Things which can cause pathological Pronation

[robertisaacs]

Thought i'd share this with y'all

As a CPD exercise the other day we tried to make a list of all the things which can cause excessive / pathological pronation (I can't use the Ov*********on word. It brings me out in hives).

How many have we missed?

Obesity

Ligamentous Hypermobile Sub talar joint (decreases effect of Sinus tarsi)

Short Calves

Short stride length

Abducted gait

Hypertonic peroneals

Tibialis Anterior function transfer

Extensor substitution

Bony deformity it STJ

Uneven ground (ie worn shoes,)

Orthotics

Frontal or Transverse planal doninance

Decreased Tibialis group power

Decreased Tibialis group stimulation

Delayed tibialis function

Hypermobile Mid tarsal joint

Long Planter fascia

Forefoot supinatus / varus

Structural HL / HR leading to failure of the windlass mechanism

Stretched / ruptured deltoid ligament

Shortened 1st met

Poor intermetatarsal stability => dorsiflexed 1st ray

Increased tibial varum

Deliberate / antalgic gait modification

Midfoot amputation

Regards
Robert

[Admin]

Hi Robert,
How about all those hard, flat surfaces we walk and stand on in the West for over 90% of the time?

Don't buy into the Greys Anatomy foot model - it was first propounded in 1857 and hasn't. as far as I know, been changed. It would seem that that's the one Root et al based their (now largely discredited) criteria of normalcy on.

Look instead at the correlation between STJ neutral and inversion (ie stick any foot into STJ neutral and it will invert). To move into plantigrade it must evert - in many cases moving into (here's that word ) overpronation - a state which simply would not happen nearly so often on uneven or soft surfaces.

You'll have read this on Pod-arena a million times (mostly posted by me ;D) - there is absolutely no evidence we have evolved for life on a hard and flat surface. I contend that these surfaces have much to do with the day-to-day biomech dysfunction and symptomology we are presented with.

Cheers,

[robertisaacs]

YOU SAID THE WORD!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! DON'T SAY THE WORD!!!!!!!!!!!!!!!!!!!!!!!(thrashes on floor, frothing at mouth and screeching like a banshee). Over WHAT exactly?!?!

Oh never mind.

I have indeed considered your "flat earth" (sorry, could'nt resist) theory before. In fact i was toying with the idea of doing a thread to discuss it. Thanks for saving me the bother.

The fact that most feet, in neutral, invert somewhat is something i also have observed. This does mean that as you say almost all (non pathological) feet evert somewhat on passive WB. I beleive The good prof kirby stated in biomechanics of the normal and abnormal foot that a "typical" position for static WB is 3 degrees or so off maximally pronated. I would tend to agree and add that i have found the rough "average" foot to be approx 10 degrees inverted in neutral. Thats certainly what i tell the hoards of non pathological and asymptomatic people who come in convinced they "O*******e because look my ankles roll in!"

However can this be said to be O**********n? I strikes me that in the natural state we find more uneven ground than soft meaning that it is as likely to evert the foot as invert it.

Also assuming that the ST/MT complex is designed as a shock absorber as well as an adaptor one's foot would need to be slightly pronated at loading in order that the foot should pronate appropriatly. If it was plantergrade with the foot in neutral the lever arm would be zero and there would be no impetus to pronate. It would also be as likely to invert as evert and as we know the invertory range is not equipped to decellerate body mass (as anyone who has had an inversion sprain will attest to their sorrow).

It also raises an interesting question about what criteria we apply to normalcy. If we ALL have feet which are inverted in Neutral can it be said to be a precursor to Patholgical pronation? One could say that people with knees pronate more, its just as true. Can we apply a "norm" which has not, for most of us, existed for thousands of years?

So is our Inverted foot position (or everted ground position if you prefer, amounts to the same thing) a precursor to pathological pronation, or simply a mechanism which allows normal, healthy, functional pronation and therefor by inference also permits... the other sort.

Interesting stuff. Good to mull.

