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Challenging the foundations of the clinical model of foot function

Discussion in 'Biomechanics, Sports and Foot orthoses' started by NewsBot, Jan 31, 2017.

  1. Personally, I like to think of the modern research as discrediting the notion of examining midfoot motion about an "oblique" and "longitudinal" axes of motion ala Manter (1941) and the function of the midfoot described in your father's writings as equally highly questionable, and on the balance of evidence, wrong. I like to think that modern research challenges the clinician to think more in terms of the axes of rotation being the consequences of the forces acting about the mid-foot; I think that modern research clearly shows wide variations between subjects in terms of, and not limited to, midfoot motion during gait, and that such variation here and in all aspects of foot kinematics can be viewed as "normal" for the species; pathological thresholds and zones of optimal stress are subject specific and dynamic; in terms of measurements: I use navicular drift / drop/ midfoot width, or dynamically using similar measures in attempt to inform my clinical decision making since we have limited published evidence to suggest that these measures are predictive of pathology. In turn, these measures influence clinical decisions in terms of foot orthoses designs such as the addition of medial and lateral flanges, shell width, arch height, medial addition depth, etc, etc. Even so, I treat the patient in front of me as n=1; the fire (wo)man; transgender; non-binary and not the scan...Manter, 1941... wow.

    Let me ask you a question, Jeff: we have a measurement technique which is used for a while, then we have modern research which shows that technique to be fundamentally flawed- your logic would have us continue to use that technique, even though it is fundamentally flawed and invalid just because we don't have a replacement for the fundamentally flawed and invalid technique, is that not your argument here???... Seriously, it can't just be me? Me? I'd happily measure nothing, rather than measure something that is worthless, invalid and wrong. Yet you seem to believe that holding on to non-science is better than accepting the scientific evidence, as long as that meets your agenda (which in your case appears to be supporting your father's writings and the family business). Wow, just wow.
     
    Last edited: Mar 19, 2018
  2. efuller

    efuller MVP

    There are an infinite number of potential instantaneous centers of rotation at the hip. You can use multiple mathematical schemes to describe a single instantaneous center of rotation.

    It's not the use of label of LAMTJ that bothers me. It is how you use it. From what you have said it appears that you believe there is an anatomical fulcrum that limits motion of the MTJ to a longitudinal axis some of the time. If you can name a fulcrum, I'll admit that you're right. I don't think there is a fulcrum. There are numerous other posts in this thread where I have expanded on the question of a fulcrum for the LMTJ axis.
     
  3. Not strictly true, it can't be infinite so long as we can measure every possible variation of:
    1. Point of Application
    2. Magnitude
    3. Line of Action
    4. Sense

    for all of the forces being applied to the hip joint at a given instant in time... Yeah, on second thoughts that's going to be close on infinite in a given individual and obviously will have big variation between individuals for the same input functions.

    I honestly think that both Daryl and Jeff wish to concede that the X, Y, Z reference system as proposed by - Findlow and Nester might be a better way forward when considering the mid-foot than those ideas put forward by Root et al., yet Jeff and Daryl are unfamiliar with the methods of conceding and admitting that they have been wrong in their previous arguments and so are now, at this point in time, attempting to shift their games, yet again, rather than conceding that they were wrong . Indeed, Daryl even seems to be intimating that he was the first to propose the technique of examining the midfoot in terms of reference planes; for the record, this was first published by Chris Nester and his team. I'd yet to see Daryl advocate this technique until today; that he is advocating it is good; that he can't admit that previously he has been wrong- not so good; let's talk about ego's within this vested interest....
     
    Last edited: Mar 19, 2018
  4. efuller

    efuller MVP

    You don't have to teach axes of motion of the midtarsal joint to teach a student to abduct and dorsiflex the forefoot on the rearfoot. They just need to know directions. When I used to teach the biomechanical evaluation I would show the students that you generally have an oval of possible motion. When I would take the foot and ab and abduct it and ask them which axis of the midtarsal joint I was moving, very few could come up with a vertical axis. This is the problem with teaching LMTJ and OMTJ. It limits the ability to understand what is happening, or can happen at the joint.

    On the other hand, I do like the notion of dorsiflexing and abducting the forefoot on the rearfoot. I don't like the Root explanation that this pronates both axes of the midtarsal joint. My explanation is that casting in this position helps to load the plantar calcaneal cuboid ligaments when the patient stands on an orthotic made from this cast. I could be proven wrong that this casting position is best at helping to increase load acceptance on the lateral side of the foot. My experience with MASS casting has supported, in my mind, that max dorsiflexion of the lateral column is a better casting position. Those MASS orthoses really hurt. I also like the mass dorsiflexion and max abduction position for casting because Root et al found it successful. I do believe they were looking at what worked. I just don't like their explanation of why what they did worked.
     
