The Other Proprioceptive Medicine

Tom,

As podiatrists we see descending rather than ascending pathology. When we talk about proprioception, this is only one part of a larger picture. Functionally, we are concerned about not falling over, hence the righting reflexes. For this to function properly, we have to have proprioception in the form of the visual righting reflex (a very primitive reflex from the fishes), the labyrinth system, and the cervical righting reflex. They work together with the proprioceptors of the foot. A deficiency in this can cause a postural distortion with foot ramifications.

Here are a few references I hope will help you.
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1309161
http://members.aol.com/gaknutson/Mechanism.html
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1275544
http://jp.physoc.org/cgi/reprint/312/1/115.pdf
http://jdr.iadrjournals.org/cgi/reprint/52/4/668.pdf

By the way, it might be easier to teach soft tissue work instead of manipulations. (For instance working on the posterior talo calcaneal ligament for a posterior calcaneus).
Also, why stop at T12. If you look at disturbances in the righting reflexes, you will start to see that problems come from higher up.

Regards,

Stanley

 

David:

Welcome to Podiatry Arena! You finally made it.

My, my....from reading your comments above.....you sure will do well on this forum....I like your style. Looks like you could become one of the better contributors. Good to have a DC with good common sense weighing in on a regular basis.

Now, on to another subject, what do you think of Sole Supports and their marketing program?? I know you do have some opinions.:drinks

 

Kevin,

Thank you for the warm welcome and encouragement. I should probably reveal some background about myself and my practice since your colleagues are not familiar with me.

I am a DC and a Cped practicing in Costa Mesa, CA. My interest in the foot & ankle began due to my own dissatisfaction in the prevailing level of service my colleagues as a whole provide with regard to foot orthoses. Chiropractors are marketed to very heavily by Foot Levelers while in their clinic, they even provide us a free pair of their 'inserts' and accompanying marketing material. Their benevolence knows no bounds!

As a result of wearing their device I developed a chronic interdigital neuroma which persisted for a couple of years. My colleagues of course offered to manipulate my ailing foot, which did surprisingly offer some relief, albeit short lived. I surmised that my problem must be one that was indeed mechanical because of the relief I achieved with manipulation and from there I began reading everything that I could get my hands on about orthoses and searching for a better path.

I did try several OTC and custom devices and yet the problem persisted. At that time a friend was selling the Quasar pad and I bought one naively believing that I had finally come upon a device that would expedite professional orthotic dispensing and help me corner the market. I was disappointed in the results with my patients and found Dr. Thomas Michaud's book on foot orthoses. This book forever changed the way that I practice and opened the door to a whole different clinical perspective for me; the podiatric model of conservative foot management.

About four years ago that same old friend began distributing a device called ScanAny, an optical system capable of capturing the plantar foot in STJ neutral and I began to use that and experiment with plaster casts as well. The rest is history as they say, I took the Cped course and became the first chiropractor in the country to become a provider for the Medicare TSB as well.

Today I split my practice between my duties as a DC and providing orthoses for several local orthopedic surgeons patients (I'm still working on the podiatrists:bang. I am lucky to have met a DPM who has become my mentor and a good friend who will answer my questions (exhaustively), who has encouraged me along the way and who I feel truly represents the conservative biomechanical approach that is distinctly podiatry. He is also a member of this board, Ed Davis.

Enough about me other than to say that I am very committed to presenting to my colleagues that there are a lot of companies out there who market to DC's (and PT's, ATC's etc.) gimmicky products and systems that have no place in the care of the foot IMO. I would much prefer that they seek a higher level of prescribing or refer to your colleagues in the best interest of the patient.

This leads me to Kevin's question regarding Sole Supports. I have been in contact with their DC consultant Stu Currie. We have had a rather lengthy discussion about their devices, his explanation none of which I buy into. I see several flaws in their design and their marketing I personally find in poor taste. I also believe that they try to obfuscate the truth by misquoting the available research to suit their own purpose and blind the less knowledgeable with illusory science, graphs and logic. I know that I will soon be excoriated by one of their minions over this statement, I invite their comments and rebuttals and urge them to wake up and smell the burning toast:deadhorse:!

I hope that you all will allow me to tag along here on the board and contribute when I have something of value to offer. In the meantime I am trying to read and absorb as much as I possibly can. I have learned that when you come from a background such as mine you find the more that you know, the less that you really know and I am merely trying to increase my biomechanical knowledge and clinical acumen.

David G. Wedemeyer, D.C., C.Ped

 

David:

Good to hear your history. I am looking forward to your comments in the future.

 

First, We Must Define Proprioception!

Proprioceptors (excluding the vestibular system of the inner ear) are located in the joints, muscles, and tendons. They function in the coordination and control movements by monitoring both stationary position and the movement (kinesthesia) of body parts and relaying that information into the CNS. This information, often referred to as joint position sense, may be perceived consciously. The receptors involved with providing proprioception are the joint receptors, neuromuscular spindles, and Golgi tendon organs (neurotendinous spindles). In addition, it has been shown by Martin & Jessell, that for proprioception to be assessed completely, cutaneous mechanorecptors must also be involved.

 

Re: First, We Must Define Proprioception!

