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Are Root Biomechanics Dying?

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Kevin Kirby, Apr 2, 2009.

  1. Jeff Root

    Jeff Root Well-Known Member

    An excellent letter from Larry Huppin, DPM, who is a consultant for ProLab Orthotics just came into my inbox on PM News. Larry replied to reader’s request for information about foot scanners. Read this and tell me if Root theory sounds like it is dying and what paradigm is best represented by Larry when considering a foot scanner.

    http://www.podiatrym.com/letters2.cfm?id=25631&start=1
     
  2. efuller

    efuller MVP

    We do have some choice in this matter. When I make/prescribe an orhotic I start with how much intrinisc forefoot valgus post I want. (Determined by maximum eversion height measurement.) Then I look at the shape of the plantar surface of the heel. If I want an inverted appearing heel and the heel appears everted, I add more medial heel skive or more plantar lateral expansion to make the bottom of the cast appear as I want it to. So, I'm making an orthotic without bisecting the heel. I've heard of one method to bisect the heel of a cast is to set the cast on the table and rotate it until the underside of heel has its center point contact the ground. So, you could say that I am using a sort of a heel bisection, but that's open for debate. I may be using the concept of forefoot valgus, but I'm not deriving how I use it with the Root paradigm. I believe it is possible to use a forefoot valgus wedge without using the Root paradigm or using neutral position. However, for someone who disagrees with that the Root paradigm will live on forever.


    Jeff, When I was at the California College, we had everyone in the biomechanics depart bisect the same heel. There was a 5 degree range in the bisections. This is just the heel bisection. When you have different loads on the lateral colulmn there will be an additional variatiion in the forefoot to rearfoot measurement. It won't matter what instruments you use if you push with variable amounts of force the forefoot or rearfoot measurement will vary. Even if you got one practioner to standardize their technique, there is no way to determine if this standardization is the correct standardization.

    Another problem with basing a prescription off of a forefoot to rearfoot measurement taken in neutral position is that the foot usually stands more pronated than neutral position and in this position there will be a different forefoot to rearfoot measurement because of the increase in range of motion of the midtarsal joint.

    Keep the usefull parts and discard what is found not to be usefull. I have not found all those 2/3 - 1/3 calculations that John Weed taught to be usefull.

    Regards,

    Eric Fuller
     
  3. efuller

    efuller MVP

    Yes, I use those techniques to change my prescription. I use a variation on the maximum proantion test I call the maximum eversion height. I do not use a forefoot valgus post higher than that measurment because that post would attempt to evert the foot farther than the available range of motion.

    I also use STJ axis location to determine whether or not to add a medial or lateral heel skive to the orthosis. I have found that there is not much corelation between STJ axis transverse plane position and pronation end of range of motion position. I can predict how STJ axis position will effect liklihood of certain pathology by STJ axis position. I would have to have a pretty good reason for trying a different approach than this.

    So, Dennis, how do your centrings vary for the different foot types and what is the logic for this variation?

    Regards,

    Eric
     
  4. efuller

    efuller MVP

    Jeff, I agree with Kevin's comments about using maximally pronated position as a more consistant reference point. However, to go beyond that we should question whether or not we need to determine if the foot, or STJ, is supinated or pronated. Treatment using the biophysical criteria of normalcy is designed to correct the "deformity" with a wedge or orthotic. An alternate paradigm for treating the foot is identifying the structure that hurts and decreasing stress on that structure. You can relieve stress on a structure without deciding if the foot is pronated or supinated.

    Regards,

    Eric
     
  5. joejared

    joejared Active Member

    Noting this particular image on your site:
    [​IMG]

    I know of at least one chiropodist who uses a felt tip marker to actually transfer the line to the plaster during casting. It seems sensible enough, segmented or otherwise, and is very useful to eliminate lab discreprencies. they also inscribe the center of the 1st and 5th metatarsals, which is particularly helpful for the 5th in some cases.
     
  6. Lawrence Bevan

    Lawrence Bevan Active Member

    I think Jeff has hit the crux of this.

    You may think you can discount forefoot to rearfoot relationship in prescribing but you cant when it comes to manufacture.

    The forefoot to rearfoot relationship may not be necessary to explain the function of a real foot but in rigid plaster cast it has to be accounted for. You may not but your lab will have to for you.
     
  7. efuller

    efuller MVP

    Sorry all, In an earlier post I meant to answer this post.

    I believe Craig did something on supination resistance and STJ axis position.

