Relative Importance of STJ Motion

Yes, it is a consideration.

Yes, we funded the study. How is that relevant, unless you are implying bias? Or are you just applauding us for funding well controlled, well executed independent research….Thank you.

Yes, they used a foam sham device as a control. A common research tool.

I don’t know all the tricks about linking files.

No idea. Maybe because, if people see that I am correct, that all axes must be considered, that posture is important, it will invalidate SALRE and maybe also his particular approach to the tissue stress model.

Looking at all axes simultaneously is useful.

The TN joint is an ovoid ball and socket and therefore has an infinite number of axes. Any one motion might employ a particular axis but again, that would be one axis of many possible. I said the ankle axis is interesting…and it is. I believe that looking at individual moments around one axis is missing the boat. Looking at all axes individually and mapping out moments would be more complete but cumbersome and would not work clinically.

Part of the challenge is making your paradigm practical and useful. Looking at the sum total of the effects of all axis is the same as looking at posture which is simpler, easier, and I believe better…. And the results are visible in gait.

Yes, rotational equilibrium around the STJ is significant in gait. Not as significant as HRA rotational equilibrium. Probably not as siginificant as the TNJ Rotational Equilibrium. The STJ has a function, sagittal plane “constraint”, if you prefer, between the talus and calcaneus to make propulsion occur more at the ankle rocker than the STJ axis. In so far as supination is necessary to accomplish that function, posture is more important. Rotational Equilibrium at the pronation end of the postural ROM will have little or no kinematic effect as many studies show. So now an orthotic is relegated to redistributing tissues stresses on the bottom of the foot. Its kind of like mopping up the mess after the spill instead of not spilling it in the first place.

Absolutely, It makes the best geometric shape for an upward spring force to be more evenly applied to the plantar surface of the foot to delay pronation, and assist in resupination before Midstance. The cast is about the geometric shape of the orthotic not any particular posture that the foot will go through in the gait cycle.

US corporations are a dictatorship. As Theodore Roosevelt said, “The buck stops here.”

I characterize Sole Supports, Inc. as a group of people who have come together for a common purpose that they are proud to serve.

At heel strike, the ankle axis has a very small moment arm with the force coming down the leg which remains true until Midstance and a very large moment arm with the GRF at heel contact which diminishes from forefoot contact thru Midstance where they are roughly zero and then as force passes to the forefoot ankle moments exerted by forefoot “constraint” increase until they peak just before toeoff.

No, you don’t understand me correctly. ALL AXES should be considered….that is the very essence of posture. STJ eversion is just a phenomena that occurs:
a. because of the direction of the HRA
b. because after the heel rolls forward, some of the transverse plane motion of the STJ becomes frontal plane.
c. Because the heel is just being pushed out of the way by the far greater Heel Rocker Axis.

Done.

Ed

 

Agreed. Dr. Trotter was fully honest and forthright in her disclosure. That is what honest researchers do. Every question that Simon asked is answered in the article.
What is your point? Are you challenging her integrity? Don't go there. She addresses that very well in the video. One minute talking to Les will dispel that notion.

Ed

 

Now we get to the crux, you want to invalidate SALRE and "his" approach. You don't say, Ed. Why? If all axes must be considered, and if in your opinion SALRE explains the biomechanics about one of those axes (the subtalar joint) then surely we need to consider SALRE?

What if people don't see that you are correct? What if people have already tried using a "prefabricated foot orthosis" prior to being prescribed one of your MASS devices? According to the best research evidence, MASS type devices will be ineffective in this situation (The Short-term Effectiveness of Full-Contact Custom-made Foot Orthoses and Prefabricated Shoe Inserts on Lower-Extremity Musculoskeletal Pain A Randomized Clinical Trial Leslie C. Trotter, DC, MBA, MSc, CPed (C)* Michael Raymond Pierrynowski, PhD†)

Nothing but speculation and conjecture, Ed. Please define how your rank "significance".

Does it? And is it? And you know this because?

And obviously since ALL AXES should be considered rotational equilibrium is as important about the subtalar joint axis as it is about any of the other axes. Viz. Kevin's work provides a valid contribution to our understanding of foot function. I'm glad we agree for a change, Ed.

 

Sorry to come in half way through. I've been a bit busy. I have a few questions Re the initial slides if it won't dislocate the discussion unduly. Sorry to go backward...



