Prefabricated vs custom made foot orthoses

Charlie:

Welcome back to Podiatry Arena.

I know of at least one study that showed better improvements in pain, speed of gait, level of disability when patients wore custom foot orthoses when compared to those in the study that received shoe inserts or shoes alone (Powell M, Seid M, Szer IA: Efficacy of custom foot orthotics in improving pain and functional status in children with juvenile idiopathic arthritis: A randomized trial. J Rheum, 32:943-950, 2005). So your assertion that there is "no evidence" that custom orthoses are more efficacious than pre-fab orthoses simply isn't true. In addition, there are also studies that show that specially modified foot orthoses work better at changing kinetics and symptoms than more standard orthoses (Williams DS, McClay-Davis I., Baitch SP: Effect of inverted orthoses on lower extremity mechanics in runners. Med Sci Sports Exerc, 35:2060-2068, 2003). Certainly this evidence would suggest that making more customized foot orthoses that are specifically designed with the patients abnormal biomechanics in mind have the potential to work much better than pre-fab orthoses. This is what I have been seeing clinically for the past 23+ years of practice and what many respected clinicians have also been seeing in their practices for the past half-century.

Please tell me what the "kinematic theory of orthotic function" is, Charlie. If you mean that foot orthoses don't change the kinematics of gait, then this certainly isn't true either. There are numerous studies that do show that both walking and running kinematics may be positively altered by foot orthoses. Here are some of them:

Orthoses decrease maximum rearfoot eversion angle

1. Bates BT, Osternig LR, Mason B, James LS: Foot orthotic devices to modify selected aspects of lower extremity mechanics. Am J Sp Med, 7:328-31, 1979.
2. Fong DTP, Lam MH, Lao MLM, et al: Effect of medial arch-heel support in inserts on reducing ankle eversion: a biomechanical study. J Ortho Surg Res, 3:7-13, 2008.
3. Johanson MA, Donatelli R, Wooden MJ, Andrew PD, Cummings GS: Effects of three different posting methods on controlling abnormal subtalar pronation. Phys Ther, 74:149-158, 1994.
4. MacLean C, Davis IM, Hamill J: Influence of a custom foot intervention on lower extremity dynamics in healthy runners. Clin Biomech, 21:621-630, 2006.
5. MacLean CL, Davis IS, Hamill J: Short and long-term influences of a custom foot orthotic intervention on lower extremity dynamics. Clin J Sport Med, 18:338-343, 2008.
6. Nester CJ, Hutchins S, Bowker P: Effect of foot orthoses on rearfoot complex kinematics during walking gait. Foot Ankle Intl, 22:133-139, 2001.
7. Nester CJ, Van Der Linden ML, Bowker P: Effect of foot orthoses on the kinematics and kinetics of normal walking gait. Gait Posture, 17:180-187, 2003.
8. Smith LS, Clarke TE, Hamill CL, Santopietro F: The effects of soft and semi-rigid orthoses upon rearfoot movement in running. JAPMA, 76:227-232, 1986.


Orthoses decrease maximum internal tibial rotation

1. Nawoczenski DA, Cook TM, Saltzman CL: The effect of foot orthotics on three-dimensional kinematics of the leg and rearfoot during running. J Ortho Sp Phys Ther, 21:317-327, 1995.
2. Williams DS, McClay-Davis I, Baitch SP: Effect of inverted orthoses on lower extremity mechanics in runners. Med. Sci. Sports Exerc. 35:2060-2068, 2003.
3. Woodburn J, Helliwell PS, Barker S: Changes in 3D joint kinematics support the continuous use of orthoses in the management of painful rearfoot deformity in rheumatoid arthritis. J Rheum, 30:2356-2364, 2003.


Orthoses decrease internal rotation/adduction of the knee

1. Stackhouse CL, Davis IM, Hamill J: Orthotic intervention in forefoot and rearfoot strike running patterns. Clin Biomech, 19:64-70, 2004.
2. Williams DS, McClay-Davis I, Baitch SP: Effect of inverted orthoses on lower extremity mechanics in runners. Med. Sci. Sports Exerc. 35:2060-2068, 2003.


Orthoses decrease maximum ankle dorsiflexion angle

1. MacLean CL, Davis IS, Hamill J: Short and long-term influences of a custom foot orthotic intervention on lower extremity dynamics. Clin J Sport Med, 18:338-343, 2008.


Orthoses decrease maximum rearfoot eversion velocity

1. Smith LS, Clarke TE, Hamill CL, Santopietro F: The effects of soft and semi-rigid orthoses upon rearfoot movement in running. JAPMA, 76:227-232, 1986.
2. MacLean CL, Hamill J: Short and long-term influence of a custom foot orthotic intervention on lower extremity dynamics in injured runners. Annual ISB Meeting, Cleveland, Sept. 2005.
3. MacLean C, Davis IM, Hamill J: Influence of a custom foot intervention on lower extremity dynamics in healthy runners. Clin Biomech, 21:621-630, 2006.
4. Nester CJ, Hutchins S, Bowker P: Effect of foot orthoses on rearfoot complex kinematics during walking gait. Foot Ankle Intl, 22:133-139, 2001.
5. Nester CJ, Van Der Linden ML, Bowker P: Effect of foot orthoses on the kinematics and kinetics of normal walking gait. Gait Posture, 17:180-187, 2003.

What exactly are you talking about here, Charlie? Do you want to elaborate further on this unusual comment? Maybe we need to start a whole new thread on just this subject alone? Could be very interesting!

Since when have foot orthoses been considered a "rigid lump of plastic"? Now you sound like someone who is making things up in order to sell their product. You may want to read this little item on straw man arguments. You are starting to use the same straw man argument technique that some of our more infamous posters use when they pontificate here on Podiatry Arena. I don't think you want to slide down into the same slippery pool of slime that these individuals continually wallow around in here on Podiatry Arena.

Tell me where anyone said "the human body really just a passive mechanical system that can be "controlled" by a little wedge under the foot." No one has said that to my knowledge and, more importantly, I don't know anyone that believes this. However, I do know of one individual that owns a foot orthosis lab and advocates foam-box casting that often uses a very similar statement in his infomercials that he pays to lecture at in seminars around our country.

I think that function is probably understood best by considering the specific biomechanics, anatomy and the physiology (including neurology, endocrine, etc) of the organism. This type of academic system has been taught standardly in podiatry schools here in the States for decades. Therefore, again, I don't know what you are talking about. Please explain.

Some podiatrists that own orthosis labs or have patented/trademarked their orthosis systems seem to think that a total contact orthosis shell is always superior to all other orthosis designs. I know that this simply isn't the case. Orthosis stiffness (i.e. load-deformation characteristics of the superior surface of the orthosis) and three-dimensional shape of the orthosis are the key to both improvement of symptoms and optimization of gait mechanics with foot orthoses.

Sounds like a good sales pitch for your company and your company's product, Charlie. Since when have the works of Manohar Panjabi been "universally accepted"? This statement that Panjabi's model is "universally accepted" is hard for me to fathom since very few podiatrists even know about Panjabi's ideas and none of the orthopedic surgeons I associate with know about Panjabi.

Good to have you back here on Podiatry Arena contributing again. Looking forward to your replies. Have a Merry Christmas!:santa:

 

I apologise in advance for the tone of my post. I've got something febrile and flu'y so my grip on civility is not so firm.

Firstly thanks kevin, for that reference list! Its always very useful to have access to resources like that :drinks.

Rant ahead.


Well gee wizz and whupty do, another person who has a product to sell. Who makes broad, sweeping generalisations about the way "orthotics are meant to work". And "the way orthotics are prescribed. Who talks about what "the literature shows" without actually quote what part of what literature. Whose

. Who talks about the optimum / best / most natural orthotic / position without offering a reason WHY its best / optimal / most natural. Who makes confident and UNBACKED claims that their orthotics work for most:

Briliant bit of tautology there btw. Who knwe that a comfortable device was what was needed. How many people go out to give their patients an UNcomfortable device.*?!