    One of the major advantages, for me, of the tissue stress over neutral position theory, is the explanation of pathology and the logic behind treatment. Peroneal tendonitis is a good example. Peroneal tendonitis is often associated with lateral ankle instability. Under STJ neutral theory people have used the rationale that we should supinate the STJ to make it more stable. In my experience this makes the problem worse. Under tissue stress you use a forefoot valgus wedge to pronate the STJ and "rest" the peroneal tendon. You could do this without looking at axis position, but in my experience, most people with peroneal tendonitis have laterally deviated STJ axes. (It's often hard to palpate the location of the axis in these individuals because they have a very strong anti supination reflex. When you push medial to their STJ axis, their peroneal muscles will contract to the slightest inversion motion.)

    Tissue stress helps you design the treatment. If it doesn't work you could have done too much or too little and you modify your treatment based on the response. When I was a student, when an orthotic didn't achieve the desired results, my instructors would start over again. I can't always say that we looked for our mistake in applying the paradigm. But there must have been one, otherwise the orthotic would have worked.

    Certainly, I would not have any surgery performed on my foot based on an xray finding alone whether the x-ray was done in neutral or not. I question how much thought went into suggesting that x-rays be taken in neutral position for making x-ray measurements. I'm trying to think of a procedure where it would be necessary to know a neutral position X-ray angle before doing surgery.

    This is an excellent argument for using STJ axis position as well as using netural position related measurements. However, I can explain pathology based on STJ axis measurements. I often have a hard time explaining pathology using the neutral position explanations. For example posterior tibial dysfunction. STJ axis position gives an explanation of why some feet are more likely to get this pathology. The windlass can explain bunion formation through reverse buckling. I challange anyone to make sense of the hypermobility explanation of bunion formation in Normal and Abnormal Function of the Foot.

    I think the neutral position concept of a not fully compensated rearfoot and forefoot varus is a very important clinical concept. However, I don't understand why you need to separate out whether it's a forefoot or a rearfoot varus. Either way the STJ runs out of range of motion before the medial forefoot gets to the ground. Now, if they only connected this to sinus tarsi syndrome which occurs when the lateral process of the talus hits the floor of the sinus tarsi when the STJ is at the end of its range of motion. We can certainly keep the concept of not fully compensated varus, but we don't need neutral position to do it.

    Regards,

    Eric Fuller
     
  8. Lawrence:

    I have been using the plane of the plantar forefoot relative to the ground as the reference position for how most of my postive casts are balanced relative to the ground by the orthosis lab for many years now. I have used this method in approximately 3,000 pairs of orthoses with very good results. This method of "cast balancing" eliminates the need for heel bisections and overall improves accuracy.

    Therefore, contrary to the opinion you expressed above, you can discount forefoot to rearfoot relationship when it comes to orthosis manufacture by simply indicating to the orthosis lab how inverted or everted you want the plane of the forefoot balanced relative to the ground when the orthosis is manufactured. There is not just "the one right way", like I was taught at CCPM, when it comes to orthosis manufacture.
     
  9. Craig Payne

    Craig Payne Moderator

    Articles:
    8
    ...all depends how you choose to define "Root Theory"
     
  10. javier

    javier Senior Member

    I want to add some questions because I know I can not provide any answers or rational explanations to this discussion.

    First of all, is podiatry an science? I have done some search on Podiatry Arena and I have rescued a not very successful thread open by David Smith
    Falsafiability of Podiatric science. I think you can find some interesting points reading David Smith comments. Mainly: all podiatric biomechanichs theories are falsifiable. Falsifiable does not mean false. Just means I can show enough data (or just one) for any of them that demonstrate flawed or wrong hypothesis by experimentation. None of the podiatric biomechanichs theories authors have been able to demonstrate their theories by experimentation. Of course, you can argue about owns Popper's Falsafiability theory falsafiability by citing Kuhn's work (The Structure of Scientific Revolutions) for example. But, any podiatrist in the world should be aware about this fact before embracing a podiatric biomechanichs theory without some degree of criticism.

    Second, before someone fire the statement "my clinical experience shows me that my theory works". I am sure that Jeff, Kevin and Dennis have high success rates or they would be out of the market years ago. Clinical evidence do not explain us how a device work or why patients refer an improvement. Can anyone tell me why a foot orthotic do not work ? Do not tell me it is patient's fault! If you have been following any paradigm you choose and you are sure that a device must work, but it does not. How can you explain it? If it works you explain using your paradigm but if not?

    Third, I can recall an historical trivia about a German Prince asking Gottfried Leibniz to explain him Newton's Principia Mathematica without the maths. Leibniz told him it was impossible. But it seems possible with podiatric biomechanics, we use the word biomechanics without the maths. Why should be we worried for such a thing like maths that it is not in our academic curriculum? It is a waste of time we said. It is all about clinical evidence, we state.

    Result: podiatry is not a science and we use the maths that run our computers for repetitive discussion without end like a Moebius strip.

    Also philosophy of science should be considered before signing a theory's dead certified.

    Just a thought.
     
