Prescribing Orthoses: Has Tissue Stress Theory Supplanted Root Theory?

What is it, that you are referring to as a "leap of faith"?

 

Therefore, if one wants to maximize the "control of excessive STJ pronation" with a foot orthosis, then it is necessary to customize the foot orthosis in such a fashion that GRF is shifted medially on the rearfoot, midfoot and forefoot so that the medial heel skive, for example, may work synergistically with the increased MLA height/stiffness to redirect GRF more medially under not only the rearfoot but also the midfoot and forefoot.

This is just “guesswork”. There is no quantification of the attempt to limit a specific degree of pronation. There is no account for what this does to the triplane motion other than supinate it.--more guesswork is needed

 

Kevin


Foot orthoses "control" subtalar joint (STJ) pronation and closed kinetic chain (CKC) heel eversion by creating external STJ supination moments.

Today's modern traditional orthotic technology does not do a sufficient job in
controlling” external supination moments.

Internal STJ moments, on the other hand, by definition, are those STJ supination torques that originate internally within the foot and lower extremity, such as from posterior tibial contractile activity.

This is a common misconception in biomechanical control. Based on computer analysis of pre and post mechanical control, muscles cannot hold against the weight bearing and pronatory forces of biomechanical motion. The forces behind the full ROM of any joint is greater than the strength of muscles.

 

Kevin

Therefore, if one wants to maximize the "control of excessive STJ pronation" with a foot orthosis, then it is necessary to customize the foot orthosis in such a fashion that GRF is shifted medially on the rearfoot, midfoot and forefoot so that the medial heel skive, for example, may work synergistically with the increased MLA height/stiffness to redirect GRF more medially under not only the rearfoot but also the midfoot and forefoot.

This would be correct if one is guessing at trying to accomplish minimizing pronation, but this is not customizing, it's guesswork at best. This is not scientific. There is no basis of science behind it.

 

Dennis,

We have a good basic understanding of the biomechanics of foot and lower extremity. Obviously we have a ways to go to gain a better understanding of foot function, but we should not ignore what we currently know. We can identify pathological conditions and the forces that create or compound these conditions. And we can create orthoses utilizing our knowledge of anatomy and physics to attempt to counter these pathological forces. The word guess is defined as "to form an opinion from little or no evidence". While not an absolute science, it is far more advanced than guesswork in my opinion.

We know that functional orthoses can be prescribed with a number of Rx variables that will resist pronation or supination of the STJ or will act to increase stability of the MTJ. For example, we know that if we invert the positive cast, make a higher arched device, apply a medial heel skive and use a more rigid shell, we will increase resistance to STJ pronation. We are not guessing what these orthotic prescription modifications will do, we know from research and from past clinical experience how these options will influence forces acting on the foot. Although we don't necessarily have the technology to measure the forces generated by the orthoses, we can appreciate the nature of these Rx options and we can see and evaluate their influence on position, motion and ultimately on symptoms.

Jeff

 

Jeff,

I have to disagree with your premise. First, because there is no principle of physics that your technology is based on, and because your current technology is so flawed in so many ways that you've never had the opportunity to see what an accurate orthosis does to foot function and how it fits the biomechanical gait cycle.

To say “ functional orthoses can be prescribed with a number of Rx variables that will resist pronation or supination of the STJ”--


We don't see eye to eye, right here. A functional orthotic for dynamic function should not resist. Instead it to should facilitate/assist or guide the natural motion in a stable and balanced manner. After all, starting at heel contact, the biomechanical motion of the kinetic chain takes about one full second of stance phase contact. A static orthotic interrupts the fluid motion allowing for instability or as I like to refer to it as “overpronation” there are I believe two (2) overpronation moments in the gait cycle using traditional orthotic technology (regardless of modifications) which limits the success ratio an orthotic should get. If I were to be able to conduct a clinical test between your technology and generic OTC products, I would have double the success ration (even by your criteria) of either product.

