Challenging the foundations of the clinical model of foot function

Another problem with Kevin's definition is the use of the word normal. Root's use of the term normal or ideal has been criticized greatly on this forum by many of you. So how can those of you who have supported Kevin's definition accept it with the use of the words "more normal foot and lower extremity function" when you can't even define or agree upon what normal function is?

 

Using your logic, Jeff, then the definition of a foot orthosis needs to only be this: Foot Orthosis: An in-shoe medical device.

Secondly, every foot orthosis, even pre-made orthoses, are "custom-fitted" in some fashion. When you go to the store and pick a size 12 orthosis for your foot instead of a size 6 foot, that is a type of "custom-fitting". In other words, even in pre-made orthoses when they are selected from the different size ranges that comes with pre-made orthoses, there is always some form of "custom fitting", whether by the individual trying them on or the salesman recommending the device. Therefore, my definition is not "wrong" nor does it demonstrate "bias".

Third, the definition I wrote over 2o years ago gets away from the arcane and unscientific "bracing" or "supporting" and "protecting" terminology that was being used by others, and then again by PFOLA ten years after I wrote my definition. My definition uses more precise terminology that is used routinely by the International Biomechanics Community.

 

Basic quantitative genetics supports the notion of partitioning the variance in any such quantitative character into genetic and environmental components. It is and always has been the proof of the fallacy of Root's criteria for normalcy. Daryl (wrongly) stated that only quantitative science is "real science", so let's run with this... think of any quantitative character linked to foot and lower extremity function; any such character can be given by P= function of: G + E + (GxE) + i; where: P= quantitative characteristic (e.g. "STJ neutral position"); G = genotype; E= Environment (all non-genetic factors) and i= measurement error. So, any human trait that can be quantified, can also be partitioned into the aforementioned components.Viz. since the genotype and its interaction with the environment is unique to every single individual on this planet, there obviously cannot be a single quantitative measure defined "normal" across everyone within a population. What colour of skin is "normal", Jeff? Normal for whom, and given what environmental factors, Jeff? As I said: Root's criteria for normalcy is fundamentally flawed. You can argue otherwise until the end of time, but you will always be wrong Jeff because science says so.

As such, here's my definition of "normal foot and lower extremity function": function during which the loading applied to each of the body tissues is maintained within their zones of optimal stress; it is unique to the individual and dynamic because it can also be defined by P= a function of: G + E + (Gx E) + i Where P= normal foot and lower extremity function; G = genotype; E= Environment (all non-genetic factors) and i= measurement error.

Thus, I can provide an alternative definition for a foot orthoses: a physical object when placed within a shoe, if successfully prescribed in terms of it's shape, stiffness and frictional characteristics, results in the loading of the body's tissues to be maintained within their zones of optimal stress.; or provides enough of a placebo effect to trick the body's brain. If it doesn't do either of these, it's an injurious object.

Hope that helps.

 

Here is what a thesaurus says
http://www.thesaurus.com/browse/custom-fit
custom-fit

• as in tailor-made
• as in tailored

Synonyms for custom-fit
adj made to order

• custom-made
• suitable
• suited

• custom-built
• designer
• perfect

• snug
• comfortable
• fitted

• made to order
• made-to-measure

• • perfectly fitted
• tailored

 

Custom-fit

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Custom-fit means personalized with regard to shape and size. A customized product would imply the modification of some of its characteristics according to the customers requirements such as with a custom car. However, when fit is added to the term, customization could give the idea of both the geometric characteristics of the body and the individual customer requirements,[1] e.g., the steering wheel of the Formula 1 driver Fernando Alonso.
The custom-fit concept can be understood as the idea of offering one-of-a-kind products that, due to their intrinsic characteristics and use, can be totally adapted to geometric characteristics in order to meet the user requirements.[2]

 

Years ago I gave a lecture titled Are Your Custom Orthoses Really Custom? I pointed out that the use of the word custom is problematic because it has may interpretations. I used a number of examples, including Dr. Scholl's Custom Fit Orthotic Inserts. Below is a link to Dr. Scholl's current website in which they state "Customized orthotics for immediate, all-day relief of foot, knee or lower back pain". While they can claim that the devices are custom fit, as you have suggested the term can be used Kevin, saying that the devices are customized is very misleading. I don't think the custom fitted part adds anything or has any real benefit in your definition Kevin, and I hope you see how misleading the terms custom, customized and custom fit can be.

https://www.drscholls.com/products/pain-relief/custom-fit-orthotic-inserts/
DR. SCHOLL’S®
CUSTOM FIT® ORTHOTIC INSERTS

Customized orthotics for immediate, all-day relief of foot, knee or lower back pain from being on your feet . Visit a Dr. Scholl’s® Custom Fit® Kiosk to get the recommended orthotic for your feet.

