Normal vs Abnormal foot function

[robertisaacs]

Ian wrote

Brian used the term "abnormal foot motion" which of course need not be linked (and I'm sure Brian does not implies this) with excessive pronation but with other aspects of foot function as well.

Equally focus is placed so much upon the amount of heel eversion and attempts to possibly control it.

My difficulty is that I am not convinced that we can talk about abnormal foot motions in these instances. We have an individuals foot function but to describe it as abnormal is possibly (?) to go to far and have us looking how to introduce normality.

For many years in I disagreeessments I have noted the level of static and dynamic eversion of pts heels when assessing them but made no real attempt to address this other than including occasional medial skives or deepening the heel cup. When making my own devices the aim was always to bring resistance to what I would have considered excessive in-roll of the MTJ at early and mid heel lift. This for me has never been an issue of them having abnormal foot function but an issue of using the device to produce (paradox coming up) a "stability" (or resistance) that moves a person from one point of instability to a different type of instability but one where hopefully their own musculoskeletal and neurological intelligence is allowed to function more helpfully.

Equally I have used lateral heel skives to alter "instability". Would expand this but I have now got an unexpected pt arrive (must put people in diary!)

This sounds interesting. Discuss.

Regards
Robert

[robertisaacs]

Ian said on another thread

1. How far below neutral might be considered normal?
2. If the foot exhibits its usual MTJ in-roll as part of a shock absorbing mechanism how much in-roll do we regard to be acceptable and "normal"? (or why do we need it on a regular surface any way? I can argue reasons but not at this point).

and

More recently I have come to value a view that it is not so much that the foot has not evolved to walk on our regular surfaces, indeed surfaces may only be indirectly relevant anyway.

Rather the foot never completed its evolutionary process (and may now never complete it) and instead became a genetically variable structure.

If this is the case (arguable) then it may mean that the foot could be considered unsuitable for over use on any surface but possibly the more natural surface is closest to it multifunction ability.

Therefore could we argue that the foot itself, by its uncompleted evolution, is predisposed to pronation at a level and at specific joints that long term is detrimental?

Brian said

They suggested that normal pronation is simply the result of the transverse plane oscillations of the hip. The greater the arch of pelvic rotation, the greater the range of foot pronation (and supination). If one accepts their definition of normal pronation, as I do, the definition of abnormal pronation becomes self evident, that is, any foot pronation that occurs when the pelvis is directing that foot to supinate. That is abnormal pronation is not defined in terms of the amount of pronation, abnormal pronation is defined in terms of TIMING.

dave described pathological pronation (which may or may not be the same as abnormal pronation) as

1) Pronation Moments (or torque) produced by GRF that are resisted by soft or osseous tissues where the force required in those tissues to produce supination moments or torque is enough to cause trauma.

and

Normal is when a person is happy with the way they are. Normal is in the eye of the beholder one might say. Certainly 'Normal' is a state of mind and not a definable physiological condition.

With true post modernist flare we all seem to be moving away from the concept of "normal" foot position and "abnormal" foot position in the traditional sense.

However we all issue orthotics to people we consider to have pathological function (usually, though not always, pronation). Sometime even when they have no symptoms (and therefor lie outside of daves rather excellant tissue stress definition) we decide we don't like how they function and seek to change it.

Are we simply considering the two positions to be two flavours of "normal" Good COP and Bad COP (assuming you have an f scan )

Are we, as Ian suggests looking at inversion in the MTJ rather than rearfoot inversion as an indicator of "abnormal function".

Basically what i am asking is if we discard the concepts of "normal" or "Acceptable" foot function with what do we replace it?

Regards
Robert

[TimVS]

Before things get too technical, I'll stick my oar in. The difficulty with normal and abnormal is that it seems clear that people can and do walk around (and run) on what would be traditionally classified as an 'abnormal foot'. So then surely the only conclusion is that for that person that foot is normal. Now I know I may be setting myself up for a fall here as I did argue in another thread for treating the asymptomatic paediatric flat foot to prevent potential problems ocurring. But I think the essential difference is that the child is an unknown quantity with plenty of growth and development still to occur. Who knows what may (or may not) happen if we do not intervene. But an adult with an 'abnormal' foot and no symptoms has a fully developed musculoskeletal system and has probably been so for years, so then what is the justification? Perhaps the answer could lie in the decreased metabolic efficiency of an 'unbalanced' gait, but other than at athletic level, is that relevant here? So in summary to all that waffle, I prefer to classify as 'likely or unlikely to cause pathology', rather than normal or abnormal. Not so succinct, but a working definition maybe?

Your service

[rothbart]

Please understand I define abnormal pronation from the neurobiomechist (Posturology) paradigm very different from the biomechanist (Rootian) paradigm. Having said that, here goes:

I realize that I have posted this before, but I feel it needs to be repeated. I define abnormal pronation in terms of timing, not degree. For example, if the right foot is pronating when the pelvis is rotating clockwise, that is, by the neurobiomechanist definitioin, abnormal pronation.