How can foot orthoses alter the effects of these proprioceptors, runningdoctor? In other words, how do foot orthoses alter proprioception, which I believe was Dr. Spooner's original question regarding the nature of how an orthosis can be called "proprioceptive". By the way, runningdoctor do you have a name??

 

Dear Simon

Proprioception: the awareness of position, movement, or balance of the body or any of its parts.

There appears to be a lack of research to show that functional orthotics change proprioception. One of my lecturers mentioned that proprioceptive changes could alter the firing timing of the leg muscles during the gait cycle. So far I cannot find any evidence of this. Perhaps you could help?

 

Dear Stanley

Thanks for the references. Firstly the Part 1 and Part 2 of the manipulation course for podiatrists goes to the knee (1) and T12 (2). The reason for the breakdown is for the podiatrists to develop manipulation skills and obtain insurance. Part 3 would be the thoracic and Part 4 would be the cervical, which is already written and for sale on http:www.brettom.com.

Improved proprioception through either prescription orthotics or manipulation is one of the benefits to minimise the risk benefit ratio of the treatment, which is part of the total quality agenda in the UK.

Regards and thanks

Tom Brett

PS I found this definition of proprioception quite interesting:

Proprioception.

It is not essential, however, that there should be a single, specific path*way for this activity. Rarely within the brain or nervous system does one area do one thing alone. It is possible that the sensory pathways for affective proprioception include the same large fibre sensory afferents that conduct information elaborated into movement and position sense. This information is likely to feed to the many subconscious motor programming areas including the cerebellum, and the sensorimotor cortex, as well as to areas which are involved in attention. It might also lead to those parts of the brain involved in affective perception.
Cole J Montero B (2005) Affective Proprioception. P 302.
Available from: http://www.janushead.org

 

Tom:

Very interesting website. Have you written anything that I can read in full without first having to buy it off of you??

I especially liked this piece off of your website:

Can't I also drink water through my mouth to rehydrate myself? I know it seems old-fashioned, to drink water through my mouth, and you don't need to buy an instructional booklet on how to do this properly, but we, as a species, have been rehydrating ourselves in this fashion quite comfortably for at least few millennia.

 

Everything on the web site is for sale and formally published with individual ISBN's, fully copyright, registered with the library of congress etc. It is my business, which I have developed since being hit in the back by a car in October 2006. Three cervical disc herniations, displaced cervical bodies and slight impingement of the spinal cord. I am not looking for sympathy but have had to cut down my clinic work load. A professional web site is also a way to manifest and repay the costs of my master degree in medical law. OK?

As far as the water is concerned it is not the method of entry but the timing. In short the water is taken enmasse with the gastrointestinal tract as empty as possible ie before breakfast. The quantity is as much good quality water as you can ingest. Wait and time the interval till you go for a leak. Good kidneys about twenty minutes. Over an hour and you have problems. Once you have given your system a good flush then regular small amounts during the day are all that is needed. That's the guts of the article, so no need to buy it. There are a few other items to make up the fee but most is printing binding and postage and the time to do it.

Regards

Tom Brett

 

Kevin,

By stimulation of cutaneous mechanorecptors.

If the proprioceptive system is malfunctioning because of repeated microtrauma associated with a mechanically malfunctioning foot (what mostly walks/limps into my office), an orthotic could be considered in an attempt to improve the mechanical efficiency of the supporting muscles (which lessens the irritation of the abnormally stressed joints) and to reestablish the normal progression of forces acting along the plantar foot. By improving the progression of forces, it is postulated that the orthotic acts to reeducate the central nervous system as to the ideal patterns for muscle recruitment. The efficacy of Orthotics in favorably stimulating proprioception was demonstrated by Novick and Kelley, as they noted orthotics that are able to decrease the range of calcaneal eversion during locomotion results from “improved tactile and proprioceptive feedback” during dynamic function.

Thanks,

Bob

Novick A, Kelly DL. Position and movement changes of the foot with orthotic intervention during the loading response of gait. J Ortho Sports Phys Ther 1990; 11(7): 301-312.

 

Bob:

Are you saying that foot orthoses work, then, by "stimulation of cutaneous mechanoreceptors"? You may want to check our discussion of this issue about 1.5 years ago titled Sensory Effects of Foot Orthoses. After reading this thread I think that you will find that very few people are in agreement with you. In addition, the available research does not support your opinions on this matter. Possibly you could provide us with some other research that shows that orthoses work "by stimulation of cutaneous mechanoreceptors".

Also, I have read the paper by Novick and Kelly and don't remember them showing that foot orthoses reduced calcaneal eversion by “improved tactile and proprioceptive feedback”. If I remember correctly, this 18 year old study suggested that orthoses may work to reduce calcaneal eversion by improved tactile and proprioceptive feedback, but this was only a guess of the authors. They produced no experimental support for their conjecture. Remember, there is a difference between an authors speculation as to why foot orthoses work and actually producing experimental evidence supporting their speculation as to how they work.

Furthermore, please provide reference(s) for your statement, "By improving the progression of forces, it is postulated that the orthotic acts to reeducate the central nervous system as to the ideal patterns for muscle recruitment." Is this "reeducation" of the CNS a permanent or temporary change? Again, I would prefer research evidence to support your arguments, not conjecture.