 

An 80 year-old woman with stage 2 adult acquired flatfoot comes into your office seeking treatment for pain related to her condition. You tell her that you believe she will benefit from a custom orthotic. She asks you what a custom orthotic is. What do you tell her? Would you use terms and a definition that might be confusing to her or would you say something more simple like “It is a shoe insert that is manufactured from a cast (or scan) of your foot that will support your foot in an effort to eliminate your pain”?

 

Depends on various factors, not least a subjective assessment of her cognitive capacity; lets face it your 80 year old female might be a retired Professor of biomechanics who could turn you inside out, Jeff. Not too hard, any better questions? Not sure why you felt it necessary to define gender in this example though...? Do you think that a patient being a female has an impact on her ability to understand what you are saying to her as compared to a male or transgender patient?

 

I defined gender because AAFF is more common in women than men Simon. We see far more cases of this in women than men at Root Lab, and it is typically worse with age. I also picked this condition because there can be dramatic collapse of the MLA and dramatic improvement in the position of the foot and leg in static stance and during gait. As a result, this condition also demonstrates how an orthosis can act to brace and support the foot.

 

That picture doesn't show that you are supporting a deformity. What that picture suggests is that there is a lot of eversion range of motion. Daryl is it possible that a perpendicular forefoot to rearfoot could have enough eversion range of motion to lift the lateral forefoot 5mm off of the ground?

(I will even concede that at the extremes there are feet that will have a more inverted forefoot to rearfoot relationship and other feet a more everted forefoot to rearfoot relationship)

I would agree that the orthosis is altering position and is probably altering forces.

I have made orthoses that have lifted the fifth met head off of the ground. I agree that this orthosis could help someone more than an orthosis without an intrinsic forefoot valgus post.

Daryl, I once asked you how orthotics worked and you said that they worked by moving the foot toward neutral position. When I asked that I specifically mentioned the support the deformity idea. You did not say at that time whether you believed that orthotics supported a deformity. Again we bump into one of the internal conflicts of the explanation of how a Root orthotic works. An intrinsic forefoot valgus post will tend to move the STJ away from neutral position.

Daryl,
For those that have not read your paper, could you tell them what the x=0 axis is? Can you tell them in fewer words than you used the first time?

Are you reluctant to use the term longitudinal axis of the midtarsal joint?

Daryl, can you explain to me, in terms of the anatomy of the midtarsal joint why this question is important?

The reason that I think this question is not important is that the longitudinal axis of the midtarsal joint is a hypothetical construct that does reflect real motion when the correct forces are used to move the joint, but in weight bearing you don't see those exact forces nor do you see motion about that axis (Nestor paper). The longitudinal midtarsal joint axis does not represent the anatomical constraints of motion. Or, said another way, there are no anatomical structures that constrain midtarsal joint motion to the LMTJ axis.

 

Unfortunately I only have enough time at this moment to answer one question. So I will address the last one here and save the others for more later.

BTW -- I don't get upset with differences of opinions on this arena -- all you have to do is listen to World Science Festival, and see how much various really great minds e.g. Steven Hawkins, Brian Green, Lawrence Krause, Leonard Suskind, Michio Kaku, etc. disagree on the great scientific questions of the age -- all whom are much smarter than anyone on this discussion -- and then you find out disagreement is part of the process of scientific discovery and the disagreements here are pretty small potatoes.

I'm not afraid to use the term LAMTJ. I know what it means, and so do most people. It's just that so many people seem offended by using that term. It describes a possible motion that can occur in the MTJ. It occurs around an axis that is perpendicular to the frontal plane. Actually you should have called me out on my mathematical error, because the equation of the line is not x = 0, but that is the equation of the frontal plane.

