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<ADMIN NOTE: I have split this topic and slightly edited it off from the DC Wedges thread</>

What happens to the patient if 'the world's "best orthotic" is sold by the world's worst practitioners'?

How does this result vary if 'the world's "worst orthotic" is sold by the world's best practitioners'?

Anyone, anyone...?

Thats part of the problem. From what I understand from all the trials and outcome studies, foot orthoses of all types seem to work in improving symptoms. That implies to me that if you are incompetent and use what might be the "worst orthotic", most of your patients will get better and you will stay in business. I assume if you are competent and use the "best orthotic", you will get better results, but there is no research to support that (based on my limited reading and understanding of the literature).

I don't think its quite qas bad as Davinci makes out ... but just look at the improvement in the 'sham' or 'control' groups in the orthotic randomised controlled trials --- they get better with "bad" orthotics. In the ones we have done, we used devices that I would never come close to using clinically, but the symptomatic improvement with them is remarkable.

__________________
Craig Payne
Department of Podiatry
La Trobe University
Melbourne, Australia
http://www.latrobe.edu.au/podiatry
__________________________________________________ ___________________________________
God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.
The views expressed above are those of the author and not that of La Trobe University
This is where I am, where are you?

I think the main issue is the potential for long term damage with poorly prescibed or poorly designed orthoses.

If the mechanical impact of the orthoses needs to be primarily in the sagittal plane, then the elevation of the heel by some orthoses may reduce syptoms. However, if the orthoses are also blocking 'normal' mechanics e.g. 1st ray function, then the long term effect may be detrimental.
A lot of the skill of prescribing functional devices is knowing how to optmise foot function e.g. Hick's Windlass, along side the pathology treating prescription variables.

Phil

I do no think we can talk about "best" or "worst" orthotics (first of all how do you define what a "best" orthotic is). This discussion is irrelevant since it does not matter how an orthotic is designed and manufactured or materials used if it accomplish it goals.

Also, the most incompetent practitioners can achieve good results if they are lucky subjects and choose the right orthotic permutation. The only difference between "best" or "worst" practitioners will be related to the ability to choose the right orthotic permutation leaving luck aside.

Thanks Pod Aus,
This was originally a question for me from Pod Aus which I wrote an answer to and then had to run out before I got to post it. So here goes....
1. The design of the orthoses is completely up to the practitioner. In the workshop portion of the course and in the course manual we discuss many design parameters including shoe type, activity level, diagnosis, body weight, foot flexibility etc. etc. In this particular question you are only varying the weight and the activity level. Both of these parameters are addressed by calibration. Calibration is based firstly on body weight and foot flexibility. Then it is modified to include activity level. In extreme cases such as a lineman in football (American football), rugby, or power lifting the activity level moves up considerably in importance. For running however we calibrate the orthoses to resist greater force. At this time we are still researching the variation of forces in various activities. There is so much more to be done. Since momentum is mass x velocity we are looking at a range of forces appropriate to a person’s weight and activity level. This can never be exact because people assume a range of velocities. Our experience is that calibration puts the runner into a therapeutic range…..and sometimes we miss calibrate. Yes, the “world’s best” still has a long way to go.
2. Best Orthotic…Worst practitioner: We require every practitioner before they have the right to use Sole Supports, take both the theory and workshop. During the workshop we do our best to train the practitioner. The leave with the DVD and a workshop CD along with a course manual that goes over casting so they can practice at home. Once a practitioner chooses to become a client, they purchase a supply kit. As a client we also give all of the casting boxes including practice boxes on request for FREE. We do this because we will NOT accept a cast if it does not pass certain QC tests (including the pen test….taught in the workshop). We call for a recast. The world’s worst practitioner might require additional training….we provide that in a variety of ways.
3. Worst Orthotic…Best Practitioner: I agree with Craig. Even the worst orthotics will alleviate symptoms….as I keep saying we do need to raise the bar.

I have attached something that I wanted to attach earlier….maybe it should be its own thread, that’s up to Admin. Please take a look and tell me what you think.Ed

I'll try again to post this attachment. I don't know what I am doing wrong. I got it converted to a HTML file that is only 2 KB. I see now, it is the wrong file type. I will ask Don to post it for me.

Don made it a link.

http://www.solesupports.com/forceDiagramSR.html

Thanks,
Ed

Totally agree - but we all probably have disagreeing ideas of what is right and wrong for that ... I am trying to come up with different research designs/methodology to test this, but are struggling to determine the appropriate outcome measure .... working on it ... (Ed - will be in touch soon)

__________________
Craig Payne
Department of Podiatry
La Trobe University
Melbourne, Australia
http://www.latrobe.edu.au/podiatry
__________________________________________________ ___________________________________
God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.
The views expressed above are those of the author and not that of La Trobe University
This is where I am, where are you?

Ed

Atachments can be tempermental, esp if large. Anothe option is what you have done and link to it.

The other option is to put the picture on any website (or email to me and I put it up on this site) and then use the vB Code to hot link to it

For your diagram this means placing the link to the image (not page) between a [img][/img] tags. To get link for picture and right click - get url from properties - for your image its http://www.solesupports.com/firstMetDiagramSR.jpg

so putting it between the tags


we get the picture..

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Since we are now talking about supination resistance, I thought it would be helpful to the readers of Podiatry Arena to provide them with an excerpt from the chapter that I wrote along with Donald Green, DPM, in a book edited by Steve DeValentine, DPM on Foot and Ankle Disorders in Children (that is now out of print and unavailable for purchase). It was in this chapter where the concept of supination resistance and the supination resistance test was first described in the medical literature, 14 years ago.

