Challenging SALRE

Pressure is a vector and so the arrow analogy is actually a good one. If you have equal force under every contact point of the foot the CoP will be in the centre of the contact points, in your imagined example this point is unlikely to be under the navicular, due to it's positioning relative to the rest of the plantar surface of the foot. Furthermore, because of the surface geometry of an orthosis, the stresses and strains developed within it under loading and especially during dynamic loading are not even, hence there will always be localised focusing of orthoses reaction forces, no matter how smooth your curves. Indeed, due to step to step variation and variation in ground reaction forces during functional activities it is not currently possible to manufacture an orthosis that could achieve this. AND, you wont manage to supinate the STJ if your CoP is the wrong side of the axis. Moreover if the CoP is directly beneath the STJ axis as in the moot point all that can be achieved is compression at the STJ. In this case, increase loading of the navicular and it's restraining structures seems a reasonable response to the force. I'd love you to explain CoP to me and everyone else here. Please go ahead, perhaps you could dress in a chicken suit to do it...

 

Simon

IE like this



Dave

 

They don't appear to be.

Not talking about the resultant force vector of the frictional force, talking about the overall net vector.

Not tonight, I'm too busy, will come back to this when I have some more time- I'm preparing lectures for conferences at the moment. There are diagram's that accompany this, so I'll copy them for you when I get time.

 

I think the confusion stems from the other forces that may be acting upon the body on the inclined plane to either draw it up or down the plane. I was thinking that the foot would be sliding against the orthoses due to the action of muscles- effectively being either drawn up or down the inclined planes of the shells surface geometry.

 

Simon,
Good point, sir. I certainly see how a foot -orthotic interface could experience friction as the foot tries to slide down the steeper m/l inclination. I will not say that this phenomena does not happen at all, but it is far less of a problem than one would think. I think that the explanation for this is anatomical. It really becomes clear when you have a giant calcaneus/talus to move around. Understanding this explains how subtalar arthrorhesis procedures work so well. In order for the talus to externally rotate, the anterior facet of the STJ must be approaching level or level.
This occurs at higher calcaneal inclination angles where the STJ axis is more vertical and lateral. It is only after the lateral rotation, that the sinus tarsi opens enough to insert the implant. When the talus is held that degree of external rotation, and the implant only has to block a primarily transverse plane rotation, there is far less compression force on the implant and this posture keeps the inclination angle of the calcaneus high. Mostly that is because the medial collumn of the foot over-rides the lateral column adding greatly to midfoot stability. The change in posture that is typical of these procedures if done properly is often surprisingly good, especially with the more advanced implants like the hypro-cure. To go off on a tangent, if you don't mind, it has been curious to me of late that we, as a profession are taking patients into the operating room to create a more functional posture and yet have not demanded that from our orthoses. Back to the point. At first glance it would seem that these implants should do damage. In fact, in my DVD, I say that they restrict too much motion. I have since modified my position on that. At one time, I would have feared that the pronatory forces would still be in effect, putting tremendous pressure on the implant. Eventually Titanium would win out over bone and cause iatrogenic pathologic fractures. Although they do restrict motion, I have spoken to numerous doctors who have done large numbers of these procedures and report minimal side effects. The reason is that when the talus is externally rotated, the rearfoot is in a functional zone where it takes little force to externally and internally rotate the talus but a lot of force to change the inclination angle of the calcaneus, which could in part be due to the archway bridge structure that Dr. Shavelson speaks of. The arch becomes relatively more self supporting....that is there is less force necessary to support a supinated foot, regardless of its neutral position. This occurs mostly because of the translation (not rotation) of the STJ axis that occurs as the foot supinates.
There is a relatively small amount or rotation that occurs around the STJ axis during gait at all. Although some rotation around the STJ axis occurs throughout pronation and supination of the foot, the majority of STJ motion occurs near the supinated end of its ROM when the anterior facet is level.

So, how does this relate to sliding down the slope of the orthoses. A more self supporting foot (one that takes less force to supinate) will necessarily also cause less m/l friction.

What is far greater a problem is the friction that comes the instant that the orthoses contacts the skin. I think that most practitioners don't realize that the impact forces that we all would love to dampen are the impact forces of pronation itself. If the foot is allowed to gain considerable momentum by dropping from supination down to pronation before it hits the top of the orthotic, considerable momentum devleops which must be dampened as well. A higher, full contact device reduces friction in two other important ways that far outweigh the slope problem. Firstly, full contact means that the semiflexible shell moves with the skin instead of against it. This grossly reduces shearing forces. Secondly the height of the arch reduces impact forces because the foot does not have to drop down to the orhtotic shell, but instead remains in full contact with it.

So how does this apply in the real world. Firstly, at one time this was a problem for my company and a small source of warranties (a bad thing). We experimented with several things and what turned out to be the solution was to completely preserve and contours to the plantar lateral surface of the foot in the lateral shell. On rare occasion when this is a problem we do have to slightly increase the height of the lateral shell. I am not sure that this modification would not be helpful to more patients but I think it would also interfere with shoe fit.

Its funny, running an orthotic lab is a huge RTC if accurate data is collected. It is a continuous ongoing experiment with a massive N (I think we did 58,000 last year) and much more this year. It is also double blinded. Neither the practitioner nor the patient nor the data collection taker (in this case our QC and technical support staff) are aware that data is being collected. When I hear postulates on how my lab creates a product that must do this or that, I have real data which I certainly do not mind sharing. We have a no questions asked, 6 mos. 50% refund policy. I assure you that all orthoses returned to practitioners in that time period are sent back. Of course some patients keep orthoses that don't work (we've all had the patient that comes in with a bag of orthotics). We call that stat: RMA which is 0.3%. Keep in mind when we ask, the number one reason for returns is that the patient did not come in to pick them up. Maybe they felt better after taping or a cortisone shot or they wore the night splint or actually did the stretching exercises that their practitioner demonstrated. I guess that happens too.

Is this what David's frictional force diagrams were about? That would be a criticism of MASS theory. We'll get to that later. This thread is about finding the flaws in the SALRE theory.

Best Regards,
Ed

 

Hey, that's one strategy. Instead of answering any of my questions, maybe you can ignore the biomechanical problems with SALRE by dismissing my points as "ramblings" when they challenge the very assumptions upon which your theory is based. I will repost it in non-pdf form with slight restructuring as Eric requested and put the pictures to the end. To help you I will highlight the questions.

BTW. My name is Ed Glaser, DPM (but you can call me Ed) and I am proud to share the title of "lab owner" with the likes of Sheerer, Langer, Wernick, Burns, Schuster, Chris Smith, Ruch and Jeff Root among others.

I am not rushing you, you should give it some thought.

In other words, you are suggesting that you leave the collapsed foot in an over pronated posture and worry about herding the tissue stresses around the plantar surface of the foot. But you have decided that is preferable to think that you are herding the stresses around (kinetics) by changing rotational equilibrium the foot around a singular axis. If you are going to leave the foot flat, you are always going to have a dysfunctional gait. Form follows function. Maybe that should be reworded: Symptom reduction follows tissue stress redistribution. I would rather think that it should be rephrased; Form and Function are Inter-dependant. Ultimately the dampening caused by hitting the orthotic with resultant soft tissue compression in the arch at or near the end of pronation is adequate to mask symptoms. Otherwise, prefabs that make no attempt to balance m/l GRF would preform far far worse than customs. Besides, even if you just wanted to dampen the impact forces of pronation would it not be more effective to begin in full contact with the plastic in a far greater amount of supination and begin the dampening with a spring action of the plastic because of its modulus of elasticity and calibrated thickness.

Remember, I have never said that rotational equilibrium does not occur. As I said, it is a Newtonian certainty around any axis. It is just that this approach leads practitioners to make flat orthoses with various tilts. Kogler's study refutes this and Craig told me of some data he had collected where a significant number of patients standing on varus wedges increased their calcaneal eversion. Then you suggest in your newsletters to add forefoot pads as well. This is all the same....herding tissue stresses instead of changing functional posture. No doubt, it is more difficult to get used to functional inserts however on the other side of the hump (which the overwhelming majority of patients have little problem with) is a more functional foot posture.

I guess if you are going to be satisfied with function at the end of pronation, all you have left is rotational moments and tissue stress dampening.

You could substitute flat feet or foot over-pronation for "medial deviation of the STJ axis and excessive external STJ pronation moments" and be 100% correct.
Why take a complex postural change, simplify it to a single axis 2D physics problem and then re-complicate it with excessive verbage that means the same thing. Oh, because you are not creating a postural change... I forgot that kinematics are unimportant to you.

But is it even the most important factor?

In other words, wherever the most pronated end of the ROM is, that is where SARLE predicts some component of your force redistribution occurs because orthotics made from this theory will not attempt significant changes in foot posture. Is that the best correction that orthosis managment has to offer?

This is what I mean by concentrating on one axis of many....and maybe not even the most significant one.

One needs to know the spatial location in all three planes. And in what posture? In its corrected posture or pinned to the endpoint of pronation where you deal only with kinetics. I would rather make a kinematic change, re-posturing of the foot, in preparation to heel strike that then allows the foot to go through a more controlled postural change during gait, yes a kinematic change, and hopefully never reaching the depths of the endpoint of pronation or reaching it much slower with less momentum and far less impulse (impact).

It is very hard to critique a biomechanical model in a vacuum. I must compare it to something. If a model were wrong, but the best we had at a particular moment then why discuss it.....unless we were formulating a new model. I am comparing two theoretical approaches that form distinct clinical pathways and treatment protocols.

One approach allows the foot to drop to near the end of its ROM to full pronation and deals with force distributions as it relates to rotation around a singular axis in that posture in order to change kinetic re-balancing around that axis.

Another paradigm chooses to create a support that attempts to make a significant change in foot posture to restore function.

Let's say both methods produced an equally comfortable orthotic, which pathway would you choose?

Respectfully,
Ed

PS: I am at home now, Don sent the Word file to me onto our office server so I will repost my full critique as Eric and Robert suggested tomorrow. I will try to reorganize it and be more concise without losing meaning.

 

Ed:

I would love to discuss my theory on how the spatial location of the subtalar joint (STJ) axis and how the physics concept of rotational equilibrium may affect the kinetics of the foot. Please, if you want to critique my theory, then indicate which points that are contained within my theory that you feel are not supported by scientific logic, physics principles or engineering concepts. Maybe this will allow us to have a useful and meaningful discussion. Also it would help if you provided references to support your critique since my paper on Subtalar Joint Axis Location and Rotaional Equilibrium (SALRE) Theory of Foot Function is well-referenced.

I would also appreciate it if you could include why you think that Steve Piazza, PhD, and his paper on STJ function is wrong since this mechanical engineer/biomechanics PhD seems to think that my ideas and research were worth including in his paper I provided earlier in this thread (Piazza SJ: Mechanics of the subtalar joint and its function during walking. Foot Ankle Clin N Am, 10:425-442, 2005). It is also noteworthy that Dr. Piazza also thinks, along with another mechanical engineer/biomechanics PhD, Greg Lewis, that tracking the STJ axis in cadaver subjects and live subjects are very worthwhile research items:

1. Lewis GS, Kirby KA, Piazza SJ: A motion-based method for location of the subtalar joint axis assessed in cadaver specimens. Presented at 10th Anniversary Meeting of Gait and Clinical Movement Analysis Society in Portland, Oregon. April 7, 2005.
2. Lewis GS, Sommer HJ, Piazza SJ: In vitro assessment of a motion-based optimization method for locating the talocrural and subtalar joint axes. J Biomech Eng. 128:596-603, 2006.
3. Lewis GS, Kirby KA, Piazza SJ: Determination of subtalar joint axis location by restriction of talocrural joint motion. Gait and Posture. 25:63-69, 2007.
4. Lewis GS, Cohen TL, Seisler AR, Kirby KA, Sheehan FT, Piazza SJ: In vivo tests of an Improved method for functional location of the subtalar joint axis. Accepted in J Biomechanics, November 2008.