Have a nice weekend and welcome to Podiatry Arena.

 

There is evidence that EMG activity may be altered in response to foot orthoses. I don't recall the authors suggesting and/ or providing any evidence that this was due to proprioceptive changes though.

You should probably read: Kirby KA. Foot orthoses: therapeutic efficacy, theory and research evidence for their biomechanical effect. Foot Ankle Quarterly 18(2):49-57, 2006

One of the names often quoted in regard to "proprioception" and foot orthoses is Duncan. Duncan described tonic reflexes of the foot and developed foot orthoses designed to work on these reflexes in children with CP. David Pratt, a UK based bioengineer has done some research in this area:

DJ Pratt: Dynamic foot orthoses. Principles and application. J Am Podiatr Med Assoc 2000 90: 24-29

But this isn't proprioception, so perhaps it might be a good idea to ask your lecturer?

 

That paper sounds excellent thank you Simon.
Kevin, dont suppose its something you could pin a link for ?

Lawrence
Podiatrist, UK

 

Lawrence;

Send me your e-mail address and I'll attach the paper in a return e-mail.

 

That sounds like some made up mumbo jumbo than something with any scientific foundation.

They never showed that! There is nothing in their methodology and results that had anything to do with proprioception!

 

Since this thread is about “the other proprioceptive medicine” which is an inaccurate interpretation of Applied Kinesiology, it would make sense to give some of their findings about orthoses and balance and muscle testing.

The practitioners that I know who teach applied kinesiology find that improper orthoses will cause normal functioning muscles to become unable to respond properly to an increasing force. The rectus femoris is the common test muscle for this. I have personally used this test to check my orthoses years ago. By having the patient stand on one leg (with the patient leaning slightly backwards against a wall for support), if the rectus femoris tests “weak”, then the orthosis the patient is standing one is in need of modification.

A category II sacroiliac dysfunction is associated with a lateral sway in stance. Orthoses can reduce an anterior innominate, and hence a category II. Therefore, orthoses should be able to decrease lateral sway in select cases.

 

Dear Podiatry Arena members,

I have my first experience of being a member and want to say a big thank you to everyone, who took part. My first enquiry was for any research as to how an orthotic can influence proprioception. The answers succeeded in stimulating further searches and some appraisal of clinical observations and the development of those observations into full blown research. Some of the comments led me to consider AK, C1 / C2 subluxations, neuroscience and how some people view various items of research and relate it to what their original concepts were.

My special thanks to Stanley, the links showed another aspect of the intricacies of the CNS. More special thanks to Kevin Kirby, I hope you are doing the early morning flush and your kidneys are in good nick.

Finally I want to leave you with a clinical observation based on my martial arts training.

If you want to dislocate a joint, alter the line of natural firing of the muscles that govern the joint, because the pull exerted by the muscle is weakened. Try on a willing friend by medially rotating the arm at the wrist, step to the side and slightly to the back and tap the humeral head anteriorly. This misaligns the governing muscles and makes the joint unstable and relatively easy to dislocate. Then of course relocate the humeral head as quickly as possible before the law suit.

So simplify the basic concept and apply this observation to orthotics and manipulation and you have a simple hypothesis:

Orthotics and manipulation can increase muscle strength by realigning the line of muscle pull to the optimum position. This then affects the adjoining structures directly and through the CNS the remainder of the body.

Regards

Tom Brett

 

Nope. As foot orthoses can move osseous segments, they will move joint axes. As a result of that the lever arm that some tendons have to that joint will increase and in others the lever arm will decrease .... ie apparent muscle strength of some muscles will appear to decrease.

 

My kidneys and my ability to keep myself hydrated were doing just fine before you enlightened me of the ideas of Yogi Bear, I mean Yogi Bhajan, a few days ago.

I don't have a clue how anything you have said above has anything to do with either the current research on foot orthoses or our current understanding of how the body functions mechanically via central nervous system (CNS) control. The "line of muscle pull" is not altered by orthoses. In order to change the "line of muscle pull", you must do a tendon transfer surgery. Foot orthoses may, however, cause a change in spatial location of the axes of motion of certain joints which may then alter the moment arms about which muscles have available to produce moments in the foot and lower extremity. The CNS may also act to alter muscle firing patterns in reponse to a number of afferent stimuli of which "proprioception" is just one of many possibilities.

I just wish one of these "proprioception" orthosis theorists would give us some good data that made sense to support their contention that foot orthoses can somehow alter the ability of the proprioceptors or proprioceptive system to function more effectively. Until then, it's all snake oil to me.:drinks

 

What's the nature of your "full blown research"?

 

How about a patient with an ankle sprain? The lack of proprioception results in a chronic ankle sprain with subsequently more stress on the injured ligaments?

