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Foot Orthotic Mirroring

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Craig Payne, Oct 22, 2010.

  1. Craig Payne

    Craig Payne Moderator


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    When doing foot orthotic research is that we are really clear on exactly what we want from the lab, so the preference is to use a cad/cam lab for this pupose.

    I often am very precise in things like arch fill (see this thread on arch fill), and say we want, for example, 5mm on each orthotic (we need to be to control for everything in research). What I really notice is the very large differences between the left and right orthotic in their arch height when they come back.

    When I talk about this to the lab, they openly admit that their clients do not like the arch hieght differences and want the pair of orthotics to look similar ... despite being 'custom made', so they mirror them (eg if 5mm arch fill is asked for, they actually do 3mm on the right and 7mm on the left, so the orthotics look similar).

    I recall Paul Paris (Paris Orthotics) and Scott Marshal (KLM) discussing this a PFOLA conference workshop a couple of years ago. I do recall more than a few in the audience being somewhat surprised that this practice went on! It was an interesting discussion.

    What do you think of this practice? What do lab owners think of this?
  2. Mark_M

    Mark_M Active Member

    I think this is a very common practice driven by aesthetics.

    To go on from your point ...when fitting a device that has been mirrored, patients describe the feeling of one orthotic feeling higher than the other.
  3. Ian Drakard

    Ian Drakard Active Member

    Hi Craig

    Using CADCAM software, I can vouch for the tendency to 'even out' differences when designing a pair side by side. The main thing that stops me taking this urge too far is that I've seen the patients I'm designing for so I know when I want them to be similar or to be different.

    I suspect that in lab practice it comes back to the quality of casts they receive- they may well feel safer averaging out differences between sides?
  4. Graham

    Graham RIP

    Having talked to my lab about this there have been many practitioners who want their orthoses to look the same from side to side:wacko:

    I have requested that my devices are not mirrored and they apply that rule to my standard. Easy!;)
  5. You be surprised by the number of athletes who balk at perfect casts when they have different arch heights.

    When I build an orthotic per a Dr's Rx and say, "that what the doc said", they shrug their shoulders and say "OK".
  6. N.Smith

    N.Smith Active Member

    I'd have to say, as a rule, it's probably the done thing with all labs. Whether it's an unwritten law or habit. I'd guess that not many poeple that dispence orthotics, (if they haven't asked for and probably expect if they look) see a difference in MLA height or any other major difference in shape between L and R orth. I couldn't tell you, how many people I've seen, come to me with orthoses that weren't "working" because of massive differences between the shape, angle, valgus, varus F/F R/F, Tib post Disfunction, Nav.Drop, Lat instability, one foot pronated, the other supinated... the list goes on! In some cases it makes a difference (more resistance) and others it doesn't (less or no resistance), so from a labs point of view, they can only do what the practitioner prescribes ie: asking for a particular MLA height or shape on the L which could be different to the R.
    This has been a contenentious issue for me for the last 25 yrs. WHAT IS THE RIGHT SHAPE AND SHOULD EACH FOOT BE TREATED DIFFERENTLY?:deadhorse:(Sorry to yell) I believe so in most cases but it probably about people understanding more of what they want to do to the foot.

    In saying that, if an orthoses made with the MLA equal in height dosen't work, (and probably won't if one of the feet have high pronation or supination resistance) then a higher MLA, stronger material, medial or lateral flange, skive, invert, etc...is needeed.

    If a practitioner wants a MLA height to be higher or stonger in material strength, are they asking for it because of the greater force resistance or because one foot is more pronated or supinated than the other?

  7. mgrig

    mgrig Active Member

    I recommend that the clinician specifies left, right or both to scan. The criteria for selection should simply be:

    A) Indicate a left or right foot if the casts look different and examination findings suggest otherwise - in such case pick the best representation.

    B) Indicate both if the casts are different and there is significant differences in examination findings.

    C) Leave blank if the feet look the same and the casts look the same and you don't really mind which cast the lab chooses (obviously this depends on how much you trust your lab :) )

    D) If you don't believe in any of the above, just ask your lab to scan both!