Ed. You said:-

I may be being slow here but this does not compute. If someone (doesn't have to be ed) could show me where I'm going wrong, I'd be obliged.

So we have a shod foot hitting the ground inverted and thus on the lateral / posterior aspect of the shoe. The argument, as I understand it, from the slide is that because this is on or near the STA it will not create a major STJ moment.

But at heel strike on the lateral border, the lateral side of the heel the pivot is not the STJ, its the lateral part of the shoe. The COG is substantially medial to this pivot (outside of the shoe) so there is a huge eversion moment acting around this pivot / axis. The shoe is pretty much attatched to the foot so if the shoe is foced to evert to land flat on the ground, the foot must also evert. Hopefully this movement is unavailable at the Talocrural joint so the only place it can happen is the sub talar joint.

Likewise with this slide

Yeahbut...

As the graphic shows, most of the foot is lateral to the point that axis leaves the foot. The moment arm is not the distance from the force entering the foot to the axis. That, as you say, is pretty much on top of it. The moment arm is from the force vector of the COP of the GRF to the axis.

So for example, and I apologise that my graphic is marginally less impressive,



In this system where the red ogythingy is the axis and the green line is the force traveling down, the momentum coming down the leg does indeed pass straight through the axis. BUT, clearly there IS a strong counterclockwise moment. That being because the moment arm is not measured from the force coming down the leg to the axis, but from the force coming up from the ground to the axis.



One of us has misunderstood here. It might be me. Hopefully someone clever will tell us.

 

Actually none Ed! What I do is take into consideration the axes a they present in each individual. Design an Rx that, based on the available evidence, best addresses the biomechanical concerns as they relate to the tissue stressed.

Of course it omits the rest of the foot! That's because it looked at the STJ axis. RE applies to all axes. It demonstrates a concept Ed!

Calibrated to what Ed! How do you calibrate these "arch supports"?

Evidence here would be a real treat Ed!

Bingo! So MASS devices work as long as the patient doesn't move! MASS is a static concept. It is unable to address temporal considerations.

Tissue stress theory takes the into consideration moments acting on all joints as the foot moves through the stance phase dynamically.

 

My point Ed is Simon asked a couple of times no answer though I would help out, some don´t have access to papers so I try and help out so others may keep up with discussions, what I beleive about the research paper not that important to the post.

by just giving the highlights Ive answer Simons question I hope. Others can read the paper for themsleves and decide for starters,

if a 4mm foam flat insole = a prefab they use daily in their clinics

if the results had of been that the flat 4mm insole was better than the full contact device would the paper would have been published

 

I think the key is in the statement I've made a few times now:

You can draw lines and arrows any where you like. Doesn't mean that's how or where they are in-vivo. As far as I can see these diagrams are just an attempt at the "blinding with science fallacy".

 

Ed said,

Quote:
MASS is the best way of controlling the moments of all axes simultaneously. That is its beauty and simplicity.​

Graham replied

Who says Ed? You? Where is your evidence to make this statement?
​

Ed answered:

Ed your diagrams do not explain why MASS is the best way of controlling the moments of all joints. The diagrams explain why there is a small moment from ground reaction force applied to the heel, at heel contact, in an unshod foot.

 

Look at it...

 

Say what it is... it's a diagram that someone who is obviously reasonably skilled in computer generated images has drawn for Ed, it is not necessarily accurate from a biomechanical perspective.

 

Thanks for playing .

But the core assumption is that the lever arm is measured from the force coming down to the axis. That's a flaw of interpretation rather than the graphic itself surely.

 

The lever arm of the external moment is the perpendicular distance from the ground reaction force vector to the joint axis.

 

Robert, you make a good point. Ed's contention that there is little moment from ground reaction force is relatively good at heel contact up until the point of the beginning forefoot loading when barefoot. However, when shod the ground contact point is more lateral and there should be a greater moment from ground reaction force. This was shown quite well in the Nigg study that examined pronation velocity with increasing lateral flare on shoes. The bigger the flare, the faster the pronation. SALRE explains again!

Eric

 

Yeah. Thats what What I said (pretty much).

So the picture is actually quite accurate. The problem is in the statement

Which makes a fundamental error regarding what the moment arm is.

