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I am grateful to Kevin Kirby and Precision Intricast for permission to reproduce this February 2002 Newsletter (you can buy the 2 books of newsletters off Precision Intricast):




Within the podiatric biomechanics community during the past fifteen years, there has been a gradual shift away from using the SJN Theory as a theoretical basis for mechanical foot therapy. One of the reasons why many podiatrists have moved away from the SJN Theory is due to some of the inherent problems and inconsistencies with this theory of mechanical foot therapy. One large problem with the SJN Theory relates to the reliability of the measurement procedures used within the standard biomechanical examination techniques proposed by Root et al over thirty years ago (Root, M.L., W.P. Orien, J.H. Weed and R.J. Hughes: Biomechanical Examination of the Foot, Volume 1. Clinical Biomechanics Corporation, Los Angeles, 1971). These examination techniques have been found to have only fair to poor intertester reliability and, therefore, can not be considered reliable from one examiner to another (McPoil, T.G. and G.C. Hunt: Evaluation and management of foot and ankle disorders: Present problems and future directions. JOSPT, 21:381-388, 1995.)

Another criticism of the SJN Theory is that the criteria for normalcy proposed by Root et al are not clinically practical since they are so restrictive that few individuals have “normal” foot and lower extremity structure (Root et al, 1971). In addition, the idea of Root et al that the subtalar joint should supinate through neutral position during the midstance phase of walking gait has been questioned by research by McPoil and Cornwall on 100 healthy, asymptomatic feet in which the subjects were more likely to have a rearfoot motion pattern which correlated to their resting calcaneal stance position than to their neutral calcaneal stance position (McPoil, T.G. and M.W. Cornwall: The relationship between subtalar joint neutral position and rearfoot motion during walking. Foot Ankle Intl., 15:141-145, 1994.) McPoil and Hunt have provided an excellent review of the problems associated with the SJN approach to mechanical foot therapy, including those listed above, and also have proposed a new model, the tissue stress model, for the approach to mechanical foot therapy (McPoil and Hunt, 1995).

McPoil and Hunt have chosen to use the tissue stress model “as the basis for developing an examination and management paradigm for treating individuals with foot disorders”. They claimed that the tissue stress model is not a novel idea since it is based on the same ideas that are already in current use in the treatment of parts of the body other than the foot and lower extremity. In addition, one of the benefits claimed for the tissue stress model is that it doesn’t rely on the use of the “unreliable measurement techniques” currently in use within the podiatric profession (McPoil and Hunt, 1995).

There have also been others that have also advocated the use of the tissue stress approach to mechanical foot therapy. Eric Fuller, DPM, has recently described the effects of rearfoot and forefoot wedging and how he uses the tissue stress approach in the clinical setting as a basis for mechanical foot therapy (Fuller, E.A.: Reinventing biomechanics. Podiatry Today, 13-3), December 2000). Dr. Fuller has also reviewed the concept of tissue stress and how computerized gait evaluation techniques along with the concept of modeling of the foot and lower extremity can help predict the stress in a specific anatomical structure (Fuller, E.A.: Computerized gait evaluation. pp. 179-205, in Valmassy, R.L. (editor), Clinical Biomechanics of the Lower Extremities, Mosby-Year Book, St. Louis, 1996). In addition, in two articles on future directions for podiatric biomechanics, I have also described the important concept of modeling of the foot and lower extremity and how modeling can be used to predict the loading forces, or stresses, which occur in the structural components of the foot and lower extremity during weightbearing activities (Menz, H.B. (moderator), Kirby, K., Cornwall, M., Rome, K., Tinley, P., Murphy, N., Keenan, A.: Clinical measurement of the lower extremity-where to from here? Australasian J. Pod. Med., 31 (3):95-99, 1997; Kirby, K. A.: What future direction should podiatric biomechanics take? Clinics in Podiatric Medicine and Surgery, 18 (4):719-723, October 2001).

Previous to the time that I first heard the concept of the “tissue stress model” in a lecture given by Tom McPoil, PhD in 1997 at the American Academy of Podiatric Sports Medicine Annual Meeting in Bellevue, Washington, I had independently developed a similar thought process and approach to mechanical foot therapy that I called “thinking like an engineer” (Kirby, K.A.: Thinking like an engineer. March 1992 Precision Intricast Newsletter. In Foot and Lower Extremity Biomechanics: A Ten Year Collection of Precision Intricast Newsletters. Precision Intricast, Inc., Payson, Arizona, 1997, pp. 267-268). In the newsletter, I described how it is more important for the podiatrist to focus on the internal loading forces, or stresses, which cause injury when treating mechanically related pathology than to just focus on determination of “deformities”. I also described how a structural engineer might use a similar approach when analyzing the stresses within the structural components of a building or bridge.