    The reasons labs do it? Because as a blanket rule it produces a more consistent product. Ask most labs and they will say (anecdotally), if there is a unilateral issue with tolerance post production, it's usually 50-50 as to whether or not the problem device was actually the one that was scanned. Why? good question, however, I am sure it has something to do with the fact that it is hard replicate your own casting at the best of times, let alone on the other foot. Craig - I am sure you have a few articles and threads on this.

    It is certainly not an issue of cutting corners or saving money, as most people on the production line would take a bilateral scan over a unilateral scan, as there is no pressure to match shapes and positions on the left and right.
  8. As far as I'm concerned, if an orthosis lab or clincian is only scanning one cast from a pair of casts to make both orthoses "more symmetrical", and they are advertising that they are making "custom foot orthoses", then they are using deceptive marketing techniques to their customers and are using substandard custom orthosis manufacturing techniques. Just because other clinicians and orthotic labs do such things does not make it right.

    Custom foot orthoses means that both feet need to be scanned or casted to produce a pair of custom foot orthoses, not just scanning/casting one foot and then having the computer produce a mirror image for the other foot! Does the eye doctor just give the lab a prescription for the right eye because "they trust their lab" so that they can make the same prescription lens for the left eye and get a pair of glasses? No. And if they did that for your glasses, what would you think of the medical ethics of that company and eye doctor that did always make symmetrical lens prescriptions for their patients even though their eye prescriptions were asymmetrical? You would think they were either crooks or incompetent, wouldn't you?

    Orthosis labs and clinicians that routinely doing these types of cost-savings measures to produce medical devices that are not indeed custom orthoses, but rather a custom orthosis orthosis on one side and "best guess orthosis" on the opposite foot side, perfect mirrored clones of each other, and still charging the customer and patient for a full priced pair of custom orthoses, are possibly placing the whole foot orthosis industry at risk regarding their business practices and business ethics.
  9. Graham

    Graham RIP

    Agreed! If we are to debate the merits of Moments and tissue stress relief the application of our orthotic therapy MUST be foot specific! Don't you think?
  10. Phil Wells

    Phil Wells Active Member

    Dear all

    Just to clarify from the point of view of my CAD lab.
    We don't mirror the plantar surface of the orthoses but DO mirror the outer profile or trimline. If we don't then the patient feels the orthoses are either too wide or narrow in one of the shoes.
    Some customers on assessing their casts will ask us to mirror the better one to provide the better shape.

    The only complications come when you receive one good cast and one bad cast with both requesting the same RX - it is tempting to mirror the good one but as we don't have all the info, we don't.
    However these are the most commonly returned orthoses for adjustment!!!

  11. Jeff Root

    Jeff Root Well-Known Member

    Does mirroring benefit anyone other than the lab? It saves the lab labor but they don't pass the cost saving on to the practitioner. How symmetrical do feet need to be in order to justify mirroring and how can the lab quantify or determine this? I don't believe mirroring is a good practice.
  12. Which brings us back to how custom an orthotic needs to be in the first place... for some very custom, for others prefabs will do, yet how do we spot the the right horses for the right courses?

    I think if the consumer is being mislead this is highly unethical BTW. But if the clinician is knowingly ticking box on prescription forms to say which foot to scan in :eek: what does that tell you?:sinking:
  13. Craig Payne

    Craig Payne Moderator

    I think we need to make a distinction between:

    1) using CAD and only scanning one cast and mirroring the other orthotic to that one
    2) making the arch fill (either CAD or plaster) and other parameters similar on both the left and right, so the pair look the same.
  14. Isn't this basically the same thing achieved by different means? If you fanny about with the casts to the point that they are basically mirror images, then effectively you might as well pick one and make the other one match? Easier still, sell a pair of prefabs (but I guess the profit margin is lower) So what, we flip a coin to decide which foot? Laugh? No, I wish I was as rich as these lab owners... who clearly care much, much less.

    Like I said some years ago: too many people in it for the money, too many people who haven't got a clue... "Tick the box for lab's discretion....." And the guys working at the labs have all the information AND how many years of clinical experience.......?


    Patient: " I've tried orthotics and they don't work"....
    Me: "yeah, I see".

    Now lets talk about how orthotics work.......