Who comes here and tells the community that it is doing it all wrong.

.

Why is it that when somebody has what they think is a good product and want to sell it that they cannot simply say "hey guys, we've come up with this and it works really well!" Why does the sales pitch always have to include a withering critique of "the way things are done now"? Who thinks they are the first to spot "THE PROBLEM" with bad orthotics.

Charlie. I've not used formthotics. I don't know what they do or how. I don't know how you work / prescribe / make insoles. So i would not dream of criticising your "model" of biomechanics until you tell me what is involved. Kindly do me the same courtesy! You don't know anything about how i, or anyone else here prescribes and makes insoles or even what types of insoles are used. So spare me the Straw man critique of the "kinematic model", which, by the way, is a term i've never heard before and seems downright silly.

Sorry. Rant over. I'm now off to shout abuse at some carol singers.


Regards And merry Christmas

Robert.

* Well, on reflection i can think of one product line.

 

NEWSFLASH "shank dependent materials can provide therapeutic support to feet and the silly Podiatrists didnt know this and had to be told it by cleverer non-Podiatists now they will have to stop selling their ridiculously overpriced hard orthotics!"

NEWSFLASH "we need a WHOLE NEW APPROACH (TM) because the results are not explainable by the mere fact that both shank dependent and shank independent orthotics push on feet to exert moments about joint axes and thus relieve strain on injured structures and just because neither type of orthotic have to produce large kinematic changes it must be because of a NEURO-BIO-CHEMICO METHOD!"

NEWSFLASH "profits in soft orthotic company sky-rocket, company director says its because of our new business model - our soft insoles wear out and need replacing so we sell more!"

NEWSFLASH "dont worry about recession we've got free advertising on internet message boards !!"

see my website if you are interested:

www.reinventingthewheeltomakemoneyf...theconfidencetoprescribetruecustomdevices.con

Merry Christmas and a Prosperous New Model Year from Customheatmouldoneborneveryminutethotics!

 

ROFLMFAO!!!!

:drinks

Robert

 

For those who've never seen it, can I make a suggestion for you educative and viewing pleasure this holiday season: "They Live" directed by John Carpenter.

Whole film here: http://video.google.com/videoplay?docid=-9005367754264973286

If you don't have time to watch it all, skip to about 30 minutes in, where he finds the sunglasses...

Everything you know is wrong. Stay Asleep. Watch more T.V.

Is it just me, or are these monsters closing in us? Call me paranoid, but I think it's getting darker here every day... Thanks to these assholes. This is were advertising leads. I made my views clear when paid advertising arrived here. Now we're getting "infomercials" from the likes of Charlie, Dennis et al. Why do they need to pay? I'm seeing it in so called peer reviewed journals almost every day. I know it's that Ronco orthotics time of year, but wait, there's more... and all of that shine, but I'm a little concerned about who's gonna be left to sing with me. One more time...

Well we know where were goin
But we dont know where weve been
And we know what were knowin
But we cant say what weve seen
And were not little children
And we know what we want
And the future is certain
Give us time to work it out

Were on a road to nowhere
Come on inside
Takin that ride to nowhere
Well take that ride

Im feelin okay this mornin
And you know,
Were on the road to paradise
Here we go, here we go

Chorus

Maybe you wonder where you are
I dont care
Here is where time is on our side
Take you there...take you there

Were on a road to nowhere
Were on a road to nowhere
Were on a road to nowhere

Theres a city in my mind
Come along and take that ride
And its all right, baby, its all right

And its very far away
But its growing day by day
And its all right, baby, its all right

They can tell you what to do
But theyll make a fool of you
And its all right, baby, its all right

Were on a road to nowhere

"if you're in marketing, kill yourself" Bill Hicks

 

Hey guys. I am formulating a more thoughtful response to Kevin Kirby's post. As you know he is a pretty formidable guy so I am thinking about it. In the meantime, I see that what I said evoked some strong responses.
Re: Pushing product.
1. If I said the same things but did not have a product, would you react the same way?
2. Do you really think I am so dumb as to think you will be influenced about products by what I say or do not say on this forum? My belief is that you choose what you use on the basis of what you think is right for a given patient. Of course we like you to use our product. Is that not natural?
3. My questions and comments are not a criticism of custom orthotics. My personal opinion is that all foot orthoses should be customized to the needs of the patient, problem and type of shoe that will be used in.
4. Custom orthotics prescribed by Podiatrists are the best solution for foot related problems that are currently possible! I do understand this?
5. I probably should not have put these particular comments on this thread because what I am talking about are potential deficiencies in the model and method by which foot orthotics are currently prescribed, fitted and modified. This is not my personal opinion. It is what I have read and heard from highly respected academic and scientific Podiatrists and Biomechanists.
6. What I am suggesting as a model and method (for your consideration comment and critique if you are interested) is not specific for any particular product. It is a way to possibly have more reassurance that the devices provided to the patient will have a beneficial effect on some assessable aspects of lower extremity function as well as relieving the patients' pains.
7. Studies showing that different types of orthotics reduce symptoms do not impress me that much either. In my experience any competent Podiatrist (or other person with some basic knowledge and skills) can reduce a patient's symptoms by changing something under the foot. This is because changing the surface under the foot changes kinetics and unless you are really unlucky this will reduce the loading on the sore part. People even get good pain relief wearing their orthotics in the wrong shoes.
8. Orthotics can also shift moments of force so that susceptible tissues become painful. They are powerful devices.
9. What intrigues me is improving the function of the lower extremity and as I understand the current literature mechanical function is not systematically and predictably altered the way we used to think it was.
10. There is growing evidence to suggest that the effects of orthoses on lower extremity function are neuromotor and that mechanical principles do not predict how an individual person will adapt functionally to a "mechanical" modification of an orthotic device.
11. It has been suggested (Tom McPoil and others) that a new orthotic model is necessary and I have developed one that I think is compatible with current knowledge from biomechanics and other medical disciplines. It's just my idea of how patients might be able to be provided with custom orthotics of various kinds that might have a more reliable and predictable effect on lower extremity function as well as symptoms. This is not a product! It can be used with any products!
12. Research and original thought will result in changes in thinking and practice that will result in improvements in how custom orthotics are prescribed and made. Saying this is not a criticism of the current devices and people who make them. It's just the way things happen in medicine and other fields.
13. I'm not interested in lower extremity function and orthotics because I make a product. I am interested in these things because so many people are having problems and there is so much potential to help them.
14. If you disagree with my ideas and interpretations of things than by all means argue the point but I would appreciate it if you could do this in another way than just attacking me personally because I happened to make a product.
15. If it is inappropriate for me to post comments on this forum because I manufacture and sell a product then please just tell me that you cannot separate me from the product and I will stop posting comments.
Have a blessed Christmas and New Year

 

PS. I got a scholarly resonse from Kevin and some "hot tongue" from Simon, Robert and Lawrence but is anyone going to respond specifically to the questions that I asked? They are questions not statements.
Kevin did address 4 of the questions and kind of agreed with what I think.
2. There is potential interest in discussing the relative merits of 3D models and the genuine body parts.
3. Orthotics should definitely not be just a "rigid lump of plastic".
4. The human body is no a mechanical system.
5. Podiatry schools in the USA are teaching people about neuromotor, endocrine and other aspects of musculoskeletal function. So, Is there merit in a new model for orthotics that is both biomechanical and neuromotor?

 

Hello Charlie,

Perhaps, you got "tongue" because of your tone, in addition to your product. The lump of plastic quote could be considered as criticism of what everyone else is doing.

As to why there is no response to your questions: They are not very good questions, because some of your terms are not well defined.