Why do we Posturologist pay so much attention to abnormal pronation? Because if the foot deviates from the influence of hip drive (foot motion directed by the transverse rotations of the pelvis), the PATTERN OF FIRING OF THE MECHANICAL RECEPTORS IN THE BOTTOM OF THE FOOT ARE DISTORTED. The cerebellum, receiving this distorted signal from the feet, distorts the body’s posture. One of the central paradigms in Posturology, is the link between postural distortions and the development of chronic pain.

Prof B

[dtt]

Hi Tim

I prefer to classify as 'likely or unlikely to cause pathology', rather than normal or abnormal. Not so succinct, but a working definition maybe?

100% agree

If the patient is Asymptomatic then for that patient irrespective of the "recognized abnormal foot pathology" then:

put another way

" if it ain't broke DON'T MEND IT"

Just my thoughts

Cheers
Derek

[robertisaacs]

I prefer to classify as 'likely or unlikely to cause pathology', rather than normal or abnormal. Not so succinct, but a working definition maybe?

A useful definition. But are we arguing semantics here?

The definition you have offered, whilst i wholeheartedly agree begs another question. That being "how do you decide whether it is likely of unlikely to cause pathology?

This question, for me, has two elements. Theres the amount of stress which will be exerted on the tissue and the threshold of thee tissue to absorb that stress without becoming pathological. The latter, certainly, has less to do with foot function and more to do with the more holistic (hate that word) status of the patient. The former is very much tied to the function of the foot.

For example. Patient comes to you with pancake feet with little or no mid tarsal stability, weight bearing navicular, medial heel strike, stj relying entirely on deltoid ligament, little or no tibialis function etc etc... but no present pain or symptoms. I suspect most of us would consider that likely to cause pathology and treat it accordingly.

But why? What was your criteria for thinking that it would cause pathology? Was it not the degree of deformity? And if you are considering the degree of a deformity you need a baseline of some description do you not? You might not call that "normal" or "optimum" but is that not what it actually is?

How many legs does a dog have if you call the tail a leg?

Regards
Robert

[Admin]

Could be defined as:

That which provides asymptomatic, non-pathological bi-pedal support/ambulation on a variety of surfaces, at a variety of speeds, coupled with the ability to carry a variety of loads.

[robertisaacs]

That which provides asymptomatic, non-pathological be-pedal support/ambulation on a variety of surfaces, at a variety of speeds, coupled with the ability to carry a variety of loads.

;D
snappy!

Still has a kinda circular nature to it. What is normal? That which is non pathological.

And what is pathological?

Etymology
From Ancient Greek ðÜèïò (pathos), “‘suffering’”) and -ëïãßá (-logia), “‘study of’”).
[edit] Noun
Singular
pathology
Plural
pathologies
pathology (plural pathologies)
(medicine) The branch of medicine concerned with the study of the nature of disease and its causes, processes, development, and consequences.
[glow=red,2,300]Any deviation from a healthy or normal condition; abnormality[/glow].

That which is abnormal.

Got to see the funny side ;D

Regards
Robert

[TimVS]

This has turned into one of those eternal semantics debates..........which is a lot more fun than EBM any day, so:

"any deviation from normal or healthy condition"

That of course would be 'accepted norms', which change of course. Healthy is probably a bit easier, so perhaps abnormal as in possibly leading to a detrimental effect in the individual's health if left untreated?

Define normal - opposite to abnormal. Define healthy - opposite to unhealthy, define unhealthy...da da da da da da da da - - name that tune

Time for bed said Zebedee

[Admin]

OK, I've altered my definition ;D.

That which provides asymptomatic bi-pedal support/ambulation on a variety of surfaces, at a variety of speeds, coupled with the ability to carry a variety of loads.

I've taken out non-pathological, since wear and tear is bound to happen - happens to us all, some joints sooner than others.

The other parts of my definition are important (IMO) and are the ones usually left out when anyone tries to define normal foot function.

I don't think there's much to disagree with there now?

[rothbart]

Very interesting exchange of concepts. What has become very clear to me is that the basic paradigms of Posturology and Biomechanics are like oil and water, they just do not mix.
What I define as abnormal foot motion is tied intimately into the hip drive theory first proposed (I believe) by Inman and Close.
What many Podiatrists define as abnormal pronation is tied to the earlier work of Root. Two very different points of view.
What one cannot logically do is combine or compare the concepts of abnormal foot motion to abnormal pronation, because the concepts come from two different worlds of thought.

Hope this helps.

Prof B

[robertisaacs]

OK, I've altered my definition .