The tissue stress model is another way of stating the idea that podiatrists would be more effective at treating their patients if they would only use some of the basic mechanical concepts that have already been used for decades by structural engineers. The model is based on the concept that any mechanical therapy designed for the patient should be based not only on the specific anatomical site of injury of the patient, but also on the nature of the pathological loading forces that are causing the injury and how to most effectively design a mechanical therapy program to reduce these pathological loading forces so that healing may be optimized. Podiatrists who use the more logical and biomechanically sound approach to mechanical foot therapy inherent in the tissue stress model are much more likely to efficiently and effectively heal the mechanically based pathology of their patients. The podiatrist that only uses the concepts advocated by the proponents of the SJN Theory, where treatment of externally apparent “deformities” guides the design of the mechanical foot therapy, likely will be less effective at treating the wide range of foot and lower extremity pathology that can be treated with foot orthoses.

[Reprinted with permission from: Kirby KA.: Foot and Lower Extremity Biomechanics II: Precision Intricast Newsletters, 1997-2002. Precision Intricast, Inc., Payson, AZ, 2002, pp. 13-14.]

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How does a podiatrist use the tissue stress approach when seeing patients? Here is way it should be done:


1. Accurately identify the anatomical structure which is injured or symptomatic.

2. Determine the structural and functional characteristics of the individual's foot and lower extremity.

3. Determine the most likely type of abnormal tissue stress which is causing the pathology within the injured anatomical structure (i.e. compression, tension or shearing stress).

4. Design a treatment protocol to reduce the abnormal tissue stresses on the injured structure and reduce the local inflammatory response so that more normal gait and weightbearing function can occur.


This is certainly very different from the way I was taught to treat patients with foot orthoses (i.e. STJ neutral theory) since this was based nearly solely on trying to get the patient to function in STJ neutral position, with little regard to the injured structure that was being treated.

__________________
Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
**************************************************

Hi Kevin,
The points you make above I believe are very valid, and we do need to shift away from the old Root version of "motion and position" when dealing with foot pathology and biomechanics. Points 1 & 2 above descibe the "biomechanical and clinical assessment" side of the equation, and point 4 the treatment. However, what I do not understand is point 3, how do we determine which type of force it is? and if it is a compression type force affecting certain structures due to end-range pronation for example. isn't the treatment protocol going to attemt to make a device which affects the "position and motion" of the STJ anyway so as end range compression forces do not occur?
Apologies if I'm a little behind on this topic, but any of your thoughts may help me get a better grasp of the new model, and how to alter our clinical practice.
Thanks,
Adam

Adam:

We can best determine the most likely type of tissue stress (i.e. compression, tension, torsion, shearing) by knowing the function of that tissue, its anatomic location and how externally generated and internally generated forces are affecting it. For example, in a patient with plantar heel pain, which we commonly call plantar fasciitis, the pain can be caused by compression stress due to ground reaction force acting directly on the plantar medial calcaneal tubercle or due to tension stress from the fibers of the central component of the plantar aponeurosis on the medial calcaneal tubercle. If it is due to compression stress, then reducing the compression stress would be the most appropriate means of relieving pain. If it is due to tension stress, then reducing tension stress would be the most appropriate means of relieving pain. Of course, probably many cases of "plantar fasciitis" are caused by a combination of compression and tension stress so that therapy will need to include provisions for both.

Another example is tenderness in the midsubstance of the central component of the plantar aponeurosis, which can be caused by both tension stress and compression stress. Tension stress would typically be caused by Achilles tendon tension during weightbearing activities and may respond to more arch support from an orthosis. Compression stress could be caused by a foot orthosis that is pressing too firmly on the medial arch of the foot during weightbearing activities and may respond to less arch support from an orthosis. Therefore treatments will vary, using the tissue stress approach, depending on the mechanical nature of the forces acting on the structural component in question.