I don't know what you mean by merits of 3d models and genuine body parts. Are you saying that models cannot represent reality? What exactly is your question?

My orhtotics can be called a rigid lump of plastic and they feel fine and enable me to walk farther without pain. The shape of the piece of plastic matters, but it still can be called a lump of plastic.

The human body can be defined as a mechanical system. Why would you think that it cannot be one? Are you familiar with free body diagram analysis?

Mechanical models can include muscle forces. If the Schools are teaching Subtalar joint axis location and Rotational equilibrium theory then they are teaching a model of mechanics that includes neuromotor input.

What is your theory?

Regards,

Eric Fuller

 

Hey Charlie.

Sorry about my hot tongue. . Here is the more formulated response. I'll hit the high points.

Yes. You're critique was poorly laid out, inflammatory (hence the flames) and not very rational. Also in the wrong thread. The fact that you used it as a vehicle for advertising your wares was just icing on the cake.

I don't fully understand your grammar here. What exactly are you asking?

Irrational statement. To discuss having "more reassurance that the devices provided to the patient will have a beneficial effect" implies some knowledge of the present level of confidence. It also infers that the present system in use by the practitioner has LESS confidence of benificial effect. Essentially this is an involved way of saying that this model POSSIBLY works better. Obviously such a statement needs supporting.

Possibly. Or possibly not. Improvement always involves change but change does not always involve improvement. Its only an improvement if it works better! If we accepted ever "exciting new paradigm" someone comes up with we'd be taking 5 steps back for each one forward!

Its not us who fail to separate your comments from your product! From your posts i know more about your product than your model. If you wish your views to be considered on their own merit then don't spend half your post talking about your product!

3.
Don't understand the question

Not a question. As a statement its also prejudical. One could as well say "orthotics should not be flaccid bits of foam". Neither are valid because both presuppose a negative connotation to the item in question and both are "staw men".

Also not a question. But if you are asking IS the body a mechanical system then i'd say that it is. With biochemical etc influnences and mechanisms of course but IMO the musculoskeletal system is certainly mechanical! Axis, pivots, moments, forces, kinematic and kinetic variables etc etc etc.

Depends if it improves patient outcomes.

Perhaps, charlie, it would be wise for you to start a new thread on your new model. Leave the Product at the door and tell us of your thinking and your new approach. Then we can discuss it on merits.

Regards
Robert

 

Charlie:

I gave you a respected response because, in previous discussions with you, you have been very reasonable and aware of the current thinking and research on foot and lower extremity biomechanics and orthosis therapy. I believe that you got "hot tongue" from the others because, recently, we have had our share of individuals claiming to be "experts" here on Podiatry Arena that were interested only in trying to sell their products/patents/trademarked ideas and who did not even come close to understanding the current research enough to have a meaningful conversation with us.

If you want to be taken seriously from here on, and not get, as you say, "hot tongue", I suggest you leave out a discussion of your product and especially a discussion of what feel are its merits unless you have some peer-reviewed research which shows that your company's product is indeed superior to other in-shoe insoles or orthoses. In addition, I would suggest that if you want a response in the future to a question, then ask one question, not thirteen questions. I only responded to a few of your questions and that took me about 45 minutes to write. I would rather not respond at all than respond in a fashion that is meaningless and curt. I am very busy, as are most of those who contribute here on Podiatry Arena, and I pick and choose what I respond to as time allows. Responding to a list of 13 questions posed by an infrequent poster on Podiatry Arena is not the full time job of anyone here.

I never said that the "human body is not a mechanical system". Please don't put words in my mouth. Here is what I actually did say:

As far as "new models", there are many models currently that include central nervous system (CNS) control as their basis. Probably most prominent is the Preferred Movement Pathway Model advocated by Benno Nigg and his coworkers (Nigg BM: The role of impact forces and foot pronation: a new paradigm. Clin J Sport Med, 11:2-9, 2001). In addition, many of our discussions here on Podiatry Arena have focused on how the CNS responds to fluctuations in moments acting across the joint axes of the foot and lower extremity. One of my favorite set of early papers on foot biomechanics are from John Hicks from about 50 years ago where he describes the CNS response of muscle firing patterns to maintain bipedal and unipedal balance (Hicks, J.H. The Three Weight Bearing Mechanisms of the Foot. Pages 161-191 in F.G. Evans (ed): Biomechanical Studies of the Musculoskeletal System. C.C. Thomas Co., Springfield, Ill. 1961). Therefore, your suggestion that the neurological or CNS control aspect of orthosis therapy is not being considered would not be an accurate statement. I consider CNS control and its effects on the kinematics and kinetics of gait and have often discussed it in my Precision Intricast Newsletter books.

I am anxious to hear about your "new theory". Where exactly is it published? Please give us references for your theory so we can analyze it and discuss it further.

Have a great Christmas!!:santa:

 

Thanks for your comments on my posts. On reviewing them, I take your points and will carefully avoid any future references to “product X”. I guess we can all benefit from a good “telling off” from time to time. It is not my intention to abuse this forum for “advertising” purposes although some of my statements let me down in this.
In replying to jerseynurse’s comments about unsatisfactory orthotics what I meant to say was that, in my opinion, this is due to deficiencies in the current understanding of the effects of the devices on lower extremity function and NOT to a lack of skill on the part of practitioners in applying the current knowledge. I should have left it at that.
I do have some ideas of how the current model and method might be improved upon (and so do others as was correctly indicated in your replies). I will give serious consideration to the possibility of contributing this to a more appropriate discussion and curb my apparent excessive enthusiasm/tone.
In interpreting published literature we ought to consider the implied bias in studies that compare the efficacy of a brand of product to that of custom orthotics, especially if the study is sponsored by the manufacturer and is not independent. One has to ask oneself “would this study have been published if the results had been different?”
Commercially sponsored studies and anecdotal reports are certainly at the lower end of the scale of evidence in which independent RCT studies and systematic and critical reviews of the literature provide better information.

In their review of the literature on the efficacy of foot orthoses (Efficacy of Foot Orthoses: what does the literature tell us? AJMP, 32:3, 1998) Landorf and Keenan pointed out that much of what we think we know is based on theory and anecdotes and is not supported by scientific evidence. They stated “Firstly, it is essential that there is further well-controlled research which evaluates orthoses under specific conditions – this is stating the obvious. Secondly, systematic and critical reviews of the literature relating to FOs are also required to assist practitioners and decision makers in understanding and assimilating the available findings.”

In, Foot Orthoses in Lower Limb Overuse Conditions: A Systematic Review and Met-Analysis, Collins, Bissett, McPoil and Vicenzino (Foot & Ankle International 28:3, March 2007) stated “The lack of higher order synthesis of clinical trials to date makes it difficult for a practitioner who wishes to use evidence-based practice in the prescription of foot orthoses.”

They also stated in their conclusions,
“There is evidence from pooled data that there is no difference between the use of custom and prefabricated foot orthoses, inferring that practitioners may use either in the prevention and treatment of lower-limb overuse injuries.”
With regard to the debate about prefabricated and custom orthotics, it seems to me that the word “orthotic” is currently inconsistently and overused and we should clarify what we mean by the terms “insole”, “arch support”, “prefabricated orthotic” and “custom foot orthosis” in this forum and more widely.
Collins et al proposed the following, “Based on evidenced published to date, we would propose the following definition for foot orthoses: in-shoe devices shaped to match the plantar surface of the foot and used in the prevention and treatment of injury, pain, and disability through the optimization of lower extremity function.”

In their opinion, the review of the literature did not support the necessity for “foot orthoses” to be made on a 3D model/cast of the shape of the plantar surface of the patient’s foot. “Custom foot orthoses, defined in the ACFAOM guidelines3 as being derived from a three-dimensional model of the foot, often are regarded to be superior to prefabricated (off-theshelf) foot orthoses. A particularly interesting finding from this review was the lack of any differential efficacy between custom and prefabricated foot orthoses, both from pooled data and individual study data that could not be pooled.”

