Biomech is simple?

[Admin]

It has indeed, and after, if you don't mind my observation, a fairly complicated fashion too .
;D

[davidsmith]

David, Robert and all

I haven't gone thru all the posting in this thread so hopefully I'm not duplicating.

Here at Pod arena is a nice example of why simple (KISS) is not always best or optimal or easiest. (in my opinion)

Goto

www.podiatry-arena.com/podiatry-forum/showthread.php?p=36913#post36913

No rearfoot to forefoot misalignments, no inverted rearfoot in STJ neutral but in stance still fully pronated with symptoms of plantar fasciitis. With this one where do you go with the simple prescription theory of just balance the foot to the ground?
Not likely to work or if it does you will just chase the compensation (and painful symptoms) somewhere more proximal.

Cheers Dave

[Admin]

Hi Dave,

What I hate about this type of forum request (the one made on Pod Arena) is that we never get all the info immediately.

In this particular case the pod said:
"I took the cast and laid it on the table, and there is no forefoot to rearfoot abnormality to correct?"

So if the cast is accurate we have captured the "normal" foot, as propounded by Root et al?


It doesn't add up.

Now I'm willing to bet that if someone else, lets say someone more experienced, took a cast there would be some RF to FF "abnormality".
At one time we would have called this compensation for equinus - to me thats a little complicated ;D - so lets just say that the RF to FF abnormality" is normal.

In my opinion (and I didn't join in the thread on Pod Arena for the reason mentioned above) the foot would need to be cast ever so slightly pronated (to flatten the arch slightly, because we don't want a lump of plastic actively pressing on the plantar structures).

Post to correct to the ground - review after a few weeks, and modify according to what the pt now presents with. I would have thought heel cushioning woud also help those atrophied heel fat pads.

Cheers,

[davidsmith]

Dave

You wrote

What I hate about this type of forum request (the one made on Pod Arena) is that we never get all the info immediately.

Agreed

In this particular case the pod said:
"I took the cast and laid it on the table, and there is no forefoot to rearfoot abnormality to correct

Yes

So if the cast is accurate we have captured the "normal" foot, as propounded by Root et al? It doesn't add up.

No it doesn't, Not if one relies on the KISS paradigm

Now I'm willing to bet that if someone else, lets say someone more experienced, took a cast there would be some RF to FF "abnormality".

Possibly, but I have seen many cases like this.

At one time we would have called this compensation for equinus - to me thats a little complicated - so lets just say that the RF to FF abnormality" is normal.

And in my opinion you would have been correct, assuming equinus is expanded to include all muscles of the legs, pelvis and lower trunk.

In my opinion the foot would need to be cast ever so slightly pronated (to flatten the arch slightly, *because we don't want a lump of plastic actively pressing on the plantar structures*).

**I agree, but Ed wouldn't

and

Post to correct to the ground - review after a few weeks, and modify according to what the pt now presents with. I would have thought heel cushioning woud also help those atrophied heel fat pads.

This KISS prescription would then end up with a rear foot post if the cast is vertically aligned and then some degree of f/foot posting to balance.

I can see the merit of taking a pronated cast to capture a lowered arch and prevent arch irritaion. This may be better than relying on the skill of someone to add plaster to the positive.
However, this sounds like: This foot does not fit the KISS paradigm, so manipulate the casting process so that it does.


There is a theory in physics that energy flows follow the line of least resistance. There was a paper written recently that proposes the Preferred Pathways theory. Then there's Dananbergs Saggital plane theory. They are all very similar in supporting the premise that muscle tightness thru the foot, lower limb and pelvis will result in compensations at the joints to allow the continuation of forward motion. EG the hips flex and internally rotate, the knees flex and the STJ pronates to release tension in the muscles that would otherwise produce a GRF that would sub optimally slow the CoM velocity. In my opinion the exact mechanics are debatable but the principle is reasonable.

By your method described I believe you may resolve the plantar fasciitis because you have allowed a midway compromise. IE allowed some pronation and therefore MLA extension but not enought to increase internal PF tension the the pathological level.
This may however induce a compensation at the knee or hip to allow for the block that you might have created at the foot and ankle complex. It is possible that this will lead to proximal pathology.

It is my opinion that one should adress the whole system to resolve the foot problem and therefore reduce the possibility of proximal compensations.

All the best Dave

[Admin]

Hi Dave,

You wrote:
"This KISS prescription would then end up with a rear foot post if the cast is vertically aligned and then some degree of f/foot posting to balance.