 

Robert,
If you were drawing a free body analysis of the talus and calcaneus, you would add in both the ground reaction force and the "body-weight" force from above. Is this what you are questioning?

 

It's only accurate if the STJ axis and the GRF vector in-vivo is exactly as drawn in the picture.

 

I will read it.

Are you really seeing STJ Supination or a change in posture. Remember, the STJ is motionless from 25-90% of stance phase. I don’t think that there is any data on STJ rotation during Jack’s test. But I will accept that there is a postural change. STJ rotation is not at all in a 1:1 relationship with postural change. Therefore you proved nothing. Again if the projected axis is parallel to the plantar fasciae there are no moments created around the STJ axis.

MASS does a much better job of explaining Plantar Fasciitis. It is simple. Raise the arch, shorten the distance from the origin to the insertion of the fasciae. Raising the arch also increases the moment around the sagittal plane axes of the foot because it increases the moment arm. Increasing the moment arm of pantar fascial force makes its kinematic effect more efficient. It takes less force (in the form of plantar fascial stress) for the fasciae to do its job.

Thus it can be calculated relatively with various postures of the foot….and it is found to be an exponential curve.

It is a sin of omission. Ignore all of the other joints in the foot and concentrate on one axis, giving it supreme importance when in fact the magnitude of moments around that axis are minimal, and then say that you are concerning yourself with moments around axes is missing the whole foot (except that axis). It is a form of tunnel vision, which the profession has been suffering since Root.

I am not saying that there is no meaning to looking at moments around one axis…. But when it is at the expense of all other axes, it is wrong. Since considering every axis individually is not practical and comes with unacceptable errors clinically, consideration of posture is a simpler approach that yields visible positive kinematic effects.

I think FFL is ForeFoot Loading not Full Forefoot loading. The load of the forefoot continues to increase through toe off.

FFL begins at 27% according to Root.

The rest of your questions revolve around how I measured 3/13. I took one stance phase high speed video (250fps). I imported it into my video editing program. I trimmed the video to begin at heel strike and end at toe-off. It yields a thick line indicating time on the video scale. I enlarged the scale to as big as my screen could hold. I then put editing marks at heel strike, the very beginning of the clip and at forefoot contact. Then I imported a high resolution ruler onto my desktop. I took selected screenshots of the thick line with the editing marks and the ruler. I imported both into powerpoint for its sizing and cropping tools. I cropped the ruler so that it could be placed right up against the thick line for measurements. Since we are only dealing with relative measurements, % of stance phase, I took the measurement of the distance from Heel strike to FFL and divided it by the measurement of the whole stance phase. Converted it to % and there you have a crude measurement of % of stance where FFL occurs.

Heel Rocker Axis.
When you are using all axes, or posture, you don’t have to have the correction all coming from one axis. Increased posture, decreases the vertical travel and loading of the PT tendon. Which axes participate may be interesting but not necessary to know in order to give that person all of the correction that his or her individual anatomy will allow.

Description of each individual moment is unnecessary. Measurement of moments is equally futile. Too much error especially when combined.

It reminds me of our early attempts to calculate the upward force of the orthotic based on the as many variables as we could muster. We considered arch height, shell thickness, graduation of shell thickness, shell width, heel cup height, modulus of elasticity of material, etc. etc. It was impossible. Maybe Pro-Engineer could do it. But there were too many variables and for each there was an associated error of measurement. Finally we concluded that you could calculate till you were blue in the face OR you could simply take a measurement of how much force the orthotic actually delivers to the body. That measurement had one error and took into account all of the variables we thought of and many more that we probably did not.

MASS Posture is a measurement taken of the foot at the most supination that a person can achieve at Midstance with the heel and forefoot on the ground. It yields the corrective shape of the spring and then all you have to do is determine how much force you want to apply in the direction of improved posture, calibrate it and you have a MASS Posture orthotic. Simple, easy, more accurate, not perfect but far better than allowing the postural collapse to occur and then selecting ONE axis, probably the wrong axis, and worrying about the kinetic see saw around it, oblivious to everything else. That is SALRE. I witnessed it being taught at the Scholl College just a few weeks ago. Kevin taught how to locate the STJ axis ONLY. Draw one axis and base everything on that. It is just incomplete in its very nature.