In considering the efficacy of a device a great deal of emphasis is placed on relieving symptoms and there is a tendency to believe pain relief validates an improvement in lower extremity function.

However, Stacoff, Lafortune, Nigg and others have questioned the significance of the kinematic effects of orthotics and this leads me to think that although orthotics reliably relieve pain their effects on function are not well understood, predictable or assessable in a clinical setting.

Williams, Davis and Baitch (Effect of Inverted Orthoses on Lower –Extremity Mechanics in Runners, Med Sci Sp Ex. 2003) showed that although the devices were successful in relieving symptoms and reducing “Peak rearfoot inversion moment and work”, they did not have consistent and predictable kinematic effects “The frontal plane kinematic response to the inverted orthoses at the rearfoot was quite variable”, “Surprisingly, 5 of 11 and 6 of 11individuals demonstrated an increase in peak eversion and eversion excursion, respectively, between no orthoses and inverted orthoses conditions”.
This study also showed that the inverted orthoses actually INCREASED Internal Tibial Rotation, “However, internal rotation in the tibia (relative to fixed foot segment) was significantly increased in the inverted orthoses condition when compared with the no orthoses condition.” This contradicts the theory that foot orthoses reduce subtalar pronation and that this is coupled to predictable alterations in movement of other structures in the foot and leg.

So, with reference to the debate about prefabricated vs custom orthoses, I am persuaded to believe that the type of device used is not as important as the way in which the therapist selects and utilizes it in relation to the patient, the problem and the footwear in which it will be used.

I also think that in comparing the efficacy of various devices we should consider the possibility that any random shoe modification can alter lower extremity kinetics and thereby shift force away from a painful area without coincidentally improving the function of the lower extremity. From this perspective, reports that a type of in-shoe device has relieved pain (in studies or testimonials) do not necessarily validate functional efficacy and people publishing such reports ought to be rigorous in presenting evidence that function improvement has also been demonstrated.

Wishing you all the best for 2009.
Charlie Baycroft

 

Hey charlie.

NOW you're talking! This is something we can get our teeth into and pull apart together!:drinks

Your's was a long (and well written) post. So lets pick a few highlights to focus on.

I agree.

The studies you reference, excellant as they are, are all somewhat flawed in that they usually pick one pathology to study (often heel pain.) As we know there are many different biomechanical circumstances which may predispose somebody to heel pain. The orthotic should, IMO be targeted to this rather than the symptom itself. For eg, an acute PF heel pain with active tendon damage cannot be considered alongside a chronic rumbling inflammatory heel pain. They are different animals! To lump them together in a study will give potentially misleading results.

Its akin to saying "bob and mandy both drive to work. Bob drives a pickup, mandy a moped. They both break down. What is the best garage to take them to.". Its inapplicable because whether you take them to a car garage or a moterbike centre will not be chosen randomly in real life! A study on 100 bobs and 100 mandies would show equal efficacy of the two types of garage. One might then conclude that there was no benefit to having a special garage for mopeds as they perform no better than Car garages in a study. You see where i am rambling?

They also refer to "custom casted" usually in context of a standard root prescription. This, IMO, is fallacious as who among us only uses one device and one prescibing modality? As you say what prescription and what type of orthotic chosen in real life depends on the patient, the lifestyle, the footwear and the problem.

This bears on another point you made

Hmm. I'm not sure this can be derived from

There is a difference between saying that the literature does not indicate a substantial difference and that no difference exists!

There is a danger that we overextrapolate from these studies. They examined one pathology with multiple causes, a very VERY limited degree of customisation in the custom group and a single pre fab. Whilst the best evidence available they are still a long way from answering the question for good!

There is also the point on inductive vs deductive evidence to be considered. Much / most of what we do in biomechanics is based on deductive evidence. This cannot be definitivly stated one way or other but can well be argued in both directions.

If we take your statement

at face value consider this. A patient walks, (limps) in with a Whacking great planter exostosis at the 1st met cuniform joint. He has arthritic pain in the joint reproducable on palpation of inversion at the mtj AND superficial prominance under the base of the 1st met causing HK. Poor sod.

You want to decrease the eversion moments at the rearfoot to decrease the inversion moments at the MTJ. Would you want to put him in a prefab shell (lets say an interpod) or an orthotic casted to accomodate the exostosis? I suspect the latter. The patient, being a googledoctor, asks is this supported by the literature? No. This is based on deductive evidence. In the real world N always equals 1 and that, IMO, can superceed broader inductive evidence.


Kind regards and a happy new year!:drinks

Robert

 

Definitely.

In context, McPoil seems to be the only person of the 4 with a specific area of focus in podiatric medicine, according to their individual participation in published works. Not knowing these names, I have no idea the reputation they have, nor the reputation of the labs they worked with to provide the 179 pairs of orthotics to compare to the 179 pairs of flat sheets of material, nor the shoes that each of these patients wore. Of the remaining 3, Collins has many articles credited to him, but no specific focus of interest, and Bissett and Vicenzino seem to focus on sports medicine. Of the 4, and since I don't know any of the names, I'd be interested to know where Collins fits into all of this, and who, if anyone, financed this research.

 

Nicely written post, Charlie. :good:

While I don't have time to address all of your points, I would to comment regarding kinematic findings from inverted orthoses. I have noticed, as has also Dr. Richard Blake (inventor of the Blake inverted orthosis) that if the foot orthosis is over-inverted, that actually more subtalar joint pronation occurs, but this motion occurs in late stance phase, not early stance phase.

Therefore, care must be taken that when interpreting research on "increased internal tibial rotation" or "increased rearfoot eversion" that the authors have separated out early and late stance phase kinematics of the rearfoot/tibia in their research. This is due to the fact that the correct amount of inverted position of an orthosis will decrease early stance phase rearfoot pronation motion and too much inverted orthosis correction will decrease rearfoot pronation motion in early stance but increase rearfoot pronation motion in late stance phase.

 

I have trouble to understand this. Are you saying that an orthotic should have predictable effects on rearfoot kinematics and that the STJ should be prevented from pronating to allow the foot to hae a mobile adaptive function in the contact period of stance?

 

In reference to paper by Collins et al, it is not a study of heel pain. It is a systematic review of the literature relating to foot orthoses in the treatment of overuse conditions of the lower extremity. In the hierarchy of medical evidence such reviews are considered level 1 evidence. Another interesting thing about this review is that an effort was made to use people who were not biased toward one form of therapy or another to review the literature.
If anyone would like to read this paper, in order to give more informed comments on it, I can forward a copy.
In clinical practice there is generally a degree of bias and placebo effect because we honestly believe that the form of therapy we use is the very best option. We all have bias from our training, personal experience and professional culture to a certain therapeutic preference and it is difficult to detach from this emotional connection and change one’s opinions. The observation that one’s patients appear to respond well to a certain therapeutic modality does not invalidate other therapeutic modalities or prove that the modality used gave a superior outcome to that which might have been achieved with one of a number of other options, or to no therapy at all.