I can see the merit of taking a pronated cast to capture a lowered arch and prevent arch irritaion. This may be better than relying on the skill of (someone to add plaster to the positive.
However, this sounds like: This foot does not fit the KISS paradigm, so manipulate the casting process so that it does."

I hardly ever RF-post extrinsically. Post RF intrinsic vertical and FF-posts ( about 2 degrees for most pts) can provide control for the whole foot perfectly well. You may remember that RF posting was originally thought to correct the calcaneus/stj so that the rest of the foot followed?

To remember that you had to have done a Langer Course in about 1979 )

In fact, since full bodyweight is only on the orthosis from mid-stance I would argue that a RF post is doing little more than stabilising an expensive arch support. - so in most cases I forget extrinsic RF posts. I would want an extrinsic RF post on a post-tib or peroneal dysfunction case, to stabilise the foot a little more, bust I think those are about the only common cases where an extrinsic RF post is indicated. Others may disagree (and complicate matters ).

Pronate the cast a little for any pt presenting with plantar pain - whether PF or flexor strain. This is certainly part of my KISS paradigm.

Pt has equinus - so have we all. It may have some bearing on the case -try a heelraise, or if the pt is female ask her to go into a slightly higher heel.

I think Robert suggested on the Pod-Arena thread that a cut-out or cushioning at the heel was indicated. Again, this fits in perfectly with the KISS paradigm - after all, its common-sense. Ask a five year-old child what would help to stop the pt walking on the bone - chances are they'll tell you (provided they haven't done a Degree in Podiatry).

Above all, don't go for a one-shot cure. Try the devices, bring the pt back, expect to make alterations if the case is long-standing. Keep it simple.

You said:
"It is my opinion that one should adress the whole system to resolve the foot problem and therefore reduce the possibility of proximal compensations."

Absolutely! And given the variables inherent in treating the whole system (different clinicians, supporting surface type, and normal biological variability are just three) don't you agree that going for a one-shot cure is, in many cases, setting an unrealistic goal?

Regards,

[robertisaacs]

I think Robert suggested on the Pod-Arena thread that a cut-out or cushioning at the heel was indicated. Again, this fits in perfectly with the KISS paradigm.

No it Does'nt. Its a COMPLEX cushion. Or something.

harumph.

Robert

[davidsmith]

David

I hardly ever RF-post extrinsically. Post RF intrinsic vertical and FF-posts ( about 2 degrees for most pts) can provide control for the whole foot perfectly well.

Oh! yes I remember you saying that in the past. So am I correct in thinking that with your system you put the rear foot of the cast in a vertical position and then post the fore foot accordingly?
If this is so then even tho you have not fitted a rearfoot post you still get a similar effect. The torque thru the orthosis will apply a supination moment about the STJ with some force applied at the medial heel by the heel cup.

Above all, don't go for a one-shot cure. Try the devices, bring the pt back, expect to make alterations if the case is long-standing. Keep it simple.

This is my usual pattern of treatment.

1)Initial assessment - 2)Full Biomechaical assessment - 3)Designs and manufacture orthosis - 4) Fit orthosis, give exercises, stretching, mobs etc. - 5) Review, patient fixed most times 90% approx. Give mods if not. 6) review again if necessary 99.999% fixed now.

Get complicated and fix it all in one go-ish (usually)

I think Robert suggested on the Pod-Arena thread that a cut-out or cushioning at the heel was indicated. Again, this fits in perfectly with the KISS paradigm - after all, its common-sense. Ask a five year-old child what would help to stop the pt walking on the bone - chances are they'll tell you (provided they haven't done a Degree in Podiatry).

It's all common sense once you've studied the subject enough.

What about the person who has heel pain or plantar fasciitis and a bony heel but always wears crocs (a real case just recently) Add some more soft padding? No, - change the shoes to something stiffer and control the foot with a relatively stiff orthosis. = resolved pain. (but no padding) Not so intuitive perhaps.

You (Dave Smith) said:
"It is my opinion that one should adress the whole system to resolve the foot problem and therefore reduce the possibility of proximal compensations."

David H said
"Absolutely! And given the variables inherent in treating the whole system (different clinicians, supporting surface type, and normal biological variability are just three) don't you agree that going for a one-shot cure is, in many cases, setting an unrealistic goal?"

ABSOLUTELY!!!

How can you say absolutely and propose KISS at the same time aren't they mutually exclusive.