  11. Jeff Root

    Jeff Root Well-Known Member

    Sounds to me like a very subjective approach to foot orthotic therapy unless one relates the plane of the forefoot to the other anatomical structures to which it attaches, including the rearfoot and leg. How does one know if the plane of the forefoot should be inverted or everted to the ground? I have some lab customers who request their orthoses be corrected to a certain forefoot or rearfoot position (i.e. balance forefoot 10 degrees everted or balance cast with heel 5 degrees inverted, etc.) Nothing new there. Hopefully they are using some criteria such as RCSP, STJ rom, etc and are not just picking a number out of thin air. "Root theory" is much more than neutral postion theory as suggested. Merton Root never called it Root theory or neutral postion theory, he just called it biomechanics. Wouldn't it be great to just discuss biomechanics and leave the labels that detract from the meaing of it out of the equation.
     
  12. Lawrence Bevan

    Lawrence Bevan Active Member

    Kevin

    Having read your books I understand you.

    However what I was getting at is although a clinician may discount a forefoot deformity if you capture one in your cast it can have potentially a large effect on the shape of the device unless it is dealt with by the prescriber (or lab).
     
  13. What a fantastic thread :drinks Thanks to all taking part!

    A thought came to me last night vis a vis this comment

    Variations on which have appeared before. It was while I was eating set menu b (crispy shredded chilli beef, seaweed and special fried rice). Perhaps the original root theory was the first real recipe book. It gave us fantastic ingredients we had never seen before and a detailed recipe for how to cook them into a wholesome dish. Previous to that we had just been putting bits of meat in the oven til they went brown and eating them.

    Since then there have been new ingrediants discovered and many new recipe books written. Most of these make a dish which is unpleasant to most paletes. Some of the new ingrediants are unwholesome, many are nice but not to everybodies taste.

    Many of us are now saying that we can create new dishes by cooking some of the old, and some of the new ingrediants to make different food. Thats not to say the original recipe is less wholesome than it ever was. But must we forever use those ingrediants in the same way.

    I suppose to extend the metaphor one might say that if one is a poor or inexperianced chef its best and safest to stick to the recipe of a great one. If, however, one is a good chef, who understands how the ingrediants work, it would be a shame for that chef not to try to make their own dish.

    Regards
    Robert
     
  14. Depends which way one looks at it. If we assume that an orthotic represents a position that we seek to acheive then certainly. If we view an orthotic as something which changes forces to move away from a certain tissue stress crisis then the biometrics and morphology of the foot may have little to do with the desired morphology of the orthotic!

    For me the posting and modifacation of the shell is more about being able to extert force on the foot in the most comfortable way possible rather than acheiving a certain position of the foot.

    Regards
    Robert
     
  15. drsha

    drsha Banned

    This thread seems to me like a microcosm of modern podiatric biomechanics.
    Dr. Root gave us gifts that have been examined, expanded, upgraded and modernized. Theories have risen on Roots shoulders but they are in opposition instead of in sync as they could be. Clinically valid yet scientifically flawed ways of examination, diagnosis and care remain isolated and encapsulated without a common foundation.

    Although everyone tauts to be a whole foot specialist when it comes to examination, casting, Rx'ing and fabrication of orthotics, the bulk of the discussion remains entrenced in the rearfoot and the STJ as the center of the universe where Dr. Root started.

    There is little discussion relative to The Vault of The Foot and the forefoot or the foot taken as a whole.

    What if the center of our care is The Vault and the two bases (rearfoot and forefoot) are where the foot plants to recieve GRF and all three need equatable evaluaton, diagnosis and care?

    If we had Alladin's Lamp what would be our three wishes.

    1. Be capable of reducing abnormal moments around the STJ while enabling the musculotendonous units to fire with power and in phase (relative to gait) and translate function from aboverand into the forefoot through The Vault.
    2. Enable The Vault of the foot to be supported to the extent that it leverages the extrinsic and intrinsic musculotendonous units while reducing the need for the plantar fascia, plantar plate, spring ligament, etc to be a part of that support since these structures cannot support and perform over ones lifetime without breakdown, injury and performance issues.
    3. Enable the forefoot to be an excellent adaptive structure, when necessary, a rigid lever and supporter, when necessary and most important be able to morph and multipurpose upon command throughout all of its flexible-rigid tasks, with power and in phase.

    We need a system of examination and treatment that includes (unskewed) all three areas and a treatment protocol that includes the ability to control and correct problems where they exist and where they are best attacked.

    All the math, science, art and unexplained entities that make up biomechanics can then be organized and applied to all foot, foot type and then even further patient specific.

    We are debating mousetraps. Maybe we need to decide what we need to look differently at the mouse.

    The bias, passion and personalizations that blur our task reflect our frustration, that so far, no one of us has the entire answer and all of our theories are flawed.

    The biomechanical glass is more than half full and yet, a visitor suffering from foot and postural pain to The Arena might walk away in pain thinking it was more than half empty when most of us would be able to offer him/her some level of relief and comfort.