  5. rdp1210

    rdp1210 Active Member

    It's too bad that you don't read what someone is saying before you sit down and write something nasty, insulting, condescending or snide. I was not defending or critiquing Manter, only giving a historical account of where ideas originate. You have to understand your history of all ideas, including the context within which they were developed and the biases of the times. Your replies indicate that you have no idea of where I agree and don't agree with Root concepts. One big difference between us is that I respect those who have paved the way and you show no respect for anyone, especially anyone who has a different perspective than you do. BTW - I never heard Root lecture on the biomechanics of the diabetic foot, which now constitutes the majority of my practice. Just as Rich Blake found Root very interested in helping develop a better running orthotic, I find Jeff Root to be very willing to implement my ideas for a better diabetic orthotic. Neither were or are stuck in the paradigms of the past. However neither made giant leaps of faith from data to some of the conclusions that have been drawn lately in the literature.
     
  6. It's just the science that I respect, Daryl- no bias based on relationships from my perspective.. No "good ol' Mert" from me, yet obviously from you- and your obvious bias and "respect" towards certain individuals makes you a better scientist than me because....? Back to the science post 1941, if we may... Best available science published in peer reviewed papers regarding the midfoot in the last 20 years... discuss.... Hint: none of it supports the research of Manter from best part of your *n+1 years ago"- no critique of Manters research from you or Jeff, yet a point by point take apart of Hannah Jarvis's work... hmmm wonder why? It's just that the best part of 80 years of research on the midfoot that you choose to ignore; don't lecture me on reading posts here.
     
    Last edited: Mar 19, 2018
  7. Jeff Root

    Jeff Root Well-Known Member

    The problem with using X, Y and Z as a reference is that it has no anatomical significance and it does not take into account the relative position of foot and body in space. Having a leg and a heel bisection enables us to have a reference that we use to compare the relative position of foot or of segments of the foot to in space. If the entire foot is moving in space as it does during the swing phase of gait, the plane of the forefoot would be constantly changing in space and there would be no way to know if it was a result of movement of the foot as a whole, or as a result of movement of the forefoot to the rearfoot. We need landmarks on the body to use as references.
     
  8. Jeff Root

    Jeff Root Well-Known Member

    Root believed that applying a pronation force at the appropriate angle on the plantar, lateral aspect of the ff would fully pronate the MTJ. In other words, he believed that this force would move both the ccj and the tnj to their end range of motion in the direction of pronation. Although I still apply this theory in casting, I think we can assume it fully pronates the ccj but I don't know if it actually fully pronates the tnj because the force is directed on the lateral column. However, the entire forefoot does move in the direction of pronation when you load the lateral aspect of the forefoot this way during casting so I think the tnj is close to, if not fully pronated. Rather than focus on the long and oblique axis, we really need to know what is happening that the mtj as a unit and the the ccj and the tnj individually. Loading the lateral column has proven to be a very effective technique when casting for and making functional foot orthotics.
     
  9. Jeff Root

    Jeff Root Well-Known Member

    I have mentioned before that we see more ff inversion on average in casts taken prone as compared to cast taken in a supine position. I think the supine casting technique does a better job of inducing a pronation moment at the MTJ.
     
  10. Petcu Daniel

    Petcu Daniel Well-Known Member

    I'm really curious to understand how is used navicular drop and drift and midfoot width as "navicular drop emerged as an unreliable measure with only fair agreement across test sessions and use of this measure is discouraged." ( https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5131537/ ) while midfoot width is part of foot mobility measure which is explaining only 8% from "the degree of variance in peak and range of motion kinematic variables" ( https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4657281/ ). One the other side there is McPoil's et al work justifying the use of mobility in favor of navicular drop and drift: "While the measurements of navicular drop and drift have been used as a clinical method to assess both the vertical and medial-lateral mobility of the midfoot, poor to fair levels of inter-rater reliability have been reported."(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2656480/ ). My curiosity shouldn't be interpreted as advocating the using of other more or less reliable or unreliable measurements discussed in this thread! Thanks
    Daniel
     
  11. Not too sure who you are citing there Daniel as the link you posted doesn’t seem to work on my phone. However it does seem to warn of the dangers of cherry-picking references since the vast majority of studies I have read regarding reliability show reasonable ICC’s. We also have in navicular drop a measurement that is predictive of pathologies. Nice overview here: https://www.physio-pedia.com/Navicular_Drop_Test
     
  12. Trevor Prior

    Trevor Prior Active Member

    Good point regarding refs. We did a relaibility study (unpublished) at QMUL on a whole raft of foot measures. The only ones that had sufficient reliability were navicular drop (0.83) , navicular drift (0.86), change in midfoot width (0.76) and FPI (0.87). Unlike the Langley study we did intra and inter rater across sessions and these were the 4.
     