Nachemson and others have shown that the natural history of most musculoskeletal conditions is to spontaneously resolve. Landorf, Keenan and Herbert have shown that there is little, if any evidence to support the long term efficacy of foot orthoses (Effectiveness of Foot Orthoses to Treat Plantar Fasciitis A Randomized Trial. Karl B. Landorf, PhD; Anne-Maree Keenan, MAppSc; Robert D. Herbert, PhD. Arch Intern Med. 2006;166:1305-131) , “studies of the effects of orthoses are generally of poor quality, and to our knowledge, no trials have investigated long-term effectiveness.”
The movement toward evidence based medicine is resisted in all medical disciplines when the evidence does not support popular practice habits. This is common to medical practice in general. I am not criticizing Podiatrists.
In their review of the literature in 1998, Landorf and Keenan showed that evidence strongly supports the belief that foot orthoses of various kinds are productive of high patient satisfaction. Orthotics work very well. The question is how do they work?
Recent literature, as referred to in the Williams paper and the excellent (in my opinion)presentations that Kevin Kirby and Craig Payne gave in Australia last year, persuade me to believe that orthotics achieve their effect by altering kinetics (moments of force) rather than altering kinematics (movement of structures). This seems to be compatible with the “tissue stress model” presented by McPoil and Hunt in JOSPT, 12:6, 1995. Altering the surface beneath the foot changes force vectors acting on various structures in the lower extremity and if this reduces the loading on a painful structure (or small segment of tissue within this structure) then pain is relieved. Patients demonstrate this by altering gait (limping) to relieve pain in some body part.
If the tissue stress and kinetic theories are valid then symptoms can respond favourably to any random change of the surface under the foot. It also follows that changing the surface under the foot can increase the loading on tissues and create symptoms and some publications have mentioned that orthotics can have undesired side-effects.

Is Relief of Pain the Correct Measure of Orthotic Efficacy?
Applying the tissue stress theory to the literature about custom and prefabricated orthotics, it is possible that efficacy (relief of pain) can be attributed to a change in the surface under the foot, which may or may not be beneficial in the longer term or compatible with efficient function of the lower extremity (which also needs to be better understood).
In 1983, Sperryn and Restan (Podiatry and the sports physician--an evaluation of orthoses. British Journal of Sports Medicine, Vol 17, Issue 4 129-134) studied the effects of custom foot orthoses (prescribed by a Podiatrist) in the treatment of a variety of sports injuries and stated, “If only about two thirds of patients benefit from them (orthotics) and half continue their long term use, critical selection of cases is required in both clinical and economic grounds.”
In a previous post I alluded to a “lump of plastic” and received a predictable response. I was not saying that custom orthotics are just “lumps of plastic”. However, if a device has no beneficial effect on lower extremity function is it any better than a “lump of plastic” or a “lump of foam” in the case of prefabs?
I recall Harry Hlavac writing, in his foot book, that a patient’s symptoms can be relieved by using a wedge the size of a book of matches and the trick was in knowing where to put it. If the placement of such a wedge relieves symptoms is it a wedge, a prefab or a custom orthotic?
There is evidence that many types of shoe inserts relieve various symptoms and this evokes lively debate about the validity of the various studies and people’s personal preferences. However, it is implicit in the definition of the term foot orthotic device that the function of the lower extremity should also be improved and this is not well addressed by either the literature or our opinions of the relative merits of various types of devices.

 

Charlie and Colleagues:

I do believe that foot orthoses should have predictable effects on rearfoot and other segmental kinematics as long as we have accurate theory to guide our predictions and sufficient data by which to make those predictions. I believe we have come a long way in that goal from the time of 28 years ago when I was taught by the biomechanics professors at CCPM that nearly all prescription foot orthoses should be made of Rohadur, should end at the metatarsal necks and be should be made over a cast with vertical heel balancing.

I did not say what the subtalar joint (STJ) should be doing in my original posting. What I did say was that Dr. Blake and I, including many others who have used inverted orthoses for many years, have noticed that inverted foot orthoses may actually cause increased STJ pronation motion, especially in the late midstance phase of walking gait, if the inversion correction is too great and causes STJ supination instability. The point of making this comment was to emphasize that we must be very careful when discussing the kinematic effects of foot orthoses on the rearfoot and/or tibia in that we are very specific as to when the rearfoot/tibial motion is occurring within the stance phase of either the running or walking gait cycle.

My theory of why this somewhat paradoxical kinematic phenomenon occurs is that during late midstance, when the foot is preparing to move into propulsion, the central nervous system (CNS) is constantly monitoring the effects of external STJ moments from ground reaction force (GRF) acting on the foot and the internal STJ moments acting within the foot from muscle/tendon tensile forces. This afferent information to the CNS is processed along with the hard-wired and learned neuromuscular firing patterns from the CNS to determine how the individual responds to the perturbations in GRF patterns that may come from events such as stepping on a small rock or stepping on an inverted foot orthosis.

When there is an excessive medial shift in GRF on the plantar foot that causes the center of pressure (CoP) to be either too close to the lateral side of the STJ axis, directly under the STJ axis or medial to the STJ axis, then the lack of adequate external STJ pronation moment from GRF during late midstance (that is necessary to counterbalance the internal STJ supination moment from gastrocnemius-soleus muscle activity) is recognized by the CNS as a potentially dangerous situation of supination instability of the STJ. The CNS will then modify the neuromuscular firing patterns to the lower extremity during late midstance and propulsion to 1) increase the contractile activity to the peroneal muscles to increase internal STJ pronation moment, 2) decrease the contractile activity to the deep flexor muscles to decrease internal STJ supination moment, and 3) decrease the contractile activity to the gastrocnemius/soleus muscles during propulsion to decrease internal STJ supination moment.

The direct result of these CNS-directed alterations in firing patterns to the muscles of the lower extremity in response to excessive STJ supination moments being generated by an over-inverted foot orthosis is an increase in late midstance STJ pronation motion, a decrease in STJ supination motion during propulsion, a decrease in ankle joint plantarflexion motion during propulsion and a decrease in relative length of the propulsive phase of walking gait.

Therefore, foot orthoses should be considered to have both direct kinematic effects where they "push the foot" into a new joint position and indirect CNS effects where the "push on the foot" from the orthosis results in an alteration in CNS firing patterns that ultimately alters the magnitudes and temporal patterns of internal joint moments within the foot and lower extremity.

Hope this discussion helps to better explain a specific example of why I believe that we should never neglect the critically important role of CNS control of the lower extremity muscles in the design of foot orthoses for our patients.

Happy 2009!:drinks

 

Hey Charlie

This is something close to my heart and something which has long been argued. Ask anyone who knows me my view on homeopathy and they'll tell you that! However i think your argument here is flawed on two grounds.

One is your definition of EBM. Craig hit me with this one a while back when we were splitting this very atom. This a A quote from Sackett, who wrote the book on EBM

For me the key point here is the "neither alone is enough" statement. Published evidence is essential but is inherently flawed by the act of controlling extranious factors. Personal experiance is essential but is inherently flawed by our inate irrationality. So here we have a discrepancy. We have deductive evidence and experiance which shows a justification for custom casted device, but also some inductive evidence which shows no such justification. Is it therefore prudent to abandon the former in favour of the latter? As Landorf states and you quote

So i contend that when weighing the importance of the two elements of EBM we cannot discount either in favour of the other.

What you describe as the move towards EBM must be made using both available evidence AND "practice habits".

The second Point on EBM is that which i alluded to earlier in terms of inductive and deductive evidence. This, for me, is where biomechanics is different from the more esoteric unsupported modalities. I cannot point to a paper which shows concluesivly that the orthotics i issue work better than pre fabs, or indeed placebos. Neither can the homeopath. I can state that empirically i get good results. So can the homeopath. However i can provide reference to theoretical papers and constructs which support a deductive rationale for HOW and WHY what i do might work. The homeopath cannot.

To pick up on another of your points:-

Yep, no problem here. Forces are what cause damage, not movement. Of course altering moments beyond the residual moment in a joint will also affect a kinematic change but its the kinetics we're aiming at. No revalation here.

Yep, again no revalation. Of course it changes more than vectors, it changes timings, degrees of loading, can change kinematics and axial positions also but i catch your drift.

Eh?!?!

Don't see your point here at all! Do you mean that ANY change can cause improvement in symptoms? Especially as you go on to say:

What is your point here? Are you infering that the effect of a surface change under the foot is random? Are you saying that some changes will have a beneficial effect and some a detrimental? I really don't see where you are going with this! Could you clarify please?