    Which one of us is willing to say that there is one theory amongst the pack that is the most well rounded and applicable to incorporate all the others so that we can use our combined talents and energy positively?
    Don't look at me (hahahahahaha).
    dennis
     
  16. That, Dennis, is because only you and about 12 other pods recognise it or use that terminology! :bang:. And you have singularly failed to reach number 13 on this forum by my reckoning!


    Whilst neoteric biomechanics is an interesting little sideshow its scarcely one of the dominant models for biomx now is it. :eek:. Lets not divert a rather interesting thread on Rootian / Tissue stress biomechanics into another Neoteric sales pitch / tar and feathering. Bored of that now!:deadhorse:

    Sorry. Bad day again.

    Robert.
     
  17. Griff

    Griff Moderator

    Nah it can't be that many subscribing to that pish surely...
     
  18. Interesting. Straight forward question, that requires a straight forward answer in numerical digits (if I get one from Dennis, I'll drink my own... again): Dennis, how many people have requested and paid you to use your patented system of foot classification?

    I'm considering using it in a piece of research, how much would this cost me?

    I'll give you ten pence and a big orange. Not a penny more, or strike me dead.
    Sorry for the diversion 'beer but: "you know", another baby peeled, is one less potential scum bag roaming the street.

    Chin up
     
    Last edited: Apr 8, 2009
  19. DTT

    DTT Well-Known Member

    Dennis

    Ive tried, oh how Ive tried to resist this

    BUT:D

    Wish # 1 :- To have an OFF switch on your mouth

    Wish # 2 :- To enable you with a brain that can integrate with others.

    Wish # 3 :- Last but not least

    To have the intelligence to wonder why , we are not interested in doing that
    :rolleyes:

    Do please try and keep up if you have the mind to continue in this great discussion BUT .......:rolleyes:


    Cheers
    Derek;)
     
  20. Dennis

    "He wants the world
    Screams everything
    Follows in love
    Love brings the fall"
    70 cities as love brings the fall- simple minds
     
  21. drsha

    drsha Banned

    I'll give you ten pence and a big orange. Not a penny more, or strike me dead.
    Sorry for the diversion 'beer but: "you know", another baby peeled, is one less potential scum bag roaming the street.

    Nah it can't be that many subscribing to that pish surely...

    I predict that it will turn personal and ugly as Kirby's arguments and skills are shown to have many of the same flaws as he denounces others with. At some point, The Administrator will close the thread as he does with all opposing threads whether meritorious or not. I am calling this symptom complex "Arenaitis".

    I translated all terms into something understandable by all.
    I have no translation for the vault since there is no term for that area in your inherited or invented language.

    and I will not dignify your slime with any other form of retort.

    Dennis
     
  22. Super! Can we get back to the grown up stuff now please?!

    R
     
  23. Dennis: You alone have finally discovered my true intentions here. The SALRE Death Star was almost completed. And I thought I could rule as Emperor of the Dark Side.....er......Podiatry Arena...........until you came along..........
     

    Attached Files:

  24. Jeff Root

    Jeff Root Well-Known Member

    Hey Kevin, how did you put a photo in this thread? I have a picture of a calcaneus that I wanted to post earlier but I couldn't figure how to do it. I know it isn't as handsome as Darth Kirby, but I want to post it anyway! I would appreciate a tip from an arena veteran like you.

    Thanks,
    Jeff
     
  25. Jeff:

    When you go to make your posting, at the very bottom, under "Additional Options" click on "Manage Attachments". That should do it for you.

    JPG files are the easiest to work with for photos since they are compressed images and require smaller file sizes. You may want to limit their viewing size so they aren't too big. Large images may make the image more difficult to view on some computers. For example, if you use a program such as Corel PhotoPaint or Adobe Photoshop, you can change the dots per inch (dpi) setting and the image size (e.g. 4.0" x 6.0") of your photo so that the rather large image files that now typically come from modern digital cameras (5-10 megapixel) are reprocessed into a smaller size that will allow nearly everyone to view the image on their computer monitors without needing to scroll up and down or left and right to see the whole image.
     
    Last edited: Apr 9, 2009
  26. Jeff Root

    Jeff Root Well-Known Member

    Kevin, thanks for the help with attaching files. I wanted to show some photos to help explain the calcaneal bisection technique that I was taught by Dr. Root. I hope they will be uploaded with this posting.

    To bisect the heel, place the STJ in neutral. Palpate the posterior, superior crest of the calcaneus simultaneously with the tips of both index fingers. Draw a short line segment midway between the tips of both fingers (look for tissue landmarks when palpating, then draw the first segment). Re-palpate and verify location. Move inferiorly and palpate and then draw a second line segment. Repeat until the superior half of the posterior calcaneal surface is bisected. Continue the remaining bisection without further palpation by drawing an extension of the upper line segment inferiorly.