 

This discussion of the proprioceptive effect of foot orthoses is something that I come across frequently from Foot Levelers in one of our chiropractic newsletters. Not surprisingly you can find a number of particular labs touting “improved proprioceptive input” as a result of wearing their particular inserts. They even confuse the physical properties of balance with proprioception (I hope that we all agree that they are mutually exclusive):

http://findarticles.com/p/articles/mi_qa3987/is_/ai_n9150353

or confuse the two known organs that are the major sensory receptors mechanoreceptors and nociceptors (both of which are found in skin, muscles and joints) with the properties of proprioception.

http://www.ptproductsonline.com/issues/articles/2008-02_03.asp

This does not occur and is well documented in current neurology texts that clearly demonstrate this fact. Neither Principles of Neural Science (2,p342) or Guyton's Basic Neuroscience (3,p.103) use the word proprioceptor in their respective lists of sensory receptors.

Recall that proprioception generally refers to the perception of body position. Generally speaking, in order to perceive anything, some type of input is required. In the case of proprioception, it occurs in response to afferent input that is initiated in mechanoreceptors. Principles of Neural Science clearly states that proprioception occurs as a consequence of afferent input. To my understanding that would suggest that proprioception is a byproduct of unconscious afferent impulses and not a specific and separately identifiable sense produced from an as yet unidentified and separate organ of sense.

We are also told that mechanoreceptors are subserved by large diameter axons (A-beta or larger), and nociceptors are subserved by small diameter axons (A-delta or C). Three main types of peripheral receptors allow for proprioception to occur including: 1) mechanoreceptors in joint capsules, 2) mechanoreceptors known as muscle spindles, and 3) cutaneous mechanoreceptors (2,p.347). Clearly, it is mechanoreceptive input that results in the perception referred to as proprioception.

According to these authors mechanoreceptors can only sense mechanical deformation of the tissues in which they reside, and such stimulation ultimately results in proprioception. I propose that the property of propriocetion is then a complex of tissue mechanoreceptors, afferent pathways, the spinal cord, brain stem, cerebellum and cerebral cortex. The integrated function of all of these components results in the complex phenomena that we refer to as proprioception and it is not a specific and separately identifiable effect of one specific sense organ and pathway.

I also believe that nociception plays a more important and primary role in the effect and production of altered proprioceptive input. Mechanoreceptors are known not to respond to tissue damage stimuli and nociceptors are well documented as having this feature when you examine these texts. Mechanoreceptors can produce nociceptive input but this is a more central phenomenon and not a peripheral one.

Those of you espousing the improved proprioceptive input theory of orthoses are invited to read these texts and hopefully this will shed a more factual and evidence based knowledge of how proprioception actually occurs. I was never taught any of these theories in my neuroscience courses at Cleveland. It appears most of these theories are promulgated by extra-curricular programs that are searching for a method to explain their newfouond interest in neuroscience.

To answer Stanley’s question it is my belief that the altered proprioception (which is a real consequence of severe or chronic ankle sprain) is a result of nociceptive input from tissue deformation acting on the nociceptive system and not a direct “proprioceptive” consequence that occurs to an existing peripheral sensory organ known as the “proprioceptor”.

Regards

 

Dave,

Thank you for the excellent neurology course.

In 1955, Freeman in his classic article on articular deafferentiation, discussed the damage to the ligaments which first resulted in a loss of the mechanoreceptors in these ligaments. He advocated "balance excercises" to restore the stability of the ankle.

 

The sort of eg that I was refering to would be a "classical" overuse injury that usually responds to foot orthoses. Lets take plantar fasciitis as the eg; for an orthotic to work it has to reduce the mechanical loads in the injured tissue. If an orthotic does works via proprioception, how would that change mechanical loads in the tissue? If we "improve" "propriception" with the use of a foot orthotic, how have we reduced the mechanical load in the plantar fascia?

 

Stude DE, Brink DK. Effects of 9 holes of simulated golf and orthotic intervention on balance and proprioception in experienced golfers. J Manipulative Physiol Ther 1997;20:590-601.

Yes Kevin, I agree, there’s not much out there in regard to PCFOs and proprioception.

Although this trial uses a stock orthotic not molded to a positive mold and is typically taken off the shelf on the basis of measurements taken from a foot impression or the patient's shoe size. Nonetheless, if there are positive gains attained utilizing this particular “stock” orthotic, what does that say about a functional orthotic?

Given the current trends in the health care industry, it would be nice to know whether proprioception can be improved with either inexpensive stock orthotics—as opposed to having patients spend hundreds of dollars on true custom orthotics.

 

How did they measure proprioception?

 

Simon

Tim Pratt wrote something about full blown research

You replied

I would like to know the answer to that one too.igs:
Was it along the lines of dislocating you mates shoulder, selling him a link to a web site on medical law and seeing how long it took before there was a perception of a full blown law suit.

The null hypothesis being.

Mates recieving glenohumeral dislocation during full blown martial arts classes and wearing proprioceptive insoles dont sue as fast as those not wearing proprioceptive insoles and not attending martial arts classes.:dizzy:


Quote from a web site

:sinking:

Does this include if I use the Tim Pratt technique for shoulder dislocation on my mate at MMA tonight?


Who is Tim Pratt?:bang:

Send a crisp £20 note to me in Folkestone Kent and if you can prove you are an intrested party I'll send you a link to Lord Lucan and your £20 note will be cashed in for beer on Friday night.