__________________
Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
**************************************************

Kevin,
So we've identified the tissue, lets take your example of a patient with plantar heel pain, due to tension stress from the fibers of the central component of the plantar aponeurosis on the medial calcaneal tubercle, how do I make an orthotic for this patient? How should I cast the foot? How should I balance the forefoot to rearfoot on the positive cast? What degree of rearfoot wedging should I add? In other words, how do I arrive at my orthotic prescription in the tissue stress paradigm?


Also, when I have dispensed the devices, how do I know whether I have altered the moments favourably? Now some bright spark is going to say, "because the patients symptoms improve". But we all know that this doesn't answer the question because symptoms can improve for a multitude of reasons, without necessarilly changing moments.

Best wishes,
Simon

__________________
Who? What? When? Why? Yeah? And? So? What?

"My mission drive is to open up my eyes, 'cause the wicked lies and all the sh!te you say..." http://www.youtube.com/watch?v=V4NW5S1UTPQ

"Science is the antidote to the poison of enthusiasm and superstition."

Simon,

The tissue stress theory of mechanical foot therapy is not comprehensive enough to provide an exact prescription protocol for all foot pathologies. However, it will allow guidance of the clinician toward an orthosis prescription that is quite likely to accomplish the goal of making the patient less symptomatic.

For example, if it is determined by the clinician that the pain in the plantar heel is caused by increased tensile force within the medial fibers of the central component of the plantar aponeurosis pulling on its origin at the medial calcaneal tubercle, then I would design the orthosis with specific modifications that would tend to reduce the tensile force within the medial fibers of the central component of the plantar aponeurosis. This may include designing the foot orthosis with a 5 mm polypropylene shell, 4/4 degree rearfoto post, a 3-4 mm heel contact point thickness, 2 mm medial heel skive, 16 mm heel cup, minimal medial expansion thickness, a plantar fascial accommodation, and a 2-5 forefoot extension of 3 mm thick korex.

To answer your other questions, the foot would be casted in STJ neutral position using neutral suspension casting technique described by Root et al. The forefoot to rearfoot of the positive cast would be balanced so that I am not creating either an excessive STJ supination or excessive STJ pronation moments with the orthosis. I don't use "rearfoot wedging" in the orthosis since all the correction is made into the orthosis....BTW, is "rearfoot wedging" some form of British podiatric orthosis therapy??

If these specific modications then are shown at followup examination to have resulted in improvement of the condition (i.e. by increased subjective comfort and decreased tenderness on plantar heel), then one could logically conclude that the foot orthosis has reduced the tensile stress within the medial fibers of the central component of the plantar aponeurosis, which was the original mechanical etiology of the patient's complaints. Of course, other potential explanations are possible, but I think those questions are best left to the researchers who have the time to explore such ideas.

By the way, the orthosis likely accomplishes the goal of reducing the tensile stress within the medial fibers of the central component of the plantar aponeurosis by decreasing the net forefoot dorsiflexion moment and decreasing the net first ray dorsiflexion moment since the function of the medial fibers of the central component of the plantar aponeurosis is to increase forefoot plantarflexion moment and increase the first ray plantarflexion moment.

This tissue stress approach to mechanical therapy is all quite logical and mechanically coherent, as long as one understands the principles of modelling and free-body diagram analysis. I see that the biggest problem with many podiatrists using the tissue stress approach successfully is their relatively weak physics and biomechanics backgrounds. In other words, most podiatrists don't know the difference between a stress and a strain, a moment and a force and don't understand how modelling approaches may be used to determine internal forces within the foot using only a knowledge of the anatomy of the foot and the external forces being applied to the foot. The podiatrists who were engineers will be using the approach with no problem at all since it makes total sense to them. The podiatrists who struggle with basic mechanics concepts will never completely grasp these ideas so that they will likely achieve only mediocre results with their foot orthosis therapy.

__________________
Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
**************************************************

I've put my tin helmet on and am vigorously waving my white flag and gingerly putting my head above the parapet. If there is a bit of residual quaver in my voice forgive me but at least as long as it's only my head that's showing you won't see the damp patch spreading across the front of my trousers. Apart from that if you bite my head off I won't have lost anything that vital.

In this thread the phrase 'tissue stress' has been variously associated with 'approach', 'model', 'theory', 'concept', 'paradigm'.

I would like to associate it with the word 'axiom' which I will narrowly define as a self evident truth. It (tissue stress) is a self evident truth that needed to be shouted out loud on a few occasions to get it to the forefront of interested parties minds but axiomatic in esence is what it is.