What I see is that the movement of the planes of motion with traditional technology is carelessly thrown to the wind. Inverting or everting a cast in only ONE PLANE does not allow for the proper movement of the planes of motion as well (remember a triplane motion). Modification in 1-5 degrees is perhaps a thousand Rx in my world. Yes, you can have successes, because after all you've reduced some excessive overpronation, but without the science basis you can only get close, you'll never achieve complete and total success as I do. So, I do believe your technology and outcomes are predicated on guesswork of “ a good basic understanding of the biomechanics of foot and lower extremity”



Although we don't necessarily have the technology to measure the forces generated by the orthoses,

Here again, I have to disagree. First the technology is available to measure the forces and all available data that a program like Tekscan already has. However, I disagree that you're trying to measure the forces generated by the orthotic. The forces to be measured are a result of the the biomechanical device
barefoot and then with the orthotic. That's how you see and measure the difference.

And when you do that you can come up with the theory, that efficiency in biomechanical motion will reduce tissue stress.

 

Kevin

All in all, I have changed the ways I teach biomechanics and foot orthosis therapy multiple times over the past three decades and expect I will change again before I retire from practice. The bottom line is that we need much more research before we can say what orthosis production techniques are best and, until that time, we must keep an open mind to new ideas so that we don't get left behind as a profession when a better idea and/or technique comes along.

I find this statement of yours to be outragious. When you are well enough aware of the validity and accuracy of fluid mechanics and biomechanics. You lack the courage to even investigate fluid technology and orthotics because you realize it so totally conflicts with your concepts and theories.

Podiatry has already been left behind. While there have been successes, there have been more hostilities towards orthotics, and today approx 70 years later you're still engrossed in the same abysmal technology. Still talking and theorizing how to make modifications to resist pronation. How to move or counter forces instead of how to harness those forces to the way you want those forces to behave. Yes, an outrageous statement.

 

Jeff,

I want to add something to our discussion. Because my premise is to simply reduce and minimize pronation movement by simply “balancing” the foot structure, there is no need to concern myself with whether the pt has PF or any biomechanical inflammatory disorder.

Balancing the foot so that the structure and lower extremity can work in its own natural biomechanical alignment. Placing the foot in this position allows the structure to work so that the axis of each joint is as near to congruity as possible.

Trying to make an orthotic by thinking like an engineer and build it to counter specific forces and maladies is bass ackwards as far as I'm concerned.

 

Dennis,

In most cases the goal of functional orthotic therapy is to prevent pathological forces while enabling healthy forces that are necessary for ambulation. By the nature and definition of triplane motion, if there is motion relative to one cardinal body plane then there must be motion occurring simultaneously relative to the other two body planes. Therefore, if we invert the cast and influence the frontal plane component of STJ motion, then there must be an influence on the motion (forces) occurring in the other two body planes. For example, if my inverted orthotic decreases heel eversion by two degrees (a frontal plane measure of STJ motion), then I must have produced changes in the other two planes of motion. Unfortunately we don't have a method for measuring STJ motion, only the frontal plane component of it (i.e. heel inversion and eversion). So even something as simple as a pure wedge can produce triplane changes because of the nature of tiplane motion.

Jeff

 

Dennis,

Lets look at the biomechancis of a soccer player and determine how his foot should function. He will utilize his entire STJ ROM as he runs, pivots, kicks, slides etc. His foot does not function in a "balanced" manner. Or take a look at the biomechanics of the left ankle of a baseball player hitting from the right side. His forward foot (left foot) will often invert severely at the STJ and ankle when he swings and he will often bear weight on the lateral upper of his shoe as he completes his swing. These are examples of activities that require extreme ranges of motion and this "imbalance" is necessary to perform the task successfully. So I don't know what a "balanced" joint or foot is. The joints and the foot must be able to assume a position that will enable the individual to accomplish the task in the best manner possible.

Jeff

 

Dennis, Jeff and I use the same "orthotic technology". There are principles of physics that are used when we use that technology. Have you seen my center of pressure paper or Kevin's rotation equilibrium paper? Saying that there are no principles in physics in the use of that technology is just plain wrong.

Dennis, if you want to understand forces you have to think like an engineer. If you want to understand how to reduce stress on anatomical structures (stress = force/ area) then you need to understand forces. You also might want to think like an engineer when you want to measure "biomechanical efficiency". What do you mean when you use that term? If you expect "biomechanical efficiency" to reduce tissue stress you are going to have to explain how the forces on anatomical structures are changed.