In addition, I again wrote about the supination resistance test which I invented. This was first published in the November 1997 Precision Intricast Newsletter and was again compiled into my second book (Kirby KA: Foot and Lower Extremity Biomechanics II: Precision Intricast Newsletters, 1997-2002. Precision Intricast, Inc., Payson, AZ, 2002, pp. 155-156). This newsletter is posted on the lab's website. Supination Resistance Test Newsletter

The supination resistance test is very nicely explained by the principles described by the Subtalar Joint Axis Location/Rotational Equilibrium Theory of Foot Function.

__________________
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
**************************************************

Javier,

My point exactly, hence why this is a perfectly relevant discussion. Appropriate orthotic design and application must be based upon a specific set of risk factors and functional test results. Therefore the clinician must have a structured rational when prescribing orthotic therapy, and review the patient at set intervals (short, medium, long term). Then orthotic modification, dependant upon patient reponse and risk-factor variability, is intrinsic to the care of the patient.

The goals of orthotic therapy need to be discussed with the patient at the outset, and re-considered over time.

You are talking about a different subject here, or I misunderstood you. You bring the question regarding "best" and "worst" orthotic design and manufacturing. But, I am afraid that nobody can claim that a single design or manufacturing is better than other, since the almost infinite number or orthotic permutations.

Now, you are talking about a protocol for orthotic assessment, right? You have plenty of them. And, like orthotic design they are more or less reliable although all of them accomplish certain number of goals. But, it rises the same fact: none of these systems (or paradigms like most of you love to call them) is actually better than another. They are different ways for achieving the same goals.

If I am wrong, please correct me. But, from your last statement It seems that you are looking for the same thing that most practitioners I know: a single evidence-based medicine protocol for orthotic assessment and dispensing. From, my point of view we are very far from this and if someday it is achieved, we will be replaced since our expertise for choosing the right permutation will not be necessary.

Regards,

Hi Javier,

That is my point here. There is no 'best or worst' - only appropriate prescription if the rational for the case is sound. And this will most likely be modified depending upon the variables (footwear and activity - spikes vs. runners vs. grass-sports vs. fashion).

I make this point when I detect the 'my design is better than your design' arguement.

Patient care rational, supported by 'cause-effect' evidence and clinical experience allows practitioners to pick and choose what is 'best' for this case and 'best' for that case.

I'd suggest you and I already agree on this one.

Absolutely, although first of all we should arrive to a consensus about how foot works and how orthotics achieve their goals.

Kevin,
Thanks for the references :) . They illustrates some good points and it sounds as though your supination resistance test is a very valuable tool to determine the forces necessary to supinate the foot in the frontal plane. I am talking about sagittal plane supination resistance here.
The force diagram I drew here is turned 90 degrees and explains one of Eric Fuller's questions. In a previous tread he asks how the orthotic reaches up to bring the head of the first metatarsal to the orthotic. It is really the force applied by the plantar fasciae and the Flexor Hallucis Longus and Brevis that are acting with an increased vertical lever arm around the primarily sagital plane axis of the first ray as the first metatarsal is plantarflexed relative to the midfoot. Simultaneous decrease in the pronation moment by decreasing the Anterior to posterior distance from the axis to the ground reactive force also reduces the sagittal plane supination resistance. Hence pronated position begets further pronation and a supinated position begets further supination.
One possible reason for the decreased necessity for rearfoot posting in the MASS position, besides the obvious danger of over correction, is the fact that the STJ axis (which I believe is a concept useful only as a first approximation as it is an over-simplification), increases its slope off of the transverse plane as the foot supinates (as it moves laterally....good illustrations of this in your article). This would tend to make the frontal plane forces relative to the axial projection in the transverse plane relatively less effective and the rotational forces of the leg more effective in causing foot re-supination.

In other words, in the MASS position:
1. Frontal Plane Moments
a. STJ axis moves laterally decreasing pronation moment and decreasing frontal plane supination resistance.
b. COP moves medially as full contact causes a greater force to be spread over the MLA....decreasing pronation moment and decreasing frontal plane supination resistance.

2. Sagital Plane Moments
a. Increased inclination angle of the PF 1st ray increases the lever arm of the horizontally applied posteriorly directed force ofthe Flexors and Plantar Fasciae. see diagram.
b. Increased inclination angle of the 1st ray reduces the pronation moment of the GRF reducing sagital plane supination resistance.

3. Transverse Plane.
a. Increased slope, off the transvers plane, of the STJ axis increases the efficiency of the external rotational moments of the leg and thigh as the trunk rotates anteriorly at the ipsilateral hip joint during gait which reduces transverse plane supination resistance.

MASS position has so many positive effects as it allows a much gentler touch of the orthotic because the full contact redistributes the force evenly over the entire surface of the orthosis and the supination resistance in all three cardinal body planes are sumultaneously decreased.

The important points are:

1. MASS position makes resupination easier in all three planes.
2. To control the foot you must apply a force and to do so it is most efficient and comfortable to spread that force evenly over the entire plantar surface of the foot (which effects a far more efficient translation of COP medially than traditional posting technologies). Hence full contact and never any arch fill.
3. Full contact is only tolerable within certain force limits (a therapeutic index) therefore the correct force and flexibility must be applied (hence choosing a material of the correct modulus of elasticity and callibration...already quite advanced but an ongoing project getting more acurate as research continues).
4. Positioning the foot in greater supination before heel strike dampens pronation by creating a time delay.
5. MASS position at midstance places the Talar head on the anterior facet preventing rotation around the cone shaped posterior facet in the sagital plane which increases the efficiency of propulsion.
6. End ROM of the STJ, midfoot joints and MTP are never reached thus far more efficiently decreasing or eliminating tissue stresses.
7. Dramatic positional changes require more muscular adaptation and can cause transient muscular, ligamentous and joint pain during the adaptation period. This may require more agressive physical therapy. ROM exercises, muscle strengthening exercises specific to the patients gait changes are highly recommended....ideally this can be accomplished with a PT referral.