  13. Petcu Daniel

    Petcu Daniel Well-Known Member

    -Ben Langley,Mary Cramp, and Stewart C. Morrison, "Clinical measures of static foot posture do not agree", J Foot Ankle Res. 2016; 9: 45. Published online 2016 Dec 1. doi: 10.1186/s13047-016-0180-3 PMCID: PMC5131537
    -Andrew K. Buldt, George S. Murley, Pazit Levinger, Hylton B. Menz, Christopher J. Nester, and Karl B. Landorf "Are clinical measures of foot posture and mobility associated with foot kinematics when walking?" J Foot Ankle Res. 2015; 8: 63. Published online 2015 Nov 24. doi: 10.1186/s13047-015-0122-5 PMCID: PMC4657281
    -Thomas G McPoil, Bill Vicenzino, Mark W Cornwall, Natalie Collins, and Meghan Warren, "Reliability and normative values for the foot mobility magnitude: a composite measure of vertical and medial-lateral mobility of the midfoot", J Foot Ankle Res. 2009; 2: 6. Published online 2009 Mar 6. doi: 10.1186/1757-1146-2-6 PMCID: PMC2656480

    Trying to avoid my cherry picking referencing I've indicated the third reference. Also, "a limitation" of my post could be choosing the articles based on the author's expertise/name rather than my deep understanding of each article's methodology. But I think this could be similar with an average clinician profile so I think my curiosity is somehow justified
    Daniel
     
  14. Petcu Daniel

    Petcu Daniel Well-Known Member

    But is unpublished which I think will increase the probability for someone to read first Langely study!
    Daniel
     
  15. Jeff I started a new thread on this - https://podiatryarena.com/index.php?threads/forefoot-supinatus-definition-2018.109990/
     
  16. Not me I am hear to discuss, learn and maybe help others. Many of us go down different paths re biomechancis, and just like real paths they change directions

    But 1 point when you throw in a reference to a paper from say 1964 can you post the pdf so at least I have a chance to read it? Thanks I am just catching up from the last week
     
  17. Trevor Prior

    Trevor Prior Active Member

    Cannot argue there, just surprised he got the result he did - interesting it was the measure that required a change in position i.e. needed a baseline which of course is one of the problems with this type of clinical test and why some use the sit to stand approach for ND.

    Strictly speaking, the conclusion is perhaps not as accurate as it could be. What about, if he had compared to another practitioner and they were relaible but he was not. So, is the test unrelaible or unreliable in his hands?

    All that said, does not take away fromt he fact that any measure requiring a manipulation of position has an inherent risk of poor reliability.
     
  18. Petcu Daniel

    Petcu Daniel Well-Known Member

    The description of the technique in the above mentioned overview is starting with: "Position the patient in standing so there is full weight-bearing through the lower extremity and ensure the foot is in the subtalar joint neutral position (“talar head congruent”)."
    I should continue to read the rest of the technique?
    I specify that my questions are not pro or against one or another of the theories discussed here but to try to learn! Thanks
    Daniel
     
  19. Petcu Daniel

    Petcu Daniel Well-Known Member

    Seems that Ben Langley is studying only the intratester reliability as only "one investigator with three years experience of static foot assessment conducted all testing". Also his technique is using "subtalar joint neutral as determined by congruence of the talar head". In this case it is right their statement "The use of this measure for foot assessment is discouraged." ??

    How did you measured the ND in your article?
    Daniel
     
  20. Petcu Daniel

    Petcu Daniel Well-Known Member

    Apologies for torturing English language! Too late to edit it!
    Daniel
     
  21. Jeff Root

    Jeff Root Well-Known Member

    For those of you who assess navicular drop and/or navicular drift in your biomechanical exam, what would be your treatment objective with an orthotic be if the patient exhibits excessive navicular drop or drift?
     
  22. Depends on the problem the pt has.

    But say the pt has an increased supination resistance and Tibialis Anterior issues combined with increased Navicular drop and drift it will help define the Orthotic design features and give me some ideas of the issues which might occur.

    So design features might be medial skive increased arch height with medial flange and a D filler that extends medial to the device
     
  23. Jeff Root

    Jeff Root Well-Known Member

    Trevor and Simon, please explain how you use navicular drop/drift in developing your orthotic prescription and in evaluating the effect of your orthotic devices. If you find excessive navicular drop/drift with the patient barefoot, do you measure navicular drop/drift with the patient standing on their orthotic devices and compare this measurement to the patient's barefoot, no orthotic measurement?
     
  24. Trevor Prior

    Trevor Prior Active Member

    Just to be clear as I stated, we did not publish so not an article. However, myself and the other tester (a physio) used the same technique as described - we plapated the head of the talus so that the TNJ was congruent which is, in my opinion, erroneously considered to be STJ neutral.