Regards
Robert

[TimVS]

Also assuming that the ST/MT complex is designed as a shock absorber as well as an adaptor one's foot would need to be slightly pronated at loading in order that the foot should pronate appropriatly. If it was plantergrade with the foot in neutral the lever arm would be zero and there would be no impetus to pronate. It would also be as likely to invert as evert and as we know the invertory range is not equipped to decellerate body mass (as anyone who has had an inversion sprain will attest to their sorrow).

OK, it's Friday, but you've lost me I was with you with the rest. Please elucidate, expand, or whatever.

HAV (he he) a nice weekend

[ianl]

Hi Rob

How about ethnicity. One of the folks on my degree course did a study on foot posture and ethnicity and found a significant difference between ethnic groups and foot posture.

Slightly off tack but still relevant, I hope.
One of the things that brought David and I together for a while was a view that if you take the view that feet in NWB neutral exhibit inversion and that it is common to experience further inversion still in the forefoot in relation to the rear, and that this could, arguably, be considered"normal" Caucasian foot in that it is the most common NWB position I see, then for the foot to work on the regular surface we have it must work in a pronated position. (That plus the view that we thought orthotic intervention can generally be simply than we often are led to believe).

Now I do not have a problem with this. That the foot works below neutral in a pronated position is to my mind normal. (Whatever our view about neutral it still provides a starting point . Yet if the foot functions below it as normal why do we give it any significance anyway?

The questions that might arise then may be:

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).

Any answer to these may well be considered arbitrary not least because there are likely proximal influences on foot function as well so the whole thing becomes a hugely circular argument that even with the arguments on Pod Arena do not seem to square. The one thing in podiatric biomechanics that seems to have agreement is that it is forces and not motion.
(you could argue that the Windlass is not so important on some surfaces)

Now the view that the foot has not evolved to walk predominantly on our regular flat can be argued against by suggesting we walk in footwear etc or that the pavements over a distance exhibit different camber but none of these actually match the variable surface of natural terrain with its more common, frequent but subtle undulations.

You could argue that looking in a shoe will show indentation in the liner over time and that this makes for variation but it does not, I would suggest it is an indentation from repeated use and that these indentations then become the environment in which the foot seems to predominantly operate in.

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?

If the above is a load of rambling Bo****ks my apologies especially as I can blow holes in it myself and others have given it a hammering any way, but I needed something to do when I got up earlier this morning.

Cheers
Ian

[Admin]

Hi everyone,
This pretty much encapsulates my "flat earth" theory (like it! ;D).

A healthy hominid foot is capable of adapting to whatever surface it has to. This was true 1.6 million years ago, and is true today.

It is capable of both slow and rapid ambulation, or simple support, on a variety of surfaces, carrying a variety of bodyweight/load.

It was never designed to last75/80 years (or whatever our current average lifespan is in the West.

It was never designed to be used shod, or on one surface for most of the time.

Given time, it will adapt to one surface, but to the detriment of other joints, and movement on other surfaces (aquired Pes Planus is one example).

That's my research MSc Thesis - but bioled down a bit!
;D ;D ;D

[rothbart]

The question that still needs to be answered is: What is abnormal pronation?

This was a question looked at with great interest at the Istituto Superiore di Sanita (the premier research facility in Italy). I suggested that first one has to define what is Normal pronation. This discussion took us to the work of Inman and Close, done during the 1940s at University Hospital in San Francisco. 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.

Prof B

[Admin]

Hi Brian,

I agree with the gist of your post, with the caveat that the amount of pronation is pretty much dependant upon the supporting surface (whether hard and flat or irregular and soft), and whether the foot is shod or not.

It may seem I'm talking semantics but these two factors, whilst influencing the gait of most of us on a day-to-day basis, are missed out of pretty much all the gait studies I've looked at - these are usually done barefoot in a gait lab (which generally has a uniformly hard, flat surface).

[deekay38]

Robert

Things that cause pathological pronation (in the closed kinetic chain during the stance phase of gait)

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.