Finally, I asked a question a few posts back. I would value your thoughts on it!

Kind regards
Robert

 

Dear Robert
Sorry, I cannot get the quote thing to work on the forum and when I try to click post it chucks me out. So, I have written this in word and am copying it in. Either I am dumb or Podiatry Arena doesn’t like me or both?
1st and foremost. I am neither saying nor implying that an insole out of a bag is equal to or superior to a custom prescribed orthotic device. I do not like the term "prefabricated orthotic". It is an oxymoron that poses the questions. For whom? For what problem? For what activity and what sort of footwear? Some products can be modified in various ways to provide an adequate temporary or more long-term solution for a specific patient and some cannot.
The therapy is the knowledge, experience and expertise of the therapist.
I sense, correctly or incorrectly, that you are taking some of my comments rather personally and are tending to defend your experience and skill. Podiatrists do sometimes take offence at the comments of "outsiders" like myself. While I do not have any basis for judging your skill and professionalism, my sincere hope is that they are both excellent. Why would I presume otherwise?
I think I already stated in other posts that IMO Podiatrists are skilled and ethical medical professionals. If some are not, it is not my place to judge. What more can I say?

EBM. Of course I agree with you that clinical experience is relevant and valid. However, there are occasions when beliefs and habits do benefit from the findings of scientific research. I also think it is true that medical professionals often react quite negatively to research findings that challenge their habits and beliefs. This is because they are doing what they believe is in the patient’s best interests and are reluctant to risk change.
I also know that clinically N=1. You kind of learn that from practicing medicine for over 35 years. One also learns that our understanding of the human body in sickness and health is often inadequate, flawed and has the potential for great improvement. That's maybe why we "practice" medicine and can always become better at it. Scientific research helps us with this.
You asked about abandoning custom orthotics in preference for “prefabs”. I hope that you are not implying that I suggested this because I never did.
In relation to clinical “reality”, one generally only gets to assess the response to the treatment that one used and not to other treatments that might have worked as well or possibly even better. If I started to make a point with “in my experience” you would be justifiably sceptical of what I said if your experience was different from mine.
As you say “I cannot point to a paper which shows conclusively that the orthotics I issue work better than pre fabs, or indeed placebos. I can state that empirically I get good results.” Please do not take this personally but this is the big problem with clinical experience. Every practitioner follows their own intellectual and emotional inclinations and very few formally review patient outcomes from a long-term and statistical perspective. You say that you get good results but that does not mean that your patient’s could not get equally good results from another therapist or by using different methods. For instance if you only ever use a few of the available modalities you cannot say what results you or your patients might have achieved with alternative or no therapy at all. I don’t know of any medical practitioners who do not believe the same things about what they do. Various people have varying ideas of what good results are for them and their patients. The homeopaths that you referred to might also make the same claims (and they do). You could be a person of such great charisma that the placebo effect (directly proportional to the confidence of the patient and the therapist) of whatever you do might be hugely powerful. Patients could perceive you as such a genuine caring guy that they could never bring themselves to tell you that their orthotics are un-satisfactory. One thing I learned early in my career was that patients are more impressed by how you treat them than by what you treat them with. I think it is reasonable to place personal “experience” and case reports at the lower end of the scale of evidence and non-biased systematic reviews and meta analyses of the literature, like the Collins paper I referred to, as 1st order evidence as Sackett also said.
Tissue Stress and kinetics. Because the sole of the foot is the "sole" physical interface between our environment and the musculoskeletal system the interaction of the foot and the surface beneath it can have a great effect on the magnitude and direction of linear vectors and rotational moments of force acting on various structures. Forces produce tensile, compressive and shear loadings on tissues. If and when these loadings overcome their resilience the effected tissues generate pain by various mechanisms (mechanical and/or chemical). In many cases, which we label "overuse syndromes", the site of tissue overloading is actually quite small and the actual tissue pathology (inflammation, degeneration, disruption, etc.) is often uncertain. If we change the interface between the foot and the environment we can alter the force acting on the symptomatic site. If the forces are reduced in magnitude or directed away from the site of pain then the pain is likely to be relieved. Since the area of tissue that is producing the pain is generally quite small (even though the pain may be perceived over a greater area) one ought not to have to alter the force moments or vectors greatly in order to reduce or redirect them away from this small site.
This is what I understand the tissue stress theory to be about. It is explained in more detail and with reference to other orthotic theories in McPoil and Hunt’s paper, which I quoted previously.

What I am saying is that if the target area of tissue is small and discrete, a random change in the interface between the foot and support surface has high statistical probability of reducing the loading on it and relieving the pain.

I am going on to hypothesize that this relief of symptoms does not verify an improvement in lower extremity function.

I am not using this explanation to find fault with any orthotics. What I am saying is that pain relief might not be the ideal or correct criteria for evaluating orthotic efficacy. In saying this I am not denying that pain relief is still very significant to the patient and therapist. However, I am prepared to defend my opinion that it is not all that difficult (in general, not specifically for some difficult case you might offer as an argument) to relieve symptoms by modifying the surface beneath the foot in a random way. That is why testimonials from satisfied users of “orthotic” product A to Z are not evidence and rather invite the response “no big deal, what effects did they have on function?”

If, by definition, a foot orthosis should relieve symptoms and improve the function of the foot and leg than a study that evaluates pain relief does not necessarily assess orthotic efficacy if it does not assess function as well.

The conclusions of studies comparing custom orthotics and mass produced innersoles that there is no difference in efficacy may be valid in relation to symptomatic effect but I am suggesting that they may not be valid in relation to the effects on lower extremity function. Custom devices should be superior in relation to functional efficacy.

I am sure that you are aware of instances in which patients have pain relief when wearing their orthotics in the wrong shoes or from borrowing a friend's orthotics. People also get relief by changing shoes, buying OTC insoles or ordering “custom” orthotics over the Internet or an 0800 number. This is an illustration of what I am trying to say. Did the pain get relieved? Yes. Were the orthotics correct (borrowed or in the wrong shoe). No! Have you seen patients get relief from horrible orthotics "prescribed" by non-Podiatrists? I have and offer the same explanation. Random alterations in force vectors reducing the loading on and stress in symptomatic regions of soft tissue structures.
Yes, I do believe that it is really simple to relieve a patient's pain with orthotics and that almost any shoe modification is statistically likely to achieve this by randomly changing the magnitude, direction and rotational moments of forces acting on the site of the pain.


What may be lacking in relation to foot orthoses is an agreed, and valid clinical way to assess their functional effects. Perhaps we should begin a thread dedicated to discussing the various functions of the lower extremity (support, locomotion, postural stability, adaptation to surfaces under the foot and others you might think of) and how to assess and improve them with foot orthoses?
We used to think we could do this by looking for kinematic changes and some people had the ability to accurately replicate the findings of a hi-tech gait lab with their own eyes as the patient walked across the room (some still claim to have this unique ability). What I perceive from my reading (I will never again say "the literature") is that although foot orthoses do produce kinematic changes, these are neither predictable, significant nor systematic and there is currently some support for the hypothesis that the mechanism of action of orthoses is on kinetics (changing vectors and moments of force). If you would like to read some interesting things I recommend Benno Nigg’s website, www.biomechanigg.com.

I am saying that a random change under the foot can relieve pain but that does not mean the object used to create this random change actually meets the definition of a functional foot orthosis. I am not saying that custom orthotics create only random change the surface under the foot.

BTW. How do you incorporate STJ axis and rotational equilibrium theory into your prescription for custom devices and how do you validate the effects of the resulting devices on the function of the patient’s lower extremity? I would sincerely like to understand this better.