To do #2 above without #3 has led many researchers to abandon the entire concept of beginning the control of the foot. Foot orhotic manufacturers have opted for comfort over correction to reduce warrantees. Challenge the patient's feet to assume a more efficient functional position to reduce and even reverse deformity instead of only decreasing the tissue stresses that cause symptoms. The way out of pain is sometimes through the pain....which will be considerably decreased with good physical therapy.

Respectfully,

Ed

Ed,

Since medial arch raising and flattening are primarily sagittal plane motions, and not necessarily the dorsiflexion-eversion-abduction and plantarflexion-inversion-adduction that the words "pronation" and "supination" represent, then I believe that the term "supination resistance" in your sagittal plane analysis of the first ray is a little confusing. In the past, I have performed similar analyses and used terms such as forefoot plantarflexion moment or first ray plantarflexion moment to indicate a medial longitudinal arch raising moment and forefoot dorsiflexion moment or first ray dorsiflexion moment to indicate a medial longitudinal arch flattening moment (Kirby KA: Foot and Lower Extremity Biomechanics II: Precision Intricast Newsletters, 1997-2002. Precision Intricast, Inc., Payson, AZ, 2002, pp. 139-152). See one of my illustrations below from my lecture on "How Do Foot Orthoses Work".

Otherwise, I understand your explanation above and, even though I don't completely agree with your analysis and opinions, I believe we are starting to share enough common ground so that we can have more interesting and educational discussions.

Attached Images

Forefoot plantarflexion moment.jpg (68.5 KB, 949 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
Sacramento, CA 95825 USA
My location

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

Actually the supination resistance test you describe could be considered similarly a frontal plane change but the truth is that there is no elevation of the MLA or pure plantarflexion of the 1st without triplane motion in the closed chain. In the closed chain, single plane motion does not occur in isolation. If the plantarflexion was performed in the open chain during slipper casting as suggested by Prolabs …that would be more possible. The graphic you show illustrates the presence of GRF and Downward force of gravity acting through the tibia but does not show or compare different positional changes and their relative effect.

We need to redefine exactly "How Do Foot Orthoses Work" which is very different depending on which foot orthotic we are talking about. Different designs work differently. Some work by reducing terminal tissue stresses others cause a repositioning of the STJ and rear-foot to place the foot in greater supination throughout the gait cycle. The question is which method is more efficient and gives the best long and short term clinical result. That is where we may differ.


Ed

Ed, I don't think this quite answers my question. A patient stands on an orthosis and the orthosis creates different locations of forces acting on the foot. Which forces, from the orthosis, cause the arch to be higher? Where are they applied? Now, I would agree with you that it would be possible for the muscles to cause supination of the STJ and plantar flexion of the first ray, but this is a central nervous system response to the orthosis. Are you saying that your orthoses work through a centreal nervous system response or are you saying that pressure in the arch from the orthosis raises the arch, or a combination of both?

How long will the muscles be able to hold the foot in this position?

I'm not sure that you can say that supination begats more supination all of the time. If you supinate the STJ a little bit, with the muscles, there will be a lateral shift in the center of pressure causing a greater pronation moment acting on the foot especially in the more medially deviated STJ axis foot. Now, if you supinate the foot enough the entire plantar surface, and lateral surface, of the foot will medial to the STJ axis and then there will be a supination moment from ground reaction force.


On average how many degrees do your orthoses supinate/invert the STJ? Is this enough to make a significant difference in the location of the STJ axis?

You refer to transverse plane and frontal plane forces. The forces perpendicular to the transverse plane are a function of body weight and in the vast majority of activities will be orders of magnitude larger than forces parallel to the transvers plane. Therefore the position of force relative to the transverse plane projection of the axis will tend to be much more important than forces perpendicular to other planes.

STJ axis movement and Center of pressure movement. Which one moves faster with STJ supination. My bet is on the COP. If cop moves faster laterally than the axis there will be an increase in pronation moment. A few degrees of supination from muscular activity will cause the cop to be at the lateral border of the foot. There may be some feet, with a laterally position stj axis that the axis may move further laterally, but I would bet that the majority of feet, with muscular supination will not increase supination moment from ground reactive force with a supination motion. On the other hand you could believe that the orthosis causes a direct supination moment, but that is best done with a medial heel skive, which you do not use. (To supinate the foot you would want to push on the bony structure furthest medial to the STJ axis which is the medial tubercle in most feet. In most feet the medial arch bones are deep to 2cm of soft tissue and cannot be directly pushed on by an orhosis.)

I don't understand how increased inclination of first met decreases pronation moment. Are you saying that there is more force under the first met in this position? Position does not correlate with force. If you supinate your foot, with muscles, and then plantar flex your metatarsal maximally and it just touches the ground the center of pressure will be lateral.

Respectfuly,

Eric Fuller

If you will read the excerpt from my chapter in Steve DeValentine's book again, you will see the following sentence: "Basically, the supination resistance test involves subjectively determining the amount of lifting force which the physician's fingertips must apply to cause supination motion at the STJ." Therefore, contrary to what you state, I am not looking for a frontal plane change but, rather, a tri-plane movement of the STJ when I perform the supination resistance test, as I originally described it.