I would imagine that when you were a student being feed the ideas of the time your head was always asking why? I wouldn't imagine that it took you too long to come to the conclusion that biomechanics of that time was, in a rather blind, possibly deluded, undoubtedly erroneous way, trying to reduce the stresses on traumatised or painful tissues. The therapeutic prescription never knowingly included a fairy dust sprinkler.

My sense is that if tissue stress wasn't mentioned at the time it's because it was axiomatic?

Duck!

Bill

Bill:

I don't know what your experience was, but at the California College of Podiatric Medicine, studying with the people who created Root's subtalar joint neutral theory, I can tell you for a fact that orthosis prescription was based on what "deformity" was measured, not necessarily what specific structure was injured. In other words, whether the patient had plantar fasciitis, peroneal tendinitis or posterior tibial tendinitis, a patient with a "fully compensated rearfoot varus deformity" and "3 degrees forefoot valgus deformity" always got a vertically balanced Rohadur orthosis without a forefoot extension. I not only was taught this approach as a student, but this STJ neutral approach was something I taught to podiatry students as a Biomechanics Fellow at CCPM.

Please tell me how this above approach indicates that the design of the orthosis was based on the axiom of reducing tissue stress and not reducing "compensations" for deformities?

__________________
Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
**************************************************

Agreed, that we have been calling our approach many things. Mainly, I have been using the term theory because it has not been fully proven. However, I beleive that it can be proven. I believe that we can predict which anatomical structures will be injured with some measurements. That we can predict which treatments will reduce stress on structures, that the stress will in fact be reduced and that symptoms will resolve when they are reduced. Maybe not for all diagnoses. The research has yet to be done. The other nice thing about tissue stress is that you can develop research questions that can be tested. You can't test neutral position measurements because they cannot be done accurately across practioners (heel bisection, leg bisection, etc.)


They didn't know they were including a fairy dust, but there are some gaps in logic. "Lock the midtarsal joint" looks a little bit like fairy dust. Especially if you start to believe that imaginary lines alligning, or not alligning, control the motion of the midtarsal joint.


Eric

I agree.

Bill

According with the references, the location and peak internal stresses [as risk factor for ulcer development] can't be accurately predicted by interface pressure measured with pressure mats. Also, acommodative treatment doesn't decrease the pathological internal stresses !! How can be applied tissue stress theory in these situations ? Based, mainly on clinical tests [STJ position, Lunge test, Jack's test,...]?

Thanks,
Daniel

Tissue stress is certainly not fairy dust. It has a strong place in the future of biomechanics. However, as Tiisue Stress, by your own pen is not fully proven, not researched, based on belief and prediction, what gives you the right or ability to posture as if other theories that are parallel to yours that you don't agree with should be deemed less valuable than yours?

Dennis

Because tissue stress can produce testable hypotheses. I predict that people with a medially deviated STJ axis will be more likely to get posterior tibial dysfunction because there will be a higher moment from ground reaction force. And I predict that lowering the pronation moment from ground reaction force will improve posterior tibial dysfunction.

Dennis, why do you think any foot type is more likely to predict any particular pathology? Why would you change the way an orthotic is designed for one particular foot type versus another? If you can't answer the question what have your lab technicians been doing differently when they see cast with one foot type as opposed to another, then the system is not testable by others. That is why I deem your system less valuable.

Eric

Forces damage tissue. Position and motion do not damage tissues. Treat the forces, not the motion and position .... (I have spent the last ~20 years treating motion and position becasue that what I thought we were supposed to do )

__________________
Craig Payne
__________________________________________________ ___________________________________
Follow me on Twitter | Run Junkie | Latest Blog Post: Foot pronation is not associated with increased injury risk in novice runners wearing a neutral shoe
God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.

It's interesting that podiatrists trained at the California College of Podiatric Medicine in the 1970's and 1980's (including myself) were dogmatically instructed that foot orthoses were meant to "prevent abnormal compensations", "make the subtalar joint function in neutral position", "lock the midtarsal joint" and "bring the calcaneus to vertical". All of these ideas are wrong and should be signficantly modified or discarded if one is striving to achieve the goals of foot orthosis therapy utilizing the tissue stress approach which are to:

1. Decrease pathological loading forces on the injured structural components of the foot and lower extremity;
2. Make the patient asymptomatic, and;
3. Optimize their gait pattern.