    However, there is some logic in the poisition, albeit after the fact, in that Simon and kevin demonstrated that the STJ axis in the transverse plane follows the line of the neck and head of the talus, thus we are by default, realigning the axis. Deviation form this point potentially gives some indication as to the degree and direction the axis is moving and the relative balance across the foot. All unproven of course and pure conjecture on my part.

    The main reason for doing it was because this has been how the test has been described and the data avialbale int he litereature.
     
  25. Trevor Prior

    Trevor Prior Active Member

    So the degree of drop / drift gives me an appreciation of the degree of compensation in the transverse and sagittal planes though the midfoot. As I mentioned previously, the surgical approach to flat foot relies heavily on stabilising the medial column and thus, this assessment gives an appreciation of the mobility.

    If I have a flatter foot type with a low arch profile and low navicular drop, then this is a stiffer foot type compared to a similar foot with a higher degree of drop / mobility. Thus, if I am using an OTS device, I would select one with a lower profile for the first example and potentially a higher profile for the second one. If custom, then I may be less aggressive in my cast correction / the profile of the device between the two.

    In one of Nester's papers, he found some correlation between arch height and tibial rotation. We know that patients with medial knee OA often have high external knee adduction moments but only around 67% respond to lateral wedging. This is likely to be due to a different plane of copmpensation. I have seen patients with this condition who, when we perform 3d analysis (no joint moments) have high tibial rotation and demonstrate increased midfoot motion. When then tested on a device to reduce the midfoot motion they have symptom relieve. Thus, IMO, tibial rotation is a potential contrbutor of pain in some patients with medial knee oa that can be helped by orthoses if this is combined with increased midfoot motion.

    In reality, what this gives me is an appreciation of the mobility (which yo can get without measuring) so that I can try to exert an influence on the foot which allows for the mobility and hopefully optimises comfort which we know to be an important factor.

    Do I routinely re-test patients when on their orthoses - no - I have a colleague that does most of the issuing and I tend to see the patients for review. At this stage, if there are issues with the orthoses, then this is soemthing I will evaluate as I believe it gives some idea as to the degree of influence one is having on the foot. However, this is just one aspect of what I look at and I far prefer to perform a dynamic assessment which may be using inshoe pressure or 3d kinematics or both.

    Trevor
     
  26. Further to Trevor's post, amongst other things I look at the ratio of drop to drift- when there is a high drift component I will tend to include a higher medial flange and lateral clip, since this generally means we have greater abduction moment of the forefoot on the rearfoot about the dorso-plantar midtarsal joint reference axis. Yes, I do repeat navicular drop with the orthosis in-situ, but also perform a quasi-dynamic orthosis deformation test as described by Kevin. Like all measurements it is simply one tool in the bag. For the record- I prefer a sit-to-stand version, but sometimes perform both with talar congruency included.
     
    Last edited: Mar 20, 2018
  27. Jeff Root

    Jeff Root Well-Known Member

    I believe that navicular drop and drift, whether you measure if or just observe it is a good technique to gain a clinical impression as to how the foot functions. On many occasions I have demonstrated to patients how an orthosis might help them by placing my fingers under the talonavicular area and perform a navicular drop demonstration after they have performed a navicular drop demonstration without my support. By placing my fingers under their TN area it is easy to demonstrate how supporting their proximal MLA area can reduce STJ pronation and can reduce rearfoot adduction or relative ff abduction and dorsiflexion.

    I have been thinking a lot since this latest round of PA discussions (which I do value and appreciate in spite of the occasional head butting: I need to remind my self to be less sensitive and to try to remain professional when things get heated) about where can we find common ground. I think we often battle more over semantics than we do over other things. For example, my father Merton Root (how is that Simon, I satisfied both of us!) wrote about feet that demonstrated excessive verticality of the oblique axis of the MTJ. These are the patients that demonstrate excessive navicular drop and drift (greater navicular plantarflexion and adduction) in the navicular drop/drift test. These patients demonstrate increased ff abduction during stance as compared to individuals with a less vertical oblique MTJ axis. Personally I don't get too hung up nor do I feel personally invested in a lot of the terminology we use. For example, researchers have tried to describe the axis or axes of the MTJ. This research is extremely valuable but from a practical standpoint, I feel I that I can appreciate differences in the range and direction of motion of the MTJ during open chain, clinical examination and dynamic function of the MTJ in spite of all the competing theories.

    In Simon's link about the navicular drop/drift test, we seen use of the term neutral position of the STJ in this test. Yet in other discussions, we have had heated debate about the definition, validity and reproducibility of the neutral position of the STJ. Personally I detest the term Root theory. Perhaps if we would focus more on finding the best methods and techniques for treating patients and less time and effort worrying and arguing about who's theory it is or who's theory is most correct, then we might be better off, at least clinically speaking.
     