The graphic was intended to show you, and the other readers of Podiatry Arena, that "supination resistance" is not a good term to describe the sagittal plane medial longitudinal arch (MLA) mechanics that you depicted in your illustration. Rather, my graphic illustrated how the MLA moments that can cause either MLA flattening or MLA raising can be described as a forefoot dorsiflexion moment or forefoot plantarflexion moment. It was not meant to be a complete description of the kinetics of the midtarsal joint. I will give a more complete lecture regarding this topic, along with Chris Nester also speaking on his kinematic research on the MTJ, at the PFOLA meeting in Chicago in early December.

I agree that we differ in how we think foot orthoses work. From the research that I have reviewed and through over two decades of writing and thinking about this subject, I believe that all foot orthoses work, no matter how they are designed, by altering the locations, magnitudes and temporal patterns of ground reaction force (GRF) acting on the plantar foot during weightbearing activities. One lab may produce a higher MLA orthosis without a rearfoot post and produce increased STJ supination moment by shifting the GRF in the MLA more medially, while another lab may produce a orthosis with slightly lower medial arch, add a rearfoot post, deep heel cup and medial heel skive and shift the GRF in both the plantar heel and MLA more medially, producing even greater increases in STJ supination moment. In my opinion, one is not better than the other. They are, instead, just two different ways of accomplishing the same orthosis goal: to increase the external STJ supination moment from the orthosis in order to counterbalance the internal STJ pronation moments that are causing injury or abnormal gait function.

From an earlier posting you wrote:

I don't quite understand why you think that the STJ axis is a "first approximation as it is an over-simplification". The tracking of the STJ axis is now of major interest in many biomechanics research centers and I am now involved in research with the Penn State Biomechanics Lab in trying to determine how we can track it better in live subjects. Here is the paper of my work with the lab from two years ago that will soon be published in Gait and Posture (Lewis GS, Kirby KA, Piazza SJ: Determination of subtalar joint axis location by restriction of talocrural joint motion. Gait and Posture. In press. 2006).

Here is where we discussed this earlier on Podiatry Arena:
http://www.podiatry-arena.com/podiat...=9914#post9914

Steve Piazza, PhD, a mechanical engineer that has his PhD in biomechanics and is currently working at Penn State, just wrote a nice review paper on the importance of STJ axis determination (Piazza SJ: Mechanics of the subtalar joint and its function during walking. Foot Ankle Clin N Am, 10:425-442, 2005).

Here are some excerpts from Dr. Piazza's paper:

If you need further references on the research over the past 50 years on STJ axis mechanics so you can become better educated on the importance of this very important joint of the foot, I would be happy to provide these references to you or any other readers that are following along.

__________________
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 and Eric,
I want to give a complete answer to both of you but time is not on my side right now. I am leaving this morning on a 10 day five city lecture tour followed by research meetings (new high speed camera ariving soon....can't wait) and then 10 days in Hawaii. I will do my best. Also our article in Biomechancs Magazine this month has made such a stir (we are getting 30+ new clients a day), we have to expand every aspect of our company....and all while my my lecture schedule is insane. Besides that we are writing an advanced lecture and the fourth generation 3D graphics are extreme cutting edge stuff (which requires input on camera angles, lighting etc.) Meanwhile we are writing and editing more articles and building an employee enhancement center, expanding our office space, and trying to leave some time for recumbent bicycling and playing music (I play guitar, banjo, mandolin, fiddle and Uke) learning electronics (hobby restoring old radios) and all that doen't include my charitable and local political involvments. And then family (four kids and four grandkids) do come first. Don't get me wrong...I love this...this is the life I created for myself. Some folks seem to live on this site....I use it as a distraction and a wonderful outlet to bounce my ideas off some of the most brilliant minds in foot biomechanics in the world (thank you Craig, Deiter, Phil, David, Kevin, Eric, Simon and too many more to name) So please excuse any delay in answering. I am so looking forward to relaxing in Hawaii. Thank God for my wonderful wife...and our brilliant team at Sole Supports....without them none of this would be possible. They deserve a vacation. I think you can link to the Biomechanics Mag. article on our website.

Life is Good,
Ed
www.solesupports.com

Ed,

After having met you, I believe that you are wonderful employer and family man. However, in the time you took to tell us that you could have answered the questions or at least put some thought into the answer of those questions. I'll try and remember to re post the question in a couple of weeks.

Have a good vacation, with kindest regards,

Eric

Ed,

Having read your article in Biomechanics Magazine, I have some questions for you. While it appears that there are aspects of “Root Theory” that you may not understand, my question relates to the rationale behind your theory and not what is wrong with Root theory.

The casting technique you endorse obviously captures the plantar contour of the foot with the midtarsal joint in either a supinated (triplane) or plantarflexed (sagittal plane) position. Casting the foot with the MTJ in a supinated position or with the forefoot plantarflexed at the MTJ should in fact encourage some degree of supination at the MTJ and in theory, should increase resupination moments at both the STJ and the MTJ or decrease the pronation moments at these joints.

My understanding of your approach from talking to a few practitioners who have attended your lecture and who have worn your orthoses is that you use a fairly flexible device. In spite of that, they complained of medial arch or transverse arch irritation or discomfort resulting from excessive MLA or transverse arch pressure. Since this is a small sample size, perhaps this is the exception, but it was a consistent comment from those I spoke to. I know from thirty years of personal experience in manufacturing prescription foot orthoses that the amount of pressure that an individual patient can comfortably tolerate in the MLA is highly individual, due in part to anatomical variation and individual preference. Excessive MLA pressure from an orthosis can produce plantar fibromas along the medial slip of the plantar fascia, which is a potential complication with perception orthotic therapy.

