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Technology: Choosing a digital foot scanner

Discussion in 'Biomechanics, Sports and Foot orthoses' started by admin, Oct 7, 2009.

  1. admin

    admin Administrator Staff Member

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    Lower Extremity Review have a recent article from Larry Huppin on Technology: Choosing a digital foot scanner. We have had a number of previous threads on digital scanners, but two comments did jump out at me:
    What say you?
  2. Bruce Williams

    Bruce Williams Well-Known Member


    Casting Rule #1: Non-weightbearing casting is the best method to ensure that the first ray will be plantarflexed.

    There has not been a study done to see whether this is actually the case. Before I started utilizing a flat bed scanner I changed my technique using plaster. I found a way to plantarflex adn invert the lateral column, instead of DFing or "maximally pronating" it - this had an effect on the medial column where it was usually already sitting maximally plantarflexed.
    If that is the case, and I think it is, then there is rarely a need to PF the 1st ray regardless of how we cast.

    Casting Rule #5: The negative cast must capture a perfect representation of the plantar aspect of the foot while the foot is held non-weightbearing in subtalar neutral position.

    Says who? This is another one of those things that are passed down with no research to ratify it or not. There are different ways to cast. I am a proponent of capturing a true representation of the plantar aspect of the foot, but STJ neutral is a vague term and non-wt bearing neutral has it's problems as well.
    In one of more of the studies I've read, partial weight bearing neutral was the most repeatable of all casts. Non-wt bearing neutral does not mandate that the AJ be at 90 degrees or the need flexed or extended, or say anything about rotation of the hip etc.

    I appreciate Larry's take and respect him greatly. I just think it is time for us to explore other opinions and to finally start studying this in more detail.

  3. joejared

    joejared Active Member

    I have customers that do semi-weight and non-weight bearing casting. I don't know that anything would be productive in terms of discussing which method of casting is best, except to inspire a riot. I just make the device work how they want it to, within reason, and let them play and determine for themselves what they prefer to do. Personally, I prefer non-weight bearing castings, because it is as close to perfect as possible as matching a non-weight bearing plaster cast, and best reflects what the foot's natural shape is. The main difference between semi-weight bearing and non-weight bearing casting from a software perspective is expansion and fill levels, and closely parallels the difference between plaster and biofoam casts. For those that prefer to have exclusively non-weight bearing casts, I just suggest removing the window which also makes the blind spot (The angle of incident between the laser and camera) irrelevant. As to that word, "Perfect", well, perfect within +-1mm is adequate from a depth perspective. and lengths and widths are relatively subjective and vary from lab to lab, as do styles.
  4. joejared

    joejared Active Member

    To me, and just an opinion, but weight bearing vs non-weight bearing is synonymous with non-destructive and destructive testing. Losing the natural shape of the lateral column, met pads and heel would tend to encourage the orthosis to emulate the shape of the floor rather than the foot. Again, just an opinion.

    And here I am, arguing that the article is right... -cough- I'll shut up now.
    Last edited: Oct 7, 2009
  5. Bruce Williams

    Bruce Williams Well-Known Member


    thank you for pointing out the real issue in this discussion, that being, can you emulate a non-weight bearing cast technique in partial WBing or full WBing.

    I think you can adn I do so regularly in Partial WBing.

    I find it funny that people continuously say that the natural position of the foot is when it is non-wbing. Isn't the "natural position" of the foot when it is in use... from heel contact to toe off?

    I see people eliminate the lateral arch in all types of casting in an effort to "lock or maximally pronate" the lateral column. I think this truly throws the baby out with the bathwater. There is more than one way to "lock" the MTJ in casting, and still allow the foot to pronate on the device. The question is does a partial wbing cast allow for a truer position of the foot in midstance than a foot casted nwbing?

    I think it does.
  6. joejared

    joejared Active Member

    That's a valid argument, and then think about the lines of force on the fat pads. To me, intuitively matching the foot and changing the fill level would still mimic the shape of the foot to some extent, and more evenly distribute force as that foot is being used. I guess my question would be how much difference it makes. When I match my own personal devices for my feet to the natural curvature of the mid-tarsal joints (newarch=y) , I find that I am more comfortable standing in front of my machine as it machines parts for me. So yes, I do favor knowing the natural shape, to more evenly distribute force across all of the bones. Conversely, it also tends to immobilze those same joints. With a weight bearing cast, it is more difficult to locate where the medial arch blends into the cuboid region. So, from my perspective, a weight bearing cast is more destructive than a non-weight bearing cast, albeit more consistent according to studies.

    I think we're in agreement. Wait 5 minutes and this rat brain may suddenly find a reason to disagree. ;-) With partial weight bearing, dependent on force, I'm assuming the lateral column isn't completely compressed, therefore it is still possible to see the midtarsal joints, at least as a shape. At least then, we have a choice whether or not to flatten it out. A recent development I'm completing now, actually does flatten out the lateral column for valgus post, but it's a choice and a software function, rather than what could be considered a kludge around a weakness in a system. The number 1 complaint labs I work with are bad casts. The chief culprit in terms of casts is UPS/FEDEX, and in particular, biofoam casts. They're cheap, easy and fragile. I've yet to see a consistant casting method that most practitioners use, but there's will be considerably more data to work with soon.