That’s just it Eric, your question tells the focus. I am not worrying about moment changes around the STJ. I am re-posturing the foot. So I have no moments to measure or approximate. Certainly, measureable changes in moments of all joints occurs when you change foot posture. Axes translate to a better place. In SALRE terms, you are changing the medially deviated STJ axis, through axial translation to a more normal axial translational position. But that is ONLY ONE of the many axes that you are changing in translation, moments, etc. So the medially deviated STJ axis is not an anatomic anomaly, it is one place the STJ axis can be. If it can be translated to the normal position thru postural change it will be one piece of the puzzle. Maybe not the most important piece for any given diagnosis but ONE positional piece only of a 28 bone puzzle.

If timing of this thread was a little better, I would be able to give you data from our recent trip to the Smithsonian that shows, that the idea, that there is an anatomic variation in STJ medial to lateral placement or a variation in geometry that would yield medial to lateral deviation is simply not true. When we complete the analysis of the 209 calcaneii we have as 3D objects in virtual space you will see what I mean.
Data just does not support the theory. There is certainly some medial to lateral deviation, but adjusted for size, the bell curve is tall and narrow.

SALRE does not deal with postures at all. It is single axis. SALRE can be used to look at how one axis has effected a certain diagnosis but by definition it leaves posture to the wind.

Kinematics describes the motion of joints. Postural change involves kinematics and kinetics.

What is wrong with SALRE:
• It is a single axis theory omitting consideration of all other axes.
• It chooses the STJ axis only, which has relatively little moments around it through much of the gait cycle and very small ROM. In other words, it not only chooses ONE axis but the wrong one for many diagnoses…..like plantar fasciitis.
• It leads to a strategy of application of the Tissue Stress model that uses various mods to influence kinetic distribution often at the Pronated end of the postural ROM of the foot. We will discuss that soon.
• There is little anatomical medial to lateral deviation in the STJ according to actual measurements I personally took.
• The rest of the foot is NOT a rigid functional unit: which is a central wrong assumption of the theory.
• It claims to influence kinetic forces and moments with no measurement of those forces.
• It addresses a pathologic motion AFTER it has occurred.
• Its application will at best slow down the progression of deformity, not stop it and never reverse it.
• It only deals with the masking of symptoms.
• Research shows minimal to no kinematic effect overall.
• Some studies show the orthotics may be harmful for some diagnoses.
• Flat tilted shells with mods can be easily duplicated by WalMart, Dr. Scholls, Foot Leverlers or the Good Feet stores by taking a generic, low, flat, shell and adding various mods to it.
• I personally don’t enjoy playing Mr. Potatohead, moving mods around the shell to get a lesser effect when I can influence posture and make a visible kinematic change for the better.
• In Physics for a formula to be right it should be simple, elegant, symmetrical like: F=MA or V=IR or E=MC2 . The application of the SALRE theory is like quantum physics. We know the Schrodinger equation is not complete because it is long, ugly, asymmetrical and there are too many particles. The application of SALRE is ugly too; lots of mods, lumps, bumps, grooves, phalnges, tilts, posts, skives, wedges, put on the orthotic as an ART not a science. It is ugly.
• There are more reasons SALRE is wrong, but that is all I can think of right now.
Thanks,
Ed

 

Of course there is some variation allowing small moments to occur but the general idea or relative magnitudes is clear.
Ed

 

Whats perfect posture Ed ?

How do you define posture ?

and do you still think the motion of pronation is bad ?

 

Yes you have had the diagrams drawn to demonstrate your point of view! Well done. Maybe you could get ya' man to draw the GRF force vector so that it's really lateral to the STJ axis too. I happen to agree that the ankle plantarflexion moment may be greater than the subtalar joint eversion moment at strike, but your diagrams aren't evidence for that are they?

Here you go, I've drawn an alternative position for the GRF vector on one of your diagrams Ed (mines the black arrow). Now the moment is bigger. Which is right, your position or mine? And how do we know?

 

Ed!

Once again:

Of course SALRE omits the rest of the foot! That's because it looked at the STJ axis. RE applies to all axes. It demonstrates a concept Ed!

I ask again!

Calibrated to what Ed! How do you calibrate these "arch supports"?

I ask again!

Evidence here would be a real treat Ed!