  28. Petcu Daniel

    Petcu Daniel Well-Known Member

    Why sometimes? I suppose is less reliable than sit-to-stand version without talar congruency!
    Thinking at Chen's article: "Assessment of subtalar joint neutral position: a cadaveric study" a second question: which is the significance of talar congruency in the context of your test?
    Thanks,
    Daniel
     
  29. Because when I’m teaching students I show them both techniques. Talar congruency was taught by Langer as a method of placing the subtalar joint in neutral.
     
  30. Petcu Daniel

    Petcu Daniel Well-Known Member

    Do you teach a technique associated with subtalar joint neutral only from a pure historical perspective, an imposed curricula or because of something useful for learning process? I'm asking this being interested by the teaching method and in the context of the discussions from this thread were it was suggested (at least in my understanding) that someone could start learn directly with TST.
    Thanks,
    Daniel
     
  31. rdp1210

    rdp1210 Active Member

    I actually practice "Phillips' theory" of biomechanics - this includes many of Root's concepts, as well as those from Sarrafian, Winter, Scherer, Richie, Kirby, my own father, Ward, Inman, Gozna, Dananberg, Schuster, and many others as well as my own experience, experiments, and logic. I have offered the following: the only truly unique idea that Root added to the literature is what I call "The Root Postulate" which is the concept that in static stance the midtarsal joint should be at its pronation EROM. I see Fuller pretty well has adopted this concept as he talks about all his forefoot valgus wedges. Everything else that Root taught can be referenced from somewhere in the literature (yes, even the STJ neutral concept) though he may have put his own spin on it and spun it into a complete foot function picture.
    So it's time to discuss particular concepts and to let personality go. Let the discussion move forward into discussing just one concept -- what are the advantages and disadvantages of the subtalar joint having a neutral position? I personally believe that the advantages far outweigh the disadvantages. Let those who disagree with there being a subtalar joint neutral position post their reasoning and evidence without invoking the name of that biomechanics professor in California.

    Daryl
     
  32. I teach it because those are the variants of the test described in the literature- remember that the palpating of congruence just gives a starting position for the test- it does not have to signify STJ neutral nor anything else- its just a starting position from which a test that has previously been shown to be a predictor of pathology has been described in the literature. I didn’t invent the test! That is all, there’s nothing deep nor mysterious; no ulterior motive. Do I think this start position represents a tautological definition of the STJ position? Maybe or maybe not, depends on who’s tautological definition you start with. Could I teach this technique without using the term “STJ neutral”? Absolutely. Do I think it’s the best start position for the test? No, that’s why I use sit to stand.
     
  33. Jeff Root

    Jeff Root Well-Known Member

    The problem I see with the sit to stand technique is that the quantity of weight born on the foot changes when going from sitting to standing. While sitting there is less compression of the plantar tissue and fat pad of the foot. So we can't tell how much of the change in navicular position is due to osseous movement and how much is due to increased compression and displacement of the plantar tissue when going from a semi-weightbearing condition to a full weightbearing condition. In addition, I think the standing start position is more clinically relevant because I can use it to gage, in part, how my orthotic might influence the position of the foot in one standing condition (no extra external influence) to another standing condition (an external influence under the medial column, my fingers). I'm often surprised at how little pressure the subjects foot actually places on my fingers when I use them to support the TN area, which tells me that my orthotic stands a good chance of reducing navicular drop/drift, thereby reducing both STJ pronation and ff abduction and dorsiflexion.
     
  34. Petcu Daniel

    Petcu Daniel Well-Known Member

    I think it make sens this observation! A thickness decrease between 10 to 14% in different plantar regions from sitting to standing is reported ( https://www.ncbi.nlm.nih.gov/pubmed/25426574 ). In the same time, McPoil et colab. is proposing foot mobility magnitude as an alternative to "poor to fair levels of inter-rater reliability" of navicular drop and drift (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2656480/ ). And one of the reference positions used is a non-weight bearing one! Which will explain only 8% from "the degree of variance in peak and range of motion kinematic variables" ( https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4657281/ )
    Taking into account above mentioned arguments how do you decide which reference position is more significant from a clinical point of view?
    Daniel
     
  35. efuller

    efuller MVP

    I really feel that theory is important. When I was at CCPM I remember the surgeons joking about biomagic. A theory should be internally coherent if want thinking students to believe what they are taught. A lot of students will just do what their teachers did and if that is relatively effective, they will continue doing the same. In the clinic, we can do what works. On an academic forum we should strive the truth of which theory is better than another. Or put another way, as described in our recent discussions, we should use science to figure out which is the best theory.
     