You may want to also explain why Craig Payne and his coworkers were wrong when they also found a significant correlation of STJ axis location to supination resistance (Payne C, Munteaunu S, Miller K: Position of the subtalar joint axis and resistance of the rearfoot to supination. JAPMA, 93(2):131-135, 2003). In addition, you should explain to all of us why the mechanical engineers that I did a bicycle study with at UC Davis over 16 years ago were wrong when they found a significant correlation of STJ axis locationto knee joint loading forces during cycling (Ruby P, Hull ML, Kirby KA, Jenkins DW: The effect of lower-limb anatomy on knee loads during seated cycling. J Biomech, 25 (10): 1195-1207, 1992). While you are working on this project, maybe you could also explain to all of us why you think that multiple recent foot orthosis studies performed in the last 5 years:

1. Mundermann A, Nigg BM, Humble RN, Stefanyshyn DJ. Foot orthoses affect lower extremity kinematics and kinetics during running. Clin Biomech, 18:254-262, 2003a.
2. Williams DS, McClay-Davis I, Baitch SP: Effect of inverted orthoses on lower extremity mechanics in runners. Med. Sci. Sports Exerc. 35:2060-2068, 2003.
3. MacLean C, Davis IM, Hamill J: Influence of a custom foot intervention on lower extremity dynamics in healthy runners. Clin Biomech, 21:621-630, 2006.
4. MacLean CL, Davis IS, Hamill J: Short and long-term influences of a custom foot orthotic intervention on lower extremity dynamics. Clin J Sport Med, 18:338-343, 2008.

are all wrong when they have been shown to be consistent with my prediction of 16 years ago that foot orthoses work to limit pronation in the foot by increasing the external STJ supination moments on the foot (Kirby KA, Green DR: Evaluation and Nonoperative Management of Pes Valgus, pp. 295-327, in DeValentine, S.(ed), Foot and Ankle Disorders in Children. Churchill-Livingstone, New York, 1992).

These scientists that I have been doing research with over the years (I am not just a "theorist", as you said earlier) have produced significant scientific research that has been published in high-end, peer-reviewed biomechanics journals that support the concepts embodied within the SALRE Theory of Foot Function. The SALRE theory is based on the following papers I have had published over the past 21 years:

1. Kirby KA: Methods for determination of positional variations in the subtalar joint axis. JAPMA, 77: 228-234, 1987.
2. Kirby KA: Rotational equilibrium across the subtalar joint axis. JAPMA, 79: 1-14, 1989.
3. Kirby KA: Subtalar joint axis location and rotational equilibrium theory of foot function. JAPMA, 91:465-488, 2001.

When you finally provide us with references to the scientific literature so that your discussion is not solely based upon your unsupported conjectures as to how you think the foot works, and that also seems to be based on your desirve to financially promote only your orthosis company, then I will take the time to respond. In addition, Ed, we are all still waiting, especially after all your pontificating, for you (and not someone who works for you that you pay to do research for you) to author, or coauthor, even a single published scientific research paper or theoretical paper in a peer-reviewed scientific journal that describes your ideas on foot function. I won't hold my breath.

Hope you and your family have a Happy Thanksgiving.:drinks

 

Ed

No, This was a follow on to Robert's query about the effect of an incline plane on the forces and moments about the STJ.
To know this it might be importtant to know - Can the degree of posting allow direct transmision of these forces without allowing the foot to slide in side the heel cup?
Probably at inclines in the range we use for posting it seems it can but there is a problem on deciding how best to model the mechanics of the effect of a wedge under the heel. The problems being that it is difficult to characterise the action of the wedge as a static model because where in time do you make the analysis? Its fair enough to analyse in terms of forces due to gravity ie vertical forces, what are the horizontal forces at a certain time and position? and how doe they effect the overal action of the incline? What are the true coefficients of friction? what is the force dictribution within the heel cup at any point of interest? How does the heel deform to with the appled forces? When that is done I could do a 3D model and see how the projected force vector from an inclined orthosis might act about the medially deviated STJ.

One could make intuitive assumptions about the force vector of interest eg while braking the reaction force vector would be more posteriorly and laterally deviated from the vertical and during propulsion the vector would be more anteriorly and medially deviated from the vertical, assuming a standard gait function.
The problem with assuming a standard gait function and then projecting non standard forces like those that you might find in a non standard gait function is there is an obvious mismatch. Therefore we need to know real 3D forces which we can collect and characterise in terms of 3D GRF action on the sole of the shoe but not at the foot orthosis interface.

Dave

 

When we look at the friction of the foot-orthoses interface it does not really exist. Most people wear socks. You would really need to examine the friction between the foot and the sock as well as the sock and the orthotic cover material or shell. You would expect that a foot to orthotic coefficient of friction would be very different to the sock to orthotic friction.

Another variable is often the friction between the orthotic and the shoe. The importance of this can be seen by the wear that often exists on the inside of the heel counter.

To calculate the true coefficients of friction then you would have examine all of the possible interfaces that exist.

As orthotics are rarely just even wedges (DC not included) it complicates things to work out the coefficient of friction at a certain location or angle of the orthotic and to have that then be valid for a global friction measure.

 

Steve

Very true but if we want to further our understanding of the mechanics of a system then reductionism to some level is a limitation we have to accept.

To answer you and Ed at the same time I have sketched (scribbled some would say ) a model of the calcaneous with STJ axis (C) orthoganal to the global axis set and tilted 10dgs by the placement of a wedge. The first set of calculations determine the 3D moments about C in terms of the global axis set ie how you might intuitively imagine them in the same axis set of a room for instance. Then I have calculated in the local axis set 10dgs inverted. Then I rotated the axis thru 43dgs of dorsiflexion and recalculated the moments in the local axis set and finally I have recalculated the moments in the local axis set as it is medially rotated by 25dgs. This is not a true 3D cumalitive representation of moments about the STJ axis with 43dgs Dflex and 25dgs medial rotation but rather a representation of moments at each position. However it gives a good idea about how the moments change magnitude and even direction as the axis of interest is rotated withinn the boundaries of the reaction forces. Next I could incline the calcaneous backwards so that we could compare the difference in moments about C. The only problem with this (well not the only problem) one problem with this is that the calcaneous in the stance phase is never likely to lean back except at heel strike, but we wouldn't want to post it that high eh! Would we ED?



So we must have some firm foundation for our deductive reasoning because by merely guesstamating or using intuition to validate a mechanical theory it remains in the realm of metaphysics at best. In which case it becomes difficult to falsify and has a great probability of being rejected than the theory that is based on some accepted axiom and can be considered to be easily falsifiable and therefore has less probability of being rejected. Niether one is true but one is higher up the probability scale of truth than the other. Therefore we need to explore how to falsify the theory, which is what we are attempting to do with SALRE in this thread. While at present we cannot replicate and precisely and reliably measure the actions of the orthosis we need to use simplified models that explore the axioms that support to the theory, if these are easily falsifiable then the theory that they support is also highley likely to be accepted.

In a simple way that is what I am trying to do in this discussion, go back to basics and see how they uphold our intuition and theory. You may notice that a 2D model is more easily understood than a 3D model and so that is a good place to start in my opinion. Unfortunately I don't have the maths to successfully analyse these problems with all the variables, known and unknown, included.

Cheers Dave

 

Kevin,
Whenever you read my postings, take a nice deep breath and relax. Anyone who knows me, knows that I am the most laid back person in the world. I have low blood pressure. My wife says that I don’t have high blood pressure, because am a carrier. I am passionate about learning and this is my subject, too.
You spent over 2200 posts discussing your theory, I think that this is the first time you ever defended it. You freely attack everyone else’s theories and then even under the protection of the ground rules, you dismiss all criticisms. Consider yourself privileged. No such ground rules were in effect when my theory was under attack.
Anyone reading this can see that you have surrounded yourself with believers, even worshipers on this site. No one has the balls to even question what you think….except me. We know that if one accepts all of its assumptions, the physics, engineering and logic works out beautifully. For that, I give you enormous credit.
When evaluating anything, you are determining relative value and relative importance. It is best to first examine its assumptions. If you are given wrong assumptions, then any theory can build a solid set of 2D physics problems, perfectly solved that will work mathematically but not be the best solution to the puzzle. I am not challenging the physics of rotational equilibrium. Newton was 100% clear on that. So your force diagrams all work out. Well done.
What evidence do we have that the primary cause of all foot pronation and supination is a kinetic rotational equilibrium around STJ axis with the foot pinned into near maximal pronation, other than the expert opinion of Kevin who got his information from Root, Orien and Weed. I think that they did a pretty good job with what they had. I think we could do better now.
BTW, We are all jealous that you learned biomechanics directly from the source. I also graduated from the class of 1983. I was accepted to all five schools, in fact California accepted me sight unseen. We could have been classmates. Actually if I had known that a new paradigm of biomechanics recently emerged out of CCPM and its founders were still teaching there, I probably still would have gone to NY. Who knew back then that today we would be this deep into biomechanics? Maybe I am thankful in some way that I was not so influenced by them, that I focused on a singular axis to describe foot function.
It is not sensible to even discuss a theory if we cannot agree on the validity of its basic assumptions. Howard Dananberg, who is quite brilliant, described a biomechanical model wherein Functional Halllux Limitus is cause and pronation more of an effect. His brilliant insight made us first look into the sagittal plane for the solution to this 3D puzzle, the foot. It is my opinion, that his assumption, that foot function revolves around primarily the first MTP stiffness is also incorrect. However neither will I deny that it is present and is a significant factor soon after heel lift; although not dominant. His kinetic wedge is used my thousands of docs. Hey, maybe you disagree with his basic assumption too, and instead find your equilibrium closer to the STJ axis.
If I do not accept that a kinetic equilibrium in a near fully pronated posture designed to redistribute force, to dampen terminal tissue stresses is a worthy goal then the SALRE theory never gets out of the starting gate.
I have read hundreds of posts by you on this arena and all concentrate completely on STJ axis location and equilibrium of moments as the major determining factor in orthotic success. I hate to admit it, but I have read 95% of your writings. The common thread with all of it is the dominant controlling influence of the spatial location of the STJ axis; as if it was primarily influenced by anatomical variation. When even if it were more significant than other axes, its spatial variation in anatomical location is far less than the relative changes in axial location due to foot posture. The math here is relatively easy, David, you seem to be the physics diagram guy, but better yet, I will have Santana, my 3D graphic animator insert a downward force of the leg into an animation of gait which we already have, then place in the relevant axes, first one at a time and then in pairs, to compare the relative forces and their moment arms. We could even vary the magnitude of the force via standard force plate measurements and place the equal and opposite GRF and ORF (as Kevin named it) in temporal sequence. I think that such a model would clearly show axial contribution as it varies according to moment arms, axis locations, etc. In the process you can observe STJ axial translation and how that influences the problem, solution and outcome through postural and non-postural correction. If anyone has criticism of the accuracy of the animations, we can change it and re-render…no problem. The basic bone models came from the ultimate human project in Australia and the animations are done in 3D Studio Maxx. This will of course take more time, but I don’t see this discussion ending any time soon and it will be educational to all….including me. I will call him on Friday. The rest of my company is closed but he works weird hours.
In terms of references, there are none that challenge or support your basic assumptions. If there were, they would not be assumptions. It is for each clinician to decide which model of foot function works for them.