 

Well yes. Like the thought experiments. But I don't think thats my point. My point is that the annotation of the diagram is fundamentally incorrect! To estimate the lever arm one needs the body weight AND the GRF force and vector. The slide in question shows only one.


Although I agree when you say

The flaw is more fundamental than that. If the forces and vectors ARE exactly as in the picture (and they probably are for somebody) the contention that in that foot there is no lever arm because the downforce bisects the axis is wrong.

 

I'm talking about the slide in post 20, not the ones to do with lateral heel strike GRF vectors. I think we are talking about different slides here. The lateral heel strike has a different problem!

 

My problem with this one



Is that the GRF is shown a the instant of heel strike. As soon as the rest of the calc loads (a tiney TINY fraction of a second later) even before the forefoot loads, the GRF arrow will be further forward. The GRF arrow, if you look carefully, does not enter the foot UNDER the calc, but behind the plantar surface, where the surface is about 45 degrees angled!

Now imagine that foot when the COP is a fraction further forward and think about the GRF then. When the COP has advanced to just under the talus the GRF arrow (assuming it is vertical, which it isn't) will be well lateral to the axis.

Cover the bottom half of the picture above and you get the idea.

I can't do computer 3d modeling, but I could explain it better with a plaster foot, a chopstick, a masonary drill bit, a VLS tickertape of COP drawn on the base of it etc. Perhaps someone who uses VLS a lot (hint graham) could tell me how long it takes on average for the COP to advance to the point where it is lateral to that axis. As a % of stance.

And, to re iterate, this assumes GRF vectors don't exist and I'm pretty sure they do!

 

I've seen STJ supination with pulling the hallux up. I'm sure someone can come up with a video showing it. Would believe it then? At the Biomechanics Summer School in 2007 I had a volunteer who was videotaped supinating with dorsiflexion of the hallux in stance.

Your engineering is wrong in the last sentence above. If the axis has some angle relative to the transverse plane then of course the projection of the axis into the transverse plane will be parallel with the fascia. However there will be an angle between the actual axis (not the projection) and the plantar fascia that will allow it to create a moment at the STJ.

I've taken cadaver specimens and pushed posteriorly on the talar head and pulled anteriorly on the insertion of the plantar fascia. I got supination of the STJ in all 5 specimens that I did that on. So, I may not have proven it to you, but I have certainly proven to my self that the plantar fascia does create a supination moment. The diagram of this can best be seen by looking at the frontal plane as opposed to the transvserse plane. Remember STJ equilibrium is a three dimensional relationship.

If it so simple, can you explain how an orthotic raises the arch. Just because you stand on a piece of plastic, does not mean that your foot assumes the shape of the plastic.

Ed, if you raise the arch and remove tension from the fascia there is no force from the fascia to gain a lever arm advantage. The arch has to be supported by forces from some other structure. This is why I keep asking how an orthotic raises the arch. The arch has to be maintained in that position when there is no tension in the plantar ligaments and no tension in the plantar fascia. Ground reaction force and body weight are still there trying to flatten the arch.

I really don't understand what your talking about in your last sentence above.

Ed, I don't know how many times we have to tell you this. People who use SALRE don't ingnore information about other joints.

Why do you think that the magnitude of the moments is so small that it does not cause pathology/ excessive strain. That is the whole point of SALRE. In some feet the magnitude of the moments is much greater than in other feet.

Ed, you should recheck your methods. Your results are in conflict with my EMED data and the Root diagram that you published. When you watch someone walking toward you, you will see heel contact, lateral forefoot contact, and then medial forefoot contact. FFL is defined as the point when you have medial forefoot contact and this occured at 27% in the Root, Orien Weed diagram.

Ed, if you refuse to examine moments, you cannot make claims like, "Increased posture, decreases the vertical travel and loading of the PT tendon." I will concede that if you reduce the amount that the STJ moves you will reduce the travel of the tendon, but this may not correlate with load in the tendon.

So Ed, how much force did the orthotic actually deliver to the body and how did you characterize it and measure it?

So, your explanation is that it just does?

And you should be able to explain the kinetics when you change the posture. If you don't, you don't know what you are doing.

Eric

 

Straw man. You can use SALRE and look at other axes simultaneously.

The whole point of SALRE is that moments will vary with STJ axis location. It will be higher in some as compared to others. Those with higher moments will be more likely to have pathology. I disagree with you that STJ moments do not effect tension in the plantar fascia.