  36. efuller

    efuller MVP

    I will admit my concept of preloading the lateral plantar ligaments with an orthotic casted with the calcaneal cuboid joint maximally dorsiflexed comes directly from what I was taught at CCPM. The reason that I like talking about the ligaments at a particular joint is that it much less confusing than talking about pronation about a longitudinal midtarsal joint axis. If you accept the published position for this axis, when you push upward on the cuboid the navicular should rotate downward. This doesn't happen. I'm trying to come up with a better explanation for their clinical success.

    The idea that the STJ can be in neutral with LMTJ pronated is confusing. A third year podiatry student reads their lecture syllabus and sees the biophysical criteria for normalcy. In the same lecture syllabus they read the STJ pronates when it hits the ground. When the STJ pronates, the long axis of the MTJ will supinate. At some point the motion stops. So, how does the STJ stay in neutral with the LMTJ pronated? You need force from the medial forefoot to keep the STJ from pronating out of neutral position. That same force that stops pronation of the STJ will supinate the MTJ. The normal foot cannot exist. Confused yet. Some proponents of the use of LMTJ talk about the medial arch of the orthosis limiting STJ pronation. How does a force from the medial side of the orthosis not supinate the LMTJ?

    Now just look at a standing foot. Bodyweight pushing down on the top of the talus, ground reaction force pushing upward on the medial and lateral forefoot. Both sides of the midtarsal joint will be dorsiflexed and the plantar ligaments of the TN and CC joints will at some point, limit dorsiflexion of the distal bones on the proximal bones. Sometimes, there will be more load on one side of the forefoot. There will be more tension on the plantar ligaments on the side of the foot with more load. I'm including the plantar fascia with the plantar ligaments. Much less confusing.

    Things break because of too much force, not too much motion. If we want to understand foot pathology we should be looking at forces and not motion.
     
  37. efuller

    efuller MVP

    You can't prove a negative. You can't prove something doesn't exist. So there cannot be any evidence that STJ neutral does not exist. On the other hand, those that believe that there is a neutral should be able to produce evidence that it exists.

    The definition of neutral position is circular. It's a position that's not pronated nor supinated. A pronated position is on one side of neutral and a supinated position is on the other side of neutral. Which brings us to the we need a zero point. If we are walking through the desert and come upon a number line with a finite length, we can arbitrarily choose any point on that line as neutral (zero) and all points on one side of our arbitrarily chosen point will be pronated (negative) and on the other side..... For the believers in neutral position why are the three methods of finding neutral position not arbitrary? Are they all the same position? Why would one method be better than another?

    As to the benefits of neutral position. It has been suggested as position from which different feet can be compared. Again, those that believe it its use for this should be able to come up with a reason for using this position and not another position.
    As a casting position for orthoses. This casting position will tend to create a cast with a higher medial arch than a weight bearing or semi weight bearing cast in most feet.

    What other benefits are there?

    Critique of the ideas with no names mentioned. It is not about personality, it is about ideas.
     
  38. drhunt1

    drhunt1 Well-Known Member

    Neutral position doesn't exist? Wow! I don't concur. In my practice, with my patients, neutral position is attained when the foot is suspended off my exam chair...just like it is in swing phase of gait. This can be easily determined. Growing pains in children and RLS in adults, according to the preliminary findings of my study, occurs because the STJ is maximally pronated to the point of a subluxating force, (gravity and the body's weight), creating a transient synovitis. This pain is then referred up into the lower extremities...usually the lower leg. Don't make this concept any harder than it really is. For reference, I'm attaching a pic of Dr. Evans measuring talar height...IMO, a waste of time...
     

    Attached Files:

  39. rdp1210

    rdp1210 Active Member

    Thank you Eric for responding to the question and keeping the discussion about ideas. That is what this arena is for. If you do any listening to World Science Festival, you will find the same type of serious debates over some very big ideas, e.g. string theory, multiverse, dark matter, etc. So I take comfort that if minds much greater than those who write here can debate so energetically, a little debate here is probably healthy.

    As to your circular argument case - yes, you can call it a circular argument. However the great minds also debate over what the number zero is. Please define it without using the words positive or negative. The number zero is a starting point from which to count. It's hard to have "one" if you don't have "zero". Likewise you can't have a "pronated" position if you don't have a "neutral" position. I have considered the point of having a neutral position vs. not having one, and I find the advantages far outweigh the disadvantages. Consider how much harder it is to compare foot types and foot functions without a neutral position. Houck et al (2008, Gait and Posture) showed that identifying foot pronation relative to a neutral position showed much more pronation occuring than when measuring pronation against a ground based coordinate system. Also you can talk all you want about kinetics, but let's face facts -- most people do more standing than walking, so far more people are in a state of static not dynamic function of the foot. If they stand all day without the subtalar joint in neutral position, is there more soft tissue stress around the joints? Are they more likely to sustain soft tissue damage? Without a neutral position, can we develop a predictive science, especially for those who only stand and don't do a lot of walking? Also think about teaching the beginner. You have many years of experience to guide you, but having a neutral position makes it so much easier for giving a beginner a basis from which to start. As I noted, as I consider the option of having or not having a neutral position, there are far more disadvantages not having one.