    As you can see from the pictures, the superior aspect of the posterior calcaneal surface has a parabolic shape. A parabola can be bisected. As long as the examiner locates the superior apex of the posterior calcaneal surface and then palpates it inferiorly at even points both medially and laterally, the calcaneus can be bisected with reasonable accuracy. Even if the individual has a haglunds deformity, the bisection will still represent the midsagittal point of the calcaneus as long as the apex is used as the starting point.

    While it is reasonable to question the scientific and clinical significance of heel bisections, it would help if we all used the same technique. The technique I described and linked to in another posting (see http://www.root-lab.com/takingagoodcast_p2.htm) and described in part here, it the technique that is need to evaluate Dr. Roots theories and conclusions. If practitioners or researchers use different techniques, it adds significant variability to their results and makes if difficult to compare the findings of one individual to another. Unfortunately in my thirty plus years of doing this, I have seen way to much variability in heel bisection technique.

    Respectfully,
    Jeff
    www.root-lab.com
     

    Attached Files:

  27. Sammo

    Sammo Active Member

    Every action has an equal and opposite reaction.

    My reaction to DrSha's posts.

    NNnnnngggghhhhhhh...... aaaarrrrrrrrggghhhhhhhhh... hhhhhhmmmmmmmmffffffffff

    YOU'RE A TWAT!!!!!

    How can you in one breath preach about the virtues of your system, say how wonderful it is and then in the next breath start slagging people off for asking reasonable questions..

    You are proposing a system of foot typing and orthotic prescription, not a bloody religion! It needs to be backed up with more than "It is because I say it is so!"

    One thing I have come to realise on this forum is that:
    1) People can often be opinionated, sometimes strongly, occasionally to a fault, however:
    2) There are many open minded people and all are willing to teach others and learn from all. I truely believe that anyone can bring information to the table here that is useful to everyone.. it doesn't have to just come from the big boys!
    3) this forum is a truely amazing professional resource because I think alot of the time the podiatrists working in specialist fields are often working on their own be it a) due to geographical location b) no-one else in their team or hospital knows more than they do, or works in a simliar way in their specific field (because it is a small profession). This forum gives us an amazing platform to bounce ideas off some very smart people and to have a professional conversation with others in your field.

    Do you speak to people in life like you do on the arena?? If you owned a market stool and someone came and tried to ask you questions about your goods would your response be as aggressive it is here? How about if you were a drug rep?

    Reasonable people respond reasonably when being spoken to with reason.

    "He's not the messiah, he's a very naughy boy!"
     
  28. Petcu Daniel

    Petcu Daniel Well-Known Member

    Hello,

    I believe it's interesting to hear some comments to the article :

    "Subtalar neutral position as an offset for a kinematic model of the foot during walking", by Jeff R. Houck, Josh M. Tome, Deborah A. Nawoczenski

    Gait&Posture, Volume 28, Issue 1, Pages 29-37 (July 2008)

    Abstract The lack of a common reference position when defining foot postures may underestimate the ability to differentiate foot function in subjects with pathology. The effect of using the subtalar neutral (STN) position as an offset for both rearfoot and forefoot through comparison of the kinematic walking patterns of subjects classified as normal (n=7) and abnormally pronated (n=14) foot postures was completed. An Optotrak™ Motion Analysis System (Northern Digital, Inc.) integrated with Motion Monitor Software™ (Innovative Sports, Inc.) was used to track three-dimensional movement of the leg, rearfoot and first metatarsal segments. Intrarater reliability of positioning the foot into STN using clinical guidelines was determined for a single rater for 21 subjects. Walking data were subsequently compared before and after an offset was applied to the rearfoot and first metatarsal segments. Repeated measures of foot positioning found the STN position to be highly repeatable (intraclass correlation coefficients>0.9), with peak errors ranging from 1.9° to 4.3°. Utilizing STN as the offset resulted in a significant increase in rearfoot eversion (p=0.019) during early stance, and greater first metatarsal dorsiflexion (p<0.007) across stance in the pronated foot groups that was not observed prior to applying the offset. When applied to subjects with differing foot postures, the selection of a common reference position that is both clinically appropriate and reliable may distinguish kinematic patterns during walking that are consistent with theories of abnormal pronation.

    Sincerely yours,
    Daniel
     
  29. The intrarater reliability of bisecting a calcaneus and finding subtalar joint (STJ) neutral position can be quite good for one examiner or for a group of examiners that all work together and continually compare notes on how the techniques are beiing done. As for me, I would estimate that I am probably within +/- 2 degrees of drawing heel bisections, finding STJ neutral position and measuring forefoot to rearfoot relalationship in my patients [I still do these measurements along with the other standard Root measurements on all my patients receiving orthoses and still teach these techniques and have been teaching them to podiatry students/residents for the past 25 years.)