So you have not stated the problem you have with this. I see no problem with functioning asymptomatically at the end of range of motion.

You are at odds with the literature on this.

It doesn't have to be a rigid body. When you apply forces to deformable bodies they will still create moments acting on those bodies.

I have an unpublished study that showed that a varus heel wedge shifted the center of pressure under the heel. I looked at it once, I shouldn't have to look at it for every patient.

Motion is not pathologic. Injury comes from excessive force.

It won't cure hemorrhoids either. But there is no orthotic treatment that has been shown to reverse deformity.

Given the choice, would you rather be pain free or would you like to function in the position of your foot that Ed Glasser thinks is most appropriate. I think most people will accept pain free.

Being pain free is not masking of symptoms.

We are talking about moments not position. Why do you need a change in kinematics to reduce symptoms?

Yeah, those Sole support devices you made for me really hurt. I'm not saying that they would hurt everyone, but there are some people who will not tolerate a high arched device.

These points are not a criticism of SALRE.

M = I alpha. (moment = moment of inertia x angular acceleration) This is SALRE. It may seem like quantum physics to you because apparently you don't understand it. It is quite simple and elegant. I guess beauty is in the eye of the beholder.

Now you are just name calling. I think you owe SALRE an apology.

Eric

 

MASS is actually NASS!

Narcissitic assumptive Sales System!

 

Interesting comment Graham. Would it surprise you that Ed has changed the meaning of that acronym before (and thus the focus)?

 

Really? What does MASS stand for now and what did it stand for before?

 

I call new thread! I'm still waiting to here about the force down the leg running through the axis = no moment arm thing.

I think I'd like to here from Ed why he changed the name.

 

While you're waiting take a look at this picture and then read this paper http://www.japmaonline.org/cgi/content/citation/78/4/159 (for some reason my pdf of this won't upload, but you can access it through Kevin's paper archive- maybe Kevin will upload it here?), see if you can spot the difference- challllllllange! Hint figure 10.

 

Really Simon.

You see, Ed markets very heavily to my profession so I am very familiar with his pet theories, ideas and marketing. Due to this, something niggling in the back of my mind concerning Ed's previous statements, marketing and his latest assault on SALRE here hit me full in the face yesterday. I realized that Ed had made an error and hoped we wouldn't catch it or see it for what it was.

I feel it is mortally embarrassing for Ed and his merry band of employees. Can you feel it yet Ed, do you know what I'm alluding to? Because our interaction here has been so delightful, I am more than pleased to share it with the rest of the biomechanics community for all to judge for themselves.

Never bring a knife to a gunfight :empathy:

 

My weapon of choice is the AK-47 http://en.wikipedia.org/wiki/AK-47 , never leave home without it. So.............

 

This sounds like it´s going to be gooooooooooooood

 

Here's figure 10 for those with no access to the article

 

Thats real nice son,

This here's what I carry

 

Thanks Ian, Kevin and his colleagues evaluated 100 radiographs in their article, which led them to state: "In all of the subjects in this study, the lateral calcaneal tubercle would never be a weightbearing structure during normal ambulation except possibly at the instant of heel contact when the calcaneus is most inverted". In Ed's picture above the relative talar to calcaneus positions indicate that Ed is attempting to simulate maximum pronation at the subtalar joint with his model. So why is the lateral tubercle of the calcaneus resting on the table? Root et al, didn't show the calcaneus to be positioned thus with the subtalar joint in this position (figure 10 above) and Kirby and colleagues found none of their 100 subjects to have a calcaneus positioned in this way. So why is Ed showing it like this?

Just an observation.

 

You can put as many lights and sites on it as you like, it's what comes out of the barrel when you squeeze the trigger. And if there's one thing about the AK-47, it usually works when you squeeze the trigger, and if it doesn't it's easy to strip down and rebuild in the field. What happens when you get a bit of grit in that, Rob?

Anyway, I thought your weapon of choice was the English longbow? "A more elegant weapon for a more civilised age": Obi-Wan

 

You're right of course. The longbow is a thing of beauty and grace, a gun can only ever be a cold ugly machine.

But we digress. Lever arms. I still want to hear from Ed why in post #20 he describes the sub talar lever arm as the distance from the descending force to the axis.