I'm tired of beating my head against the wall about what Nester did and how having a 3 axis system of the MTJ is not contradictory. Please go back and reread how I explained it in Albert's book. Nester showed that there is one instantaneous axis of motion. However the motion around that instantaneous axis is a composite of motions around 2 or even three axes. Do we need to go back and discuss the hip again? How many axes of motion does the hip have? It has 3 cardinal axes, but it has infinite number of instantaneous axes? How hard is that to understand? Pick up a book on linear algebra please! Elementary math, dear colleague.

Did you ever take casting lessons from Mert Root? If you did, you know that he placed an eversion force against the forefoot until he felt the STJ start to also move. At this point he said that the MTJ had reached its EROM around the LAMTJ. That was the point at which pressure against the forefoot could start producing those moments around the STJ axis. Before you reached that point, no moment was being placed around the STJA. We definitely need to do a lot more work on this aspect of exactly where the EROM of the MTJ is. And of course you have to consider that the EROM may be different for different people based on the radius of gyration of the foot and the full equation of the STJ axis. Also remember that the moment of inertia of the foot around the STJ may be different at every position of the STJ, because the STJ axis moves relative to the foot. I am grateful that his whole question of the EROM of the MTJ is what got Milt Wille, that mechanical engineer with no pre-requisite training in foot anatomy, to get involved with Root, et al.

BTW -- I too am continuing to learn, and what I said 10 years ago, I may not fully believe today so please do not throw up quotes that I may have made 10 years ago as where I stand today. I will look forward to your review my poster at I-FAB and we'll talk a lot more.

Take care,
Daryl

 

Daryl, this is an excellent point that too many people fail to appreciate. When casting the foot Root taught that you first need to position the patient's hip and leg so that when the foot is dorsiflexed with the STJ in the neutral position, no rotation of the leg or STJ occurs. If you apply too much force, the leg will eventually internally rotate and the foot will pronate at the STJ. If the STJ pronates it indicates that the clinician is applying too much force on the lateral side of the forefoot. This casting position should be achieved with the foot vertical or as close to vertical as possible. It should be noted that there are some subjects who, when you dorsiflex the foot to resistance at the ankle, tend to pronate at the STJ more readily because their foot abducts or everts more easily due to the orientation of their STJ axis. In that case, it may be necessary to grasp the medial and lateral margins of the heel to prevent STJ pronation during casting or to have an assistant stabilize the leg to prevent leg rotation . When you place the STJ near the the neutral position; and then place your thumb in the sulcus and then evert and abduct the forefoot with the patient totally relaxed, you will exhaust the range of eversion and abduction at the MTJ before the STJ will begin to pronate. Root et al stated in their casting manual that the foot should be dorsiflexed to resistance and that it is not necessary to dorsiflex the foot to 90 degrees to the leg and that doing so would cause the STJ to pronate. These points are all addressed in their casting manual.

 

I still haven't had anyone attempt to answer this question. Kevin, Simon or Trevor, would you care to explain how this is possible if the orthosis is not acting to brace or support the foot or a part of the foot?

 

Jeff, it is not that the foot orthosis does not "brace" or "support" the foot, it is just that this terminology "brace" or "support" is not precise, has multiple meanings, and, as such, may be ambiguous and meaningless, and therefore, should not be used within the definition for "foot orthoses".

Support (definition): bear all or part of the weight of; hold up.

For example, does a flat insole, with no contour, "support" the foot? Yes the flat insole does support all the weight of the foot against the shoe insole (board). So would you consider a flat insole that supports the foot to be an orthosis? I wouldn't. Therefore, using "support" within the foot orthosis definition is confusing and ambiguous since even a piece of paper or flat insole can "support" the foot.

Brace (definition): a device that clamps things tightly together or that gives support, in particular.

Does a foot orthosis "clamp things tightly together"? I don't think that this either is a very good term. Or does "brace" mean that the orthosis immobilizes or limits motion? In some cases it may limit motion but in other cases it may facilitate motion. For example, in the case of functional hallux limitus, the foot orthosis with a reverse Morton's extension probably increases 1st MPJ motion so that would not be an immobilization or limitation of motion or "bracing". Again, using "brace" within the foot orthosis definition is confusing and ambiguous since the foot orthosis does not "clamp the foot tightly together" or "immobilize" the foot or even always "limit the motion of the foot" since sometimes, the foot orthosis allows more motion to occur.