    The problem comes when I examine a foot and then another podiatrist I don't know examines a foot, and we try to discuss what each of us found in the patient. This interrater reliability can be quite poor with each of us drawing the heel bisection differently on the calcaneus, each of us finding a different STJ neutral position, each of us loading the lateral forefoot with different loading forces and thereby coming up with widely different numbers for forefoot to rearfoot relationship that may be as much as 5 degrees or more from each other. I have seen these large errors repeatedly in my 25 years of teaching these techniques.

    Therefore, I like to still bisect the calcaneus, measure STJ range of motion, measure forefoot to rearfoot relationship, and measure relaxed calcaneal stance position on all my patients receiving foot orthoses since I feel these measurements give me a better idea of how to compare the structure of one patient's foot relative to the other tens of thousands of feet that I have seen and measured over my practice career. However, if a podiatrist calls me from another state or another country and tells me they found a 5 degree of forefoot varus deformity in their patient's feet, I have little confidence that this is what I would also measure in the foot due to the large errors in performing these measurement from one podiatrist to another that I have seen during the last quarter century. This is one of the major problems with using the forefoot to rearfoot relationship in discussing foot biomechanics, there is such a great lack of consistency in measuring techniques from one examiner to another that it prevents meaningful scientific research of the effects of forefoot to rearfoot structure on foot biomechanics.
     
  30. A few questions for the Easter holidays:
    Do foot orthoses "work" by modifying the forces beneath the foot?

    How do the angles I can measure on a patient relate to the magnitude and location of the forces I need to change under the foot?

    How do changes in the angles of orthotic posting relate to changes in the magnitude and location of these forces? 1 degree = ? Newtons? 1 degree = ? mm shift in centre of pressure?

    The fact that we still work in angles is a reflection of the history of podiatric biomechanics. If we erased history and started today, would we still be talking in terms of angles?

    Prior to the work of Merton Root, were angles used in the manufacture of foot orthoses, or is this entirely due to his system?

    Forget what you think you know, think outside of the box- how would you do it?

    Happy Easter.
     
  31. Jeff Root

    Jeff Root Well-Known Member

    Yes. See "Some Practical Points In the Anatomy of the Foot", Boston Medical and Surgical Journal dated August 4, 1898. Yes, that's correct, 1898! R. W. Lovett and F. J. Cotton
     
  32. efuller

    efuller MVP

    A good paper. Some obvious points. Measurements of increased arch height e.g. calcaneal inclination angle corelated with decreased pressure in midfoot and incrased pressure in forefoot if I remember correctly. 1st met lenght was another duh measurement. (longer more pressure.)



    J Biomech. 1999 Apr;32(4):359-70.
    Structural and functional predictors of regional peak pressures under the foot during walking.
    Morag E, Cavanagh PR.

    College Health and Human Department, The Center for Locomotion Studies, Penn State University, University Park 16802, USA.

    The objective of this study was to identify structural and functional factors which are predictors of peak pressure underneath the human foot during walking. Peak plantar pressure during walking and eight data sets of structural and functional measures were collected on 55 asymptomatic subjects between 20 and 70 yr. A best subset regression approach was used to establish models which predicted peak regional pressure under the foot. Potential predictor variables were chosen from physical characteristics, anthropometric data, passive range of motion (PROM), measurements from standardized weight bearing foot radiographs, mechanical properties of the plantar soft tissue, stride parameters, foot motion in 3D, and EMG during walking. Peak pressure values under the rearfoot, midfoot, MTH1, and hallux were measured. Heel pressure was a function of linear kinematics, longitudinal arch structure, thickness of plantar soft tissue, and age. Midfoot pressure prediction was dominated by arch structure, while MTH1 pressure was a function of radiographic measurements, talo-crural joint motion, and gastrocnemius activity. Hallux pressure was a function of structural measures and MTP1 joint motion. Foot structure and function predicted only approximately 50% of the variance in peak pressure, although the relative contributions in different anatomical regions varied dramatically. Structure was dominant in predicting peak pressure under the midfoot and MTH1, while both structure and function were important at the heel and hallux. The predictive models developed in this study give insight into potential etiological factors associated with elevated plantar pressure. They also provide direction for future studies designed to reduce elevated pressure in "at-risk" patients.
     
  33. Petcu Daniel

    Petcu Daniel Well-Known Member


    Let’s consider that “thinking outside of the box” means understanding of modeling the foot using Finite Element Approach. Please, take a look at Mr. Vinicius Aguiar de Souza’s thesis, named: “Design of Insole Using Image Base Analysis” at http://repository.dl.itc.u-tokyo.ac.jp/dspace/bitstream/2261/15280/1/K-01162.pdf
    “Indeed, this knowledge may go a long way toward preventing and healing mechanically-based injuries among our patients” – from “Emerging Concepts In Podiatric Biomechanics”, by Mr. Kevin Kirby
    My question is:
    - where is the equilibrium between very sophisticated, hard to understand and somehow limited theories at the moment, and the need to solve now the patient problems or to teach in the educational system?