That’s easy. Just look at the titles of the articles. They are not about your model, they are about finding the axis more accurately. You are the biomechanical foot theorist in this group. You have established the relative importance of STJ axis location and they are just assisting you in finding it. I think that Mike Piernowski might disagree far more intelligently about Dr. Piazza’s methodology, but that is not at question here. I’ll guess that all his physics is perfect. He is looking for a way to find the STJ axis because you told him that it is the dominant factor. We’ll soon see if it is.
BTW, this is evidence that your model is about ONE axis ONLY! What is he trying to locate better? If it weren’t your only consideration, then why go to this trouble to accurately pinpoint its location. That location must be so critical. No other factors matters, but if our determination of this singular axis location is off by one mm…….devastating.

Craig was not wrong either. I agree, it takes more force to raise a flat foot than a supinated foot. Do a computer “find and replace” function. Replace “medially deviated STJ axis” with “over pronated foot” and it would be equally true. It is a tribute to you that he even tested your theory or used your verbiage, some of which is excellent, btw. Since STJ axis location is primarily influenced by foot posture his work also makes sense. We already knew that it is harder to support a flat foot than a supinated foot. That is why I encourage practitioners to use a more supinated posture to geometrically model their orthoses after.

Bicycling is a whole other subject which depends on an efficient sagittal plane transfer for force from the gastroc to the pedal. Locking of the STJ in the sagittal plane, will yield more efficient force transfer. We measure 135 cyclists at 100/80/60% Heart rate with an ergometer and found a 2.5% overall improvement in power output comparing no orthotic with MASS position orthotics, with one group (competitive cyclists) increasing 11%. Stu has all the data. Not sure where it is on our list of priorities right now for publication.
Hey these are great baseline studies. I appreciate when people do these. We will soon have data from a university study that we are doing with 6 camera system. That should be interesting to compare except that three out of four of those are on running. We’re still trying to better understand walking. We are hoping that the economy recovers so that we can afford our own 6 camera system in 2009. Hope for Change.

All just expert opinion: How about some RCT’s.
Are you saying that the proof of SALRE is that you have more credentials? An extremely weak argument. Einstein had no credentials when he came up with relativity. Edison only went to school for 3 months, when those with credentials, his teachers, sent him home because he was “addled”, was home schooled by his mom till he was 12, then educated himself. Yet he had 1097 patents including wax paper, the battery and synthetic rubber. Credentials are your badges. Wear them proudly and in good health. They don’t prove anything.

 

Indeed, more here:
http://www.tsb-web.org.tw/isb2007/isb2007-paper/ISB/0781.pdf

http://www.ncbi.nlm.nih.gov/pubmed/16298465

http://tsb-web.org.tw/isb2007/isb2007-paper/ISB/0660.pdf

http://www.wipo.int/pctdb/en/wo.jsp?wo=1998020758&IA=US1997020427&DISPLAY=DESC

 

Robert, Ed and all

The original proposal was to challenge SALRE.

I have re read Kevin Kirby's original paper and some of his other papers and writings related to SALRE and tissue stress reduction.

I have also read Ed's web site and all the papers on Ed's web site plus all his writings here and the earlier attached paper.

I have explored the question of whether friction or the lack of it will negatively affect the SALRE theory and I have evaluated if the 3D nature of reation forces changes significantly the basic premise of the theory as it was explained using 2D models. In both cases I find they do not.

Primarily SALRE merely states the nature of forces acting upon it and how the moments caused by those forces are significantly changed by the spatial position of the STJ axis at any point of interest thru the stance phase of gait.

Secondly SALRE takes the view that the STJ is one of the most important joints of consideration when evaluating foot function in terms of pathological changes.

This second premise seems perfectly sound and has been observed by most and confirmed by experiment by many prominent researchers.

Ed takes the view that

1) SALRE is invalid because wedges placed under the heel cannot resupinate the STJ from a pronated position.

2) The sub talar joint is merely a secondary axis to the heel rocker and is carried along as the heel rotates mostly as a passenger.

3) All the other joints of the foot add up to a more important consideration for foot posture and stability than mereley considering the STJ.

4) The medially deviated STJ axis is a position intimatley related to rearfoor pronation and that posting a foot in this position is little more than useless or lazy at best.

5) The porposed effect of GRF on SALRE is invalidated by the normaly dorsiflexed angle of the STJ IE when considered in 3Dimensions it will not act as proposed by Kirby.

6) That either the STJ is not triplanar or that Kirby has not considered its tri planar aspect in terms of SALRE and only sees it as a see saw.

7) The STJ cannot affect the foot posture or mechanics after heel strike. The shadow of the STJ axis is not as important as SALRE suggests.

8) Fancy maths and modeling is ok but its not real world.

to reply to those premise

1) SALRE is not a blue print for an orthotic design SALRE is an examination of the funtion of the foot in terms of the STJ and the forces acting upon it . SALRE does not conclude that the only way to change the action of the STJ is to use a wedge or skive, even tho it is said by Kirby that these are techniques that can be and are used regularly and in his opinion effectively.

The clinician can now understand the principle of SALRE and apply an orthosis design to suit the foot he is treating and in a way he considers to be the best way to address the required changes in forces and moments that will influence foot posture and pathology.

2) I, and it seems many others, cannot see why the STJ cannot be considered a major or even most influencial joint of action in the consideration of foot mechanics. The application of a MASS paradigm design does not allow uncontrolled or random motion of the STJ. As far as I can see the MASS design merely changes the point of application of forces to achieve the goal of controling pronation about the STJ. In other words the wedge is extrapolated from the heel into the medial arch. The point here is does pushing up under the arch achieve resupination more effectively than the heel wedge and other intergral orthosis design and does it do it safetly. The mechanics of this heel rocker carrying the STJ along for a ride is not clearly explained and has not been observed, published or confirmed by research by any prominent people.


3) Forces acting on all the other joints certainly will alter the foot function but this is covered in detail in the thesis by Kevin Kirby. I.E. The action of forces on joints distal to the STJ will influence the action of the STJ. As Kirby explains, the position of the foot and its joints relative to the STJ will profoundly effect the action of the STJ and by implication the opposite would also be true.

4) First, posting is not part of the theory or premise of SALRE. So to criticise SALRE on this basis is illogical. Secondly, a medially deviated / rotated STJ axis is a feature of a foot in any position you choose to assess it in. It is a relative position of reference not an absolute position. SALRE merely states how the action of the foot is changed by the relative position of the STJ axis be it lateral or medial.

5) With the exception of the STJ obtaining a completely global vertical aspect, however the normal spatial location of the STJ axis is set the deviation of that axis in the global transverse plane will affect how the forces and the magnitude and direction of the moments act about it. Forces lateral to it will tend to increase pronation moments. Even so in terms of the local axis set the lateral forces will always cause eversion or a -x rotation.

6) Since I'm not clear as to the meaning then - 1)The triplanar nature is well considered. 2) The STJ does have a triplanar action and it would be rediculous to propose it does not. Kirby characterises the STJ as a see saw for the benifit of communication of the idea to clinicians who are not trained in mechanics. He does not believe the action is the same as a see saw only analogous to it. This seems obvious to most but is a large point made by certain detractors.

7) The reason why the fore foot strike affects the action of the STJ is due to the nature of the projection of the STJ axis. As long as there is a physical connection then the shadow of the axis is as long as it needs to be. This is a basic principle that should be understod by anyone particularly those critiquing mechanical theories and designing engineered products.

8) How, in the real world, do you design engineer and manufacture a product like a new orthosis without maths and modeling and how can you prove your research or refute others without those tools.

Just say It really works enough times and loud enough for enough people to listen presumably Sorry Robert, just a small dig for the detractor there.
Faynites!

I think the detractors of SALRE, which are few, seem not to realise the following point:

The consideration of the foot or even the whole body as a mechanism within the boundaries of Newtonian mechanics is a sound premise. Clearly it does not propose to constrain the user of the principle to any pre determined orthotic constuction design or even to use an orthosis at all.

Certainly it does not promote the use of one type or make of orthosis over another. What it does do is allow the skillful proponent to reach well considered conclusions using deductive reasoning based on a solid foundation of physics. How then the resolution of pathology is implemented is down to the individual clinician. MASS might be a tool that he or she might sometimes use, however they will always utilize the system of mechanics and SALRE is mereley a part of that useful system.

To conclude, SALRE is the principles of Newtonian mechanics applied to the STJ in particular nothing more or less than that. It is not a reccomendation of a certain orthotic design. This then should be the basis of any critique.

All the best Dave Smith

 

Ed, before you reply you should take a deep breath. Remember attack the idea not the person.

Not that the reason that people come to the website is related to SALRE, I do not have the sense that we are all here on podiatry arena to surround Kevin and boost his ego. Attack the idea not the arena.

Are you, or are you not questioning that motion around the STJ axis is determined by Newtonian physics. What assumption are you questioning? Are you making the distinction between foot pronation and STJ pronation?

Ed, I don't really have a problem with going off topic, but I don't think you should complain when others do.

Could you expand on your last sentence. I'll bring in another theory related to SALRE. The tissue stress approach to foot biomechanics. The theory goes that when anatomical structures are placed under too much stress, injury will occur. Treatment of overstressed painful structures is based upon reducing stress on those structures without shifting too much force to other structures. We decide how to design an orthosis by modeling the injured structure and then incorporating design features into the orthotic that were determined from the modeling to reduce stress on the structure. Some of the time this will involve SALRE. A prime example is peroneal tendonits. These patients feel better when you increase the pronation moment and pronated position of the STJ.

If the patient's symptoms are relieved in a maximally pronated position why do we need to do more? Could you explain to me what is wrong with relieving pain in the maximally pronated position?

More later.

Eric

 

Kevin wrote:
I agree. STJ axis location is only one variable that affects the kinetics of the foot.
Ed replied:
But is it even the most important factor?

Eric Replies:
I agree with Kevin that STJ axis location is a very important factor in foot pathology. Ed, are you saying it is not important? Why?

Kevin wrote:
However, a factor that superficially seems unrelated to STJ axis location, such as a reduced or excessive STJ range of motion (ROM) may also significantly affect STJ kinetics. For example, an excessive STJ pronation ROM may affect STJ axis spatial location by allowing more medial translation/internal rotation of the STJ axis (due to more medial translation/internal rotation of the talar head/neck relative to the plantar foot) during weightbearing activities and thus increase the external STJ pronation moments when compared to normal. In addition, if there is a severe restriction of STJ eversion ROM, then this may cause the maximally pronated position of the STJ to have a relatively lateral STJ spatial location that may cause the foot to not only be maximally pronated at the STJ but also be laterally unstable. This unusual combination of mechanical circumstances can be seen in congenital varus "clubfoot" conditions where calcaneus is highly inverted in the STJ maximally pronated position .

Ed replied to Kevin:
In other words, wherever the most pronated end of the ROM is, that is where SARLE predicts some component of your force redistribution occurs because orthotics made from this theory will not attempt significant changes in foot posture. Is that the best correction that orthosis managment has to offer?

Eric Replies to Ed: Ed, is pain relief your goal? If pain is relieved and prevented why do we care about posture?


Kevin
Both walking and running, and any other weightbearing activity for that matter, will be affected by the spatial location of the STJ axis.
Ed replied:
This is what I mean by concentrating on one axis of many....and maybe not even the most significant one.