I visited the link to your company that you posted below your name but I couldn’t find any information about the nature of your products. I was hoping to find something that might indicate the nature of the materials that you use in manufacturing your orthoses. If you subscribe to a casting technique that is supposed to enhance resupination of the foot, I would think that you would want to use a material that is sufficiently stiff to support the foot in the manner casted. Since I couldn’t find any specific information about materials on you site, I am left to assume that the information that was conveyed to me by those who have worn your orthoses is true (ie. the device has a high arch but is considerably more flexible that conventional functional orthoses). If you are using a flexible shell material, how might you explain this apparent contradiction of mechanical objectives?

Respectfully,
Jeff Root
www.root-lab.com

Jeff (and Ed, Don and Stu):

Thanks for coming to your father's rescue here. I also read Ed, Don and Stu's (all work for SoleSupport insole company) article in Biomechanics Magazine this weekend and was quite shocked about many of the errors within the article about your father's work. Here are some of the errors I found in the article:

I never heard Mert Root, John Weed, Bill Orien, Tom Sgarlato, Chris Smith or any of the other "founding fathers" of STJ neutral theory say that the rearfoot post was the main part of an orthosis. In fact, the rearfoot post wasn't added into the Root Functional Orthosis (per my memory of the story) until Tom Sgarlato had a dentist friend show him how to use dental acrylic and add it to the orthosis. Before that time, the orthoses did not have rearfoot posts. We were taught as podiatry students at CCPM to dispense the orthosis shells, have the patient back in three weeks and then have the rearfoot posts added onto the orthosis at the reappointment visit. I was taught by Drs. Root, Weed and Smith that the rearfoot post was simply added to an orthosis to allow the foot to have four degrees of motion at heel contact and stabilize the orthosis against the tendency of the patient's foot to deform it.

This statement was not referenced in the article and this statement is false. The area of the foot which is most medial to the STJ axis is the medial calcaneus and therefore, is the area of the foot that has the most potential to cause increases in STJ supination moment with an increased application of plantar force at the medial heel such as from a Blake Inverted Orthosis, DC Wedge Orthosis, or medial heel skive orthosis modification. Ed, Don and Stu, how can you justify making this statement without references and how can you ignore the mechanical fact in your article that the medial arch is often, in many feet, lateral to the STJ axis??

Contrary to what I have seen written in now a few articles, Mert Root did not base neutral position on Wright's study. Without going into a lot of detail, which Eric Lee has already done so in his articles on Mert Root(Lee WE: Podiatric biomechanics: an historical appraisal and discussion of the Root model as a clinical system of approach in the present context of theoretical uncertainty. Clinics Pod Med Surg, 18 (4):555-684, 2001; Lee W E: Merton L. Root: An appreciation. The Podiatric Biomechanics Group Focus. 2(2): 32-68, 2003) , Mert Root thought of the concept of STJ neutral position while in a shower one day in 1954, a full ten years before Wright et al published their paper!!!

"One morning in 1954, just by luck I guess, I was standing in the shower without any thought about the foot and all of a sudden the concept of neutral subtalar joint positon flashed into my mind. I could hardly wait to get to the office to substantiate it. That's what turned out to be the key to my being able to contribute to podiatry." M.L. Root, 1989 (excerpted from Lee WE: Podiatric biomechanics: an historical appraisal and discussion of the Root model as a clinical system of approach in the present context of theoretical uncertainty. Clinics Pod Med Surg, 18 (4):555-684, 2001.

Mert Root did not "misinterpret research". Mert Root was much more aware of STJ rotational positon than D.G. Wright ever was (I previously worked with Gib Wright, the primary author of that study, and it is much more likely that Wright misinterpreted Root's work than Root misinterpreted Wright's work, in my opinion!). To suggest in your article that Mert Root made a "leap" based on only one article shows your complete ignorance of the literature available on the history of Root's discovery and development of STJ neutral position, shows how little you know about how much Mert Root knew about foot function and is basically disrespectful to Dr. Root's significant contributions to podiatry and other health professions that use foot orthoses for treatment of mechanically-related foot and lower extremity disorders.

Again, another error in your article. Neither Mert Root, John Weed, or Bill Orien ever advocated using talo-navicular congruency as a method of determining STJ neutral position. In fact, John Weed made a point to us to not use TN joint congruency for determining STJ neutral position during our second year of podiatry school since he said it did not represent STJ neutral and would be affected by the amount of forefoot adductus deformity the foot displayed. TN joint congruency, as a method of determining STJ neutral, did not start at CCPM but apparently first started at the podiatry colleges on the east coast of the US. I first saw it being used by Langer Labs in about 1981 as the proper way to position the foot during negative casting.

In addition, I don't know where you got the idea for the following statement "This is a position in which any evident forefoot varus or valgus angulation relative to a supposed ideal rearfoot position (one-third the total available range from inversion to eversion; i.e., a "vertical" calcaneus) is eliminated." This is totally false and again shows a lack of understanding on your part. Please provide any reference by Dr. Root that says that the foot is casted with the forefoot varus or valgus eliminated during casting. Who taught you how to do negative casting, Ed, Don and Stu?? Certainly it wasn't Dr. Root, Dr. Weed or Dr. Orien!!

I liked the nice touch of having a full page ad for "The Bottom Block Seminar" in the page facing the introduction to your article in Biomechanics Magazine. I'm sure that had nothing to do with your article being published.

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__________________
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,
I only have time for a real brief reply. I think the author is confusing the concept of the rearfoot post with the triplane heel cup. My father was adamant about the importance of maintaining the plantar, non-weightbearing contour of the heel during casting and the cast modification process, in order to create a triplane heel cup in the orthotic shell. That’s why he did not advocate applying any plaster expansion or making any modification to the medial, or plantar medial aspect of the heel on the positive cast. You enhanced this concept by actually shaving plaster off of the plantar, medial heel (Kirby or medial heel skive technique) to increase the supination moment produced by the shell to enhance the control of the triplane heel cup.