    Somebody please tell me why the casting process is important... how does it ultimately determine the geometry and or load/ deformation characteristics of the device? Somebody explain to me how one casting technique can result in an orthosis of such unique geometry that this shape cannot be achieved by any other casting technique... bet you can't.
  15. Jeff Root

    Jeff Root Well-Known Member


    Say two practitioners cast the same patient. One takes a good, well contoured cast that conforms to the foot. The other takes a poorly contoured cast due to cast separations, inadvertently pronating the foot, poor technique, etc. Both practitioners order an identical "standard" functional orthosis from the same lab. One practitioner gets back a device that closely conforms to the foot while the other, due to the nature of the negative cast they submitted, gets a device that doesn't conform to the foot nearly as well. So while it may be possible for both casts to produce a very similar device if they were modified in a way to create a similar orthoses, it isn't likely that they would get similar devices back since the lab doesn't know the shape of the foot, just the shape of the cast.

  16. Jeff, you miss the point. With manipulation both casts can be made to have the same geometry- hence this thread. Moreover, you appear to be making the assumption that somehow conformation to the foot = good. I'm not so sure that this is always important. Ultimately, foot orthoses can influence only two physical characteristics: geometry at the foots interface; load /deformation at the foots interface. End of story. So we need to understand how these two characteristics combine beneath a single individual foot to bring about the desired effect. We are not there yet. Lack of conformity under the foot might well be the key.
  17. Jeff Root

    Jeff Root Well-Known Member


    I'm not missing the point. What I'm saying is that if two practitioners take very different casts of the same foot the probability that the resulting devices will have the same shape (geometry) and therefore will have the same loading characteristics, via manipulation of the positive cast, is very low.

    Create a positive cast and make ten duplicates in biofoam. Send them to ten different labs with the same instructions and you will get some significantly different orthoses geometrically speaking because of how labs process their casts. Then send the same patient to ten different practitioners for casting and have those practitioners send the casts to ten different labs, and the geometric differences will be even greater.

    So while I agree with you in theory that it may be possible to get the same geometry from different shaped casts, I think in reality it is higly unlikely.

    The other point is that the orthosis conforms closely to the cast of the foot in some areas, but intentionally deviates from it in other areas. This is the purposes of our individual style of cast modifications. I recently had a doc tell me how our medial heel skives are more aggressive than other labs. That’s because we actually alter the shape of the positive cast while many labs water down all of their cast corrections because of fear of the device being returned because it actually influenced forces. Too many plain vanilla orthoses out there for my taste!

  18. Are they though, Jeff? If we had tight prescriptions regarding the required geometry of the finished device, enough time and effort could result in the same thing.
    As you will recall, I've been saying that for about ten years. And that's the point! I send my identical casts to the different labs, I get different devices, yet the patient still gets better... Devil's advocate Jeff- "Your lab is better because......?"

    Agreed, but in reality, how much does it really matter so long as it's pushing in the right direction with enough force? How do you measure where and how much reaction force your devices are producing, Jeff?
  19. Peter G Guy

    Peter G Guy Member

    Hi everyone
    I am currently on the Advisory Board at Paris Orthotics in Vancouver, BC. I did a lecture on " Inside the Orthotic Lab" for a conference about 3 years ago. I interviewed 5 or 6 lab owners from Canada and the US for this lecture. Jeff I think I ask you some questions via email.
    I did a segment on cast mirroring. I pretty much told the audience sometimes the lab has no option to mirror the cast because one of the two casts are just bad. They can make an orthoses from only one of the the casts produced. That is why a lot of labs mirror the casts. I assume most of the practitioners on this thread are good volumetric plaster casters or 3D laser casters so this may not be problem for you but this a problem for the lab owners everyday.
    Anyone else who consults for a lab may already know this. I was unhappy about mirroring until I started to closely look at the casts coming into the lab. What does the lab owner do, phone every client and tell them their casts are bad. What you can do is ask your lab about how you can improve your casting.
  20. Pete:


    Tell the podiatrist that their casts are bad, that your orthosis lab only wants to work for podiatrists that take good casts most of the time and offer to train them to take better casts. If they say they don't have the time to learn to cast more effectively or if they say they don't like your policy, then I would tell them that they should find another orthosis lab to do business with.