Eric asks Ed:
What is wrong with paying attention to the STJ axis? Where is the criticism of SARLE


Ed replied to Kevin:
One needs to know the spatial location in all three planes. And in what posture? In its corrected posture or pinned to the endpoint of pronation where you deal only with kinetics.

Eric replies to Ed:
To apply SARLE you don't need to know the position of the axis in all three planes to change the moments. I would agree that you would have to know the position of the axis in all three planes to calculate the moment, but we don't need to calculate it, we only need to change it. If we don't change the position of the joints, we can assume that the axis is in the same position before and after the intervention. Then, if we had shifted the location of the center of pressure under the foot, in the correct direction, we know we have changed the moment in the correct direction. If the symptoms are not relieved we will know that the center of pressure should be pushed farther in the direction that the model would predict. This is the usefulness of SALRE. From modelling we can figure out what moment is required. That way we don't attempt to supinate feet that need to be pronated.

Ed, can you explain why we need to worry about being pinned to the endpoint of range of motion? How do you or I know what is the best posture of the foot?


Ed wrote:
Let's say both methods produced an equally comfortable orthotic, which pathway would you choose?

Eric answers:
I would choose the one that puts the least stress on the most structures. If this was equal, I would not care which orthotic I wore, if they both relieved my symptoms. Ed, would you wear an SARLE orthotic if it relieved your symptoms? If not, why not?

Respectfully,

Eric

 

To Kevin, Eric and all following this discussion:
This thread is called Challenging SALRE . I thought it might be nice to actually challenge it.
Before I even begin my critique of the SALRE theory, let me discuss Kevin’s and Eric’s answers to my original question. Why does pushing up on the arch, lateral to the STJ axis cause a pronation moment but results in supination?
Kevin explains that the STJ axis acts like the fulcrum of a see saw and that part of the plantar pressure lateral to the axis is moved more medially when pressing up on the arch, decreasing its lever arm and therefore decreasing the pronation moment.
If that was true, then Kevin and Eric have a major conflict. Eric says that his arch drops when you push up on it, except when the force is applied at a point medial to his Medially Deviated STJ Axis. When you push up on his arch, it goes down. That is very strange, and I have never seen anyone else exhibit that but Eric is observing it.
If Kevin’s explanation was correct then the upward force applied to the medial navicular which lies just medial to the medially deviated axis (MDA), would have a similar effect to the upward force applied in the MLA lateral to the axis. Decreasing the net supination moment by offloading forces more medial to the axis.…..causing foot pronation. Again, that is where Eric exhibits supination. Who is right here, Kevin or Eric? You both seem to be on the same side but saying the exact opposite thing. Simon then suggests what would happen if the COP were a arrow instead of the net effect of a widely distributed force and tries to dislocate the navicular or strain the spring ligament to raise the arch.
Certainly anyone can easily see that pushing up on the arch will raise the arch. In Kevin’s supination resistance test you lift the arch with two fingers. What are you doing? Applying a vertical force to the arch and raising it. What else raises the arch… external leg rotation, windlass, and muscular contraction. I have never seen someone lower the arch by pushing up on it in the closed chain. Whether or not it is hard or easy to resupinate it will always go up when you push it up. This is a pretty easy experiment to do. Take a child and push up on their arch. I just did and it went up. I don’t think that this is a geographical phenomena.
Before I begin my critique, let me separate two things here: STJ pronation/supination vs Foot pronation/supination
Closed Chain Supination of the Foot (CCSF)….which is a change in POSTURE which involves increasing the height of the MLA. This involves a complex series of bony interactions which reposition bones in all three planes and works around a multitude of axes….most of which are sagittal plane as evidenced by the fact that the foot shortens in supination indicating that it is decreasing the radius of the arc of the MLA . CCSF increases arch height.
Closed Chain Pronation of the Foot (CCPF)…. which is a change in POSTURE which involves decreasing the height of the MLA. This involves a complex series of bony interactions which reposition bones in all three planes and works around a multitude of axes….most of which are sagittal plane as evidenced by the fact that the foot elongates in pronation indicating that it is increasing the radius of the arc of the MLA. CCPF decreases arch height.
Open chain STJ pronation and supination which consists of a rotation around a single axis between the talus and calcaneus. When talking of moments and forces it is convenient to oversimplify and reduce the problem to a see saw as you did here and in your article. But that see saw must be triplanar and not its shadow on the horizontal (plantar parallel) plane.
Closed chain STJ pronation and supination which is specifically the rotation which occurs around the STJ axis during CCSF and CCPF. This is picking our just the rotation of one of the many joint axes and looking only at its individual movement or equilibrium.
(abbreviations are only meant to save me time….thanks).
Comment: Rotational Equilibrium is a simple Newtonian certainty around any axis. It is basic first semester physics. I have no disagreement that it exists around every axis of the body. It is the SAL of SALRE that is questionable.
Now, to a broader critique.
In order to evaluate the theoretical model of Kirby, the SALRE theory, you must first look at the assumption it is based on.
The following assumptions, which are the very heart of this theory, are questionable:
1. The assumption that the STJ axis is the only relevant axis of motion determining pronation and supination of the foot and that the foot functions as a uniplanar seesaw around it. The foot has many joints that contribute to foot pronation and supination both between numerous bones and between the heel and ground (heel rocker axis) and between the forefoot and ground (MTP rocker axis).
2. SALRE theory further reduces the complexity of closed chain foot function to forces acting on either side of a singular axis’ projection onto the transverse plane. Not using the axis itself, but its shadow in the transverse body plane or plantar parallel position. This makes the axis primarily a frontal plane axis although in actuality it may vary considerably from this plane.
3. It also assumes, by omission of any discussion of it, that closed chain foot posture is irrelevant to corrective strategy. The foot, apparently, has only a normal or deviated STJ axis. This implies that foot function is solely determined by a given axis type (ie: Medially Deviated STJ Axis (MDA) = over-pronated foot) which is the transverse plane projection (2D) when the foot is held in the open chain in the “plantar parallel” position. This position involves making the weight bearing surface, without an orthotic, on a plane that would represent the ground or horizontal plane. The foot must usually dorsiflex to achieve this position through the application of pressure on the distal plantar surface of the forefoot. This will necessarily yield a more pronated if not fully compensated posture.
4. It assumes that this plantar parallel itself can be accurately and reliably estimated.
5. Another assumption is that the timing of corrective forces is irrelevant, whether they occur at the heel strike or after the foot has fully pronated.
6. A sixth assumption is that the pronation of the foot (raising and lowering of the MLA) is in a 1:1 relationship with rotation around the STJ axis.
7. Also it must be assumed that the orthotic correction does not make a postural change in the foot, for the measurements to have relevance. If for example the foot is severely pronated with considerable flexibility, it will exhibit a Medially Deviated Axis in the plantar parallel position, and the most corrective posture for that foot might be 30 degrees higher in calcaneal inclination angle. The location of the STJ axis when fully compensated has little significance compared to the actual 3D triplane orientation of the axis which will contribute somewhat to foot function following corrective orthotic control.
There are numerous other questionable assumptions but for brevity, I think that these seven may suffice for now.