That which provides asymptomatic bi-pedal support/ambulation on a variety of surfaces, at a variety of speeds, coupled with the ability to carry a variety of loads.

I've taken out non-pathological, since wear and tear is bound to happen - happens to us all, some joints sooner than others.

The other parts of my definition are important (IMO) and are the ones usually left out when anyone tries to define normal foot function.

I don't think there's much to disagree with there now?

Never fear, i'm sure we could come up with something! Just for fun.

I like the "other bits". As you say they do get forgotton. And i am SO looking forward to discussing "flat earth" next month.

I'm still not sure that your definition incorperates our pancake footed pain free friend.

I'm a little surprised nobody has said "ok smart****" whats YOUR definition then.

This month i think of normality or abnormality in terms of efficiency. Or more precisely, inefficiency.

If i was going to try to define normal function it would probably be based on the following.

"Function which is asymptomatic. Function which balances tissue stress loads in an efficient way between the structures capable of performing their tasks both between limbs and within the limb. "

The first bit i think is self evident. The second bit reflects a lot of tissue stress theory. If a function is inefficient then it increases tissue stress on the disadvantaged structure. Doubly so when you throw davids variety of speeds/loads in to the mix.

So for example a foot with poor tibialis group function might apply more load to the PF to control the position of the foot. A foot with an ineffective PF might pass the load along to the deltoid ligament, or even compression of the sinus tarsi.

If the patient has low tissue stress thresholds i might use orthotics to control a function only very slightly "abnormal"(inefficient). In a patient with a high tissue stress threshold inefficiency can be more easily "absorbed.

I look forward to your comments. I shall be terminally disappointed if somebody does'nt tear me apart. ;D

Regards
Robert

PS
Reading this back i've just realised what a communist view of physiology this is! All structures should carry out an honest days work for an honest days metabolites! The Structures control the means of locomotion. Only when the fascist borgeois structures stop working and exploit the prolotariat structures does pathology occur! They will rise (swell) up and throw off their oppression. Long live the peoples republic of the foot.

Go spuds

[Admin]

Hi Robert,
You said (much cut):
"I'm still not sure that your definition incorperates our pancake footed pain free friend."

Yes it does! ;D ;D.

I haven't mentioned arch height or foot shape or overpronation or anything....... .

[robertisaacs]

Very interesting exchange of concepts. What has become very clear to me is that the basic paradigms of Posturology and Biomechanics are like oil and water, they just do not mix.
What I define as abnormal foot motion is tied intimately into the hip drive theory first proposed (I believe) by Inman and Close.
What many Podiatrists define as abnormal pronation is tied to the earlier work of Root. Two very different points of view.
What one cannot logically do is combine or compare the concepts of abnormal foot motion to abnormal pronation, because the concepts come from two different worlds of thought.

Hope this helps.

Prof B

Hey brian. Sorry i did not reply to your last.

Oil and water you say? Possibly. But thats basically what milk is so lets see if we can't emulsify a little here you and I.

The aspect of timing is one which is often neglected. I suspect that is because it is so much easier to analyse static function than dynamic. Whether we like it or not most of us struggle to escape that mindset.

I think you might well be on to something there. I'll be honest i'm not particularly knowledgable about the hip drive you speak of. It sounds interesting, i might have to chase a few references there when i finish my present reading.

I do have an issue with the idea that "abnormal" or pathological is entirly a matter of timing and not degree. There is a proven (sorry, strongly indicated) reality that the more pronated a foot becomes the less efficiently much of the musculature functions. There is also a pretty solid model for increased tissue stress in assorted structures in feet which pronate to an excessive degree (achillies tendon unilateral loading for eg).

In cases of late stance phase pronation i wonder how many feet remain pronated too long because the stimulation to the muscles to recover the foot never happens and how much is because the stimulation happens... but the tibialis muscles are functioning too close to the STA to have the desired effect (ie the efficiency is reduced to the point of ineffectiveness).

I think the two world you speak of probably do combine. Unless one (or both) is completely falacious they must!. As i say i know little of the hip drive but the biomechanics model you call root (which i would define more as tissue stress / axis and levers) has some pretty visible manifestations.

The search for truth is sponsered by Neurofen. I swear its out there but its a swine to untangle.

I'm sure this will be continued...

Regards
Robert

[TimVS]

And of course we musn't forget good old Gluteus Medius - mine are terrible.

I like efficiency and inefficiency too. Like I said in an earlier thread - oo, that rhymes - it's possibly more relevant in the athlete where increased oxygen uptake due to inefficient gait could knock fractions off their time, but for the average person the cumulative effect over time might be worth considering...?

Has anyone ever done any research on incresed o2 demand resulting from abnormal gait, sorry, inefficient, no sorry, unbalanced, no wait a minute, assymetrical, erm, pathological, er um, AH! 'Wonky' that's it!