A rearfoot post is an extrinsic modification to the orthotic shell which is designed to incorporate an axial grind (ie frontal plane orthotic motion) or can be applied flat (ie. no motion). This should not be confused with intrinsic rearfoot posting, which is incorporated into the frontal plane orientation (ie correction) of the cast. Extrinsic rearfoot posting is not necessary on all orthoses but it is typically added for convenience since it is more convenient to remove it than to add it after the orthotic device has been dispensed. My own personal orthoses that I have been wearing for years have no extrinsic rearfoot post since I don’t have any problem with excessive rearfoot motion or excessive calcaneal eversion.

Thanks you for taking the time to provide such a detailed response to the Biomechanics artilce.

Respectfully,
Jeff Root
www.root-lab.com

Eric,
The point that I am making quite specifically here is that the repositioning of the foot acts to change the relative lever arms of the GRF and the windlass mechanism to decrease the resistance to supination and increase the force necessary for pronation. In other words orthoses that reposition the foot into greater supination are more effective at helping the foot function better as opposed to walking continuously along the peak of the roof. The foot is not passive in this.

No, its simple mechanical advantage.

The latter, although certainly the CNS controls voluntary muscle function and has a significant effect.

Not very long…..that’s why people need their orthoses like they need eyeglasses. Eyeglasses do not improve the structure of the eyes, just the function.

Why don’t we just start with walking and standing.
You are ignoring the fact that as you supinate the foot with the muscles the STJ axis moves laterally and the foot is off any orthotic.

Interesting theory but it has nothing to do with gait. What is actually measured with the emed in the GSU study is that supination with Sole Supports shifts COP medially onto the MLA.

A true custom orthoses will do this to a variable degree dependant on the patient’s anatomy. What the exact “average” is could be researched but is irrelevant to clinical practice. You want to give each patient the maximal amount of correction that they can tolerate with their individual anatomy without oversupinating.

The ease of resupination of the foot is positionally dependant and has everything to do with the inclination angle of the first metatarsal. It is not just magnitude of force but does the position of the foot create a situation, in pronation, where the windlass is more of an isometric stabilizer of the first MTP than an active plantarflexor, as it is in supination.

Irrelevant in gait. The muscles are making fine adjustments. Read Dananberg’s article on Sagital Plane Biomechanics. Once again, you are trying to introduce a force that is not present in gait or standing and when applied lifts any foot almost completely off the orthotic in MLA.

What is more direct than FULL CONTACT. Done best by the medial heel skive….what a joke!!!
Yes 2cm under the heel too. Fat bad, bursae, skin etc. Redistribute force per unit area over a far greater area and finer tuning of forces necessary to resupinate is possible.

Very simple. Decreased lever arm for the GRF to apply torque around the axis of the 1st ray; decreased distance from the MTP to the medial cuneiform.

Once again….with muscles….the Sole Support respositions the foot with direct force, the muscles and in this case ligaments (windlass) have an easier time resupinating in this new position.

Respectfuly,

Ed :)
www.solesupports.com

Ed,

You have just stated the primary flaw in your entire paradigm. Clinically, a patient doesn't require the maximum amount of correction they can tolerate in order to control their symptoms. The patient requires only enough correction to eliminate their symptoms or to improve their function to a clinically acceptable level. In your paradigm, by virtue of the casting technique you endorse, you assume that ALL feet require more control than the average functional orthosis provides. This is simply false! Using your eyeglass comparison, it would be analogous to saying that since some individuals have a vision problem which is under-corrected, we should give everyone the strongest vision correction that they can possibly tolerate. In reality, the amount of correction required to create ideal vision is highly individual and must be determined on an individual patient basis.

Any competent orthotic laboratory will allow the practitioner to determine how much correction the individual patient requires and will enable this correction to be designed into the prescription. For example, Root Lab’s Rx has four levels of medial arch height for the practitioner to choose from, in addition to the amount of plantar fascia accommodation (if any), the amount of intrinsic inversion or eversion they want in the cast, the amount of intrinsic or extrinsic rearfoot and forefoot correction, and a multitude of other accommodations, modifications, and shell configurations to increase or decrease the amount of "control" as required. Like prescription eyewear, orthoses should be designed (prescribed) for the needs of the individual patient and not based on some average. Your assumption that everyone needs to have their re-supination moments increased is inherently flawed.

It is true that some practitioners may not take full advantage of the prescription or may not thoroughly consider the prescription needs of an individual patient, in order to get the best possible outcome. That is not a flaw in “Root Theory” but rather is a flaw in how the theory is implemented by some practitioners.

Respectfully,
Jeff Root
www.root-lab.com

Now that you have replied we can start the debate.


Originally Posted by efullerEd, I don't think this quite answers my question. A patient stands on an orthosis and the orthosis creates different locations of forces acting on the foot. Which forces, from the orthosis, cause the arch to be higher? Where are they applied?

And Ed answered:
Ed, I understand your point. My question was asking something different. How does an orthosis reposition the foot. You sort of answered this later, but you got my hackles up by not answering what I asked.


Originally Posted by efuller Now, I would agree with you that it would be possible for the muscles to cause supination of the STJ and plantar flexion of the first ray, but this is a central nervous system response to the orthosis.

How does the foot, on top of the orthosis, get repositioned to gain mechanical advantage. Your orthoses are sitting on the floor and your walk up and step on them. In the absence of the orthosis your foot would achieve equilibrium in a certain position. How does an orthoses create moments acting on the foot so that the foot will sit, in equilibrium in a different position.