    Now I am open to listening to various arguments as to where that neutral position should be. I believe the jury is still out. Root described several ways to try to identify that position, and there may be times those various methods are coincidental, but there may be times when they are not. Having taking casting lessons from Root himself, I have often pondered his methodology of finding neutral position without any palpation of the STJ nor the TNJ, which is where he was taking casts of the foot. He described the motion of the STJ as an arc of motion, and the neutral position being the point where you reached the bottom of the arc. After greatly thinking about this over the years, my interpretation of this description is this: Imagine a valley between two hills. When you are at the bottom point of the valley, it takes positive work to move in either direction. At any other place it takes positive work to move in one direction and negative work to move in the other direction. So it is with the STJ. In utilizing clinically Root's technique for finding neutral at the bottom of the arc, what I believe I am detecting is equal passive tensions on both sides of the joint when trying to move it in either direction. In any other position I find it takes less force to move it one direction than the other direction. Now this is TISSUE STRESS at its BEST and should be one of the cornerstones for anyone stating they believe in tissue stress theory. However some serious scientific work needs to be done on this idea to see if it holds water, i.e. we would need to put strain gauges on all of the tendons and ligaments that cross the joint, and then measure the total strain in all of the structures as the STJ was moved through its total range of motion.

    I will address your other points about the relationship between motions in the MTJ and the STJ later. I believe Clint Jones wrote an interesting viewpoint a few years ago (btw - Clint felt that some of writers on this arena really unfairly rubbished him) which he dubbed "wring theory". I have told him that what he wrote was really describing in different words was MacConnail's twisted plate theory. I have found that very few people, including the medical students I teach, have very little confusion in this concept.

    Thanks
    Daryl
     
  40. Not having the time currently to directly address the comments of others here, I am including a discussion here that I wrote on the subtalar joint "neutral position" from a month ago.

    Inaccuracies in Root et al Theory: Is Subtalar Joint Neutral Position a Scientifically Valid Measure?

    What is the subtalar joint (STJ) “neutral position”? Merton Root, DPM, and his colleagues, John Weed, DPM and William Orien, DPM, popularized the concept of the STJ “neutral position” as a midrange position within the range of motion of the STJ that they felt was the optimal position for the foot to function in. Unfortunately, the STJ neutral position itself is a rotational position of the STJ that has never been adequately defined in a scientific manner. A precise anatomical definition of the STJ neutral position (i.e. knowing exactly where the articular facets of the talus and calcaneus articular facets are in relation to each other) is necessary for researchers to determine whether Dr. Root’s theories are reliable and accurate. Currently, the STJ neutral position is not a scientifically valid measure of rotational position of the STJ.

    The definition for STJ neutral position used by Root and co-workers is “that position of the subtalar joint in which the foot is neither pronated or supinated.” Root et al's definition of the STJ neutral position as being “neither pronated or supinated,” is a big problem. It is likely the best example of a tautology or "circular reasoning" within podiatric biomechanics (Root ML, Orien WP, Weed JH. Normal and Abnormal Function of the Foot. Clinical Biomechanics Corp., Los Angeles, CA, 1977). How do you scientifically test for something that can't be defined? Answer: you can't!

    Tautology is defined as “the saying of the same thing twice in different words, generally considered to be a fault of style”. The tautology of Root et al’s definition of STJ neutral position is very easy to see. When I first heard this definition of STJ neutral position as a 1st or 2nd year podiatry student at the California College of Podiatric Medicine over 35 years ago, I remember a very uncomfortable feeling that something just wasn't right about the terms "pronated" or "supinated" being used within the definition of the neutral position of the STJ.

    Using Root et al’s definition of STJ neutral position we must first be able to determine whether the foot is “pronated” or “supinated”. Said another way, we must first determine where within the STJ range of motion STJ neutral is in order to determine whether the foot is “pronated from neutral” or “supinated from neutral”. However, since Root et al defined STJ neutral position as being “that position of the subtalar joint in which the foot is neither pronated or supinated”, then their definition of STJ neutral is a circular, or a tautological definition. In other words, until the clinician decides where “neutral position” is within the STJ range of motion, they can’t decide whether a certain STJ rotational position is either "pronated" or "supinated" from “neutral”.

    This lack of a anatomically-based and non-tautological definition for STJ neutral position creates great difficulty for scientific study of the STJ neutral position. In fact, without a proper anatomical definition for STJ neutral, our current concept of STJ neutral has no scientific validity. It is non-testable for scientific purposes.