Cheers LoL Dave:drinks

 

Craig,

What you originally wrote was:

I did a quick look on Google for some things that would help this discussion, and I found this article first:
http://www.podiatrytoday.com/article/6182
This is not plantar fasciitis, but you wouldn’t expect that to be the first condition that would be researched regarding proprioceptive dysfunction. If you wanted to do research on proprioceptive dysfunction you would do it on ankle sprains.

This article talks about the change in medial lateral sway:
http://cre.sagepub.com/cgi/content/abstract/18/6/624
Notice there is no change in AP sway. AP sway occurs with a Category I pelvic subluxation, which is not related to the foot.
I was curious how you would explain the change in medial lateral sway?

Regards.

Stanley

 

Why does the effect of foot orthotics in chronic lateral ankle instability have to be via proprioception; why can't the effect be totally mechanical by resisting a supinatory force?

Why does that have to be proprioception? Foot orthoses alter pressure on the plantar mechano-recptors creating an additional signal that the CNS can act on. Perhaps is how the orthoses influenced sway; BUT, that is an exteroceptive pathway and not proprioception.

If someone has pain from an excessive rearfoot pronatory force at the insertion of post tib muscle, who cares about AP sway .... they need a mechanical force applied to reduce that stress in the tissue.
If someone has a chronic lateral instability, they need a mechanical pronatory moment to counter the supinatory moment causing the lateral instability.

I have no doubt foot orthoses have sensory or neurophysiological effects; that has clearly been should in many sway and balance studies. BUT, if there is to be an improvement in symptoms the stress in the tissue needs to be reduced.

For eg: if someone does have pain at the insertion of the post tib muscle from excessive pronatory rearfoot forces, how will proprioception or sensory changes help that? Perhaps the orthotics provide an extra sensory signal for the CNS to act on to "correct" that excessive rearfoot pronation? How does it do that? Perhaps the gluteal muscles fire more to externally rotate the limb; or perhaps the post tib muscle fires more to supinate the foot ----- surely these are BAD things as they lead to increased muscle activity (one of them of the injured structure) and a greater gait inefficiency.

 

Why does the effect of foot orthotics in chronic lateral ankle instability have to be via proprioception; why can't the effect be totally mechanical by resisting a supinatory force?

Why does that have to be proprioception? Foot orthoses alter pressure on the plantar mechano-receptors by creating an additional signal that the CNS can act on. Perhaps this how the orthoses influenced sway; BUT, that is an exteroceptive pathway and not proprioception.

If someone has pain from an excessive rearfoot pronatory force at the insertion of post tib muscle, who cares about AP sway .... they need a mechanical force applied to reduce that stress in the tissue.
If someone has a chronic lateral instability, they need a mechanical pronatory moment to counter the supinatory moment causing the lateral instability.

I have no doubt foot orthoses have sensory or neurophysiological effects; that has clearly been should in many sway and balance studies. BUT, if there is to be an improvement in symptoms the stress in the tissue needs to be reduced.

For eg: if someone does have pain at the insertion of the post tib muscle from excessive pronatory rearfoot forces, how will proprioception or sensory changes help that? Perhaps the orthotics provide an extra sensory signal for the CNS to act on to "correct" that excessive rearfoot pronation? How does it do that? Perhaps the gluteal muscles fire more to externally rotate the limb; or perhaps the post tib muscle fires more to supinate the foot ----- surely these are BAD things as they lead to increased muscle activity (one of them being the injured structure) and a greater gait inefficiency.

 

Craig, in Dr. Richie’s article it says:
The authors concluded that medial posting of foot orthotics rather than lateral posting was the best way to achieve improvements of postural control. They speculated that the medial posting reduced pronation.12,13 This is the first suggestion that reducing foot pronation vial medial posting would help someone with lateral ankle instability. This suggestion runs contrary to the accepted notion that inversion instability is the dominant mechanical problem with ankle instability conditions.
This negates both your theories (that of a mechanical effect, and that of an exteroceptive pathway).

Craig, the more a foot pronates, the greater the pronatory moment. If there is a proprioceptive deficit, the muscle fires later, and the tension required to negate the pronation increases. So not only is tension in a muscle required, but when the tension is developed.
I don’t know how the orthoses cause the orthotics provide an extra sensory signal for the CNS to act on to "correct" that excessive rearfoot pronation, or whether it does it at all.

 

The article does point out some important things, but does not tie them together very well. I will try to tie them together.

There is more than one cause of lateral instability. (The paper points out some of the pathways one should consider when thinking about postural instability: proprioception, reaction time, reflexes and muscle strength.) However, the article does not address subtalar joint axis position and its relation to the two kinds of instability.

The first kind of instability is laterally deviated STJ axis. This is the foot with chronic sprains and very strong peroneals and weak supinators.

The second kind of instability is associated with sinus tarsi pain. Talliard ('82 I think) noted that people with sinus tarsi syndrome had decreased peroneal activity when walking. When sinus tarsi was anesthetized the same subjects had normal peronal EMG activity. I disagree with Talliard's explanation. My explanation is pain avoidance. It hurts when there is increased peroneal activity because this causes increased compressive forces in the floor of the sinus tarsi in the already maximally pronated foot. So, people with sinus tarsi pain inhibit their peroneal activity. So, when they walk on uneven terrain they have an increased peroneal reaction time because of the inhibition from pain avoidance. This inhibition is the cause of ankle instability seen with sinus tarsi syndrome.