Answer 1: they work through simple mechanical advantage.
How do the orthoses change mechanical advantage? A they change position. Question how to they change the position?

Originally Posted by efuller Are you saying that your orthoses work through a centreal nervous system response or are you saying that pressure in the arch from the orthosis raises the arch, or a combination of both?
Answer 2: I think you chose both. Could you describe how pressure in the arch changes the position of the foot?

Originally Posted by efuller How long will the muscles be able to hold the foot in this position?
How long do you think that foot can tolerate high pressure in the arch? Pressure high enough to alter the position of the foot

Originally Posted by efuller I'm not sure that you can say that supination begats more supination all of the time.
Ed, I'll put it more strongly. Your contention that supination begats more supination is wrong for the vast majority of feet. Reasoning will follow below.


Originally Posted by efuller If you supinate the STJ a little bit, with the muscles, there will be a lateral shift in the center of pressure causing a greater pronation moment acting on the foot especially in the more medially deviated STJ axis foot.
Later, in my original post I describe the race between COP movement and axis movement. I said that with a little bit of STJ supination from muscular activity there is a lateral shift in the center of pressure. The center of pressure will move laterally and the STJ axis will move more latterally. I am saying that the COP moves more lateral than the axis does, thus createing a greater pronation moment.


Originally Posted by efuller Now, if you supinate the foot enough the entire plantar surface, and lateral surface, of the foot will medial to the STJ axis and then there will be a supination moment from ground reaction force.
Ed, I disagree. This has something to do with gait, especially in the foot with a more laterally deviated STJ axis. A small amount of unexpected supination will cause the entire contact point of the foot to be medial to the axis and the foot will supinate to end of range of motion. aka sprained ankle. Or it will not supinate to end of rom and you may get peroneus brevis avulsion fracture of the 5th metatarsal.

What is measured, in the GSU study is that there is pressure in the arch when the patient is standing on them. Did the study measure the amount of supination? Did it measure posterior tibial EMG activity.

My contention is that as you stand on MASS casted device you feel discomfort in the arch and you use your posterior tibial muscle to supinate the foot to raise the arch of the foot so there is less pressure in the medial arch. Don't get me wrong, this can be a good thing for some feet. However, it is a bad thing for other feet. When I wore the devices you made me, after 2 hours I had pain in my posterior tibial muscle. Trying to go longer than that gave me pain in my arch. (My theory is that since the PT tendon hurt, I used it less and let the foot back down onto the arch where there was high pressure, which caused the pain.) So, this is how you can have a more supinated position with pressure in the MLA. So Ed, how do you think an orthosis changes the position of the STJ, if it is different from above?

Originally Posted by efuller

On average how many degrees do your orthoses supinate/invert the STJ? Is this enough to make a significant difference in the location of the STJ axis?

Ok, why an orthosis works may be irrelevant to the clinical outcome. However, we are not in the clinic. We are in an academic forum debating how orthoses work. You have made the contention that supination begats supination and I tried to make the point that a few degrees of supination that you get from standing on an orthosis is not enough to significantly move the STJ axis. So, the question is relevant to our discussion. Jeff's point was a good one. Not everyone needs to be in their MASS position. Not everyone needs to be more supinated. I am questioning your assumption behind MASS. I am also questioning whether or not your devices supinate the foot enough to get into the position where the positive effects of supination that you describe happen. So, how many degrees the STJ supinates on the device is relevant to the theory of how you believe your devices work. It would be a nice way to prove your theory is correct. Your theory, as I understand it, is that the foot functions better in a more supinated position and your devices put the foot in a more supinated position. An important part of the evidence for your theory would be the number of degrees, on average, the foot supinates on your device. And does clinical outcome correlate with number of degrees inverted?

Originally Posted by efuller You refer to transverse plane and frontal plane forces. The forces perpendicular to the transverse plane are a function of body weight and in the vast majority of activities will be orders of magnitude larger than forces parallel to the transvers plane. Therefore the position of force relative to the transverse plane projection of the axis will tend to be much more important than forces perpendicular to other planes.
I'm not quite sure what you are saying, but I have to disagree with the notion that ease of supination has everything to do with the position of the first ray. More important is magnitude of pronation moment on the STJ.

Originally Posted by efuller
STJ axis movement and Center of pressure movement. Which one moves faster with STJ supination. My bet is on the COP. If cop moves faster laterally than the axis there will be an increase in pronation moment. A few degrees of supination from muscular activity will cause the cop to be at the lateral border of the foot. There may be some feet, with a laterally position stj axis that the axis may move further laterally, but I would bet that the majority of feet, with muscular supination will not increase supination moment from ground reactive force with a supination motion.

I disagree, it is relevant in gait. I'm not quite sure what you are saying. Could you expand on how Sagittal plane biomechanics relates here. Try standing and supinate your foot a little bit. Is there a significant shift in the location of force under your foot?

Originally Posted by efuller
On the other hand you could believe that the orthosis causes a direct supination moment, but that is best done with a medial heel skive, which you do not use.

It's not the amount of contact, it's the location of center of pressure. I will agree that pressure in the arch will tend to shift the center of pressure more medially. The question then becomes how the pressure in the arch is transmitted to the bones to change their position.

Originally Posted by efuller

(To supinate the foot you would want to push on the bony structure furthest medial to the STJ axis which is the medial tubercle in most feet. In most feet the medial arch bones are deep to 2cm of soft tissue and cannot be directly pushed on by an orhosis.)

I disagree. The plantar fat pad and skin are nearly as thick in the arch as in the heel. In the arch you have to add the intrinsic muscles and extrinsic tendons along with the nurovascular structures.