One has to agree to these assumptions to even accept the theory itself.
The foot has a complex, tri-planar, three dimensional architecture, the shape or posture of which determines its actual degree of supination or pronation and therefore its function on the ground. Within this complex of 26 bones and 33 joints there are many axes involved in the movement from supinated posture to pronated and vice versa. Some joints, such as the STJ, exhibit a somewhat singular axis which may dramatically change its orientation for various postures of the foot. Some axes are probably more critical than others, but to say that the forces acting around the STJ axis are the singular determinant of whether a foot pronates excessively or not seems arbitrary. A foot, at mid-stance, that has seen its arch collapse to the floor will indeed have a medially deviated STJ axis at that point. But all the medial-to-the-axis force in the world is functionally useless unless a re-supinated posture of the foot is restored prior to heel lift. It can modify tissue stresses for symptomatic relief but restoring posture is the most therapeutic goal.
Any argument over the theory and strategy of foot correction should begin with an agreement about the goals of correction. Postural restoration is superior to tissue stress modification whenever foot flexibility allows it. It is also a universally held truth in all of orthopedic medicine that form or posture and function are interdependent and that healthy function is the key to orthopedic health.
From a mechanical leverage perspective, the foot correction game is lost when the foot is allowed to pronate beyond a certain point. Supination resistance studies support the exponential difference in forces required to re-supinate an over-pronated foot versus a moderately pronated one.
Naturally the pronated foot also exhibits a medially deviated axis. Calling a flat foot a “medially deviated stj axis” is a distinction without a difference; it just rewords in greater complexity the obvious. Therefore controlling foot posture right after heel strike is critical. A collapsing, flexible foot will need a three dimensional template under it in full contact to both limit the extent of pronated posture and assist full re-supination. This respects the fact stated above that pronation and supination are distinct postural shapes in the closed chain rather than a seesaw motions in the open chain. The full contact yields many points of control that comfortably distribute the corrective forces; the full contact model of correction or template is a custom geometry for every foot.
A neutral cast taken off weight bearing is inaccurate (as Craig’s research demonstrated), half pronated and then further arch filled to deliver a low flat smooth invented generic shape. Such a shape should be considered a prefab. To understand what is then done to salvage such a cast you have to look at how podiatry grew up. A practitioner would debride corns and calluses and then make pads to redistribute tissue stresses or herd them around the plantar aspect of the foot. When orthotics came along our predecessors pealed them off the foot and stuck them to the top of the orthotic. All kinds of pads, grooves, apertures, tilts, flanges, were invented as tricks to redistribute plantar forces enough to yield some degree of relief. This approach leads to guru-ism. The guy with the biggest bag of tricks is the guru. In your newsletters each diagnosis is met with a listing of such modifications aimed at herding the tissue stresses around the bottom of the foot.
When the corrective platform mirrors the plantar shape of the corrected postural goal it can resist pronation from all angles, blocking rotation of all tarsal joint axes in all planes simultaneously by its geometric shape –without guesswork. It manages the complexity of foot architecture by emulating it. This is the essence of “custom”. Each cast captures the foot in a corrective posture and tells us how to control it by yielding its unique geometry when we put it in a functional posture. A triplane, three dimensional puzzle gives its own solution. In contrast, SARLE theory takes the complexity of the foot, reduces it to a uniplanar seesaw, then devises a complex system of guesswork to control it.
Insofar as the SARLE model of foot correction does not significantly achieve postural restoration it is not any more useful than other approaches that rely on localized points of plantar pressure.
Now let’s have a more in depth discussion of why these assumptions are not correct or relevant to real anatomy, foot function or clinical intervention:
1. SALRE theory is predicated upon the subtalar joint axis being chosen as the axis about which pronation and supination primarily occurs. Although I have more recently heard Kevin lecture on the MTJ axis as described by Nester being a contributor and nearly parallel to the STJ axis. The same argument of relative forces and moment arms could be made with a multitude of axes. Why is the STJ so special? For example one could use the axis of forward roll of the posterior calcaneus…the Heel Rocker Axis (Jacqueline Perry, MD’s “heel rocker mechanism”, referenced by Dananberg in his article on Sagittal plane biomechanics) . For forward gait it would be as pictured below. If this were chosen as the axis with the greatest influence on CCPF and if Kevin’s explanation of why pushing up in the arch causes supination were correct, a force applied in the arch would have the exact same effect on the Heel Rocker axis among others. Assuming this see saw analogy. Vertical force applied on the supination side of the axis but with a shorter lever arm would offload supination forces with greater lever arms. First criticism is that many axes could be chosen and in fact ALL axes of the foot should be considered relative to their contribution toward changes in Foot Posture and function.
2. I have never seen a foot move like a See Saw during normal gait except in the swing phase.
3. Look at the force distribution at midstance. Look how much of the foot is lateral to the medially deviated STJ axis. This see saw does not have its fulcrum in the center with the same force on each side. The fulcrum is way to one side and a huge over bearing force is on the lateral side. The see saw is pinned to the ground on the distal lateral side. You are forced into full pronation. How much force would it take on the medial side to rock that see saw….enormous force. How much force would it take and with what lever arm to counteract the huge pronation moments around this one axis, let alone around the numerous other axes of the foot. The foot would always therefore seek its maximally pronated posture, stopped only by tension on the plantar tissues or the direct support of the orthotic in the MLA. In other words, the foot will continue to collapse until it either reaches the end of its ROM or is directly supported by the MLA of the orthoses.
4. Temporal Argument: The axis of the STJ moves from a more lateral and vertical at HS to more medial and horizontal at the end of pronation. It has a far greater axial translation than rotation. This occurs to varying degrees dependant on foot type and ROM. As the STJ axis becomes more vertical, there is more transverse plane rotation than frontal plane. The shadow of the STJ axis is projected onto the plantar surface of the foot or a horizontal plane (plantar parallel position) gives it generally a more frontal plane illusion. This encourages practitioners to direct their correction in the frontal plane only via wedges and skives.
5. At what point in the gait cycle are you measuring this axial position? In the plantar parallel position you are applying a forefoot upward force only. It will yield maximal pronated position. You might be able to predict how the foot will behave around this singular axis at maximal pronation. This will only be relevant if you are not making a kinematic or postural change in the foot with an orthotic during the gait cycle as it will predict what will happen at the pronated end of its ROM. If your orthotics a flat enough…this might be relevant. It has very little relevance if you actually desire to affect foot posture and function.
6. At what point in the gait cycle should you be picturing this axis in its triplane orientation? In the closed chain, where the orthotic will primarily function, what foot posture would you choose to capture? Fully pronated? Half pronated? Neutral? MASS? Fully supinated? I have asked this a half dozen times and never gotten an answer. Kevin, What position do YOU cast the foot in? In your newsletters you state that you have never cast the foot in any other way than off weight bearing pop suspension cast in neutral position while lying supine. I have heard you criticize neutral in many posts and publications but have yet to hear what position you actually cast the foot in. I propose a corrective posture: MASS What is yours. Or is the cast so arbitrary that it is not used to communicate the actual geometry of the orthoses? That would leave all corrective forces to be applied by the various additions to the shell. Lumps, bumps, tilts, skives, inverted pours (referenced to what?), flanges grooves and various tricks to eek function out of shells that are just slightly north of fully pronated. After all, podiatry grew up cutting out various pads to herd the tissue stresses from areas of pain to other areas of the foot. You describe these repeatedly in your newsletters. Use this set of modifications for this diagnosis. Prolabs, with Paul Scheerer offers something similar in his design options which he calls “pathology specific orthotics” which is nothing more than a classification of which modifications go with which diagnosis…. Very similar to your recommendations in your newsletters. Walmart and Dr. Scholl ( http://www.footmapping.com ) recently teamed up to offer a low flat smooth generic invented shaped shell with various lumps and bumps. Their goal is to mimic the tissue stress redistribution popular in traditional podiatric orthoses. Should we not differentiate ourselves from Walmart? Two Meta-analysis studies by McPoil’s group and Landorf equate the ability of custom orthoses to mask symptoms. The jury is in. Insurance companies increasingly do not see the additional value of “custom” over prefab. If we are to continue to sell custom orthoses we are going to have to raise the bar. If we make a visible change in the gait cycle by significantly changing foot posture we can claim that prefabs cover up symptoms where customs change function.
7. Now lets look at the actual passage of weight through the foot. COP passage is basic to every pressure mat, F scan and e-med. We have all seen the “ideal” proposed by Elftman and most have seen enough f-scans to get a general idea of what is happening in pronated, normal and supinated feet. See picture above:
How long after heel strike will it be before the COP passes the Medially Deviated Axis, and lies on the lateral side of the axis. Of course, that is why we pronate after heel strike, right.
Again this is true of several axes including the Heel Rocker axis. Which axis contributes more will also be a matter of rotational equilibrium as well, which is a Newtonian certainty. We therefore must look at force magnitudes and lever arms. Pick any point in time. Magnitude and direction of force being identical, it would reduce to a comparison of lever arms.
Lets look at Heel strike, through midstance in three conditions: the normal foot, Medially Deviated Axis and Laterally Deviated Axis. In all three cases, the lever arm is far greater for the Heel Rocker Axis than the STJ axis. Therefore, the heel rocker axis would dominate.
8. In the explanation you gave in response to my question. The vertical force is a COP, meaning that it is not applied as a pinpoint vector on the plantar navicular. It may be treated that way in a simplified force diagram. A vertical force in the arch, if applied through full contact would offload much of the plantar surface of the foot. Ideally it would evenly redistribute the force per unit area on the plantar surface of the foot. Both sides of your see saw would be offloaded although I agree that the lateral side more.
The assumption that pronation of the foot is primarily a rotational phenomena around the STJ axis. This is the very basis of the SALRE theory.
I am not saying that the STJ axis has no role or function. Nor am I challenging the fact that some rotation around the axis occurs.
It is more likely that the Heel Rocker Axis has a greater effect.
Graphs in Root's book of STJ motion show a 6 degree motion of the STJ during stance phase. Two degrees supination and four degrees pronation. You may question the accuracy of these findings. Six degrees however does not explain the amount of pronation that we observe in the foot.
The heel is essentially round on its plantar posterior surface....where heel strike occurs. This allows the heel rocker mechanism, on first approximation, to act as a ball rolling forward. Alternatively one might consider the pivot point to be the where the heel contacts the ground. This forward roll is obviously caused by the moment arm between the force coming down the leg and its instantaneous pivot point on the plantar posterior heel. A round heel’s choice of axes is large because a ball can roll in any direction. For forward gait it can be estimated as primarily sagittal plane with the axis pointed slightly anterior lateral to posterior medial, accounting for the forward and slightly medial roll of the calcaneus from heel strike through maximal pronation. This axis accounts for much more of the phenomena of pronation of the foot than STJ rotation. If one were to choose a singular axis as being most important, they might consider the Heel Rocker Axis.
Now lets think about the relationship between rotation around the axis in the closed chain with foot pronation and supination. Is it a 1:1 relationship? My observation, although I have no real data here, is that when going from a pronated to a more supinated posture, most the actual rotation around the axis in the closed chain occurs on the supinated end of its ROM. Very little actual rotation is available until the foot reaches a more supinated posture where the anterior facet of the STJ on the calcaneus become at or near level. At that point I begin to observe considerable rotation, but the axis of the STJ is more vertical at that point and most of the actual rotation, which can be seen as tibial external rotation (look at and mark the crest of the tibia to see this) occurs in the transverse plane. I have seen this on several thousand individuals as a byproduct of casting the foot in MASS position. One can postulate therefore that the function of STJ rotation occurs in this zone….which I call the functional zone of foot posture. The function being….to externally rotate the head of the talus so that it rests on a level anterior facet, blocking sagital plane motion between the talus and calcaneus. This creates a rearfoot complex that is rigid in the sagittal plane and allows for a “rigid lever” effect and a propulsive gait.
In the flexible flatfoot (medially deviated axis), when full pronation is reached, the STJ has very little rotation available. It can no longer rotate into pronation because it is at the end of its ROM. Rotation in the direction of supination is limited by the steep valgus angle of the anterior facet. To worry about rotation at this point is too little too late. Why did you allow the foot to even drop to such a pronated posture?
If we know that the foot ideally heel strikes in supination, why would anyone wait until the foot drops all the way to “neutral” before beginning to control its motion? Yet many still cast in neutral.
The STJ axis leaves the plantar posterior foot at the point of heel contact. The ground reactive force is very close or exactly crossing the STJ axis at that moment. There is little or no lever arm, yet pronation occurs at an alarming rate. At that moment, the foot is going from open to closed chain and Kevin’s see saw analogy is most relevant, yet the moment arm is insignificant. The heel rocker axis though has a huge lever arm and what do we observe…..a forward roll of the calcaneus that continues until the ligaments and other plantar tissues reach terminal stretch or the motion is counteracted by an orthotic that supplies an equal and opposite force….creating rotational equilibrium.
So, why then do many practitioners get such great “results” using flatter, even heavily arch filled orthoses? Pronation is a progressive disorder. As we go through life we continue to increase the amount of pronation that occurs until the “tissue stresses” occur faster than healing and one of many possible symptoms is experienced. The orthoses that works at or near the end of pronation is comfortable and reduces symptoms because as we approach this zone….which I call the pathologic zone, the soft tissues are stretched near the end of their ROM and are already dampening the impact force of pronation itself. Now the foot hits the orthotic and the final bit of pronation force is dampened by compression of the soft tissues. This is just enough to mask a symptom without making a significant positive change in foot function and hardly any change in foot posture. Some practitioners will be satisfied with symptomatic cover up, others desire to change foot function. I am among the later.
If symptom cover up was all we expected out of medical care we might choose to bathe in cortisone or have our heart surgeon remove just enough plaque to reduce angina from our coronary vessles. I would prefer my cardiac surgeon to return me a functional open blood vessel to feed the heart muscle. That’s just my opinion….take it for what it’s worth.
The treatment that you prescribe to control over pronation, based on the SALRE theory, consists of tilting the heel in the frontal plane. This may be harmful. Geza Kogler’s study in JBJS showed increased tensile stretch on the plantar fasciae with the addition of varus or valgus rearfoot wedges or posts. Often irregularity in surface geometry, like grass, the sidewalks in NY or the gravel parking lot at my building have a far greater variation in frontal plane tilt than any post of skive and yet I don’t find them particularly therapeutic other than to strengthen core musculature for better balance.
I see a lot of fancy mathematical calculations in single planes that are very interesting. But when you do a bunch of calculating based on wrong assumptions; you get the wrong answer.
Ed

As promised this is a slightly edited reprint of the pdf file. I see none of the picture came through. sorry.
Eric and Robert, I have a busy schedule, I fully intend to answer your posts fully.... have patience please.

 

Of course not. I say that rotational equilibrium is a Newtonian certainty.

There are seven listed in the last post.

Yes, clearly defined in last post.

I elaborate and discuss tissue stress modeling in last post.

Also explained in last post fully. Eric, You are the doc. You make the clinical decision for the patient. If pain relief is all we need, just cut the nerve or better yet, Tom Sgarlatto makes an excellent pain pump.

Cheers,
Ed

 

Wow, not an ounce of substance in the last three paragraphs…..just personal attacks. I especially enjoyed the “flannel, flim flam and humbug to bamboozle those who cannot see thru the illusionism” but I hope the venting was therapeutic for you. Back to the real world, if you don’t mind.

The goal is stated in the article.
“Because of the variability of research fi ndings and the increasing use of custommolded
and -fabricated orthotics to manage foot-related lower extremity problems,
further research is warranted. Therefore, the purpose of the current study was to
investigate the effect of rear-foot- and forefoot-posted custom-molded orthotics
(PAL) and mediolongitudinal-arch-supported custom-molded orthotics (SOLE) on
plantar pressure in participants with ≥7º of forefoot varus over a 6-week period.
Forefoot varus cutoff if greater than 7° was determined based on retrospective
orthotic research conducted by Donatelli et al.14”

I can’t tell here if you are just being childish or are making a point. I may have to call a WAAAMbulance.