Eric

 

Dennis, can you explain what you mean by balance? Can you explain why balance is a good thing? Can you explain how balance will improve pathology? Claiming that balance is natural is meaningless.

Eric

 

Jeff

You're putting the horse before the cart. I hold that the fluid technology I am talking about is for staright up walking and running straight ahead. I'm not talking about complex ROM activities. I do not even recommend the fluid orthotic for any lateral motion sports, even though I have used it successfully myself for tennis and basketball. But I'm not a competitive player and I would vehemently not recommend it for someone who is.

The world is full enough of biomechanical injuries from just basic walking.

As for the word “balance” and your confusion about it, rather than define what you already know, take a look at the computer scan on my front page. What you see is what I'm referring to as “balance”. If you have a question about what you see, please feel free to ask.

 

Eric

I'm not sure where I stated that balance is natural. Balance among each articulation (the axis bisects the
center of the joint) affords the least amount of wear and tear to the biomechanical structure. If you don't see that as healthier, than I can't help you.

 

Eric

There are two forces that I'm concerned with, wt bearing and pronatory. I do understand those. I don't need to think like an engineer to harness them into a more efficient manner, I simply need to let the hydrodynamic technology do it for me. I only need to figure out the Rx of the volume of fluid to accomplish that.

If I want to measure the efficacy of those forces I can look at a computer analysis of a barefoot, the same foot wearing a traditional technology orthotic and one with fluid. While I don't present that information in detail on my site (because it is for the lay person)--look at the scans on my site and see if you can determine if there is any validity to my term “balance”?

 

In their book on Biomechanical Examination of the Foot, Drs. Root, Weed, Orien and Hughes wrote:

There really should be no such thing as "podiatric biomechanics", but I fear there is. In podiatric biomechanics there seems to be very little standard and commonly accepted terminology. I wonder if there is any other branch of medicine where the terminology used to discuss the practice of medicine and the theories that surround it are as convoluted as they seem to be in "podiatric biomechanics". I would say that the advancement of clinical treatment and knowledge of the foot continues to be seriously impaired by a lack of specifically defined and commonly accepted terminology.

Jeff

 

Post # 528

Dennis, an axis is an imaginary line. We can use imaginary lines to represent something. What are you representing when you said "Balance among each articulation (the axis bisects the center of the joint) affords the least amount of wear and tear to the biomechanical structure." Can you explain what you mean by that sentence?


Eric

 

Apparently you do not understand weight bearing force. Weight bearing force is the pronatory force when it is in one location and it can be a supinatory force when it is in another location. So, you can't explain how hydrodynamic technology "harnesses" forces.

How would you measure efficacy of a force? I've looked at your website. When we discussed your website last time I believe I pointed out to you that you need to look at the force between the orthotic and the foot and not the orthotic and the ground.

Eric

 

indeed said similar earlier in the thread

There is a specifically excepted terminology in the world of Biomechanics - no idea why that should get thrown out when you add Podiatric to Biomechancis :wacko:

and the pure Biomechanics world even discuss the foot

 

Jeff


I would say that the advancement of clinical treatment and knowledge of the foot continues to be seriously impaired by a lack of specifically defined and commonly accepted terminology.

Really? Are you saying that clinical Tx and knowledge is impaired by confusion in terms? What has that got to do with my trying to let you know about a new technology in the treatment of podiatric biomechanics?

I don't think that the terms are that confusing. Is our level of understanding podiatric biomechanics
dictated by terms? Let me ask for example: I've seen the term “balance used in threads on PA. What would be your definition of this term in relation to orthotic alignment?

Perhaps if you discussed the concept of fluid technology as I wrote about in my article: http://www.podiatrytoday.com

How do you see this scientific technology in relation to biomechanics?

 

Eric

I don't see what is so complicated here. If a joint works in congruity, it is more efficient than if “forces” force it to deviate from its most congrous position. This is referred to as subluxation.
Subluxation creates “instability” or overpronation. This is less efficient. This instability over time combined with the rest of the biomechanical criteria the lower extremity is comprised of will potentially cause an inflammatory build up.

 

Eric

You're wasting my time.

