . Taddei et al 2021
     
  11. efuller

    efuller MVP

    It is not a paradigm shift if you just rename concepts from another paradigm. How do your foot types differ from the neutral position based foot types?
     
  12. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Be more specific. Are If you are referring to Roots classification based on his concept of STJnp?
     
  13. efuller

    efuller MVP

    Yes.

    What is the difference between a pre clinical clubfoot deformity and a rearfoot varus. What measurements do you use to determine foot types?
     
  14. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Rearfoot varus is a positional deformity where the entire foot is inverted relative to the ground when the subtalar joint is in its neutral position (see diagram below)

    Rearfoot Varus.jpg
    This foot structure is a construct that, from an embryological point of view, can not exist.

    PreClinical Clubfoot Deformity is a structural congenital deformity in which the calcaneus and surgical neck and head of the talus do not complete their ontogenetic torsional development and remain in supinatus.

    I use a dynamic test (Knee Bend Test) as a differential assessment (PreClinical Clubfoot Deformity vs RFS).

    If you want a complete presentation on PCFD I suggest you read:
     
  15. efuller

    efuller MVP

    That is not the definition of rearfoot varus. In rearfoot varus the heel bisection is inverted to the ground. This exists. What is the difference between preclinical clubfoot and a rearfoot varus?

    Brian can you cut and paste a description of the test you use to differentiate foot types?
     
  16. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    I was taught: with the patient prone, STJ placed in its' np, the posterior bisection of the calcaneus is evaluated relative to the posterior bisection of the distal aspect of the tibia.

    Do you diagnose this foot structure with the patient standing/sitting, looking at the heel bisection relative to the ground?

    But again, this foot construct does not exist.

    Are you a Podiatrist? If so, I would be interested in knowing where you obtained your DPM.
     
    Last edited: Nov 5, 2021
  17. efuller

    efuller MVP

    Going on the attack rather than trying to educate. Sign of a charlatan.
     
  18. Rob Kidd

    Rob Kidd Well-Known Member



    Please may we learn to spell sagittal?
     
  19. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    No offense intended. And my curiosity was not meant as an attack. I have simply never met Eric and was wondering who I was conversing with. And Rob, we all make typo errors. Just look at my typo error in the title of this discussion - Razon (should be Razor)

    Eric, to answer your question, standing, a patient with a PreClinical Clubfoot deformity would appear to have a severe flatfoot. Gravity forces the calcaneus and medial column of the foot (which are in supinatus) to roll inward, forward and downward until the plantar surfaces rests on the ground.

    The PreClinical Clubfoot Deformity is a congenital deformity involving both the calcaneus and entire embryological medial column of the foot, both being in supinatus.
    • Calcaneal supinatus is a structural twist (transverse axis) within the bone. Relative to the ground (uncompensated, standing) it would be twisted so that the medial plantar surface would be elevated, apex (highest) medially, tapering to nothing laterally.
    • Medial column supinatus is a structural twist involving the talar head and neck, navicular, medial cuneiform, 1st metatarsal (only) and hallux. Relative to the ground (uncompensated, standing), the 1st metatarsal and hallux only would be inverted and elevated relative to the ground, the apex of the elevation being medially, and tapering laterally. (The proximal supinatus being obfuscated by the contour of the ILA)
    This explains what we observe during gait analysis: At heel contact the foot abnormally pronates (due to calcaneal supinatus). And continues to pronate at foot flat thru pre heel lift (due to medial column supinatus) when it should be resupinating.

    From the above, the differences between Forefoot Varum and the PreClinical Clubfoot deformity are cogent.
     
  20. scotfoot

    scotfoot Well-Known Member

    Ockham's foot types .

    Type 1 -Habitually shod - Typically very weak and in need of a lot of strengthening .

    Type 2 - Habitually unshod - Typically a much more robust looking structure than the habitually shod and up to twice as strong .

    After a certain stage of development you can't get a type 1 to change to a type 2 but you can make it a lot stronger and reduce running injuries by half .

    For many runners, this would seem to be the classification that matters most .

    As you can see from the figure below, Ockham's foot types are easily recognized .

    [​IMG]
     
  21. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    I agree, muscular strength is lost in the shod environment - the old apothegm, Use it or Loss It is very sage. However, I believe it is not the complete answer.

    If you were born with a PreClinical Clubfoot Deformity, no matter how muscularly strong the feet may be, they will still abnormally (gravity drive) pronate, which in time, can result in chronic musculoskeletal pain.

    My solution would be to split the time between using the proprioceptive insoles and walking without shoes., e.g., strengthen the foot musculature and decrease the aberrated pronation.
     
  22. scotfoot

    scotfoot Well-Known Member

    Agreed .

    Minimal shoes work fine in younger people , D'Aout et al .

    Speculative .
     
  23. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Back to the initial subject of this thread - Do you believe we are making the field of Podiatric Biomechanics too complicated to understand?

    I, for one, believe so.
     