With respect Dave, It appears you keep adding bits to your KISS. I think your hedging your bets Dave. Its becoming more of a SNOG. (This is not a anacronym just a pun.) This appears to be a case of keep it simple and if necessary get complcated when it doesn't work and do some modifications for all the more involved things. (if one has the skill)

What do you mean by "one shot" exactly. - One protocol?
Each clinician can only go by his own experience and good ones in my opinion use their education, experience and skill to build their own protocols, which work for them. This is good but they should also be able to incorporate new ideas as they come along. So that there are no fixed paradigms and each patient is treated as an individual. Everyone has to start somewhere tho before they can build up there skills. KISS is a good starting point but it doesn't appear that you stick rigidly to that protocol Dave.

Anyway if I get complicated it justifies my fees and my many years of expensive study. It just has to be complicated.
Patients like to feel like one has been thorough, and to them a long time spent entering data, poking, proding, saying hmmmm? with a knowing look and bamboozling with science is worth every penny. As long as they get fixed at the end ;D

And another thing - how complicated is your pressure mat system - now thats HI Tec -squared.

Cheers Dave

[Admin]

Hi Dave,

You said:
"Oh! yes I remember you saying that in the past. So am I correct in thinking that with your system you put the rear foot of the cast in a vertical position and then post the fore foot accordingly?
If this is so then even tho you have not fitted a rearfoot post you still get a similar effect. The torque thru the orthosis will apply a supination moment about the STJ with some force applied at the medial heel by the heel cup."
Cast as normal, then hold the cast with heel vertical. Does the medial or lateral side need a wedge to keep the heel vertical?
Thats where you post. An intrinsic vertical-posted RF takes up far less room in the shoe than a 4 degs varus extrinsic RF post. If it does apply a supination moment about the STJ thats good.

Then you said:
"1)Initial assessment - 2)Full Biomechaical assessment - 3)Designs and manufacture orthosis - 4) Fit orthosis, give exercises, stretching, mobs etc. - 5) Review, patient fixed most times 90% approx. Give mods if not. 6) review again if necessary 99.999% fixed now."
I do an initial assessment, where I talk to the pt, carry out a cursory exam to be sure myself that orthoses will help, and explain the next step and fee scales. The exam is mostly to do with quality and quantity of ROM.
2nd visit - gait analysis, data capture and casts.
Write an Rx based on what I find on the casts and what I find on the gait analysis.

Then you said:
"What about the person who has heel pain or plantar fasciitis and a bony heel but always wears crocs (a real case just recently) Add some more soft padding? No, - change the shoes to something stiffer and control the foot with a relatively stiff orthosis. = resolved pain. (but no padding) Not so intuitive perhaps".
But why would soft padding work for heel pain and/or plantar fasciitis?
The padding will only work for a bony heel.

Then you said:
"With respect Dave, It appears you keep adding bits to your KISS. I think your hedging your bets Dave"
Adaptability is something which allows we Homo Sapiens to survive in tough spots!
;D

Seriously, the KISS paradigm is what I work with. I've taught it along with Ian Linane, and to more than a few people on this forum.
Using it newcomers to biomech have been able to obtain good results on patients after one two-day workshop.

Assess the feet as above (don't take measurements of any kind, ever)

Take casts and work out which side you want to post. Post 2 degrees (usually). Don't forget to pronate the feet a little if the pt has plantar pain.
Normally intrinsic FF posts are the order of the day. Unless the patient presents with retro-patellar knee pain. Extrinsic FF posts work better with retro-patellar pain. The reasoning behind this is also simple. Most retro-patellar pain is produced when the knee is bent and on weightbearing. Going up or coming down stairs for example. Since bodyweight tends to be mostly on the forefoot in ascending/descending a chunky extrinsic ff post (but still only 2 degrees) to maximise transverse plane control seems to do the job.
Forget flavour-of-the-month additions and subtractions to the basic orthosis - I'm not saying they don't work - just that they don't fit the KISS paradigm

Find a lab who will turn out good quality work with a reasonable turnaround - make sure they store data digitally for re-orders down the line.
Choose a couple of types of orthoses (one for ladies, one for men, one for sport) and stick with these for most of the time.

Use a vertical loading system and carry out gait analysis if you want - but its optional.

Tinker with the orthoses or heel height (chiropody felt is good for this) if you don't think the result is optimal for that pt.

I think that in the past we have been able to demonstrate that if people simply believe that this model works then it will work for them. If they want to find out how it works (BTW this is not necessary for it to work) they can always do an MSc or a PhD in Bioeng.

And finally (I think ) you asked:

"What do you mean by "one shot" exactly. - One protocol?"
No, fit the orthoses once and expect a cure. Which is what, in my experience, many pods do.
Sometimes orthoses need to be altered, sometimes the alteration can be as simple as a non-standard non-slip top cover. Other times the orthoses may need to be narrowed or shortened. Often the patient is only aware of the need for alterations after a few weeks have passed.