In attempting to explain some of the studies the article http://www.podiatrytoday.com/article/6182
has some really tortured logic.

From the article

Lateral body sway over a fixed foot in single leg stance causes closed kinetic chain pronation of the rearfoot. A body “falling” laterally would need to fire the medial leg flexors (i.e. tibialis posterior, flexor digitorum longus and flexor hallucis longus) to pull the tibia medially over the fixed foot. If this does not occur, then further closed chain pronation of the rearfoot would use up all available range of motion of the subtalar joint and further lateral sway would force the foot and ankle into sudden inversion.
Pronated feet have used up all their available range of motion in the subtalar joint so lateral body sway will immediately force the ankle into inversion. Pronated feet will generally have their subtalar joints functioning at end range of motion. Joints at extremes of range of motion have been shown to have compromised proprioceptive input. This is why nearly all patients with advanced stage adult-acquired flatfoot will demonstrate significant balance deficits with clinical testing.​

Pronation causes supination????? :craig: (This one should be added to the list of things that we were taught in school that aren't really true. I do remember hearing this logic in podiatry school, but I thought that no one would believe me that it was actually taught.) I really don't see how the logic in the second paragraph above works.

Now you can explain the results of the studies sited much better with the sinus tarsi pain explanation of lateral instability. The study showed that medial posted orthoses improved postural sway more than laterally posted orthoses. It also showed that this effect was not immediated, but happened weeks later. This would certainly be true if the medially posted orthosis took time to relive the sinus tarsi pain. When the sinus tarsi no longer hurts, the peroneal activity would return to normal (less inhibition) and balance would be improved.

So, I disagree with Stanley's contention that the results from the article counter both of Craig's original points.

Stanley, I'm not sure what you meant when you said, "I don’t know how the orthoses cause the orthotics provide an extra sensory signal for the CNS to act on to "correct" that excessive rearfoot pronation, or whether it does it at all."

A varus heel wedge orthosis will act to shift the center of pressure under the foot to decrease the pronation moment from the ground. Another theory on how orthotics work is the pain avoidance theory. It is uncomfortable to have high amounts of pressure in the medial arch. A person could their posterior tibial muscle to supinate their foot to decrease pressure in the arch. I would agree that this is not really proprioception as I understand the definition. Does that address what you were saying?

Regards,

Eric

 

Thank you to Stanley for alerting me about this interesting discussion. I would ask that Eric and others read my peer reviewed, published article on the subject:
Effects of Foot Orthoses in the Treatment of Chronic Ankle Instability. Richie DH. Journal of the American Podiatric Medical Association 97 (1): 19-30, 2007. The article you discuss which I wrote for Podiatry Today was a brief overview of the detailed review which I published in JAPMA and was the result of careful review of over 100 previously published articles on the subject of chronic ankle instability, proprioception, and the use of foot orthoses.

Eric, I can tell you that there has been no documented proof of a "laterally deviated subtalar joint axis" and correleation with chronic ankle instability. Your conjecture about this condition and the association of sinus tarsi pain and ankle instability are just that..pure conjecture. Since 1982, there have been several elegant studies on peroneal reaction time and use of local anesthetic in patients with chronic ankle instability. I suggest your read my article for more details and explanation of the gamma motor neurons and muscle spindle apparatus.

Finally, you mis-quoted me in stating that I proposed that "pronation causes supination". Where is this written? My paragraph describes closed kinetic chain compensation of the foot during LATERAL BODY SWAY. Please re-read this paragraph and you will see that there is no suggestion that one movement of the foot causes another movement. I am suggesting that lateral body sway will induce a motion in the ankle joint complex, which, when end range is reached, will then cause an opposite movement during the lateral fall. Yes, this was not taught to you when you were in school, and is still not taught today.

Doug

 

Doug:

Good to see you on Podiatry Arena again.

In the last 20+ years that I have been measuring subtalar joint (STJ) axis location in patients, I have seen at least 100 cases of patients with unilateral chronic inversion ankle sprains that also have had a laterally deviated STJ axis on the foot that had suffered from the inversion ankle sprains. I have also written on this concept in October 1989 and July 1995 (Kirby KA: Foot and Lower Extremity Biomechanics: A Ten Year Collection of Precision Intricast Newsletters. Precision Intricast, Inc., Payson, Arizona, 1997, pp. 177-178, 187-188). In addition I first published the concept that a laterally deviated STJ axis can cause lateral ankle instability in my paper in JAPMA over 19 years ago (Kirby KA: Rotational equilibrium across the subtalar joint axis. JAPMA, 79: 1-14, 1989) and specifically mention that patients with laterally deviated STJ axes have increased frequency of inversion ankle sprains and peroneal tendinitis in 2001 (Kirby KA: Subtalar joint axis location and rotational equilibrium theory of foot function. JAPMA, 91:465-488, 2001). I have taught this concept at the California College (School) of Podiatric Medicine as part of the biomechanics curriculum for 20 years now and have also taught this concept in numerous national and international seminars over the past 20 years.