  24. scotfoot

    scotfoot Well-Known Member

    I believe that current Podiatric Biomechanical thinking is, in some ways, too simplistic, with important elements omitted completely .
    However, IMO , the biggest problem that the field has is the hitherto huge underappreciation of the functions of the muscles of the foot .
    I am not saying anyone is at fault for this , just that recent research has shown how weak our feet have been made by modern footwear . No one really knew the extent of this before the publications of the last few months, but things now need to change, IMO .
     
  25. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    I would not be surprised if your were somewhat frustrated in the paucity of comments on your viewpoints regarding the importance of muscular strength in the feet. Podiatrists may have very little to say on this subject.

    Just an example, in a prior discussion, I downloaded photos visualizing how inappropriate orthotics/insoles weaken the muscles in the feet. My point was, orthotics prescribed under the umbrella of treating abnormal pronation, is like prescribing ketamine (a strong anesthetic) for insomnia. Before using any type of device under the feet, the practitioner must first determine the cause of the abnormal pronation, and treat that cause directly.

    For example, if the healthcare provider were to dispense a proprioceptive insole designed to treat RFS, and the patient actually had a PreClinical Clubfoot Deformity, not only would the insoles not work, they could actually increase the patient's symptoms. This happens all to frequently among practitioners using orthotics. (And the sad fact is that many Podiatrists may not even be aware that iatrogenic symptoms can occur anywhere in the body, including the occlusion)

    And so how many Podiatrists responded to this discussion? If my memory is correct, not one!!!

    I believe you may be experiencing the same paradox on this forum, what should be of interest, maintaining muscular strength in the feet, is not. Or worse yet, ignored.

    My advice, be persistent with due assiduity, and eventually your message will be heard.
     
  26. efuller

    efuller MVP

    So, the pre clinical clubfoot deformity is a combination of rearfoot varus and forefoot varus. Brian you are just renaming existing concepts.

    What is uncompensated standing? How does one stand uncompensated?
     
  27. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Eric,

    I disagree. If you had read my paper (see above), it goes into the embryological ontogenetic development of the fetus during the first trimester. It explains exactly what the PreClinical Clubfoot Deformity is. And it is totally different from what Root labeled Forefoot Varum.

    I have a suggestion, read my paper. And then let's discuss this in detail.
     
  28. efuller

    efuller MVP

    Brian, usually if you want people to read your stuff you post a pdf of the paper. Do you still have the original word processing file that you submitted for publication? Could you pull that up and copy and paste the full definitions of your foot types and not the partial ones you posted above?

    What is uncompensated standing? How does one stand uncompensated?
     
  29. efuller

    efuller MVP

    If you take the mechanics out of biomechanics, you no longer have biomechanics. Ignoring the laws of physics does not mean they do not exist.
     
  30. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Uncompensated: foot maintained in STJnp weight bearing (positioned by examiner)
    Compensated: relative to RFS and PreClinical Clubfoot Deformity - pronated
     

    Attached Files:

  31. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    There are two paradigms: Roots Biomechanics and Neurophysiological Model (IMO, the one that should be used today). (Rothbart, 2010, 2011)

    Root Biomechanics - many discussions on this forum, a great deal of physics in the discussions
    Neurophysiological Model - more neurology, less physics.

     
  32. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    FYI, when I place a citation of one my publications, click on the title and it will automatically take you to ResearchGate where you can read or download that paper.
     
  33. efuller

    efuller MVP


    Brian, do you really not understand the discussions that have occurred here on podiatry arena. There are more than two paradigms of foot biomechanics. The Root paradigm, and your "paradigm" are the same in that both based on neutral position measurements of the foot to describe deformities. Your measurement method is different, but describes the same "deformity" as Root. The Root paradigm describes compensations, caused by foot types, that cause the foot to move away from neutral position. The flaw in this thinking is the assumption neutral position is normal and the foot is supposed to stand in that position. Another flaw in this thinking is that the foot starts in this position and moves out of it.

    Why is neutral position normal?

    There is very little physics in Root biomechanics. The difference is that Root focuses on kinematics with minimal to focus on kinetics. Kinematics is the study of the motions. Kinetics is the study of the motions and the forces and moments that cause those motions. The discussions on the arena in which physics have been involved are usually trying to refute the Root model and propose a different paradigm that we call the tissue stress approach.
     
  34. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Eric, again, I totally disagree with you. Root's Forefoot Varum is a construct that does not exist. When you review the embryological development of the fetal foot, this becomes very apparent. The paper I directed you to read, describes this in detail. Hopefully, you will have time to read it.

    Talar supinatus is a supinatus of the entire embryological medial column of the foot. This places the 1st metatarsal and hallux and only the 1st metatarsal and hallux in supinatus. Root's forefoot varum describes the entire forefoot inverted, that is all 5 metatarsals. I am at a lost how you equate these two.
     