The theories promoted by my biomechanics instructors at CCPM taught us that "preventing abnormal compensations" was meant to include preventing abnormal compensation motions with no mention that compensation should also include preventing abnormal compensation moments. The idea that foot orthoses should attempt to prevent abnmormal compensation is not a bad one as long as it is understood that any abnormal compensation motions directly results from abnormal componsation moments.

Since one can not have a change in rotational motion or have a change in rotational position in the foot and lower extremity without a change in moments, we should then rightly conclude that the term "compensation" does not need to include the concept of motion or position within its definition. Intead, the term "compensation", relative to foot and lower extremity function, should be defined as follows:

"Compensation" is an alteration in moments acting across the joint axes of the foot and/or lower extremity that is caused by the mechanical interaction between the foot and the ground in a weightbearing environment and which may be modified by structural, positional or functional abnormalities of the foot and/or lower extremity. (Kirby KA: "The Biomechanics of Compensation for Foot Deformities", in Kirby KA: Foot and Lower Extremity Biomechanics II: Precision Intricast Newsletters, 1997-2002. Precision Intricast, Inc., Payson, AZ, 2002, pp. 33-36).

__________________
Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
**************************************************

Hi,
Kevin has explained the tissue stress approach to managing foot pathology very well, and I agree that "position and motion" do not damage tissue, but rather forces do... However, if we were then going to treat the "abnormal forces" how would we go about it any differently than by attempting to alter the position and motion?
The tissue stress model gives us a better understanding of foot pathology, but my real question is - how do we relate that to changing our biomechanical assessment and orthotic presciption? Wound't we still be doing the same assessment and prescription at the end of the day, just with a different understanding of what we were doing?

Adam

To all:

your personalizations that are often denied as existing, including inviting me to a sanatorium and paying for my meds, will no longer goad me off topic.

This 2006 posting from Craig defines a moment where TS went off on a tangent from which it has never recovered IMHO.

His black/white statement of:
Forces Damage Tissue (True)
Position and Motion do not damage tissue (False)
By denying his 20 previous years of biomechanics and setting a course that obviated the need for position to play a part in biomechanical diagnosis and treatment was an overreaction IMHO.

Position certainly does damage tissue in addition to the fact that forces damage tissue.

To say that our choices must be one or the other and not some custom combination of each for every patient lacks logic IMHO.

IMHO, totally denying the import of position just because STJ Neutral is not the optimal one, is a mistake that I for one, have not allowed myself to make.

Craig et al:
How does this stack up to your postulates on what to do when the evidence we need to proceed is lacking since Eric has admitted that it is lacking?

In debate:
Dr Root made us positionalists even through he discussed and practiced engineering (ask Jeff).
The TSers, following Craig and Kevin have made us engineers treating forces and deny position and motion even though they claim to take architecture into account.
In reaiity:
Todays Rootians do not practice the functional part of biomechanics as much as they could and
TSers do not practice the structural part of biomechanics as much as they could.

Logically, a melding of the two makes common sense and does not obviate the work, teachings or benefits of either.
The Foot Centering Theory of Structure and Function begins with such logic.

Kevin's postulates that started this posting state quite clearly (over and over):

How does a podiatrist use the tissue stress approach when seeing patients? Here is way it should be done:


1. Accurately identify the anatomical structure which is injured or symptomatic.

2. Determine the structural and functional characteristics of the individual's foot and lower extremity.

3. Determine the most likely type of abnormal tissue stress which is causing the pathology within the injured anatomical structure (i.e. compression, tension or shearing stress).

4. Design a treatment protocol to reduce the abnormal tissue stresses on the injured structure and reduce the local inflammatory response so that more normal gait and weightbearing function can occur.


This is certainly very different from the way I was taught to treat patients with foot orthoses (i.e. STJ neutral theory) since this was based nearly solely on trying to get the patient to function in STJ neutral position, with little regard to the injured structure that was being treated.

FFTing is a starting classification system for practicing biomechanics that determines the structural characteristics of all feet which then can be treated functionally by, in the TSers case with TS.

As stated on these pages it is 100% accurate although not very specific eliminating the main problem of Root's classification system that is too specific to be accurate or reproducible.