That's it there are no more. All those things on your list Robert have a possible correlative relation ship to the above but do not necessarily lead to pronation at all and certainly not pathological pronation.

It is often taught that there is a balance of moments and when the balance is not in equilibrium then there is motion or a tendency to motion in the direction of those positively balanced moments and that that motion causes pathology when it is too great.

This is not so and is only a aid to understanding the action of forces about a fulcrum. Like saying electricity flows from positive to negative - its a nice concept that allows useful understanding of the nature of electricity but it is not strictly true.

In the balance of moments there IS ALWAYS EQULIBRIUM in any structure or mechanism.

So when you have 'x' moments on one side of a lever system there will be exactely the same magnitude of moments on the other side. In the foot and the STJ in particular the FORCE that produces supination moments that balance pronation moments produced by ground reaction FORCE may come from many sources EG the ground, the shoe, the orthosis and of course the TISSUES of the foot. If the it is the former that produce the FORCE to produce supination moments then everythig is probably OK in terms of tissue trauma. If the tissues of the foot are the main source of the FORCE resisting pronation then it is more likely, but not necessaryily so, that this will lead to trauma in those tissues.
Only if those forces are high enough to produce internal stress that is pathological either in the short term or the long term.

what do you say?

Cheers Dave Smith

[deekay38]

Robert

Just to carry on from my last post.

The point of students understanding the tissue stress model is that there is no need to learn and remember all the possible scenario's that are supposed to cause a certain tissue trauma.
IE as in your list. A list such as that could go on for ever and still not contain the scenario that applies to a particular patient of interest. Either that or the scenario is not apparent to the assessor. Indeed it would be entirely possible or even easy for a person to misinterpret the reason for a persons pathological condition based on the fact that they have some recognisable pre existing gait variation that is a list that say's this is pathological.

Understanding Anatomy and applying engineering principles IE Biomechanics will, overall, be more reliable and consistent than applying treatment paradigmes. (Where paradigm in terms of the clinical application means - lists of conditions or variations with corresponding lists of treatment or interventions IE in the form of - If A, then B)

Having said that it may be that such lists are useful in the initial stages but a student should eventually be able to evaluate a patient and analyse the tissue stress problem based on biomechanical principles.


Cheers Dave

[deekay38]

Dr Rothbart

Quote
"The question that still needs to be answered is: What is abnormal pronation?"

Why?
Abnormal for one person is not abnormal for another so we can't have a reliable definition. Statistically we can have Normal and Abnormal or a Mean and sd. That's fine for statisticians but statistics do not apply to an individual and that is who we deal with as clinicians. What is an abnormal shoe size for a white Male? n = 1000 Mean = size 9 sd = +/- 2 sizes. Our patient has size 14 feet is he abnormal?

Quote
"They suggested that normal pronation is simply the result of the transverse plane oscillations of the hip. "

Could you clarify "transverse plane oscillations" please ?

Quote
"The greater the arch of pelvic rotation, the greater the range of foot pronation (and supination)."

Whart is an "Arch of pelvic rotation" ? what is it relative to?

Quote
"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."

So - if I am walking on a surface with a camber that is perpendicular to the axis of the STJ IE it causes my foot to continually pronate, then this is abnormal since my "Arch of Pelvic Rotation" tend to make the STJ supinate at some point in time but it in fact remains pronated.

If I walk on a flat surface and my "Arch of Pelvic rotations" make my STJ pronate and supinate at the correct time but I still get pathology IE pain then by your definition this is still normal.

This is a statistical definition again.

Defining 'Normal' is, in my opinion, over rated . There is no real normal, it just the way it is and how we change the way it is, if we wish, when there is pathology.

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.