  35. efuller

    efuller MVP

    Brian, Perhaps your confusion is in your understanding of the Root paradigm. How can a forefoot varus not exist by the definitions in their paradigm? I am lost as to how you see a functional difference. Your prescribed treatment would be the same as the Root paradigm.

    The discussion of embryological development is irrelevant to the discussion of the mechanics of the foot.
     
  36. scotfoot

    scotfoot Well-Known Member

    The discussion of embryological development is irrelevant to the discussion of the mechanics of the foot.[/QUOTE]

    Yes, I also have a problem with this line of thinking .
     
  37. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    In order to understand my research spanning the past 40 old years, one must first be conversant with the embryological development of the foot, specifically, up to and including, week 12pf. This provides the reader a basic understanding of the normal ontogenetic torsional changes that transpire as the foot evolves from the foot pad, through supinatus (unwinding), and finally into the fetal (plantargrade) structure. Once this is understood, one can quickly appreciate the possible aberrations that can occur if this process of unwinding is prematurely interrupted.

    Basically, the following structurally aberrations can occur: Clubfoot Deformity, PreClinical Clubfoot Deformity, Primus Metatarsus Supinatus (aka RFS) and Plantargrade (fully completed torsional development).

    The structures Root described, from an embryological point of view, cannot exist because they violate the innate paradigm governing ontogenesis. In simplistic terms, the footplate unwinds heel to toe (Streeter 1945 1948, 1951), thus the maxim: as goes the calcaneus, so goes the talus.

    Basically, comparing any of the foot structures in Root’s apophthegm to the above four structures, is like comparing apples to rocks. It’s simply, IMO, an exercise in futility.
    Read my paper, than we can go into this discussion in more depth.

    • Streeter GL 1945, 1948, 1951 Developmental horizons in human embryos. In Contributions to Embryology, Vols. 21, 32, 34. Washington DC. Carnegie Institution of Washington
     
  38. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    I have been very surprised with the apparent continual use of Root Biomechanics among DPMs today. I had anticipated that once Root's foot classification was proven false, it would be discarded in practice. Apparently, not so.

    A few days ago, I had an epiphany during a conversation with Dr. Steven Levitz, a professor at the New York College of Podiatric Medicine. He told me that Root Biomechanics was still being taught at their college.

    Just another example of how major paradigm shifts slowly excogitate.
     
  39. efuller

    efuller MVP


    Getting back to the beginning of this thread. Bringing in the embryological development is an unnecessary complication of the task of looking at the foot in front of us. Using the "embryological point of view" prevents you from seeing the possibilities in other paradigms or in your case how your foot types are essentially the same as Root's foot types. You are using embryology to explain how the foot types develop. How the foot types develop is irrelevant to how the foot types behave mechanically. Your embryological point of view is preventing you from seeing the similarities between your work and Root's. If you deny its existence, you won't put the work in to understand it.

    You still haven't addressed the basic flaw that your system, and Root's system, have in common and that is the starting point of neutral position. Why should the foot typing be based on neutral position. In your paper, you said over 95% of feet don't stand in neutral position. Why should you use a position that is clearly abnormal in the sense that it is quite rare.

    Another interesting quote from the paper was that Rothbart's foot type was the same as Morton's foot. You plainly admit to renaming existing concepts.
     
  40. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Eric,

    Excellent inquiries! I will address them individually.

    You perceive that “the embryological foot types are essentially the same as Root’s foot types.” Can you be more specific? Exactly why do you believe Root’s foot types are identical to the embryological foot types?

    You stated “You are using embryology to explain how the foot types develop.” Absolutely correct.

    You stated: “How the foot types develop is irrelevant to how the foot types behave mechanically “

    Here we disagree. Understanding the structure of the aberrated foot clearly defines how that foot will move during ambulation. For example: If you are dealing with a PreClinical Clubfoot Deformity:
    • at HC the calcaneal supinatus will drive the foot into gravity drive pronation
    • at flatfoot thru HL, the talar supinatus will force the foot to continue in gravity drive pronation (when it should be resupinating).
    In a prior discussion I downloaded a gait video of a patient with this deformity showing exactly what I have written above.

    You questioned: “Why should the foot typing be based on neutral position” Can you be more specific. I do not remember making that statement.

    You stated and questioned “In your paper, you said over 95% of feet don't stand in neutral position. Why should you use a position that is clearly abnormal in the sense that it is quite rare.” Can you be more specific?

    A sizeable portion, IMO, donot stand or function around their anatomical np. This is because a plantargrade foot is not predominant in the population.

    Point of fact: Patient’s born with either the PCFD or RFS will not function around the STJnp.

    You stated correctly: “Another interesting quote from the paper was that Rothbart's foot type was the same as Morton's foot.” That paper was written nearly 20 years ago.

    At that time the embryological foot types were not fully developed conceptually and I thought that the RFS was a 3 dimensional construct of Morton’s foot. In time that proved incorrect. The two foot structures are totally different.
     

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