It adds a 5th postulate to Kevin;s and that is:

5. Determine the location of the area of the foot that is generating the pathological forces (rearfoot/forefoot/both/neither) so that treatment of the structure can be incorporated into biomechnaical care and design a treatment protocol to improve the structural pathology of the injured/weakened/collapsed structure.

IMHO, discussing FFTing is not a deviation from this thread, it a vital addition that needs inspection and appreciation.

or you need another structural paradigm to upgrade or replace Merton's.

Dennis

You can still alter forces without changing position and motion. A change in position/motion of the rearfoot is not associated with outcomes (we have had a thread on this, but sorry I can not link to it as on a really slooooooow connection here at JFK and it will take forever to find it)

__________________
Craig Payne
__________________________________________________ ___________________________________
Follow me on Twitter | Run Junkie | Latest Blog Post: Foot pronation is not associated with increased injury risk in novice runners wearing a neutral shoe
God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.

Hi Craig,
I understand that a change in position/motion of the rearfoot is not necessarily associated with outcomes... However, my question still remains - If we were then going to treat the "abnormal forces" how would we go about it any differently than by attempting to alter the position and motion of the foot with orthoses?
(ie wound't we still be doing the same assessment and prescription at the end of the day, just thinking about it in a different way?) BTW I would like to read the thread you mentioned on this topic in your last reply if you have time to provide me with a link.

Thanks again,
Adam

Adam

Its now 2.00AM and I made it to LAX ... still have another day of work tomorrow before heading back ... just come from the 5 degrees below and snow of Montreal .... I guess that better than the 42 degrees in Melbourne :p

The thread is Kinematic change and foot orthoses outcomes.

__________________
Craig Payne
__________________________________________________ ___________________________________
Follow me on Twitter | Run Junkie | Latest Blog Post: Foot pronation is not associated with increased injury risk in novice runners wearing a neutral shoe
God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.

Here is a 2002 example of a totally unproven (to this day) piece of self proclaimed expert opinion by Kevin Kirby DPM quoted from his self published work.
Jeff Root's Rules #4

This has been promated by Dr. Kirby and his followers for these eight years and I am sure that, like the Rootians, it has become accepted as fact or proven by its faithful like Jeff Root and his followers are to The Rootian paradigm.
This is known as BIAS.

Could any of you give proper evidence that my clinical outcomes, or those of any other practicing Biomechanist are "less effective" than anothers or even better could you give evidence that you are "much more likely" to have better clinical outcomes as Kevin opines?
Dr Sha

Actually, I hate to say it (really, really hate to say it), but I'm with Dennis here.

I think the tissue stress approach is the most logical and best one. I think it is the only one which will grow with our increasing understanding and I think it provides the best clinical outcomes. But I will freely admit that these are only my opinions. I have no evidence that TS performs better clinically than STN, pre fabs or any other model.

If we would hold others to task for the substance of their claims (and I think we should) it behooves us to hold ourselves to the same standards. Expert opinion, and I can think of none more expert than Kevin, is valid and valuable, but it remains only opinion and should be stated as such.

That said, this newsletter was a "lightbulb moment" for me a few years back and I remain very grateful that it was penned and placed in the public domain.

__________________
Robert Isaacs
Specialist in Biomechanical Therapies
www.Footprintspodiatrysolutions.co.uk

small, yellow, leech-like, and probably the oddest thing in the universe

Semper in excretum sum sed alta variat

The reason that we cannot give proper evidence that the methods you use create worse clinical outcomes is that we don't know the methods you use. You have yet to fully describe them. That's why I've been asking you to explain how you modify an orthosis for the different foot types. Yes, you did post something, but it was something like for this foot type I use the forefoot centering technique. But you did not describe the technique. If you can't describe the technique you cannot test it against another technique.

It would also be helpful if you would explain the logic of why you think this modification would work. The tissue stress approach provides very good logic as to why a certain prescription should work. There is published proof about how lateral wedging can relieve medial knee pain and this well explained and predicted by examining moments at the knee. I would agree that very few other things have been proven about the tissue stress approach, but you can't say there is no evidence.

Dennis, part of your technique relies on the standard Root (neutral position) technique. There are logical flaws in the Root technique. For example, the neutral position theory isn't quite clear on how the orthotic is supposed to work. One proposed mechanism is that the orthotic supports the "deformity." However this deformity is measured in STJ neutral position non weight bearing and the vast majority of feet don't stand in neutral position. If you were going to support the forefoot to rearfoot deformity, shouldn't you support the forefoot to rearfoot deformity that exists in the position of stance. (As the STJ pronates from neutral, the range of motion of the STJ increases thus increasing the amount of forefoot valgus that would be measured in the more pronated position of the STJ.) This is flawed logic for both centering and neutral position paradigms.