If I can make a person happy with the way they are then that is normal enough for them and me. I am not concerened about the timing of thier STJ oscillations relative to their Pelvic Arch oscillations or anything else that defines them as normal.
Usually this means reducing tissue stress. Sometimes it means changing their gait so that it feels or appears more 'Normal' to themselves or some concerened thrid party. (Ethical issues)


Sincerely Dave Smith

[dtt]

Hi Robert , Dave , Davidh, et al

Also assuming that the ST/MT complex is designed as a shock absorber as well as an adaptor one's foot would need to be slightly pronated at loading in order that the foot should pronate appropriatly. If it was plantergrade with the foot in neutral the lever arm would be zero and there would be no impetus to pronate. It would also be as likely to invert as evert and as we know the invertory range is not equipped to decellerate body mass (as anyone who has had an inversion sprain will attest to their sorrow).

So put simply ( the only way I know how sorry) you are talking about the pronation of the calcaneum at initial contact causing the MTJ to unlock to move the foot into pronation (ok so far ?)

But if you plantarflex the foot you neutralise the eversion of the calcaneum to stj neutral thereby stopping the locking of the MTJ to provide the rigid lever to the propulsive phase ?? ( just so I have got my understanding right?)

So

Defining 'Normal' is, in my opinion, over rated . There is no real normal, it just the way it is and how we change the way it is, if we wish, when there is pathology.

Goes back to my 3 lever theory, if you take the calcaneum mid tarsal ,1st ray /mtj as the basis for a "normal" motion moving in a sagittal plane ( AS A BASIS) the variation from the "norm" can then be evaluated TO SUIT THE PATIENT PRESENTATION AND TOLLERANCE.

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.

I couldn't agree more Dave every patient is an individual not a text book "statue"

Usually this means reducing tissue stress. Sometimes it means changing their gait so that it feels or appears more 'Normal' to themselves or some concerned thrid party

And when you have said and done all unless the biomx are correct (to suit the patient not the text book) the end product is useless so perhaps, are we being TOO RIGID with our application ??

Just my thoughts

Cheers

Derek

[robertisaacs]

;D
This is great, we've got a model each!!!

Tim

The point i was making, very inarticulatly is that the foot has to start with the axis one side of the midline for pronation to work.

Get a door. Open it 90 degrees then push directly into the hinge. It don;t move. Now close it by about 10 degrees and push at the same angle. Now it moves.

Any clearer?

Dave
Glad to have you here buddy.
Whilst i hesitate to disagree with a mind of your calibre (ie understands properly how vectors work), i fear i must.


You said

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.

Thats a nice definition. I'm stealing that one. However i have a few problems with it.
1. from a pedantic viewpoint it excludes pronation caused by hypertonic peroneals. So ner.

2. In essence this definition is a better version of the question rather than the answer. I agree that the cause of pronation... is pronation moments. However this is somewhat tautological. I was looking for a list of factors / scenarios which might cause this state of affairs.

All those things on your list Robert have a possible correlative relation ship to the above but do not necessarily lead to pronation at all and certainly not pathological pronation.

Correct. Which is why i was very careful to say that this was a list of things which CAN cause excessive / pathological pronation.

IE as in your list. A list such as that could go on for ever and still not contain the scenario that applies to a particular patient of interest. Either that or the scenario is not apparent to the assessor. Indeed it would be entirely possible or even easy for a person to misinterpret the reason for a persons pathological condition based on the fact that they have some recognisable pre existing gait variation that is a list that say's this is pathological.

Understanding Anatomy and applying engineering principles IE Biomechanics will, overall, be more reliable and consistent than applying treatment paradigmes. (Where paradigm in terms of the clinical application means - lists of conditions or variations with corresponding lists of treatment or interventions IE in the form of - If A, then B)

Having said that it may be that such lists are useful in the initial stages but a student should eventually be able to evaluate a patient and analyse the tissue stress problem based on biomechanical principles.

I entirely agree that no such list could ever be viewed as a "treatment flowchart". As you say the best way to view biomechanics is the more "freeform" approach based on engineering. However as an intellectual exercise i found the list stimulating.

Pleasure to chew the cud with you Dave

Regards
Robert

[robertisaacs]

Brian

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.