    Sincerely yours,
    Daniel
    :confused:
     
  34. efuller

    efuller MVP

    Dennis,

    I'm pretty sure that everyone on this mailbase will understand the anatomy and articulations of the foot. How do you translate vault into anatomy? For example, the first metatarsal is connected to the medial cuneiform with plantar ligaments etc. Then how does an orthotic support the vault directly when there is an inch of soft tissue between the skin and the bones?

    Regards,

    Eric Fuller
     
  35. Petcu Daniel

    Petcu Daniel Well-Known Member


    Mr. Kirby,

    Thank you for your comments! There are some questions which are interesting for me:

    - How is tested the examiner in order to know which are he’s ability to produce reliable measurements related to a specific measurement?
    - Which definition of “experience” is more accurate [hope not to be separated by the original article's context] for example?
    - “ Experience was defined as taking a minimum of ten negative cast impressions per month for at least the previous 12 months “” – “Variability of Neutral-Position Casting of the Foot“,– by Viviene Chuter
    - “Both examiners underwent a lengthy training period with the measures used in this evaluation. Training sessions consisted of the evaluation of patients by each therapist independent of the other. Each patient's measurements were discussed and remeasured jointly if discrepancies existed. Approximately 20 of these training sessions were conducted over an 18- month period prior to this experiment.” Reliability of a Diabetic Foot Evaluation, by Diamond JE
    - “The principal investigator has been involved in the orthotics clinic at Elliot Hospital for 1 year and is considered a consultant in the physical therapy department for foot management. The other two examiners have been involved in the orthotics clinic for 2 years and are also consultants to other physical therapists in the area of foot management.”- lnterrater Reliability of Subtalar Neutral, Calcaneal Inversion and Eversion, by K Smith-Oricchio,

    - How can be made a difference in the results of measurement, between:
    - Non-human errors: the errors generated by the measurement method, parameter definition, etc.
    - Human errors: the errors generated by personal examiner’s skills.

    Sincerely,
    Daniel
     
  36. Jeff Root

    Jeff Root Well-Known Member

    I spoke with Dr. Shavelson last week at the Midwest Podiatry Conference. This was the second conference where I had an opportunity to spend some time with Dennis and hear him present his philosophy, for lack of a better word, of orthotic therapy to me.

    I told Dennis that I have not studied his functional foot typing system, so I can't necessarily agree or disagree with it at this point in time. Yesterday I searched the word vault, to see if I could improve my understanding of his use of the term. I found the following definition for the word vault (http://www.merriam-webster.com/dictionary/vault):
    a: an arched structure of masonry usually forming a ceiling or roof b: something (as the sky) resembling a vault c: an arched or dome-shaped anatomical structure <the cranial vault>2 a: a space covered by an arched structure ; especially : an underground passage or room b: an underground storage compartment c: a room or compartment for the safekeeping of valuables3 a: a burial chamber b: a prefabricated container usually of metal or concrete into which a casket is placed at burial

    My question to Dennis is, why do you use the term vault rather than arch? Wouldn’t it be better to use standard nomenclature like medial arch, which consists of the sagittal and transverse arch of the foot? I do tend to agree with Dennis that some orthoses do not provide sufficient support of the arch. However, functional orthoses are not just arch supports.

    If you increase the height of the arch of an orthoses, it may or may not be well tolerated. I wore orthoses for about a year that had no medial arch filler to test the theory proposed to me by Arnie Ross, DPM that you don't need or should use less medial filler. While I could tolerate the devices, they were never as comfortable as my regular devices that had a modest amount of medial arch fill. Perhaps if I had used a more flexible shell, they would have been more comfortable. But it seems to me that using a more flexible shell would contradict the notion of supporting the arch.

    A traditional Root type functional foot orthotic is made with a semi-rigid material (Rohadur, polypropylene, etc.). So, if you increase the arch height and decrease the shell stiffness, what have you done to the function of the foot? Are there feet that are better off treated one way or the other? I'm willing to consider the options.

    Respectfully,
    Jeff
    www.root-lab.com
     
  37. Jeff, do you have a copy of this that you could send to me please?
     
  38. Jeff Root

    Jeff Root Well-Known Member

    Simon,
    I coincidentally received this article from Daryl Philips, DPM the same day you posted your question on the Pod Arena. This is a fascinating article by Lovett and Cotton. They made a clip that attached to the ankle which had a horizontal projection from the medial and lateral malleolus. They instructed the subject to stand as naturally as possible (relaxed calcaneal stance position, angle and base of gait?) They took a perpendicular from the medial and lateral projections and marked it on a piece of paper on which the subject was standing. They then took a straight edge and constructed a line from the medial heel and the most medial aspect of the forefoot. They then measured the angle created between the malleoli and the line representing the long axis of the medial border of the foot.