Now let's look at my definition: "A foot orthosis is a custom fitted [this may not be correct in all cases, but is likely true in many cases, so you can take this part out of my 20 year-old definition if it makes you feel better] in-shoe medical device [this is correct] which is designed to alter the magnitudes and temporal patterns of the reaction forces acting on the plantar aspect of the foot [this has been shown by research to indeed be the case] in order to allow more normal foot and lower extremity function [that is the one of the main therapeutic goals of foot orthosis therapy] and to decrease pathologic loading forces on the structural components of the foot and lower extremity during weightbearing activities [this is the other main therapeutic goal of foot orthosis therapy].

Even though I wrote this definition over 20 years ago, my definition of foot orthoses is certainly more specific to what orthoses actually are and what they are intended to do. In addition, my definition is much more up-to-date and consistent with the existing research than the PFOLA definition of "foot orthoses". The PFOLA definition is not only ambiguous but is also an inaccurate description of what foot orthoses actually are and are actually intended to do for the bipedal human. In other words, the PFOLA definition of foot orthoses would have been acceptable 50 years ago, but it is not acceptable now with what we currently know about foot orthosis biomechanics.

 

What I still find interesting is why we are still even discussing the MTJ at all.

We know there is motion between the Cuboid and Navicular.

We should be discussing the calc-cuboid joint motion and talo-navicular joint motion

 

A bit of reading around the area of physics, kinematics & kinetics and materials science will answer this rather simple question for you Jeff. Some people also call this ‘biomechanics’... “It’ll never catch on” (Spooner, 2018)

 

Yes Mike, we know that in most people the navicular-cuboid joint is a syndesmosis, with a few people having a synarthrodial joint. There is indeed a small amount of motion in this joint. But how much can the calcaneocuboid joint move before the talonavicular joint moves? It is MINISCULE in comparison to the total ROM of both joints moving together. I also realize that you can manipulate the cuboid. Dananberg makes it a big part of his practice. Please provide your references for relating the independent CCJ and TNJ motions compared to the combined motion of both joints together. We're talking about models in any biomechanics discussion - so give us a little break. You have no model to replace the MTJ model with. When you do, I'll buy your book.
BTW - do a little research on the fact that the speed of light changes a little bit in various years. That's why they had to end up defining the length of the meter in terms of the speed of light, in order to make the speed of light never change. Now that is what you can call a real circular argument from our top scientists. I recommend that you read a little bit of Rupert Sheldrake on "The Science Delusion."

Daryl

 

The bone pin studies should be the place to start. Yes there are some issues due to small numbers of test subjects and the use of local anaesthetic.

Not ever going to write a book so you won't have to waste your time reading. Basically I can't string two sentences together with proper punctuation and correct spelling, plus it would be outdated before it was finished.

Still doesn't take away from the fact there is motion

 

So did I argue that there wasn't any motion? I have the studies, I know there's motion. But it's not significant enough at this point in time to have a great impact on trying to describe or predict what's happening in the entire foot. I think you could spend much more time in studying the motion of the cuneiform-navicular joint motion, both the common CNJ motion and the independent CNJ motion. That's a lot more important than the motion between the nacivular and the cuboid.
Daryl

 

Agreed that the motion of the Navicular goes through is significant. And much easier ti discuss if not thinking about the MTJ but the Navicular at it's joints

 

I don't catch your drift. You really can't talk about the navicular moving against the talar head in either CKC or OKC without talking about concomintant CCJ motion (except for very small amounts of motion in the navicular-cuboid syndesmois). The movement between the cuneiforms and the navicular is much more complicated and needs much research.

 

I did not get into the discussion on the definition of a foot orthoses although it is intersting how my question morphed into this aspect of the debate.

My question was about how we describe waht we are doing in an easy to say format if we do not say we are correcting / controlling etc.

Eric gave an example of modifying forces with a forefoot pad with a U around the symptomatic joint - I would call this a redistributive.

So perhaps we should simply say we are modifying the forces under the foot and then use the terminology that may be incorporated: wedging, redistibution, shell flexibility, support (where we are using support) etc.?