    These are the decisions that orthosis labs must make on their way to becoming a quality orthosis lab. Remember that quantity doesn't always mean quality.
  21. Chirotech

    Chirotech Member

    In all these discussion i understand that all is using either CAD/CAM or a plaster cast.. How about those who uses heat mouldable type of casting like the ones mostly the French Podiatrist are using, they have this machine that can take the foot impression and able to get the positive cast of the foot and produce a heat mouldable orthotics immeadiately, it comes out well customised as each foot was taken in a neutral impression with the guide of the practitioner of course..And the material is very functional it seems and it fits well in most shoes i.e ladies shoes in particular...
    Whats is all your view in this technique as it has been around for quite some time, most French Podiatrist are using them and i have seen a number of my Frech customers using them. Definitely they are not prefabs....

    Thank you

  22. Neutral position hey, is that the Root neutral or the Langer neutral or the cadiver study which says that neutral not neutral neutral and while we are at it why is neutral important ? also do these devices end up looking mirrored.
  23. Ian Drakard

    Ian Drakard Active Member

    No- these inherently are not mirrored as they are direct moulded (usually), so this probably isn't the thread to dicuss these. I think they have cropped up in discussion a few times (Sidas is one of the main companies) so will try and search for the threads later- it may be a good topic to revisit.
  24. Hi Ian that was my point, maybe I should have just asked what the post had to do with mirrored orthotics by labs. Should stick to my normal bull in a china shop approach.

    but as you suggest a revist on another thread might be good.
  25. Ian Drakard

    Ian Drakard Active Member

    not used to your subtle approach ;)
    stick to breaking the china :hammer::drinks
  26. DanthePod

    DanthePod Member

    I think that Simon is really on the right track. We have been manufacturing CAD/CAM orthotics for over 15 yrs and have continued to upgrade and evolve our technology. We are a small lab so we have flexability in evolving our approach. I believe that the ability to prescribe orthotics to optomise the foots function is as dependent on key morphological characteristics as it is dependent on a clear assessment of the forces involved and understanding how any key sagittal plane restrictions can impact. Once armed with this information we should be able to make a more functionally efficient device. Why use CAD/CAM because as we evolve the understanding of the technology we can minimise human error better. Improvments in clinical understanding and protocols , minimising the orthotic lab evaluators role, improving tha accuracy of design application and manufacture once the parameters have been selected are alll integral to untimatly providing a better product. :bang:
  27. Chirotech

    Chirotech Member

    Well neutral is the man key in Foot functions isn't it, with the basic ROM in a normal foot that does have the normal foot functions...
  28. Hi Chiro in one word No . I won´t expain on it here as not to take away from the thread but read these threads -http://www.podiatry-arena.com/podiatry-forum/tags/index.php?tag=/subtalar-joint-axis/ it will get you started thinking a little differently. Goodluck it´s fun journey that I enjoyed.
  29. mgrig

    mgrig Active Member

    As a former lab employee I will have to defend the labs on this one. I don't believe it is a cost cutting method.

    - There are probably more than 12 stages that a pair of orthotics pass through during production.

    -Scanning both may effect two stages directly, and it is safe to assume that their workload would increase by appox 50% = around 10% more work for the entire lab.

    -But wait, down the production line --> shell grinding and top cover suddenly don't have to worry about matching shell lengths/widths and met pad placements etc...while it would not account for 10% less work on their part it certainly does make the job easier (as testified by those who work in such positions).

    However, if a lab does intend to mirror casts they should be completely up front and honest about it, explaining their reasons and supporting any customer who chooses to not mirror their devices. It should be up to the CLINICAN as to whether or not they want to match arch heights, mirror orthotics (if so which one?) or not to mirror orthotics at all.

    Also note, just because an orthotic is mirrored, does not mean that it has to have the same prescription variables.
  30. joejared

    joejared Active Member

    Let the practitioner prescribe. If s/he complains about the arch heights being different with different forefoot/rearfoot posting amounts, I'd be more inclined to verify the medical licenses or at minimum, suggest that it's what they asked for and/or respond with the noted differences in arch height of the casts supplied. In the theory, every foot orthosis should be treated the same and undergo the same process of manufacturing, unless otherwise specified by the practitioner. If a doctor complains about differences in arch heights with different posting amounts, or even the same posting amounts, the first thought that comes to mind would be good, that means both feet are being used in the process of making the devices and the likelihood that the devices are not based on a library device is decreased.