Apparently you do not understand weight bearing force. Weight bearing force is the pronatory force when it is in one location and it can be a supinatory force when it is in another location. So, you can't explain how hydrodynamic technology "harnesses" forces.

I I have explained, you don't get it!

How would you measure efficacy of a force? I've looked at your website. When we discussed your website last time I believe I pointed out to you that you need to look at the force between the orthotic and the foot and not the orthotic and the ground.

You just don't know what you're looking at

 

Dennis,

My comment is not direct at you alone. In order for a group of individuals to have meaningful communication about a technical topic, we need to have a common language and we need to know the definition and connotation of the terms being discussed. While I know the definition of "balanced" and of "foot" or "joint", I don't know what a "balanced foot" or a "balanced joint" is or what it means to you.

The term "balanced cast" is used in reference to the technique of processing a positive cast for the fabrication of a functional orthosis. When we "balance a positive cast" we add a plaster-of-Paris bar or platform underneath the met heads which positions the positive cast with the heel in an inverted, vertical or everted position when we place the plantar surface of the positive cast on a counter top that is parallel to the plane of the floor. The angle of the cast should be determined in by the prescriber. If the forefoot of the cast is intrinsically corrected or balanced, then the plane of the forefoot relative to the ground is influenced by the angle of balancing and by the forefoot to rearfoot relationship. For example, if the heel of a cast that has 10 degrees of forefoot valgus is balanced with the heel 5 degrees inverted, then the forefoot will be balanced 5 degrees everted to the plane of the floor. The term cast correction is also used to describe this same process. Rather than say we balanced this cast, we could say that we corrected this cast with the heel 5 degrees inverted.

We can also accomplish the same thing by extrinsically posting the forefoot of the orthotic shell to position the device in the frontal plane. In this case our forefoot platform would be applied parallel to the plane of the met heads and the entire shell would be extrinsically posted to bring the forefoot and rearfoot to the desired angle relative to the floor. Does this answer your question? I will respond to your other questions in another post later today.

Jeff

 

Eric



There are principles of physics that are used when we use that technology. Have you seen my center of pressure paper or Kevin's rotation equilibrium paper? Saying that there are no principles in physics in the use of that technology is just plain wrong.

I never said that there is no physics involved in biomechanics. Of course there is. What I said is there there is no principle of physics that you're technology mechanism is based on.
Hydrodynamic technology on the other hand is predicated on the Archimedes principle (displacement)--the entire biomechanical gait cycle (stance phase) is loading or unloading predicated on that principle of physics. Can you say the same? Or at least point to where it does??







Dennis, can you explain what you mean by balance? Can you explain why balance is a good thing? Can you explain how balance will improve pathology? Claiming that balance is natural is meaningless.

After Jeff's post earlier I can see I need to address “balance” a little more.
If you look at the scans on my site, look at how the hydrodynamic effect changes the GRF under the forefoot. Because some mets have higher and lower pressures, the hydrodynamic effect is to “balance” those unequal forces. Compare that to the same foot with traditional technology and compare the “balance” of those forces. If you can't see the difference, I can't help you any further.

As for how balance will improve pathology, is unnecessary for me to respond to.

 

Dennis,

This is from your website:

This is an example of my concern about your use of terminology. The term pronated refers to position and the term pronation refers to motion. Pronator, which is not a scientific term, is typically used to describe an individual with excessive pronation (either in range or duration I suppose and is typically preceeded by the word excessive). By definition, when the foot is in the neutral position at the STJ it is neither supinated nor pronated. The neutral position of the STJ is just one point in the ROM of the STJ. You state that natural, neutral and optimal have the same meaning. But the foot can't be in the neutral position and a pronated position at the same time. It's like saying that 0 is a positive number. Zero is neither negative nor positive.

The term balance as you use it means what? If balance is a state of equilibrium, then the foot could be in balance at any point with the ROM of the STJ. It could be balanced with the STJ maximally pronated, maximally supinated or anywhere in between.

Jeff

 

Jeff

Jeff,

There are so many things that deserve your concern more than the example you've thrown into the mix. Stick to the discussion at hand. I don't want to explain the above now, however your last statement

“The term balance as you use it means what? If balance is a state of equilibrium, then the foot could be in balance at any point with the ROM of the STJ. It could be balanced with the STJ maximally pronated, maximally supinated or anywhere in between.”

absolutely NOT the way you stated it. Balance is achieved when it reaches the equilibrium state at midstance—not a state of equilibrium, which would imply something else.