    In other words, without the definition of "STJ neutral" having assigned to it precise reference to the three-dimensional relationship of the articular facets of the talus relative to the articular facets of the calcaneus, we have no testable definition for STJ neutral. In addition, we don't have a single method for clinical examination for STJ neutral position that can be reproduced reliably by different examiners. As a result, there are large inter-examiner errors in determining “the” STJ neutral position. The result of this large inter-examiner error is that one examiner may determine the STJ neutral position as being possibly 2-3 degrees pronated or supinated away from another examiner’s determination of STJ neutral, both of them saying that they have found “the” STJ neutral position, and both of them also thinking the other examiner is wrong.

    I learned six techniques for determining STJ neutral position during my student years and during my year of Biomechanics Fellowship at the California College of Podiatric Medicine (CCPM) from 1984-1985. These are as follows:

    1) Palpation of the talo-navicular joint for “congruency”. This method is popular, and seems to have been mostly promoted initially on the east coast of the United States during the 1970s. However, the talo-navicular joint is not the STJ and, for that reason, both Drs. Root and Weed condemned the talo-navicular palpation method of determining STJ neutral as being inaccurate in the lectures I heard them give and my conversations with them.

    2) Palpation of the talo-calcaneal joint for “congruency”. I heard Dr. Root lecture on this subject many times but never saw anyone demonstrate it or reproduce it in all my years of working with Dr. Weed, Dr. Ron Valmassy, Dr. Chris Smith, Dr. Richard Blake, Dr. John Marczalec, Dr. William Sanner and Dr. Lester Jones, all of whom were Dr. Root’s students and taught biomechanics at CCPM during my student years and my year as Biomechanics Fellow. In all my studies of the STJ, I have never been able to reliably palpate the margins of the STJ clinically, even in the most thin patients. I don't believe it can be done reliably on a large range of patients.

    3) Curves superior and inferior to the lateral malleolus. This method is described in Root et al’s first book (Root ML, Orien WP, Weed JH, RJ Hughes: Biomechanical Examination of the Foot, Volume 1. Clinical Biomechanics Corporation, Los Angeles, 1971, pp. 118-121). However, this method was considered to be a secondary method and not overly reliable or accurate by the professors of biomechanics at CCPM probably due to its range of error and the large variability in shape of the lateral malleolus.

    4) Skin lines in sinus tarsi. This was a favorite method of Dr. Chris Smith, one of my biomechanics professors at CCPM, and involved pronating then supinating the STJ until the skin lines within the sinus tarsi of the STJ were “relaxed” or visible but not stretched. Again, there is likely a fairly large range of error in this method from one examiner to another and I saw no other professors at CCPM use Dr. Smith's technique.

    5) Feeling for “flat spot” within range of motion of the STJ. This was the technique for determining STJ neutral position which was most heavily favored by the biomechanics professors at CCPM and is the technique which I still use to determine the "STJ neutral position". Unfortunately, there has been no research on using this method to see how accurate and reproducible it is. My educated guess is that the "flat spot" within the range of motion of the STJ represents the point of maximum congruency between the posterior articulating facets of the talus and calcaneus within the range of motion of the STJ.

    6) 1/3rd-2/3rd method. Root et al taught that the STJ neutral position is that position where the supination range of motion is twice that of the pronation range of motion. "From the neutral position of the subtalar joint, two-thirds of the total prange of frontal plane motion is inversion (with supination) , and one-third is eversion (with pronation: giving a ration of 2:1 ((Root ML, Orien WP, Weed JH, RJ Hughes: Biomechanical Examination of the Foot, Volume 1. Clinical Biomechanics Corporation, Los Angeles, 1971, pp. 38). None of the biomechanics professors at CCPM used this method when teaching in the biomechanics clinic at CCPM. However, Dr. Weed taught us this method during our second year of podiatry school at CCPM, that we were tested on.

    In conclusion, there are significant problems with scientifically attempting to study the "STJ neutral position" due to the lack of a firm scientific definition for neutral position in the STJ. As such, the concept of a "STJ neutral position" is likely not scientifically valid. Large inter-examiner errors occur when determining STJ neutral position which make all such studies which use STJ neutral position as part of their research potentially meaningless or suspect.

    That is not to say that the STJ neutral position concept is not a useful clinical and theoretical concept. It would be helpful to know, both clinically and for scientific research, exactly when a STJ is "pronated" and when a STJ is "supinated". However, until we can scientifically validate where exactly the talar articular facets should be relative to the calcaneal articular facets of the talo-calcaneal joint, the "STJ neutral position” must be treated as an unreliable clinical measurement. In other words, "the STJ neutral position" that we determine clinically is currently, at best, simply an approximation of a mid-range of motion measurement of the STJ that will vary significantly from one clinician to another. As a result, when "STJ neutral position" is seen in any research on foot biomechanics, the research must be viewed with a very critical eye and assumed to be of little value scientifically.
     
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