3D Model of the foot. I am referring to the Collins review of the literature and can send you a copy to read if you wish. What I am asking is what is the basis for believing that an orthotic is not custom if the shell is formed directly to the person’s real, actual, live foot instead of to a 3D model of that foot? IE, if one forms a thermoplastic material to the sole of the foot, in a desired posture and then balances this “shell” with appropriate posts but no 3D model of the foot is used is the resulting device “custom” or something else? IMO, the use of a 3D model/cast originated as a necessity for forming scalding hot sheets of hard plastic to the desired shape and not necessarily because it improved the efficacy of the resulting devices.
Homeopathy? Releasing the “energy” and “detoxifying” the chemicals in a solution containing a concentration of a substance less that Avogadro’s number activated by shaking or banging it with your hand? Yes, people do report getting better but why and how? The body heals itself (Ben Franklin said “Doctors collect the fees.”). The Placebo effect is real. Some would apply Barnum and Bailey’s theory of “a fool born every minute and someone to take him in”.
Wikipedia “Claims to the efficacy of homeopathic treatment beyond the placebo effect are unsupported by the collective weight of scientific and clinical evidence.[4][5][6][7]”
I hope that a reference to Homeopathy is not relevant to this discussion, but those that practice it do often cite literature supporting their claims for its efficacy. They also use some of the other arguments that you have proposed in your posts about “inductive and deductive evidence” and how scientific methods are inadequate for determining what works in a clinical setting. Several “successful” Homeopaths with abundant patients have told me that the validation of their theory only awaits the development of more sophisticated technology.
Cheers
Charlie

 

It depends on method of modeling, to be honest. There's at least one scanner, while being a laser scanner, that doesn't even output accurate altitudes, and even my scanner had a problem longitudinal length problem due to how I was calculating steps per inch, because I had forgotten to account for belt thickness. One competing product produced an output altitude that was half of what mine did for the exact same cast, which would have produced a very conservative device in my own software. Would it have been a custom device? Sure, but it wouldn't have been as good as it could have been, due to the garbage in garbage out factor.

Any modeling of the foot must have a reasonable level of accuracy to be considered identical to conventional casting.

 

Dear Joe
Thanks very much for this interesting information about the potential for errors with optical scanners. This is an area that interests me greatly at the moment. I will have a look at your website to learn more about what you are doing.

From what you are saying it appears that there is a potential for errors to occur during the process of scanning a foot and then using this digital information to either make a 3D model (positive cast) or directly mill an orthotic. As I understand there is also a potential for error in the older process of talking a cast (refer to the the thread about Neutral Subtalar Joint position) and having the prescription information incorporated in to the process of pouring the positive cast, modifying it, forming the material to the cast and adding the posts. Some very experienced Podiatrists have told me that they generally have to adjust the custom devices in their office when dispensing them to the patient and evaluating their functional effects and the fit to the shoe.

If I am correct that there is a potential for errors and miscommunication inherent in the process of making a 3D model of the foot then why is this considered superior to forming the shell of the device directly to the patient's real foot, in he desired position, under the Podiatrists total control in the office?

This is the wuestion that I have been asking all along and it appears difficult to get an answer. Of course I could be at fault for not stating the qustion correctly?

A foot orthotic shell made using the intermediate step of making a 3D model of the patient's foot is considered custom.
Is a device formed directly to the sole of the patient's foot, by a skilled Podiatrist and adjusted as indicated also custom? If not why not?

Best regards
Charlie

 

What I was referring to were design flaws. For my own scanner, I originally calculated 1 inch of travel to be 1017 microsteps, but in reality, I needed to include the belt thickness as a part of the calculation, which resulted in 981 steps per inch, +- 0.0025 non accumulative. What a competitor is doing with one design appears to not produce the correct altitudes, but the end result is a more conservative device, because their system is erroring roughly half of the correct altitude. In a sense, it is attempting to build cast corrections into the scan, but my own software does this already so it's a real problem as far as I'm concerned. Another point on this system. As it was nearly a copy of the another scanner, it too has the inherent weakness of being unable to scan blue biofoam. That's what one gets for not coming up with an original idea.

For the network of labs I work with, typical adjustments to the original products are from 2 to 5%. I'm too disconnected from the podiatric professionals they work with to determine what's done in the practitioner's office, but I'm looking forward to this changing over the coming year. I see it as an opportunity to improve things in this area.

All egos asside, everyone makes mistakes. It's called being human. Whether it's in plaster, biofoam, or scanned, there are potentials for errors anywhere along the process of making an orthotic. Fortunately, machines don't come in with hangovers, so the more automated, the better. For my own product, the customizations will be designed for the least possible deviation from what is done in the office already, so there will likely be a number of variations, from horizontal to vertical scanning, prone to supine, and multiple possible angles. As to superior, the first thought when casting plaster vs non-weight bearing scanning is that there is no cure time. As much as a patient tries to sit still, they still move, and the plaster is sometimes deformed as a result. Then there's time saved over cure time, and time saved over shipping, from days to minutes. As to communication and training, the podiatrist themselves could do all but machine the orthotic in office if they chose to and were willing to learn. Most, however will likely prefer to simply scan the patient's foot ad fax a prescription, at least in the beginning. With proper training, almost no communication at all will be required between podiatrist and lab.

If you're referring to what to claim on an insurance form, that's one thing and usually clearly defined. Conventional cast corrections explicitly use the 3D topography of the patient's foot. What you're describing at least in my opinion is more of a subjective claim not following with conventional and generally accepted practices, although I do see a trend towards the lowering of standards, which is a concern. If your patient is happy with the results, I don't know that I could really argue the point.

 

Dear Joe
Thanks for the interesting information about scanned orthoses.
Enabling the Podiatrist to incorporate cast correction and prescriptive elements into the scan before sending it to the lab seems to me to be an advantage because it increases the Podiatrists influence in the manufacturing of the device and how it will function dynamically and statically with the patient's foot and footwear.

I was not talking about insurance as I do not believe that the motivation of insurance companies is for the best interests of either patients or health professionals. I am more inclined to agree with Michael Moore about them.

Medical standards and practices ought to be related more to research and clinical experience than to the self-interested opinions of insurance companies, whose major motivation is usually profit and the avoidance of claims.

What I am asking is why an orthotic is only considered to be "custom" if the shell is formed on a 3D (manual or scanned cast) replica of the patient's foot and not directly to the sole of the patient's foot under the control and expertise of the Podiatrist?

I am not talking about a compression formed insole made in a factory in Asia but rather a device that is formed to the patient's foot to create a custom shell and balanced by the application of wedges by the Podiatrist with his or her own hands in his or her own office.
Should such a device be considered "custom" or, if not, how should it be defined?

Cheers
Charlie

 

I would consider a device, where a preformed orthosis is modified by the clinician to be made more custom, to be called a customized pre-fabricated foot orthosis. If the orthosis is formed directly to the patient's foot, or to a 3D image of the foot, then it should be called a custom-molded foot orthosis.

 

Kevin
Thank you. I think that these are good definitions.

"I would consider a device, where a preformed orthosis is modified by the clinician to be made more custom, to be called a customized pre-fabricated foot orthosis. If the orthosis is formed directly to the patient's foot, or to a 3D image of the foot, then it should be called a custom-molded foot orthosis."

We should apply these definitions in interpretting the various studies that compare custom and prefabricated orthoses and utilize the convention that the prefabricated device should only be called a "prefabricated orthotic" only if it was not modified by the clinician to be a "customized pre-fabricated foot orthosis" or formed directly to the patient's foot to be a "custom-molded foot orthosis".

Vested interestes of sickness insurance companies aside, if a study is comparing a flexible device that was altered by a clinician or formed directly to the patient's foot with a more rigid device that was formed on a 3D image of the patient's foot in a lab, the studies are actually comparing two different types of "custom" orthoses.
If the results of such studies are interpreted as indicating that a prefabricated orthotic (out of the bag, without customization) is as effective as a custom device then I would argue that this conclusion is incorrect.