So, Dennis, the part of your paradigm that we know well has faulty logic. I suspect that the part we don't know so well has faulty logic as well. You could prove me wrong if you would explain it. Your reluctance to explain it tells me that you have either not thought it through or that you just made something up that sounded good and you don't really believe it. That is the logical conclusion that many on the arena have come to. You can call that bias if you like, but there is some logic to that bias.

The lowest level of evidence based practice is that in the absence of evidence you use treatments based on logic and the available science. Mechanical engineering is well established science. This is why I feel that people should choose the tissue stress approach over other treatment paradigms. Dennis, why should we choose your paradigm? What is your paradigm?

Eric

Just for fun. Tonight Matthew, I will be, Dr Sha.

Eric.

So, to recap, the advantage of tissue stress (TS) over Neoteric (NT) biomechanics and Root (STN) biomechanics, is that whilst neither can claim inductive outcome evidence, TS has a rationale based on known variables and physics.

In dispute I would offer the following.

There are, as you say, potential logical flaws in the standard Root method. However notwithstanding this, it works. There is abundant outcome evidence, kinematic data and patient satisfaction data which shows positive outcomes when using STN protocol.

By the purist approach, this would seem to indicate that notwithstanding its potential lack of theoretical consistancy, it can acheive positive clinical outcomes. This makes an interesting inference.

Now you might argue that the successes of STN are based on those areas where it crosses over TS. In other words, where STN produces a similar prescription to TS it will be effective. However this is speculation on your part. I might claim the same.

The problem with the TS theoretical consistancy is the degree to which it relies on A: Itself, and B: bench data. Brian Rothbart claims similar "rationale" for his model. If the foot moves the leg, the leg moves the pelvis, accepted link between pevic anteversion and the isthmus block THEREFORE insoles help fertility. This is the gulf between theorising and clinical reality. The data does not presently exist to bridge this gap for either tissue stress OR PCI's.

To mangle an expression, a good theoretical model and $1 will buy you a coffee. The clinicians following these threads are interested in theory, but also in practice.

NT biomechanics is a "formula" model of biomechanics. The cookbook approach as it is derisively called sometimes. This means there ARE comprimises in the model to make it accessible for people who do not have higher qualifications or knowledge of biomechanics. At base it is like root in that it is a straightforward "in the trenches" model. Cookbooks are not bad things. Who cooks a complex dish without a receipe? Expert accomplished chefs perhaps, but most of us can't.

Empirically what most clinicans know, but won't admit, is that when they have someone come back with an insole which has not had the desired effect, they add a bit. More RF post or a higher arch. NT biomechanics STARTS with the higher arch and equips the podiatrist with a convenient and neat way to make the modifications. The theoretical model aside, this is simply an enhanced version of what most people already do when the root device is inadequate. Its simple, accessable, easy to use and formalises what empiricism has shown us over 40 years of using root type devices.

Whilst the theorists may argue, and produce complex models, in clinic experience is king. If people take time to examine NT biomechanics they may find it actually dovvetails with what many clinicians already know. That when a lower arch, less posted device fails, a higher arch device with more wedging succeeds.

I Know I will never convince the theorists, but then I'm not seeking to. But if those people who follow these threads without pitching in, who are not interested in the high level theory that only a few dozen people in the world understand but who ARE interested in a hands on clinical approach which gives great outcomes and more clinical freedom than the root approach, are interested they may get something from this.

Regards
Dr Sha.

The views expresses in this post are NOT those of the author and are expressed purely to stir the pot somewhat and add variety to what threatens to be a thread identical to all the OTHER threads.

__________________
Robert Isaacs
Specialist in Biomechanical Therapies
www.Footprintspodiatrysolutions.co.uk

small, yellow, leech-like, and probably the oddest thing in the universe

Semper in excretum sum sed alta variat

So Bob Sha ( so I can tell who I´m addressing)

If the tissue stress approach is too hard to understand, you must be able to understand Dennis FFT approach maybe you can answer the question which Eric, Jeff Root have asked in the last month. I found some more which Davis Smith and Ian asked in 2008 today that never got answer.