You should ask Steven Cobb. He is still in the field of biomechanics. I think this was his Phd thesis.
The Actual Conclusion was:
“ The current study supports the hypothesis that an
increased degree of FV may significantly decrease singlelimb
stance PS. If decreased PS is a risk factor for
sustaining acute injury as has been previously reported,
16,17,44 the significant AP and ML PS improvements
that occurred after the 6-week FO intervention
period may be clinically relevant.
Before concluding either that: (1) an increased
degree of FV is a risk factor for acute injury/reinjury;
or (2) the improved PS associated with FO intervention in
persons with an increased degree of FV may be an
effective preventative measure for acute injury/reinjury,
the ‘‘threshold’’ at which decreased PS becomes a
significant risk factor must be determined. Further
prospective studies are required to determine this ‘‘threshold.’’
A second important clinical implication may be
related to the fact that PS did not improve immediately
with FO intervention but rather sometime during the
6-week intervention period. If FO intervention were to
be used to improve PS and potentially decrease risk of
injury/reinjury in persons with Z7 degrees of FV, it may
be important to begin FO intervention some time before
the beginning of the individual’s season.
ACKNOWLEDGMENTS
The custom-molded functional orthoses used in the
study were provided by Sole Supports, Inc, Lyles, TN.
REFERENCES
1. Cornwall MW, Murrell P. Postural sway following inversion sprain
of the ankle. J Am Podiatr Med Assoc. 1991;81:243–247.
2. Friden T, Zatterstrom R, Lindstrand A, et al. A stabilometric
technique for evaluation of lower limb instabilities. Am J Sports
Med. 1989;17:118–122.
3. Goldie PA, Evans OM, Bach TM. Postural control following
inversion injuries of the ankle. Arch Phys Med Rehabil. 1994;
75:969–975.
4. Guskiewicz KM, Perrin DH. Effect of orthotics on postural sway
following inversion ankle sprain. J Orthop Sports Phys Ther. 1996;
23:326–331.
5. Hertel J, Denegar CR, Buckley WE, et al. Effect of rearfoot
orthotics on postural sway after lateral ankle sprain. Arch Phys Med
Rehabil. 2001;82:1000–1003.
6. Hertel J, Buckley WE, Denegar CR. Serial testing of postural
control after acute lateral ankle sprain. J Athletic Training. 2001;
36:363–368.
7. Leanderson J, Eriksson E, Nilsson C, et al. Proprioception in
classical ballet dancers. Am J Sports Med. 1996;24:370–374.
8. Orteza LC, Vogelbach WD, Denegar CR. The effect of molded and
unmolded orthotics on balance and pain while jogging following
inversion ankle sprain. J Athletic Training. 1992;27:80.
9. Perrin PP, Bene MC, Perrin CA, et al. Ankle trauma significantly
impairs posture control—a study in basketball players and controls.
Int J Sports Med. 1997;18:387–392.
10. Gauffin H, Tropp H, Odenrick P. Effect of ankle disk training on
postural control in patients with functional instability of the ankle
joint. Int J Sports Med. 1988;9:141–144.
11. Pintsaar A, Brynhildsen J, Tropp H. Postural corrections after
standardised perturbations of single limb stance: effect of training
and orthotic devices in patients with ankle instability. Br J Sports
Med. 1996;30:151–155.
12. Tropp H, Odenrick P, Gillquist J. Stabilometry recordings in
functional and mechanical instability of the ankle joint. Int J Sports
Med. 1985;6:180–182.
13. Tropp H, Odenrick P. Postural control in single-limb stance.
J Orthop Res. 1988;6:833–839.
14. Cobb SC, Tis LL, Johnson BF, et al. The effect of forefoot varus on
postural stability. J Orthop Sports Phys Ther. 2004;34:79–85.
15. Hertel J, Gay MR, Denegar CR. Differences in postural control
during single-leg stance among healthy individuals with different
foot types. J Athletic Training. 2002;37:129–132.
16. Tropp H, Ekstrand J, Gillquist J. Stabilometry in functional
instability of the ankle and its value in predicting injury. Med Sci
Sports Exerc. 1984;16:64–66.
17. McGuine TA, Greene JJ, Best T, et al. Balance as a predictor of
ankle injuries in high school basketball players. Clin J Sport Med.
2000;10:239–244.
18. Root ML, Orien WP, Weed JH. Normal and Abnormal Function of
the Foot: Volume II. Los Angeles: Clinical Biomechanics Corporation;
1977.
19. Donatelli RA. The Biomechanics of the Foot and Ankle. 2nd ed.
Philadelphia: F.A. Davis Company; 1996.”

Daaaaaaaaaaaaaavid, you are getting sleeeeeeeeeeeeeeeeeeeepy. You are a true genius. I sell 6000 pair of orthoses per month by hypnotizing all of my docs and their patients. LOL. I knew someone would figure it out sooner or later. When I snap my fingers you will wake up back in SALREville where the flatfoot finds equilibrium around one axis.
BTW. I fully answered Simon’s question about this. If he believes that power of a study is important, he should disregard the less favorable part of the study (because it is underpowered) and just use the group of 27 to draw his conclusions.

Limitation is too kind. It is a fatal flaw.

It is hard to shake a paradigm that is so deeply rooted (your comments attest to that).

This is a theory article. Admittedly it is expert opinion, just as the vast majority of Kirby’s articles are. Which orthotic lab spends more than us on research? What is your annual research budget, David? Your problem is that we do the work, fund the research, collect the data, have a better model, better graphics, a better lecturer (me), and are rapidly becoming accepted as being correct. Don’t you just hate it? You’re making me feel sorry for you.
Success is so sweet.
Ed

 

Ed,

Thanks for reposting the pdf file in a text form. There are still the same criticisms in multiple places in the post. So, let me know if I miss some of your criticisms.

Many of the criticisms are straw man arguments. You misstate the premise of SALRE.

Ed, this criticism was answered in earlier posts that you have not responded to. There may be a misunderstanding in terminology. I haven't looked at the old post, but I may have said foot pronation when I meant STJ pronation. I was talking about non weight bearing when I said, there are feet with medially deviated STJ axes, that when you push upward on the medial longitudinal arch the STJ will pronate. And I agree with Kevin's comments about shifting the center of pressure. Has that been explained to your satisfaction that we can move on to the next criticism?

This criticism is essentially saying that SALRE does not pay attention to MASS. This is a classic problem of two people with different paradigms only being unable to see the other paradigm through the lens of a different paradigm. This shouldn't be a problem with us, because we both agree upon Newtonian mechanics. But apparently it is.

Since you have brought in foot posture, it is fair to criticize it in relation to our current discussion. Hicks described the windless mechanism in terms of arch raising and arch lowering. I like these terms better than foot pronation and foot supination because there is less chance of confusion with STJ pronation and supination. However, we can name all the joints of arch raising and lowering and examine the equilibrium around each of those joints. When someone stands on a MASS orthotic, we should be able to describe how the orthotic applies a moment to each of those joint to raise the arch when compared to when the foot is not on the orthotic.

Ed, would you agree that arch raising consists of metatarsal plantar flexion, midtarsal plantar flexion, STJ supination and ankle dorsiflexion? Would you add any more joints?

Ed, SARLE is only attempting to examine moments about the STJ axis. It is using these moments to explain some of the pathology seen in the foot. For example, posterior tibial tendon dysfunction can be explained quite nicely using SALRE. SARLE, is not very useful in explaining 2nd met stress fractures, and we have never said that it was. SARLE is not trying to explain all the moments at all the joints involved in arch raising. That makes this a straw man argument.

SALRE does not make the STJ axis a primarily frontal plane axis. This criticism is erroneous.

This is attempt to view SARLE through the lens of MASS. It is essentially saying that SALRE does not work if you ignore posture.

Moments will be applied to the joints of the foot by ground reaction force regardless of the position the foot is in. You look at the location of the STJ axis in the position which the foot is in. We are making the assumption that in any given position of the foot there will be a unique location of the STJ axis. Then you look at the the three dimensional relationship of the the ground reaction force vector to determine the moment from ground reaction force to determine the moment from ground reaction force.

This can be fit into the broad category of criticism of you have to know exactly where the axis is to be able to use SALRE in treatment. For treatment, you do not have to know where the axis is. All you have to do is know which direction you want to change the moment. Then you shift the center of pressure in the direction that you want to change the moment. If the STJ needs to be pronated then you shift the center of pressure lateral, if the STJ needs to be more supinated then you shift the center of pressure more medial.

I don't understand the criticism. The theory can be used all the time. The STJ axis will move with motion of the joints over time. However, the moment at any instant in time will be determined by the location of the axis at that instant in time relative to the location of the center of pressure at that instant in time. For treatment you can change the location of ground reaction force whenever the foot is contact with the ground.

How is this an assumption of SALRE?

I'd like to make three points about your comment.

The first point is similar to the point mentioned above about having to know the exact location of the axis. You can treat a foot with SALRE by shifting the center of pressure without knowing exactly where the axis. is.

Second point: You have to apply moments to the foot to achieve a postural change in the foot. Without the orthotic the foot will stand in a certain position. When you stand on an orthotic there will be different forces and moments applied to the foot so that a foot will reach equilibrium in a different position without the orthotic. SALRE can be used to explain how the orthosis can alter the moments applied to the foot to create arch raising. STJ supination is one of the joint motions that occur to create arch rasing. Therefore the orthosis would probably have to add supination moment to create arch raising.

Third point: Just what motions of what joints allow you to get 30 degree increase in calcaneal inclination angle? Are you saying that you can actually get a 30 degree increase in calcaneal inclination angle. Do you regularly see a 30 degree change in calcaneal inclination angle? Wouldn't this cause a functional equinus.

Ed, you have no case unless you can explain, mechanically, why postural restoration is superior to reduction of mechanical stress to a point where there is no pain. Why should postural correction be a goal of therapy?

Ed, in reading the other comments further in your post, I believe that the responses above have answered those criticisms as well. If you disagree, point out the specific points that you did not feel were answered.

Respectfully,

Eric

 

Eric,
I tried to break this into three or four chunks.

I think it is one of many axes that affect foot pathology. I think that it is not the most important because of moment arms between the forces that pass through the foot in the gait cycle and their relative moment arms. I think that the heel rocker axis is more important. Even if it is in second place or the sum total of all the other axes is greater than the influence of the STJ axis, then the SALRE theory falls apart. Good little what if physics problem that is not relevant to the real world.

No, pain relief is not my goal. I am even willing to cause some temporary pain to help my patients achieve better function. In the end, it is well worth the effort. Pain relief is a side effect of improved function and posture.

Eric, the criticism is seeing the foot as uni-axial and worse….treating it that way.

Probably the easiest way to determine what is the best posture of the foot is, would be to observe feet that have no deformity, especially in very active people. When we look at so many feet as a podiatrist, we see those that have excellent structure, no bunion, tailor’s bunion, hammertoes, etc. etc. These feet don’t present as often because they rarely have problems, but you may see one with a wart, or trauma, or any number of non-biomechanical diagnoses. Now, observe what posture these feet are in. You will find that they are in the functional zone (MASS position), pronate less, and are propulsive, operating efficiently so that force is used for locomotion instead of building up as deforming forces. If you do any kind of gait analysis, you must know what is normal and abnormal. These, closer to ideal feet, exhibit a closer to ideal gait.