 

Dennis,

Can you explain this further: "Balance is achieved when it reaches the equilibrium state at midstance"? During the midstance phase of the gait cycle, the STJ and MTJ are typically moving. So if during ideal gait, the STJ pronates at heel strike and resupinates during midstance, then when and how is balance achieved and specifically, what is this state of balance you're referring to? What joint or joints or structures would be in balance?

Jeff

 

Jeff

http://www.podiatrytoday.com/closer-look-principles-fluid-dynamics-they-relate-orthoses

 

As is my way sometimes not to beat around the bush


Clearly there is a reason why many use terms not in the same manor as the wider biomechanics community, it makes the product they are selling look different , new and fancy, if they get challenged they can yell and scream and make up some more fancy sounding sentences, which make no sense

Sales 101

Baffle them with Bullsh!t

 

Jeff


f during ideal gait, the STJ pronates at heel strike and resupinates during midstance, then when and how is balance achieved


I meant to address this earlier, because this is exactly what a traditional technology orthotic does. Because the STJ “resupinates” at midstance, it has already subluxed and is therefore unstable to the cycle.

With fluid technology, the rearfoot motion is deceleratting as the fluid is displaced, the calcaneous is on an incline and never reaches its full pronation capacity. Once all the fluid has been displaced into the arch chamber (thanks—Dr Spooner for this term), the STJ is in its optimal position.

 

Dennis,

How do you control the amount and direction of the displacement of the fluid?

Jeff

 

Jeff

The direction is hydrodynamically displaced (under wt bearing and pronatory forces). I think the article explains that. The amount is determined by a template that the pt stands on and displaces the excess fluid into a calibrated reserve bladder. That becomes a Rx, The lab knows how much fluid to put in from that # and the template size.

 

Jeff

I should add, that once the pt begins wearing the ortoses, then you have to evaluate whether the biomechanical fit is correct. If an adjustment (more or less fluid) is necessary, then you have to order a new Rx as the system is closed and cannot be opened.

 

This is excellent. Could not agree more. I have watched this and worked on this but have never had it explained. Thankyou.
:drinks

 

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1929869/?page=1

 

Everyone is selling something Kipper, some are just better salesmen than others. You are selling a liquid filled insole that anyone could buy from e-bay for about $12 US ,while you are selling something very similar for a couple of hundred dollars- I love your style and wish you well in your sales. Viva the Sub-genius. I'm a bit concerned that you are not offerring the magnets with them though- something to add to your strategy I think.

Love this: "when there's new technology, there's new language... it's nothing more than a new way to describe old technology" That my friend, is pure sub-genius right there. Keep up the good sales. But is it "new technology" or "old technology"? Is it new speak or old speak?

You can do better the DR Honey, keep him at ams length- he threatens your sales.

 

Jeff,

I hadn't seen any further discussion from you, I hope no one is pressuring you not to have this discussion with me, because of the information I've provided. Or perhaps you are wrestling with your own concepts?

I wanted to further elaborate on your last post


Trad tech biomechanics only loads once at midstance from HC until ff contact
then it has to resupinate. The fact that you know that makes me wonder how you don't see the fact that it's already overpronated and become unstable (at two locations). It cannot resupinate properly to become stable at propulsion.. Trad tech minimizes and reduces pronation of the gait cycle, but it doesn't do it well enough. That's why on scans you can see reductions in pressure, but you don't see consistant even reductions of press, spread out across the forefoot.. With fluid you can see the redistribution of GRF under hydrodynamic pressure each and every time.

To me, the forefoot is the visual screen of the biomechanical efficiency of the orthotic. The COP and a lot of other things are just data to be used for other things.

Fluid tehnology begins loading at hc and maintains stablity throughout the stance phase and momentarily prolongs the stability of the propulsive stage. It never overpronates (unless the Rx is underfilled) You can see all that in the scans. It's right in front of you. I've debated with EF about the ability to read scans. He said I can't read them, Kirby said I was making it up, and the evidence is right there and you can't see it? It points out the full biomechanical range of motion in the latest tech that we have. With trad tech at heel off in every scan you can see ff stability crumble (not that it was stable to begin with). With hydrodynamic function you can see the prolongation of stability at propulsion.