    They wrote: Measurement of the Rotation of the Astragalus: In order to have definite measure of the amount of anatomical pronation, the measurement of the horizontal rotation of the malleoli was fixed upon. The astragalus, being firmly fixed in the malleolar mortise, so far as a lateral motion goes, the malleoli take part in the horizontal excursion of the astragalus, which is an essential element in pronation. Some cut:

    This angle with its variations was studied in 119 measurements on 51 cases (besides measurements on 14 undissected cadavers). In this series we find:
    a) The angle varies in natural standing from 46 to 73 degrees
    b) In people with the better class of feet it is below 60 degrees
    c) The normal we should set is about 50 degrees
    d) People with painful feet are likely to have a higher angle, 60 or 70 degrees
    e) Competent feet show an appreciable, often a considerable, increase of the angle, over that of ordinary standing, when the foot is voluntarily allowed to roll inward; it may be said they have a reserve of pronation.
    f) When there is no such reserve of pronation one is likely to have symptoms some cut:
    j) Flat-feet proper, in the few cases we have measured record about 70 to 73 degrees, whether they are of a fixed or the mobile type

    Treatment: (Some cut) Many cases, however, require some actual mechanical support, for a time at least, for muscle control is only gradually learned, even if the patient persists, as many do not, and often it is necessary to give the stretched muscles a period of rest before they can take up proper function.

    Jeff continues: The authors then go on to describe common forms of treatment including felt pads and metal plates. They then go on to propose and describe a device made of strips of spring steel, riveted, and bound by elastic, and made to fit a cut-out plaster cast taken in the corrected position. This is a very interesting piece of history. Daryl said it was amazing that no one appears to have ever done anything with this paper and had they, how would it have changed biomechanics when Root can on the scene. I know this is not exactly the angles you were referring to, but I thought it was a great opportunity to plug this paper from 1898! The copy I have is not great (faxed version) but I will get it to you. Please send contact information to jroot@root-lab.com

    Regards,
    Jeff
    www.root-lab.com
     
  39. Jeff Root

    Jeff Root Well-Known Member

    For those interested, I here is a link to the article "Some Practical Points In the Anatomy of the Foot", Boston Medical and Surgical Journal dated August 4, 1898 by R. W. Lovett and F. J. Cotton. This chapter is deeply buried in this Google books link at http://books.google.com/books?id=hoosAAAAYAAJ&printsec=titlepage&source=gbs_summary_r&cad=0

    I have created and attached a PDF of the article if you want to be saved the trouble of finding it at the Google page. This is a very interesting piece of history that came to me from Daryl Phillips, DPM.

    Jeff
    www.root-lab.com
     

    Attached Files:

  40. Simon:

    I like angular measures since they are probably better at comparing interindividual varability of joint motion than displacement or linear measurements since they are not affected by the size of the foot or individual.

    Also, if I were to take the time and introduce a system that was to measure "foot deformities" to replace the STJ neutral theory proposed by Root and coworkers, then I would use the maximally pronated position of the STJ as my reference position since 1) it is highly repeatable from one examiner to another and 2) many more people stand in the STJ maximally pronated position than in the STJ neutral position.

    Patients would be measured in relaxed bipedal stance to determine the number of degrees they are supinated from the maximally pronated STJ position (eg. 0 degrees, 3 degrees, 5 degrees). As far as the forefoot plane evaluation is concerned, the number of degrees that the heel must invert from the maximally pronated position during nonweightbearing examination with the knees and hips extended and ankles dorsiflexed to approximately 90 degrees so that the plantar forefoot achieved a parallel alignment to the transverse plane could also be assessed. For example, a patient with a "rearfoot varus" and "forefoot varus" may be maximally pronated when the plane of the plantar forefoot was parallel to the tranverse plane. Therefore, this foot would have a value of 0 degrees in this position. On the other hand, a patient with a "rearfoot varus" and a "rigid forefoot valgus" may need to invert their rearfoot 15 degrees to have their plantar forefoot be aligned parallel to the transverse plane. I think that this system would certainly greatly improve interrater accuracy of rearfoot and forefoot frontal plane static measurements but, like Root's STJ neutral theory, would tell us absolutely nothing about the very important magnitudes of pronation and supination moments acting across the STJ during weightbearing activities. To do this, we need to look at STJ spatial location, which has much more signficance to the mechanical function of the foot than any of the measurements advocated by the disciples of the STJ neutral theory.
     
    Last edited: Apr 11, 2009
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