If you would use the orthotic that put the least stress on the most structures, you would choose MASS orthotics because they are in full contact and therefore redistribute force evenly throughout the entire plantar surface of the foot. You personally, just did not get over the transition period. Had you done that without modifying the orthotic you would be fine. It is interesting that your previous orthoses did so little to change your kinematics that they were no help in mitigating the break in discomfort.
Knowing what I do now, I would not wear a SALRE orthotic even if it relieved my symptoms because I have come to expect more from an orthotic. I expect a change in foot function. Unfortunately, much of the public is not educated about foot orthoses, so it is possible to sell customized shells as custom orthotics and that is exactly what the practitioners who use SALRE are doing. If you lower the bar so much that prefabs, Dr. Scholls and Walmart are equivalent to what doctors are doing, then why go to a doctor; so he can flaunt his credentials. Maybe we should take the doctors credentials and crunch them up and put them in the shoe. It would work just as well.
Respectfully,
Ed

 

Ed:

You obviously never read my paper (Kirby KA: Subtalar joint axis location and rotational equilibrium theory of foot function. JAPMA, 91:465-488, 2001) thoroughly enough, or haven't wanted to take the time to read it, or don't have the inclination or desire to try to understand what I so plainly state in the second to last paragraph of the paper:

Now, this is the second time I have pointed out this paragraph that very clearly states that SALRE theory was never meant to explain the function of all the joints of the foot during weightbearing activities. However, Ed, you continue to deceitfully use your straw man arguments saying that I advocate that clinicians only consider one joint axis of the foot, the subtalar joint, when they evaluate the biomechanical function of their patients or when they start to consider what orthosis modifications would optimize the mechanical treatment of mechanically-related pathologies of their patients. Because of your ridiculous assertions that I advocate only considering the subtalar joint in evaluating patients, I feel that I must now again speak up to defend my work in podiatric biomechanics education over the past 23+ years and bring a clear and concise defense to your twisted interpretations of my published papers, book chapters, books and newsletters.

Before and after the SALRE paper was published in JAPMA over seven years ago, I have published 258 newsletter articles, published two book chapters, published two books of these newsletters and am currently working on a third newsletter book, and have had 19 papers published in peer-reviewed scientific journals where I discuss the biomechanics of hip joint, knee joint, ankle joint, midtarsal joints, midfoot joints, metatarsophalangeal joints and even interphalangeal joints. Of course, Ed, you never bring up my multiple other published works where I very clearly state the importance for the clinician to evaluate the biomechanics of the hip, knee, ankle, midfoot, metatarsophalangeal, and interphalangeal joints of the foot and lower extremity since this would not support your ill-conceived idea that you must discredit the work of others in order to achieve your goal of promoting your techniques and ideas as being "revolutionary" and your orthotic company's products as being the "only true functional orthotics". Your contribution to podiatric biomechanics, so far, seems to me to be nothing more than a continual, self-glorifying promotion of your ideas and products by creating straw man arguments against those who you perceive to be a threat to your ideas and your economic goals.

In addition, I find it quite insulting, after spending half of my life educating the members of the podiatry profession and other foot-health care specialists on foot and lower extremity biomechanics, that you imply that I somehow only know about the subtalar joint and only consider the moments acting across the subtalar joint when evaluating patients. This is absurd and shows that when you have attended my lectures, you either didn't listen to what I said, or didn't want to comprehend it since it wouldn't fit with your straw man agenda of misrepresenting what I have lectured on or have published. To top it all off, when I am receiving criticism from an individual who has never held a faculty appointment at any of the podiatric medical colleges, has never authored or even coauthored a single article published in a peer-reviewed scientific journal and that has only made a name for himself by paying seminars around the country to allow him to lecture and self-promote his products and ideas, it makes all the diatribe coming from that individual even more annoying.

Again, Ed, I am tired of your continuous pontificating and misrepresentation of what I said in my 2001 article and what I have authored and coauthored in numerous peer-reviewed scientific journals and on what I have lectured on in multiple state and national venues and and have lectured on internationally on 21 separate occasions. I wouldn't mind your criticism of my work if you weren't always bending the facts to meet your purpose of self-promoting yourself and your foot orthosis company. However, unfortunately, you seem incapable of criticizing my theory without distorting the facts. It's too bad, because if you had presented your ideas with a lot more humility, a lot less pride, with publication in peer-reviewed scientific journals, and with less self-serving interest in selling more of your orthosis lab products, I think you could have done something useful for the podiatry profession, and not just reintroduce a modification of the Whitman plate type foot orthoses that were a standard orthosis design of a century ago (Whitman, R: The importance of positive support in the curative treatment of weak feet and a comparison of the means employed to assure it. Am. J. Orth. Surg. 11:215-230, 1913).

 

Cobblers. And why don't they work to relieve pain if you use a flat piece of 4mm foam for a few weeks before hand?

 

No. They don't. :bang:

They are in full contact with the skin and soft tissue overlying the skeleton, that does not mean they will redistribute pressure evenly. Take a mass cast the PMA will come out flat. Put the forefoot on a VLS it will have pressure peaks under the met heads. It may also have more pressure on one side or other (or indeed the centre) depending on how the COP moves as the foot loads. The areas where there is less soft tissue overlying bone will take more load when the foot is loaded in vivo. Areas which are closer to the COP will take more load.

Also the foot is not designed to have the force distributed evenly across it so there would be no particular merit to this claim even were it true!

This is the sort of claim which sounds impressive to the lay patient but is profoundly NOT impressive to people who know a little about how the foot works!:craig:

Sorry. Bad day at the office. My flattenerd pancake orthotics take a lot of making.

Robert

 

Also consider the variation in the point to point stiffness within the shell due to the variation in curvature. Unless you were to use multi-density, multi-thickness shells this would be near impossible. Guess what, even if you did have multi-density, multi-thickness shells, this would be near impossible.

 

Robert

What exactly is a flatte nerd and why do they need orthoses? Is the pressure distribution about a flatte nerd proportionally and evenly applied to its pancake surface area?

Dave

 

Flatte nerd. Star trek fan with flat feet. Of course they need orthotics.

Robeer.
Need one.

 

Ed, How does the heel rocker axis affect pathology? I will admit that there is more motion about this axis than the STJ axis, but why should I care about this motion?

So, how do you decide what function is better than another. Define function.

Ed, I did this with asymptomatic podiatry students quite a few years ago. Out of 30 students all of them stood within 3 degrees of maixmal pronation. MASS is over supinated in relation to where these people stood.

The orthotics that you made for me with the MASS technique were so painful that they I would wake up in the middle of the night in pain. I never got beyond wearing them for 4 hours for a day. I am quite sure that I would never have gotten used to them. John Weed used to joke about how if you made a mistake in making orthotics the patients would throw them at you. If I came back to your office and you told me that I need to get over the breakin discomfort, I would throw them at you. I tried to get over the break in discomfort and I could not. I then modified them to test SALRE theory and I could last longer before they hurt too much to wear. If you tell your customers to tell that to your patients, then a lot of patients won't come back to doctors.

The earlier point made about how we should not have even pressure under the entire surface of the foot was a good one. The foot should bear weight on the bones and not the soft tissues. There is a lot of soft tissue between the medial arch and the overlying bones. It is not comfortable to compress that tissue.

Respectfully,

Eric

 

Kevin,
Let's see, your article goes on for about 20 pages talking about the importance of the STJ axis and has this little disclaimer paragraph at the end saying it is not all about that axis. This is the Subtalar Axis Location Rotational Equilibrium theory is it not? I talk about the whole body too, but that is not the core of your theory, is it? Your theory is about the SUBTALAR AXIS only.

I could literally reference hundreds of posts on this forum where you only talk about the STJ axis location and nothing else. The straw man here IS your theory.

All this "look at my credentials" compared to yours has nothing to do with being right.

This disclaimer only serves to make your theory even more irrelevant. It simply admits how the SALRE theory only makes sense in the confines of assumptions that are untrue and will not work in the real world.

Let me summarize what you wrote. I, Kevin Kirby am great. I have all these accomplishments. You should just accept what I say as others obviously have.

Let's see, you have tried to equate MASS theory with Rothbart, SDO's, and Dr. Shavelson's work and now the Whitman plate. Talk about a STRAW MAN argument. We have nothing in common with these technologies except a few of the structural observations of Dr. Shavelson which are far more global than SALRE and look at the whole foot instead of just one axis.

Is your best defense of SALRE saying that it is wrong and then wagging your credentials about as some sort of proof? Sad.

Once again you are attacking my motives and financial partiality.....both subjects of which you know nothing and irrelevant to your defense.

Ed

 

You would expect that an article about the sub-talar joint location and rotation around that joint to consist of mostly talking about that topic. I think an end disclaimer is appropriate and has meaning.

From my own clinical experience I have gained much more insight into the rest of the foot from Kevin's other papers then I have from this his most recognised paper. To continue to criticise him as a one theory practitioner shows your ignorance of his other writings. Ed you on the otherhand seem to have little other insight of the foot beyond MASS theory. No theory can explain everything ... except MASS theory it seems. It is not even a theory really but more of a technique.

Your suggestion that you make the foot function rather than relieve pain has no basis that I can see. How can you prove function or posture is ideal other than that is what you say it is. Sorry, but I am a bit sceptical about your opinion as well as your motives.

The fallacy of authority is always a trap for those with influence. I think Kevin has been more open to criticism of his theory then you have about yours. He has also been much better at replying to those criticisms while you have ignored most of them. I think he has shown a better grasp of the scientific method then you. No theory can be proved 100% right. Theories are concepts that we use to interact with the world. While the theory has not been disproved by evidence we can use that theory but there is always the possibility that a better theory will come along.

As clinicians rather than researchers we need to make value judgements about the theories we use. One of the main factors in that value judgement is the credibility of the person making the theory. Quality research, published papers and no financial interest in the theory count for a lot. Kevin easily has it over you in this respect. I would say that your position is seriously undermined by your failings in these three areas.

SALRE is much more useful clinically than MASS. (my opinion)

 

Yes it has meaning. It serves to invalidate SALRE.

The title of this thread is “Challenging SALRE”. I have read the vast majority of Kevin’s work and have yet to come across another theory. Actually, Newtonian Physics will explain everything. MASS is a theory in as much as Neutral Position theory is Root’s theory. Kevin though has still yet to describe the position that he casts the foot in.

Neither you nor Kevin know anything about my motives. I have already given you many logical proofs and more will follow. Look at Adult Aquired flatfoot. That is a posture that is pathologic.

I can’t imagine how anyone can answer every post better than I have. Kevin has mostly ignored, dismissed and given empty arguments based on credentials. You are saying that what makes Kevin right is that he published more articles…..very, very weak. Kevin is open to criticism? What a joke. He thinks he is, by virtue of his credentials, above criticism. He may be your hero but that still doesn’t make him right.

We do quality RCT’s, not just expert opinion articles, which is what most of Kevin’s work is. We have published papers and my financial success is just another testament to the free market voting for the best orthotic with their dollars. I am not saying that Kevin’s relative lack of financial success is proof of the inadequacy of his theory……I believe that its inadequacy speaks for itself. You speak as though you have experience with SALRE but none with MASS…..yet you are quick to criticize that which you have never actually tried. Your evaluation is therefore just hero worship, personal prejudice or blind supposition. I have tried rootian and SALRE orthoses both on myself and my patients. My results with SALRE and Rootian orthoses were hit and miss, inconsistent, and generally unsatisfying which is why I developed a new paradigm.