How can you begin to understand anything if not 1 question gets a direct answer ?

I don´t really think the tissue stress approach is that hard to get you head around, as in all things it can get high brow, but saying it´s too hard so I will dismiss it is just lazy in my option- this does not mean you have to use it, but to say you will or you want you have to look at it.

__________________
Mike Weber.



Crazy Mary

Hey Michael-san

You'll have to jog my memory on the questions....

But regarding tissue stress (which is of course the topic of THIS thread, keep on topic you BAD man.)

Its a simple concept in the same way as the ideal technique for bowling is "hit the middle". But there is a million miles from that to being a simple thing to execute clinically.

Root is based in part on rearfoot measurements and much criticism has been leveled at this due to the inaccuracies of rearfoot measurement.

Tissue stress, as described below, has little such measurement. However there is a MASSIVE presumption in the steps kevin describes.

Answer me this. How "repeatable" or "accurate" is the average Podiatrist at

"Accurately identifyingthe anatomical structure which is injured or symptomatic."

Hmmm? Any tests been done on this? How many times have you seen a patient diagnosed with condition X when you think they have condition Y? Plenty if you are like me.

Now the whole logical basis for the TS model is step 1. If this is not 100% (and I doubt anyone will claim it is) then the rest of the process is only as good as the initial step.

And UNLIKE STN or NT biomechanics, the treatment can be radically variable based on the diagnosis of affected structure.

So if we are going to be fair, and not biased, perhaps we should recognise this rather large source of potential error in the TS model (since we look for them in other models) and accept that it renders the model dependant on the podiatrists diagnostic skill to a much higher degree than root or STN. If the first step of TS was reliable then the rest of it is indeed logically sound, but lets not lose sight of the fact that we have no real idea what degree of inter tester repeatability there is on the identification of injured tissue.

So, some questions for YOU about TS

1. Do you accept that the subsequent steps of the model all rely on step 1 being accurate?

2. Do you accept that podiatrists, being fallible, will get this step wrong from time to time.

3. Do you accept that we will never really know how MUCH of the time this is.

4. Do you therefore accept that the "logical consistancy" of the TS model is based on the accuracy of a completely untested measurement?

5. Do you accept that an incorrect diagnosis of compressive vs tensile knee pathology will have the following effects based on the model

STN, No difference to treatment if you get it wrong
NT No difference to treatment if you get it wrong
TS Potential to treat a tensile medial knee complaint with a lateral wedge which will increase abduction moment in the knee, amplify pronatory moment and generally "do harm"

hahaha
Bob sha


The views expresses in this post are REALLY REALLY NOT those of the author and are expressed purely to stir the pot somewhat and add variety to what threatens to be a thread identical to all the OTHER threads. Honestly, just playing Shavelsons advocate.

__________________
Robert Isaacs
Specialist in Biomechanical Therapies
www.Footprintspodiatrysolutions.co.uk

small, yellow, leech-like, and probably the oddest thing in the universe

Semper in excretum sum sed alta variat

Hope the headache is getting better Robert.

two things I would like to highlight from yesterdays discussion.

1 - All tissues require stress, thats how they stay strong. The tissue stress approach is dealing with tissue that has due to forces acting on them has become pathological.

2 The tissue stress approach is the most flexiable approach as I suggested and Eric high- lighted, we can adjust the treatment plans according to what results we have with the intial treatment plan. Where as those who begin with measurments, unless the foot changes if the measurments we taken well and the cast taken well and the device made well, The orthtoic provided will be the same everytime.

And one other thing I would like to highlight.

The tissue stress approach does not just mean orthotic intervention.

once the stressed tissue has been found the forces on that tissue can be reduced the best way, that maybe with an orthtoic that maybe with modified training etc, but I beleive still fits with the tissue stress approach.

__________________
Mike Weber.



Crazy Mary

...and pee wee herman is staggering against the ropes!

The funny thing about all this is that if Dennis answered question with direct answer - even if was " I don´t know" none of this would have turned out this way. Ive looked at the 1st thread that Dennis joined the other day, there are still lots of questions still not answered in that.

__________________
Mike Weber.



Crazy Mary

I thought something more graphic might be a little more representative:

Attached Images

	PeeWeeHerman.jpg (18.5 KB, 108 views)
	ali.jpg (8.7 KB, 107 views)

__________________
Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
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