Originally Posted by efuller
I don't understand how increased inclination of first met decreases pronation moment. Are you saying that there is more force under the first met in this position? Position does not correlate with force.
When I mentioned pronation moment, I was referring to the STJ. There was more to this question and answer than was quoted.

Originally Posted by efuller
If you supinate your foot, with muscles, and then plantar flex your metatarsal maximally and it just touches the ground the center of pressure will be lateral.
The orthosis applies an upward force to the foot. Any upward force applied to the metatarsal will dorsiflex the metatarsal. Therefore there is no plantar flexion moment acting on the metatarsal, from the orthosis. If the forces were applied proximal to the meatarsal, only the force of gravity would pull the metatarsal down until ground reaction force stopped the downward movement with a force equal to the weight of the metatarsal. For the metarsal to be able to accept more ground reactive force there would have to be a source of plantar flexion moment, from within the foot, to resist the dorsiflexion moment from GRF. Ed, what creates these internal moments.

Ed, how does direct force from the orthosis change the equilibrium position of the foot?

Ed, this is a really good debate. It really gets my juices going.

Respectfully,

Eric

Jeff:

I'm glad that you entered into this discussion with Ed. I totally agree with you in your analysis of the Ed's theory that everyone needs "maximum supination correction" in order to function the best. Ed seems to think that he has come onto something new by making a non-rearfoot posted orthosis that has good conformity to the medial arch of the foot. I seem to remember ordering this same orthosis 20 years ago from the lab I use by simply ordering a polypropylene shell with an inverted balancing position, minimal medial expansion thickness, no rearfoot posting and a full length topcover.

If you read his article, from my perspective, it seems like Ed has come up with this idea of "maximal arch support without rearfoot posting" without having taken the time to read about your father's work on the history of the subtalar joint neutral theory, without reading the available research and theories on subtalar joint biomechanics and without having investigated the very wide range of orthosis design that is available from orthosis labs around the world. In fact, after graduating from NYCPM (where he probably got the idea that TN joint congruity equated with STJ neutral position) in 1983 he spent a lot of time in his garage working on his foot orthosis ideas: I agree with you that his theories and orthosis application of his theories are inherently flawed, as you say above. From all the marketing lectures he does at various venues around the country, all the unsolicited DVDs that he sends out to podiatrists around the country, and all the testimonials he has on his website, it seems as if Ed's main goal is to sell as many high-arched, non-rearfoot posted orthoses as possible and try to convince podiatrists, physical therapists and chiropracters that no one understands foot and lower extremity biomechanics quite the way that he does since, before he arrived on the scene a few years ago, we were all working in the dark without his glowing vision to enlighten us.

__________________
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,

I have to say, I admire Ed Glaser’s energy, enthusiasm, and marketing effort. There is no doubt, in my opinion, that there are many orthoses produced on a daily basis that fail to provide the therapeutic benefits that the patient requires because they are either poorly prescribed or poorly made. A poorly prescribed orthosis can be the product of a clinician who fails to properly evaluate or recognize the patient’s biomechanical condition or functional requirements, or who doesn’t properly understand biomechanics and orthotic therapy. A poorly made orthosis can be the result of laboratory standards that diminish the functional benefit of the clinicians prescription (ie over-fill, or improper cast modification, etc.). As a result, many custom orthoses have a generic look or nature to them. However, this isn’t because better quality orthoses aren’t available, it’s because those practitioners choose to order poor quality devices!

Ed’s educational experience isn’t surprising to me, as I have heard many former students at certain podiatry schools tell me that the orthoses they saw in podiatry school were very generic looking. Therefore, we need to question the quality of education in orthotic therapy that students receive. We all know that there isn’t enough time dedicated to orthotic therapy during school and that education doesn’t stop once you graduate. There are many excellent ways to enhance one’s understanding and ability in orthotic therapy after graduation.

There are a number of good, custom orthotic laboratories out there who are working very hard on a daily basis in an effort to provide their customers with high quality, functional orthoses to help patients achieve positive outcomes. There are many practitioners who achieve excellent results from their current methods and while using their current laboratories. Those practitioners that Ed is marketing to who are apparently achieving poor outcomes don’t need a new paradigm, they need to get up to speed on the old paradigm so they can get good outcomes like many of their colleagues! This requires better education, higher expectations of what can be achieved with orthotic therapy, or a better laboratory.

If you believe Ed’s claim that he is adding 30 new customers per day, and if he has any reasonable level of customer retention, he will soon own the largest laboratory in the country. Hmmmm? I’m not sure how you get the capacity to add 30 new customers per day unless you have a ton of money to pre-train employees. I could not accept 30 new customer per day as it would kill my quality!

I really haven’t been able to learn much form Ed’s website about his products or methodology. But to answer Eric’s question, I think Ed endorses plantarflexion the forefoot or supinating the midtarsal joint while casting in bio-foam. This is one of the most common casting errors in conventional, suspension casting. It creates an orthotic shell that has a transverse peak at the MTJ area with a greater sagittal plane inclination angle of in rearfoot and a greater sagittal plane declination angle in the forefoot. This does increase the STJ and MTJ supination moments. It is also frequently uncomfortable or results in breakage of acrylic orthoses, since the shell must flex under load. The only way this device can be tolerated is if you use an orthotic shell that is flexible. If the shell must deflect under load in order to be tolerated, then it isn’t supporting the foot in the position in which the foot was casted! This is why I asked Ed about his apparent conflict of mechanical objective. I am patiently waiting for Ed Glaser to respond to my previous posting asking him about the nature of his orthoses. I don’t believe you can comfortably support the foot in the position he describes, which is why he probably uses a more flexible shell. Am I right Ed????

Respectfully,
Jeff Root
www.root-lab.com