What do you see as biomechanical information, when you look at the comparison of the bf—trad orthotic and fluid?

 

Dennis,

I'm still here. Just had a busy couple of days with little time for the PA. Based on the anatomical structure of the foot, why should there be even distribution of pressure on the plantar surface of the foot? The medial arch is not designed (by nature!) to be a primary weight bearing surface of the foot. The medial arch is a bowstrung structure. As the arch lowers as the foot pronates, the tension in the plantar structures increases which resists additional pronation. We can use a device to support the arch to provide an external force to resists pronation in those who need external assistance. While your orthoses may help reduce pressure in certain areas, I don't believe that fluid provides the best distribution of orthotic reaction force.

Here is an example of why. If we look at adult acquired flatfoot, the medial arch is collapsed. We need to lift the arch and resist collapse. A fluid would move away from the medial arch as it collapses, and would possibly transfer laterally, which would increase the pronation moment.

I have to run now, but will try to keep.

Jeff

 

Jeff,

I'm not sure you realize what you said; that “The medial arch is not designed (by nature!) to be a primary weight bearing surface of the foot.??

Well, of course the ARCH doesn't perform that specific purpose, but the 1st ray does. That's the BIG BOY.and because the talo-navic has the widest rom in the foot, the 1st ray has the largest range of pronation in the forefoot and unlocks/destabilizes the FF. Remember—any part of the foot that destabilizes—unlocks RF/MF/FF—it's all linked

As for even distribution, it's not necessarily even across the board, because as you said “Based on the anatomical structure of the foot,”
The pressure across the foot is not necessarily equal press but because of the structure of the foot, each met has a different ROM—different GRF it is the hydrodynamic “balancing” reducing some areas of high GRF increasing the press in other areas. If you remember from the article, the fluid serves as a dynamic fulcrum. Other wise what are you trying to do with your orthotic having a medial arch and building upany segment of the foot?

A simple generic arch support tries to do the same thing, by spreading and therefore
balancing the weight bearing structures. By supporting the MTJ you bring the ground up to the foot.
By “spreading” out the the forces, you bring the foot to an optimal position—what we refer to as “neutral” and all that it infers(that's what I call congruent (or near congruent) joint mechanics.


I don't believe that fluid provides the best distribution of orthotic reaction force.

You either did not look at the scans or you do not understand what you're seeing.

fluid would move away from the medial arch as it collapses, and would possibly transfer laterally, which would increase the pronation moment.

Only a neurologic or fixed flat foot would do that. As I stated in the article—the lat column, forefoot and RF have higher GRF and keeps the fluid under the arch chamber.--It does absolutely not do what you stated.

 

Jeff,

Kirby just wrote that podiatry needs to get it together or it will be left behind as a profession. Well, it's already been left behind, because of the high percentage of failure with our trad tech.

I was hoping that there some among you that was not intimidated by the few who reign power and prevent a technology that would bring podiatry into the 21st century—with a valid scientific and quantitative approach. A true Rx and a better understanding of what biomechanics are really involved with each foot.

An orthotic that does exactly what we want from a biomechanical tool to help better align the kinetic structure. Then not only would you're ability to help simple problems heal and minimize re-occurrence, but help othe really needy patients that have vascular and diabetic pressure ulcers. It takes about a year to close those things, but wouldn't it be great to be confident that if you can't close it, then the pathological state is out of control and you need to concentrate on another approach to helping that pt.

Wouldn't it be great to educate the public the way dentistry did mid 20th century and start fitting children from about the age of 10 up so that we can minimize and reduce the potential for orthopedic maladies of the lower extremity.

When you can say “While your orthoses may help reduce pressure in certain areas, I don't believe that fluid provides the best distribution of orthotic reaction force.”

What about increasing forces where the segment is not carrying its full load (which is how it deflects the excessive pressure). I feel your remark leaves me wondering what kind of science background you have that allows you to overlook the effects of hydrodynamics. You don't need to be a physicist.