Craig Payne did some unpublished research on subjects with unilateral ankle sprains and supination resistance and found a good correlation between low supination resistance and inversion ankle sprains, which certainly supports the idea that a laterally deviated STJ axis is a cause of chronic inversion ankle sprains. In addition, Jay Hertel, PhD recently expressed interest to me in studying inversion ankle sprains and laterally deviated STJ axis in a research study, but I don't know if he ever started it or not.

With all this in mind, to say that "there has been no documented proof of a "laterally deviated subtalar joint axis" and correlation with chronic ankle instability. Your conjecture about this condition and the association of sinus tarsi pain and ankle instability are just that..pure conjecture", seems to not take into account the considerable efforts I have made over the last 20 years in publishing and lecturing on this concept and the independent observations of other talented clinicians that have seen the same phenomena. I would agree that a good research study has not been published on the subject yet, but this would also be the case for many other pathologies that we have good theory for, but no one has done a good project to support or reject that theory.

Laterally deviated STJ axes causing inversion ankle sprains sure makes good mechanical sense, it obeys the laws of Newtonian physics, I have seen it numerous times clinically, and have pubished it in peer reviewed journals....sounds much better than "pure conjecture" to me!:drinks

 

Doug,

Welcome, and apologies.

My mistake for misquoting. I saw the word inversion and incorrectly assumed that you were talking about the subtalar joint. I agree that the leg and foot will invert (adduct) with continued lateral body sway.

However, what do you mean by "then cause the opposite movement during the lateral fall."

When there is lateral body sway, and the foot is maximally pronated and the whole foot everts, the center of pressure will be under the lateral foot creating a high pronation moment from ground reaction force. Would you agree that the foot will tend to stay pronated unless there is a large supination moment from muscles?

In the podiatry today article

"As one can see, lateral body sway over a fixed foot during single leg stance causes a closed kinetic chain pronation in the rearfoot. A body “falling” laterally would have to fire the medial leg flexors, such as the tibialis posterior, flexor digitorum longus and flexor hallucis longus, in order to pull the tibia medially over the fixed foot. If this does not occur, then further closed chain pronation of the rearfoot would use up all available range of motion of the subtalar joint, and further lateral sway would force the foot and ankle into sudden inversion."​

Is there a typo here? If the muscles don't fire there is sudden inversion?? What is the source of supination moment?

I did hear faculty at CCPM say essentially that pronation causes supination. That is the short version of the quote above. Did I shorten it too much? I'm not clear on the mechanism.


On my contention that there are different kinds of lateral instability.

There is such a thing as a laterally deviated STJ axis. Some of the oldest literature that we have shows that there is variability of STJ axis position. (The classic picture in Inmann's book) If there is variation in the transverse plane then some feet will have more medially deviated STJ axes and some feet will have more laterally deviated STJ axes.

I have not seen any articles correlating STJ axis position with lateral ankle instability. Just because it has not been investigated does not mean that it is not true. I would bet that individuals with a more lateral STJ axis will have a higher relative peroneal muscle activity.

Doug, from your comments about my post I'm not sure that you understood the distinction that I was making between types of lateral instability. I agree that a proprioceptive defect can cause instability. So, if someone has lack of position sense, which foot is more likely to over supinate? or have an inversion ankle sprain? Someone with a more medially position STJ axis (ground will cause pronation moment) versus someone with a more lateral axis (ground will cause supination moment)? So that would be instability from STJ axis being more laterally positioned.

Individuals with sinus tarsi syndrome are more likely to have medially positioned STJ axes. Another study that I have not seen is the correlation between maximally pronated position and sinus tarsi syndrome. In my clinical experience people with sinus tarsi syndrome stand maximally pronated and I believe that this is the cause of sinus tarsi syndrome. In your podiatry today article you described how individuals who are maximally pronated have difficulty with balance. Their balance is improved by medially posted orthotics. This is entirely consistent with my conjecture on the mechanism of lateral instability in maximally pronated feet. The maximally pronated foot is entirely different beast than the over supinated foot, that does not stand maximally pronated, that complains of frequent ankle sprains.

In the conclusion in the podiatry today article it recommended against additional posting. I would have to disagree with that recommendation in the case of feet with a laterally deviated STJ axis.

Another point about the article. There is a difference between postural control and lateral ankle instability. I will agree that there is a correlation, but they are not the same thing. The title of the article is about chronic ankle instability, but a lot of the research is done on postural control as defined in the article. Roughly postural control is the ability to stand on one foot. This is a task where you have to keep the center of mass of the body over the center of pressure under the foot. When you try this, and look at your foot, you will see pronation and supination of the STJ, which is required to shift the location of the center of pressure. If you don't have any range of motion in the direction of pronation then you will have difficulty shifting your center of pressure medially and then have difficulty balancing.

Ankle instability is more commonly thought of as the tendency toward ankle sprains. Perhaps, this is just in my mind. But, this is different than postural control.