 

Daryl, what are your thoughts on Lundgren et als data which contends that some individuals exhibit more motion at the articulation between the navicular and cuboid than they do at their STJ? (A joint which has never been ignored in anyone)

 

Ian, you're missing the point. I asked this question in context to PFOLA's following definition of a foot orthosis:
"Foot Orthotic. An in shoe device that braces, supports, or protects the foot or part of the foot".
This definition was criticized by PA members. There is nothing wrong or inaccurate with PFOLA's definition since an orthosis can't produce a kinetic or kinematic change unless the device support or braces the foot in some way. That is my point, which you obviously missed! The PFOLA definition was developed not to try to impress outsiders with how sophisticated or intelligent the biomechanics community is, it was written to provide a clear definition that would serve anyone seeking to know what a foot orthosis is. While a more detailed or complex definition like Kevin's can be used, this wasn't the intent of PFOLA. We wanted laymen, government entities, insurance providers, etc. to have a simple but accurate definition of what a foot orthotic is.

When my contention that an orthosis braces or supports the foot or a part of the foot was challenged, I asked how it could produce kinetic or kinematic changes if it didn't support or brace the foot or a part of the foot. The answer is it can't and therefore the PFOLA definition is accurate.

 

Kevin, here is how you describe a foot orthosis on your own website:
"A prescription foot orthosis is an in-shoe brace which is designed to correct for abnormal foot and lower extremity function (the lower extremity includes the foot, ankle, leg, knee, thigh and hip)".
You call a foot orthosis an in-shoe brace on your own website, which is consistent with the PFOLA definition. Needless to say I'm confused by your conflicting and contradictory statements.
http://www.kirbypodiatry.com/document_disorders.cfm?id=148

 

In which case the floor is also a brace to the foot, does that make the floor an out of shoe orthosis? "Brace" is a poor and clumsy choice of words.

 

The floor was designed as a flat surface to walk on. It was not designed with the features and the intention of altering the foot surface interface to treat foot problems so no, the floor is not a brace Simon. Let me help you with some definitions:
floor
flôr/
noun
noun: floor; plural noun: floors; noun: the floor

1. 1.
   the lower surface of a room, on which one may walk

brace
brās/
noun
noun: brace; plural noun: brace

1. 1.
   a device that clamps things tightly together or that gives support, in particular.

 

Yet both work in exactly the same way- by providing an equal and opposite reaction force to the foot. The difference being that foot orthoses generally introduce curvi-linear surfaces at the foot orthosis interface which results in increased shear components to the reaction forces. Yet both do the same thing, Jeff: Shoes and the floor are both examples of devices "that braces, supports the foot", So, by your definition a shoe is a brace, the floor is a brace, in fact anything at the foots interface is a brace. Viz. anything at the foots interface is an orthosis. Nice.

 

Try billing a shoe or the floor as a medical device Simon. Good luck with that!

 

This isn't about billing and coding Jeff, it's about your definition of a foot orthosis; which is poor and weak.

 

I better rewrite this one that I wrote for my public website a number of years ago, about 15 years after I wrote my much better definition.

 

No, it is about terminology and you are trying to twist definitions. A foot orthosis is a type of shoe insert. Therefore, by definition Simon, the floor or a shoe cannot be a shoe insert or a foot orthosis! Many things can influence foot function but that does not make them a shoe insert or a foot orthosis.

 

I bill shoes daily in my new job. FWIW

 

I'm not the one providing dictionary definitions in an attempt to support my choice of words. If a foot orthosis is a "brace" to the foot, then the floor is also a brace to the foot, the shoe is a brace to the foot and the pound coin I placed inside the shoe is now also a brace to the foot. Thus, the pound coin I threw inside the shoe is by your weak definition now classed as "an in-shoe foot orthosis". Sorry, dollars in the US of A- go throw some dollar bills inside a pair of shoes- by your definition they are now foot orthoses. They will by definition "brace the foot". I guess the question becomes: if I fold up a dollar bill and place into a patients shoe so that it is now a foot orthosis because it is now a: "Foot Orthotic. An in shoe device that braces, supports, or protects the foot or part of the foot"." how much can I bill for that dollar bill, Bill?
Meanwhile in Hollywood tonight... Dollars, they're my possessions...