In some studies the "prefabricated" product has been custom-molded to the patient's foot &/or modified by grinding, posts or other additions. If people use the findngs of this study to argue that a "prefab" is as effective as a custom then what they are stating is not supported by the reults of the study.

This is what I have been trying to state all along although, as I have acknowledged and apologized for, I did not do this very well at all in the beginning.

Perhaps someone can suggest how we should go about clarifying this distinction between Prefabricated "orthotics", customized pre-fabricated foot orthoses and custom-molded foot orthoses for the benefit of Podiatrists, researchers and non-Podiatrists?

Cheers
Charlie

 

As it happens, we probably agree, but only due to miscommunication. A podiatrist using my software would be able to produce a device based on a scan of the patient's foot in much the same way as a mold, and would have total control over the design of the orthotic. Using working data in a consistant manner to produce a device is likely much more repeatable than to observe the shape of a foot and modify a prefab. However, both positive and negatives of both methods can be observed in practice.

Alot more is done to a cast, whether it be a virtual cast made from a scan or mold than to just make an orthotic from it. From an software perspective, I consider a cast of a foot or a foot the same, except that one is a positive and one is a negative, and to consider whether or not it is weight bearing, semi-weight bearing or non-weight bearing. However, more is done in cast corrections than to match an insole to a foot., and to simply match an orthotic to a foot identically is probably more harmful than helpful. It would be identical to a nofill code in my own software, not performing any fill at all. If I were to compare the moving parts to a machine, it would be like restricting 40 to 50% of the pieces from moving, to simply match the shape of a foot. One function of cast corrections, adding fill is to allow for more fluid motion, whereas other accomodations might account for physical problems with that normal motion, such as functional halix limitus, fasciatis etc. In that respect, I would have to say that unless the podiatrist also performed some other function to simulate the expansion that occurs from at least a plaster fill, it hasn't arrived yet. This is not to say, however that A ucbl type of device wouldn't work the way you suggest, but it's sort of designed to control the foot more agressively. I do see the processes as being distinctlydifferent from each other for at minimum reasons for cast corrections but then if it works for you, this would just be considered an opinion., There would likely be some comparison if the casting from a foot were full weight bearing, but I suspect that too might be too aggressive.

 

Charlie:

You may want to again read our discussion from a few years ago on Karl Landorf's study on the treatment of plantar fascitis with custom-molded "sham" orthoses and custom-modified "pre-fab" orthoses. I think this ties in very nicely with your point here.

 

I take exception to the "random" concept. If we diagnose a 2nd metatarsal stress fracture, there is a short 1st metatarsal, and a callus sub send met head, then a random change is not going to be as good as a change that decreases the force beneath the 2nd metatarsal head.

My application of the tissue stress theory is to identify the structure that is injured and reduce stress on that structure. Putting a hole under the second met head should reduce the stress on the second metatarsal. Being this specific is somewhat different than what McPoil said in their tissue stress article. They were looking at generalities, whereas I'm looking at specific anatomical structures.

Function: In the above example normal function probably caused the stress fracture. Now the patient should alter their behavior to avoid pain on the second met. Is this sub optimal function? It prevents further damage to the metarsal. One problem when talking about improving function is that this assumes that we know what the best function is. As mentioned before, the vast majority of patients would rather be pain free than function optimally.

I've seen functional orthotics increase symptoms, in other patients and in my own feet. The first pair of orthoses that I wore were extremely painful until a plantar fascia groove was added. I've also had orthotics that caused sinus tarsi pain because of too much forefoot valgus intrinsic post. However, with my current orthoses, when I leave them home for a day my feet really hurt the following evening. I reproduced this enough times to convice myself that my current orthotics are doing something good.

Again the notion of random change bothers me. It is important to recognize which orthotic modifications relieve pain and which modifications increase pain for specific conditions/ anatomical structures.

Why is function more important than pain relief? If the foot doesn't hurt than the person attached to it, can use it as he or she pleases.

SALRE is a component of the tissue stress approach to mechanical treatment of the foot. Take the example of posterior tibial tendon dysfunction. SALRE predicts that this will tend to occur more often in feet with medially deviated STJ axis feet. In feet with medially deviated STJ axes the PT tendon has to work harder (have more tension) to produce the same amount of supination when compared to a foot with an average axis. This occurs becasue the center of pressure of ground reaction froce is further lateral to the axis, which causes a higher pronation moment in the foot with a medially deivated STJ axis as compared to a foot with an average STJ axis.

Therefore, in this situation, the goal of therapy is to decrease the pronation moment from the ground to decrease tension needed in the tendon. A varus heel wedge (medial heel skive) will shift the center of pressure more medial, thus reducing the pronation moment from the ground. A valgus heel wedge will tend to shift the center of pressure more laterally, causing an increase in pronation moment from the ground.

So, in a prescription writing protocol, you should base your decision of whether or not to add a varus or valgus heel wedge to your orthosis on the location of the STJ axis in conjuction with what prescription writing variables you feel will best decrease the stress on the injured structure.


"how do you validate the effects of the resulting devices on the function of the patient’s lower extremity?"


There are many ways and I think the bottom line is symptom reduction. Yes there are some problems that will resolve spontaneously even with the orthoses in the wrong shoes. So, that is still a problem that should be solved with a larger number of subjects in the study.

You could also look at center of pressure under the foot. (I have an ubpublished study with varus heel wegdes showing a medial shift in force under the heel.) You could look at supination resistance with a varus wedge or a valgus wedge under the heel. There are many more ways you could validate the theory.

Regards,

Eric

 

Hey Charlie.

Just to pick up on a few of your points (there were quite a few!)

Not at all! If i seem frustrated it is because, correctly or incorrectly, i sense that you are generalising "the way things are done."

Sorry. You're correct that you never actually said this. But this was the inference i drew from your posts. Comments such as

Could be read as such!

Like Eric i have a problem with this as a concept! A random change to the wb surface could do one of two things. 1. Reduce the load, 2. Increase the load. I could'nt comment on which is more likely, it depends on the condition, the foot and the change made.

How do you support the claim / opinion of statistical probability?

Here again i would fundamentally disagree. How can a foot in pain be functioning well? Most people i see would rather have a painless foot functioning sub optimally than a painful foot which we consider to be functioning well!!

If this is the question you have been asking all along then my apologies! It was not clear that this was the case. Your posts are somewhat loquatious

So, a clear answer to your clear question,

The systems i have seen which allow the podiatrists to form the shell directly to the foot in the office have all been somewhat flawed. Sidas is the one which springs to mind, a low temp shell material which can be moulded directly to the foot and wedged / skived to spec. My problem with it is that i tend to find the shells lose integrety quite quickly and the wedges / posts are rarely neat.

I do carry out a pod surgery clinic where i have no access to lab facilities and here i use Duomeds (lo over hi density eva) pre fabs which i heat mould to the desired shape useing a heat gun then backfill the voids. This works, however i cannot get them as neat, stable, or durable as something moulded to a cast and ground to desired shape. The backfills are never perfect and the fit to foot is never exact.

Also the process of cast modification enables me to incorperate modifications to the cast which are not possible in chairside. For example with the systems i have seen which form the shell to the foot as you describe i suspect it is not easy to incorperate, say, a pf groove.

There are errors inherent in moulding systems, however all the systems i have seen which bypass this process have greater difficulties in terms of material durability, orthotic finish, and freedom of modification. These are logistical and practical obsticals rather than theoretical ones.

Kind regards
Robert

 

Robert:

I liked your posting above.....but its meaning was somewhat diluted by your not using the shift key when typing your personal pronoun in the middle of your sentences. Sorry, but the proofreader in me just can't fully appreciate an otherwise well-written document when proper grammar and style aren't used.

 

Sorry. Next time i will try to do better.

Robert