    Given enough tools, labs will cheat. In the absence of tools, labs will still find a way to cheat. There are times when a bad biofoam cast will come into a laboratory that is shreaded, barely providing much more than an outline. In cases like this, "mirroring" the one foot from the other can save on hassles but may well miss subtle differences between feet. In terms of data acquisition, a foot scanner in the practice can at least provide a means of safe delivery of foot data, or at minimum, a quality control checkpoint prior to electronic shipping of casts.

    More often than not from what I've seen, complaints about left and right profiles not matching are more common, in which case the topography is not disturbed by matching left and right orthoses. Averaging of topographies of 2 feet can also be done, but with newer technologies available to more accurately acquire foot data, for the majority of castings, this is an obsolete concept.

    Few wet labs truly mirror a device, to the best of my knowledge. They just grab a pair of positives off the shelf that closely match the reference cast, and use that pair instead. In fact, more than half of the diabetic inserts manufactured worldwide aren't based on the patient's foot, but rather another near match from a library of positives.

    The single largest weakness I see between the labs and doctors is the level of communication. For my own development, I'm beginning to think it's time to create a doctors database so that exceptions to the normal process can be emailed to them dynamically, such as making a mirror copy of a foot, or anything non-standard that has to be done to manufacture their product.
  31. As far as claims go that is massive and if that is so people need to be shut down and taken to court.

    But, where did that come from Joe have you evidence ? Thats a big , big statement and I guess you could say that if pressure and friction from a libary insole on a poor diabetic foot may in worse cases lead to death.

    .....................? Pandora springs to mind.
  32. joejared

    joejared Active Member

    Any evidence I have on this point would be considered hearsay, but no less true. I actually hope someday it will matter if any lab is exposed for such fraudulent activities in manufacturing, but I can think of one lab who has been exposed, with no real effect on their bottom line. They are still on of the largest labs in the US.
  33. Jeff Root

    Jeff Root Well-Known Member

    This was a known and public issue (see 2006 PM News story below).


    FBI Alleges 18M Medicare Fraud Against Dr. Comfort

    An affidavit relating to the search warrant executed by FBI agents on March 23, 2006 at Dr. Comfort Shoes outlines allegations of an $18 million Medicare fraud scheme, first reported to authorities by the company’s former chief operating officer.

    David Schlageter spoke to FBI agents on March 19, after striking an immunity deal with the government. He told the agency that Dr. Comfort - which deals in shoes and shoe inserts for people who suffer from diabetes - sold heat-molded shoe inserts that did not meet new Medicare standards for reimbursement, but claimed otherwise, over about 18 months.

    Source: Ed Zagorski - GM Today via Ozaukee County News Graphic [10/6/06]

    Editor’s note: Dr. Comfort’s response to these allegations appears in the Responses/Comments section of today’s PM News.

    RE: FBI Alleges 18M Medicare Fraud Against Dr. Comfort
    From: Dr. Comfort

    Dr. Comfort continues to cooperate with a government investigation to determine if non-custom inserts previously distributed, complied with SADMERC standards as they then existed. Recent reported events reveal that that the former compliance officer of Dr. Comfort, after leaving to start a competitive business in early 2006, sought immunity from the federal government, alleging that inserts he previously certified as compliant may have been non-compliant in sole density.

    Since the above events became known, Dr. Comfort has conducted a rigorous internal investigation that has verified that the company continues to produce the highest quality specialized footwear on the market. Dr. Comfort has received SADMERC approval for its new A5512 pre-fabricated inserts. Copies of this approval are available on our website at www.drcomfortdpm.com
  34. Craig Payne

    Craig Payne Moderator

    I don't actually have a problem with the use of a library of positives and/or a library of shells provided that:
    1. The library is extensive
    2. They are open and not secretive in what they are doing
    3. The cost savings they get are passed on.
  35. Jeff Root

    Jeff Root Well-Known Member

    Not sure how anyone can be expected to make three pairs of "custom" diabetic inserts for a total cost of $99 and expect them to be anything more than pre-fabs or something comparable.

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