With kind regards,

Eric

 

Kevin and Eric,
Thanks for the feedback and insights. I must stand by what I previously stated: there is no evidence, documented in the medical literature, that a deviated subtalar joint axis is associated with increased risk of lateral ankle sprains. Kevin, I know you have written your ideas in the lay literature on this subject, but have seen no kinematic studies which are correlated with epidemiologic research documenting increased risk of sprain with this theoretical "deviated" axis. Eric, the link between poor postural control and risk of ankle sprain has been documented in at least 6 peer reviewed studies which are cited in my paper. This pre-disposing factor is well accepted as the primary determinant of risk of ankle injury in the athlete. In my review of over 200 published articles, I never found one authority on neuromuscular control of the ankle who ever discussed a laterally deviated axis of the subtalar joint. While much of your ideas make great sense to me, I am relectant to embrace them without verifiable data which is generated from the kind of scientific study which you commonly request others to produce when they participate in this forum.

Doug

 

Kevin,
I just read my recent post, and must clarify and correct an error: you have written your ideas in the medical literature, not the lay literature. I apologize. Your lectures and articles propose an idea and suggest a validation based upon clinical experience. I think we will need more research to supplement your theory of causation of lateral ankle sprains before our colleagues and those in other disciplines will take notice.

Doug

 

Doug:

Kinematic studies alone will not produce the type of evidence that will inform us as to whether a laterally deviated STJ axis correlates with increased tendency toward inversion ankle sprains. A retrospective study of patients with unilateral ankle sprains including determination of STJ axis location in each foot would probably shed more light on this possible correlation. In addition, a kinetics study that used inverse dynamics would also give us more information on the nature of the forces and moments that cause inversion ankle sprains. Kinematic studies, showing only motion, unfortunately will not account for the internal moments and forces that occur in subjects and, therefore, will not likely give us good information as to whether the subject is, for example, using their peroneals to "resist ankle sprains" during gait.

What is very interesting is that those patients with laterally deviated STJ axes also show tonic peroneal muscle activity during relaxed bipedal stance. My 2001 paper has a photo of a patient of mine that is an example of the many people that stand with tonic peroneal muscle activity, which I believe is requred by them to keep the forefoot plantigrade during relaxed bipedal stance. In other words, without tonic peroneal muscle activity, these patients will usually maximally supinate their STJ and stand on the lateral aspect of their forefeet. The photo below is of another patient of mine with lateral ankle instability on the left, tonic peroneal muscle activity during relaxed bipedal stance and increased lateral deviation of the STJ axis on the left foot.

Last year when Eric Fuller and I lectured again at Biomechanics Summer School in England, we had one of the female podiatrists on the stage during one of Eric's workshops that exhibited this foot type and I spotted her peroneal tendons bowstringing from 20 feet away. She had a laterally deviated STJ axis, mild cavus foot structure, tonic peroneal activity (she had no knowledge of this) and, if I remember correctly, admitted to multiple inversion ankle sprains/instability. If you don't look for these patients, you won't see them.

Like Eric said, the available research on STJ axis location shows a wide range of interindividual variability of spatial locations of the STJ. In addition, from a simple kinetics standpoint, the more the STJ is laterally deviated, the greater will be the magnitudes of STJ supination moments from ground reaction force. This is not conjecture, this is simple mechanical modelling. If we then assume that inversion ankle sprains are a result of increased magnitudes of STJ supination moments that are not opposed by sufficient STJ pronation moments (which seems a very likely and plausible mechanical scenario), then I see no reason why having a laterally deviated STJ axis would not cause increased frequency of inversion ankle sprains.

Sometimes we must use good mechanical judgement to arrive at better explanations for the mechanical phenomena that occur within the human foot and lower extremity before the research literature finally comes around to support these theories. I believe that we owe this to our patients in order to provide them with the best treatments available, regardless of the lack of research that explains why patients have responded so succesfully to treatment modalities that are based on these "unproven theories".

 

I have recently assessed two patients who have inversion difficulties.

The first is a CMT patient who presented with pain along the course of her peroneals. I made her a 3mm polyprop orthoses with neutral extrinsic heel posting, 4mm lateral heel skive with lateral flange, 20mm arch reduction, reverse type mortons extension and 1st ray cutout. With the orthoses she can now walk pain free.

The second is a young adult who was diagnosed with having "developmental delay" You can see that he presents with quite marked inversion. Despite his foot/ankle position he has no pain/discomfort. I am in the process of making an ankle foot orthoses from him. I have casted his foot/ankle just off plantigrade with his forefoot in aprox 8 degrees of eversion. I am also going to modify his footwear and add a 12mm lateral heel flare extended to his 5 MTPJ.

Both of these patients have feet that have a lateraly deviated STJA and when weight bearing are very easy to supinate and very difficult to pronate (low supination resistance test). My objectives with both are to increase STJ pronation. The second patients foot cannot be controlled with a standard foot orthoses so to increase the mechanical lever arm an ankle foot orthoses is indicated.

I reguarly see patients who present with both mild and severe inversion problems (Duchenne Muscular Dystrophy, Cerebral Palsy, Spina Bifida, Charcot Marie Tooth). My rationalle remains the same when treating both groups, identify where (axis) and how (force applied) I can pronate the foot and what orthoses can acheive this.

Declan