I demonstrated my exam and casting on Martin H to the Tamworth Meeting a few weeks back. It really is very simple.

In a nutshell... much thought/hard work/trial and error have gone into producing a simple way to cast and prescribe. But that does not detract from the fact that it is quick, simple (that word again!), effective, and can be learned by most people in a matter of days.

Cheers,

[davidsmith]

In a nutshell... much thought/hard work/trial and error have gone into producing a simple way to cast and prescribe. But that does not detract from the fact that it is quick, simple (that word again!), effective, and can be learned by most people in a matter of days.

Ah! now this is an entirely different kind of fish. A simple protocol for optimal learning outcome in terms of practicle application. This is a good idea. This makes good sense clinically and commercially.
When I was working as a diver in offshore oil, already trained in mechanical engineering, I also trained as a inspection and non destructive testing engineer. This was at a shopfloor / workshop level. Principles are taught that are easy to understand and formulae are taught that give a ready reckoning, rule of thumb application. It was not entirely correct in an academic sense but worked very well for the job at hand.
Then recently I did my MSc applied biomechanics. The maths here was in principle the same as other engineering principles I had done before. However the academic level was of course much higher. Instead of rule of thumb formulae one must understand the concept and construction of formulae (eg algebra, calculus) for the job at hand and apply it in a manner that produces useful work.
Perhaps for a given application the outcome may be the same for both techniques how ever the understanding of the process that led to that outcome are much greater in the latter. Eventually, and here's the rub, there will come a time when the rule of thumb technique will not give the outcome required and then without the deeper understanding of the underlying principles no further progress can be made.

Example. I don't know how you are on differentiation and integration calculus Dave (If you as good as me then we will both be struggling) but for a rule of thumb the integral of strain = the natural log * (length final/length original) and anyone, with a calculator, could do this calculation without even knowing one principle of calculus or even algebra. However as soon as a problem came along that required to integrate in respect of time or to consider more variables then no further progress could be made.

The people that create the rule of thumb protocol, first needed to have a deep understanding of the principle before they could formulate the simple method. Which is what you have done David.
Well done, but this, to my mind does not make biomechanics simple it only simplifies the application of biomechanics. Two very different things. It also gives great feedback that will enhance the future of this method in a commercial setting. Many orthotic labs Vasyli, as you pointed out earlier, being a good example use this 'simple' rule of thumb method.

All the best Dave

[davidsmith]

David

Just to carry on from my last post. As you obviously realise, all learning is simplified to enhance understanding. As one progresses thru the levels the level of understanding increases and so there is less simplification of principles. You wouldn't teach 8year olds calculus. They would not have the background knowledge to understand it. The result would be wasted time and no learning.
Simply put tho integration and diferentiation are just fancy ways of adding and subtracting, multiplying and dividing (finding an area, defining a rate of change). But first they learn 2 + 2, 3 * 3, 4/2 etc. Then when they are comfortable with those concepts they can move on to a higher understanding.

A weekend course could not hope to teach the whole syallabus of biomechanics. Simple rules of thumb that students can take away as a conveinent tool box of interventions and that then they can use straight out of the box when they get back to the clinic. Keep it simple, Keep it useful, keep them coming back for more.
Its good, its useful, its profitable. Good principles of learning and business. What more would you want or expect

Cheers Dave

[Admin]

Apr 15, 2008 10:11:21 GMT davidsmith said:

much cut...... Simple rules of thumb that students can take away as a conveinent tool box of interventions and that then they can use straight out of the box when they get back to the clinic. Keep it simple, Keep it useful, keep them coming back for more.
Its good, its useful, its profitable.

Like I said, biomech is simple. Its as simple or as complicated as we wish it to be. But the basics - that we have not evolved for life on a hard flat surface, and that our orthoses, no matter what skives, depressions or additions they may have, are simply interfaces betrween us and the ground to allow our bodies to work more optimumly hold true for everyone practicing pod biomech.

Our teaching package was 3 X 2-day Workshops. I think everone who attended all three had at least as much practical biomech knowledge as the average newly-qual'd Pod, and some had considerably more. Newtons 3rd Law, GRF and some basic physio (trendlenberg gait etc) were included.

Sadly, we no longer offer this package - the CPD market became too full of "experts" offering their own courses.

Ho-hum .

Cheers,

[ianl]

Hi David's

The teaching approach helped a number of people, however, there were a couple who I know still feel uncertain, for whatever reasons. Perhaps it was a lacking on my own communication part, certainly the very simple approach we suggested can seem too simple and therefore make people reluctant to push it.

Cheers
Ian