Based on what? No experience with MASS? Very scientific, Steve.

Cheers,
Ed

 

Ed I must commend you on one aspect. You have succeeded in transforming a thread on challenging SALRE theory into one about MASS.

 

I spotted that.

I am swiftly coming to the conclusion that intelligent scientific discussion between Ed and "the rest" is impossible. It often seems that we are speaking different languages and the Ed's obvious contempt for any of his peers who do not accept his ideas as incontrovertible truth creates an atmosphere in which scientific debate is impossible.

One could argue the relative merits of a pepperoni pizza to a kebab. This is like trying to campare a pepperoni pizza to the Treaty of Versailles! Scientific rationality and physics cannot be used to dissect broad sweeping unsupported generalities and claims! Unshakable personal conviction and broad sweeping generalities cannot be used to refute physical testable realities! Ed seems to have failed to grasp the principle of SALRE altogether (deliberatly or not i don't know). To ask what position kevin casts in is like asking a hairdresser how short they cut hair and shows a severely limited view of the way others practice biomechanics!

Egos get in the way on both sides!

In my humble opinion the only way this debate has any chance of moving forwardigs: is if short questions and short answers are posted with no reference to individuals. Ed made a good start with the question on the OP. Simon did the same on the challenging MASS thread. But these soon got lost in the storm of arrogance, agression, condensention and boorishness!

Oh i give up.

Regards
Robert

 

Ed,

Unfortunately Ed, there is no 12 point plan for stupid. Seeing as you are obviously an expert in this area perhaps you could come up with someting and market it to the world.

Ed, you are a total embarrassment to your profession and the principals of ethics and science.

Graham

 

Interesting, pain relief is pretty much top of the agenda for the majority of patients experiencing musculoskelatal problems I've seen in the last 20 years.

Ed, please name one podiatrist here who sees and treats the foot in this way. This naivety astounds. Very bored with this now.

One last time for the kids back home: why don't mass produced orthoses reduce musculoskeletal pain when prescribed after a four week period of wearing a flat 4mm foam insole?

Taking Lawrence's line of thought, let me ask you another simple question: how do your foot orthoses work?

 

I make that 5 or 6 times this question has been asked! Perhaps that study should have asked al gore for an idea for the title!

R

 

I guess it's all part of the mass belief to ignore the evidence in front of you, even if you funded it. But the longer these threads go on, the longer you and I keep responding to this crap, the more free publicity we give. No publicity is bad publicity except your own obituary, Ed and his kind know that and I'm afraid we keep on falling into their service. Knock it on the head big boy. :hammer:

 

Hmmm. I guess you're right.

That said it is good for anyone visiting to see the regard in which this technique is held. And if you Google "ed glaser orthotics" as a lay person might you will see lots of Ed's own promotional material... and a link to one of the threads here. Podiatry arena is the only indepentant opinion i found on this product and it is, of course, all quite negative. If we did not pay attention to this issue then the googler would see only Ed's glowing self promotion (and there is lots!)

I've spoken to Podiatrists, intelligent degree trained podiatrists, who have gone for Brians posture controll insoles hook line and sinker, presumably because they have not be exposed to the raft of counter arguments!

To paraphrase, all that is neccessary for bad science to flourish is for good scientists to do nothing! And you can read that from either point of view BTW.

At least this way a newcomer to the arena will have heard the news!

 

Ed

I would like to ask some really simple and basic questions.

As I have stated before I think that your calibrated arch may be a useful addition, in some cases, to the arsenal of orthosis intervention methods currently available to the podiatrist.

It appears tho that you are of the opinion that MASS produced orthoses are the full, final and only answer to all foot pain and more proximal pain, related to postural defects of the foot. Especially in terms of comparison with conventional orthoses, the definition of a conventional orthosis is defined by yourself. These defects of posture are defined by yourself and your paradigm is satisfied by returning the foot to the correct posture, again as you define it.

1) Does this summaries your position?

It appears you pay scant regard to any previous definitions of foot function, normal and pathological, even tho it comes from many and various highly regarded and researched sources. You appear to have invented your own closed system of reasoning that is validated by its own system of conventions and so subsequently and logically cannot be invalidated by any system of reason or convention that is outwith your own.

2) Is this correct?

3) Using your own or any other system of conventions could you explain how an arch is raised by pushing up on it?

3a) How do you apply this reasoning (3) to the arch of a foot.


4) What would you define as the main weight bearing parts/areas of the plantar surface of the foot?

The sole or main function of a MASS produced product is to raise or increase the declination angle of the medial column / 1st ray and increase arch hieght. You say this many times in your video lectures / presentations.
5) When the arch of a MASS produced orthosis becomes stiff enough to stop further deflection / lowering of the medial longitudinal arch, how can you ensure that it does not apply such forces to the soft tissues and operating structures such as fascia, muscle and tendon to not cause pain and subsequent induced pathology to those parts.?

5a) Are there any link left to your video presentations?

Cheers Dave

 

Yes, the calcaneal inclination angle in relationship to the ground…. Heel rocker axis, MTP axes, cuneo-navicular joints.

Or is it a deficiency in the SALRE theory; a fatal flaw of omission. It fails to explain these things because it is a 2D oversimplification that chooses a singular axis, ignoring foot posture, sacrificing function for symptom masking. SALRE’s basic assumption is wrong, therefore the theory is a nice neat physics problem that leads doctors down a dismal abyss to a place where prefabs = customs. A dangerous path for our profession to take.

One only needs to look at the diagrams used to justify SALRE to see that SALRE is a frontal plane theory with its treatment protocol also aimed at only the frontal plane.

As I stated earlier: If this was the best we had to offer, no problem. Fortunately, it is far from the best we have to offer. Posture is critical to function and ignoring it is a gross oversight.

TRUE

Which is dictated by posture. You are highlighting the importance of posture here. Well done.

I would modify that to: for any given posture….. Oh so true! Which is why posture is so critical. Even through the lens of SALRE, or Newton ……. Would you rather apply a balancing force around one of the many axes of the foot, with the foot near the end of pronation…..OR….would you rather move the STJ, and all the other axes to a position, through changes in posture, where it take far less force to control the foot, where balance is much easier to achieve, where gait is maximally propulsive and efficient, where deforming forces become corrective forces and life becomes therapy. Sounds like utopia but it’s just physics……and the fact that form and function are interdependent.

Absolutely, and around all axes with the foot in a corrective posture where balancing and equilibrium are in your favor.

And if the foot was a block of wood with only one axis, it would be that simple. The foot is far more complex and cannot be reduced to one axis. Such an approach misleads practitioners. Kirby wandered further down the exact same path that Drs. Root, Orien and Weed led us. Toward a belief that the foot was controlled by one axis, the STJ and that kinematic change was unimportant, posture is unimportant, function is confused with symptom masking, and then simply took their frontal plane treatment and increased its intensity. Post, wedge, skive, tilt this way or that. Criticize neutral and then cast in it.

If for example the forward roll of the calcaneus were more important than STJ axis motion, would you not be trying to resist the forward roll instead? Where and When would it be most beneficial to begin to resist rotation around all the axes that encompass foot pronation?……as early as possible. In fact, preparing the foot for heel contact would be ideal. You seem to be waiting until the “foot is contact with the ground” or midstance. Too little, too late.

Because SALRE equates foot pronation / supination with STJ rotation only. If the rotational curve was not linear with time, say more rotation around the axis occurred in supination, and the SALRE based orthoses never even attempted to achieve this posture, function of the STJ would be most likely be sacrificed. You would simply be creating equilibrium around a dysfunctional axis. For example, at the end of pronation you certainly cannot rotate into more pronation and supination is often very difficult to achieve because the external rotation of the leg and talus are against a very valgus anterior facet…..highly consistent with Dr. Paynes research.

And it is answered above.

Eric, You are absolutely correct. SALRE is a good microcosm of a broader theory. Its failure is not the physics. In fact Kevin did a very good thing by applying the basic principles of Newtonian physics to one of the many axes that affect the foot. Its failure is concentrating on just ONE axis, ignoring kinematics and posture, and applying primarily frontal plane correction to a primarily sagittal plane machine. When those inadequacies are addressed….. add a corrected posture, full contact, true custom geometry, calibration, soft tissue compression and a repeatable, accurate casting technique and you have MASS theory and an orthotic that not only attempts to control function but does a far better job at dampening tissue stresses.

Certainly a 30 degree change would be greater than we would normally expect. But, in the case of plantar fasciitis for example, a 15 degree change (which is quite common) in first metatarsal declination angle will change the lever arm (measured between the axis of first met Dorsiflexion and the vector of applied force from the plantar fasciae which is approximately horizontal) enough to increase the force building up in the fasciae, needed to create supination by over 250%. A simple comparison of the cosine of 15 degrees with that of 30 degrees is enough to explain the trigonometry.
In terms of functional equinus, this can be a problem and it is why we not only recommend stretching, but have free stretching handouts on our website. I personally like the work of Steven Stark, DPM from BC Canada. His book “The Stark Reality of Stretching”, I personally use. Don Bursch, however is far more knowledgeable than me on the subject and has used the stretches in our handouts for many years successfully. For eight years he was the chief of outpatient PT at Vanderbilt University, so I defer to his expertise.

Postural restoration is superior for many reasons. I would like to write a separate post detailing the many advantages of this approach and I do not want to delay the posting of this answer, so I will write up the answer to this question separately over the weekend.
Eric,
So far, you are the only one who is actually defending SALRE from an academic, non personal attack, viewpoint. You also have displayed a very open mind, intellectual curiosity, and an honest interest in advancing our knowledge. You are fiercely committed to SALRE because it has worked for you and obviously many others on this site. I understand that.
As Kevin stated in his disclaimer paragraph;
“Hopefully, the theory of foot function presented here will serve as a useful basis for the production in the future of a more complete theory of foot function that will, likewise, be based on scientific research and clinical observation.” Kevin Kirby.
I have done exactly what he hopes for. He just doesn’t like that it is coming from me. Maybe because I did not spend my career pinning medals on myself, just worked quietly in my garage to come up with something that simply makes people better. For me this is not at all about personal aggrandizement and credit. I really prefer that credit is bestowed on Richard Schuster, DPM who came up with many of these ideas before either Kevin or I went to podiatry school. The things that are new about MASS are:
1. The MASS posture of correction.
2. Casting technique to capture that position.
3. Calibration of corrective force.
4. Full Contact in this newly defined MASS position.
5. The elimination of previous shell modifications used to redistribute tissue stress as simply unnecessary and possibly harmful when combined with MASS correction.
The important point here is that the direction of thought process, the path, was previously traveled by Dick Schuster. In many ways I simply applied a little Newtonian Physics, just like Kevin, and improved orthotic intervention. Calibration is based on: For every action, there is an equal and opposite reaction.
Anyway, this is just my way of saying Thanks, Eric, for being civil, intellectual, and open.
Ed

 

Simon and Robert,
This problem is easily solved by applying a compressive force onto the soft tissues during casting, that is not uncomfortable but causes even compression to give a TRUE geometry to model the orthoses after. We use a 1.75 psi. foam. We simply ordered foams of various compressions, compared their casting comfort for a full 3" depth. Uncomfortable rigidities would yield a geometric shape that would reflect the geometry that occurs when uncomfortable force is applied. When we have finite element analysis, we will know much more about that. For now, all I can say is, this works. It could and should be improved in many ways. That is my current research interest....and where I am headed right now.

Thanks,
Ed