 

Any reasonable person can see that the PFOLA definition of an in shoe device would not be consistent with a dollar bill. It is true that some “orthoses” do very little to influence foot function. However, PFOLA also has defined a prescription foot orthosis:
Prescription Foot Orthotic. An in shoe device that is prescribed by a qualified healthcare professional to brace, support, or protect the foot or part of the foot.

PFOLA also has a link to technical topics that describe in reasonable detail what orthoses and orthotic prescription options are. If someone is prescribing a dollar bill as a foot orthosis to treat foot problems then their license and qualifications should be called into question and their license should probably be revoked.

 

For the record: at the time that definition of "foot orthoses" was produced, what was your role / position within PFOLA, Jeff? Moreover, who else sat around the table during that pointy scratchy beard meeting when that was decided upon as a good definition? Who chaired that meeting? I'm guessing it was a definition that was decided upon in order to allow for billing and coding in the USA as oppose to a good quality global definition of what a foot orthoses is.. what was the raison d'être for deriving that definition?

 

If the coin could modify the ORF, why not to be considered part of the "in-shoe foot orthosis"?
Here I'm thinking at the clinical case from Eric's presentation from Zaragoza 2014 about modification of an existing orthoses [of course, this image have to be understood in the context of the whole Eric's presentation and I hope not to be a problem to post this image without asking Eric's permission ]
Daniel

 

I'm thinking at the sport surfaces which are not designed only for walking or running but also in order to avoid injuries. But for sure are not foot orthosis because it doesn't "encompass the whole or part of the foot"

"Foot orthoses - Orthoses that encompass the whole or part of the foot. Included are,e.g orthopaedic shoes, insoles, shoe inserts, pads, arch supports, heel cushions, heel cups, orthopaedic inlays""
ISO 9999:2011(en) Assistive products for persons with disability — Classification and terminology,

But, my question is: is not a limitation for podiatry to think at foot orthosis just in terms of "in-shoe" device? Why only "in-shoe"?
Daniel

 

I was the western U.S. representative for PFOLA:
Document. Updated January 24, 2006
Committee Members:
Christopher Smith, DPM
Mr. Scott Marshall
Mr. Paul Paris
Mr. Jeff Root

This document was reviewed by every PFOLA member lab which included individuals such as Paul Scherer, DPM, Christopher MacLean, PhD, and many DPM's who are either owners or consultants for orthotic labs. PFOLA is an international association so there was an international consensus.

For the record, this document had nothing directly to do with billing. The billing code for functional foot orthoses hasn't been changed in probably thirty or forty years. This is a whole different issue that needs addressing. The billing code and description is L3000 - Foot, insert, removable, molded to patient model, 'ucb' type, berkeley shell, each

 

Daryl it appears that you are stopping at 3 axes in this statement. The midtarsal joint has an infinite number of possible instantaneous centers of rotation just as the hip does. As you look at the bony surfaces and ligaments of the calcaneal cuboid and talo navicular joints you can see that the midtarsal joint has an envelope of motion.
If you try to put the midtarsal joint into one of the anatomists classical categories the midtarsal joint functions closest to a planar joint. Daryl I agree with you that functionally, the amount of motion between the cuboid and navicular is not that important. When the cuboid and navicular together move relative to the calcaneus and talus the available motion looks like the motion of a planar joint. Yes, the joint surfaces don't look planar, but the available motion looks planar. Would you agree that you have to accept this if you believe that motion between the cuboid and navicular is not significant? The planar joint is consistent with the observed axes of motions.

The reason that I bring this up is what you said earlier.

This question is implying that the longitudinal MTJ is a hinge like axis. After thinking about this a bit, it's not that the answer to this question is not necessary to know, it's the answer cannot be known. The MTJ does not function like a hinge like axis. If you push up on one side of the axis, the other side does not rotate downward. Compare this to the ankle joint. When you push up on the heel, the forefoot rotates downward. It does this because the bottom of the tibia acts as a fulcrum. There is no fulcrum for the midtarsal joint. If you believe differently name the anatomical structure that acts as a fulcrum.

We can't treat the midtarsal joint as a black box that has just 2 axes of motion that when you combine motion from two axes, you get a third independent instantaneous center of rotation. We have to look at the anatomical structures and how those structures can constrain motion. Where are the fulcrums of the midtarsal joint? I don't think there are any that would give us the classical OMTJ and LMTJ.