Not sure i see that. I think any definition of abnormal pronation must include elements of timing, degree, duration, and kinetics.

Its a whole other question as to whether or not Abnormal pronation is the same as pathological pronation, however i have to say i rather like Dave's definition.

Regards
Robert

[rothbart]

Dave,

You suggest that it may not be important to know exactly what is abnormal Pronation. When I wear my clinician’s hat, I absolutely agree with you, knowing the definition of abnormal pronation does not necessary improve the quality of care that I provide for my patients. However, when I wear my researcher’s hat, knowing the definition of abnormal Pronation, first necessitates knowing the definition of normal Pronation. And I would suggest, more effective therapeutic regimens are established when we understand the root cause of the pathology (e.g., how it deviates from normal).

Transverse (horizontal) plane oscillations of the pelvis refer to the repetitive clockwise – counterclockwise rotation of the pelvis that occurs during gait. When the calcaneus is weight bearing (e.g., on the ground), clockwise rotation of the pelvis will pronate the left foot and supinate the right foot. Counterclockwise rotation of the pelvis will supinate the left foot and pronate the right foot. (Wright DG., Desai SM., et al 1964. Action of the subtalar and ankle-joint complex during stance phase of walking. J. Bone Joint Surg. 46-A:361). When the heel rises off the ground, Hick’s Windlass effect will maintain the foot (more or less) in the position just preceding heel lift (Hicks JH 1954. The mechanics of the foot. II. The plantar aponeurosis and the arch. J Anat. 88:25). On my website, are animations demonstrating the pelvic oscillations of the pelvis driving the motion within the subtalar drive (normal) www.rothbartsfoot.info/NormalPronation.html and (abnormal) www.rothbartsfoot.info/NormVsAbnorPron.html

“What is an "Arch of pelvic rotation"? What is it relative to?

I coined the term Arch of Pelvic Rotation to describe the repetitive transverse plane oscillations of the hip during gait. The pelvis rotates as a unit, first counterclockwise (if you start walking with your right foot) and then clockwise. It continues this rotation until you stop walking. If you graph this motion on paper, it follows the course of an arc (a segment of a circle) – hence the term Arch of Pelvic Rotation. The significance of this rotation, I described above.

“So - if I am walking on a surface with a camber that is perpendicular to the axis of the STJ IE it causes my foot to continually pronate, then this is abnormal since my "Arch of Pelvic Rotation" tend to make the STJ supinate at some point in time but it in fact remains pronated.”

A surface with a camber does not change the direction of the pelvic rotations. Pelvic rotation is the result of the alternate swinging of the legs forward. That is when the right leg is swung forward, the pelvis rotates counterclockwise, when the left leg is swung forward, the pelvis rotates clockwise. As you can see, this has very little to do with the geometry of the surface you are walking on.

“If I can make a person happy with the way they are then that is normal enough for them and me. I am not concerened about the timing of thier STJ oscillations relative to their Pelvic Arch oscillations or anything else that defines them as normal.”

Again, Dave, I agree with you wholeheartedly if I am wearing my clinician’s hat. But as a researcher, we are daily involved with the definition and quantification of what is normal, and therefore, what is abnormal. We spend many hours investigating the function of the human body, using randomized, double blind studies, to report our findings in a way we feel is scientifically valid. We tend to dismiss subjective outcomes as being unscientific, and stress the importance of validating objective outcomes.

So, the question at the end of the day is, who is right – the clinician or the researcher. In my humble opinion, I say ‘bravi’ to both. Subjective outcomes (how the patient responds to specific therapies) are important because if the therapy doesn't work, the clinician is not going to use it! And, it is the primary responsibility of the clinician to try to help everyone that walks through their front door. They do not choose their patients as the researcher does when establishing which subjects are included or not included (e.g., criterions) for a specific investigation.

Objective outcomes are also important, because how are we going to expand our understanding on how the human body functions without meticulous orchestrated research, using the prevailing scientific protocols that have been established by our peers.

Regard,
Prof B