  7. There are a number of issues here.

    Regarding semi-weightbearing versus non-weightbearing scans- the foot can be put into many positions semi-weightbearing and many positions non-weightbearing. The trick is to manipulate the foot into a position that requires a minimal amount of positive model correction to create an efficacious device.

    As Bruce points out, the natural position of the foot is dependent upon a multitude of factors, not least: time. Subtalar neutral is only one potential position for the foot to possibly adopt during a given gait cycle. The successful clinician designs an orthosis that will minimise pathological stress on the target tissue without adding pathological stresses to the others.

    I don't buy the MTJ locking myth and I don't believe that feet don't pronate and supinate on top of foot orthoses, if that be their will. Unless the device wraps up above the subtalar joint and directly limits the joint motion, I think it highly unlikely that no STJ motion will occur.

    Why the interest in midstance? Do foot orthoses only work at this point? Personally, I try to identify the target tissue, i.e. the tissue under-stress and then work-out when during the gait cycle the pathological level of stress is being applied to the tissue and then design a foot orthosis that will reduce this stress at this time.

    Foot orthoses are 4-dimensional devices.
  8. Bruce Williams

    Bruce Williams Well-Known Member


    The interest in midstance, as always, is that is when the GRF's, ORF's, body weight, accelerations and gravity will have the most impact on the foot, and vice versa.

    I don't disagree with you on any of your other points, but do you ever design an orthotic primarily for any other phase of gait but midstance? I am discounting AFO's functional or fixed for drop foot here as I think you will understand.

  9. joejared

    joejared Active Member

    It seems appropriate to note the difference in data between weight bearing and non-weight bearing, which is what lead me to bring up the mid-tarsal joints. I thought I had considered the ramifications of conforming to the midtarsal joints as well, from both sides. The point I was making is that a weight bearing cast eliminates data, or makes it difficult to obtain.

    As for casting methods, at least in my application, it would be significantly easier to cast neutral than say, MASS post, but I don't spend my days casting patients and haven't been exposed to many casting techniques. I was taught how to use my own scanner by a podiatrist who visited me recently, and his preference seemed to be a gentle touch on the window, semi-weight bearing, neutral, feeling for neutral through the navicular while monitoring the foot for motion during the scan.

    No argument there.
  10. How so do they have the most impact on the foot at midstance? Are GRF's at their peak at midstance? Thus, are ORF's at their peak at midstance? Is the COM accelerating toward the ground or away from it at midstance? Do body weight and gravity change throughout the gait cycle?

    I frequently design foot orthoses primarily for other phases of gait than midstance. I should have thought that was easy for you to relate to Bruce.
  11. Joe, with the greatest respect I find many of your posts difficult to follow. For example, what does "a gentle touch on the window" mean? The window of what?
  12. joejared

    joejared Active Member

    What if there is no gait cycle for extended periods? Would a corrective device intended to aid/correct through a gait cycle be helpful or harmful? Should the patient's activity level or specific activities be a consideration in making an orthotic device? As for the latter question, dependent on velocity, I'd have to say force changes, dramatically. Weight only changes from planet to planet, give or take a big mac.
  13. Bruce Williams

    Bruce Williams Well-Known Member

    Sorry Simon, I'm obviously as dense as you attempt to make me out to be in your last post.:bash:

    Dazzle us with examples of the orthotics you make for other gait phases please!

  14. joejared

    joejared Active Member

    Sorry. Light pressure so as not to deform much of the planter surface by the window. Some contact was necessary so as to immobilize the foot during the scan, and as a result, some of the resulting data matched the window instead of the foot, but not enough to really matter. (Okay, subjective term) The window of the scanner was what I was referring to.
  15. Of course activity is important in orthosis design. In my experience the majority of over-use pathologies stem from activity as oppose to inactivity. Although the most obese of patients sometimes get problems from standing still, the forces exerted on the body are far higher during movement activities, be them walking, running, hopping, skipping or jumping gaits.

    I think "changes" the data is a better description. We don't know if it changes it for better or for worse.

  16. Bruce, it is not my intention here to make anyone out to be dense, it is a shame that you feel that way. Personally, I read and write on this forum in an attempt to learn more and to share my knowledge. In answer to your question, I give as an example any device with a functional forefoot extension. You can also manipulate the morphological characteristics of the rearfoot post or the orthosis shell. My point (that I thought you would understand) was that if, for example, we want to manipulate the Centre of Pressure pathway (you have suggested in one of your papers that changing centre of pressure pathway is a desirable and measurable effect of an efficacious foot orthosis), then this variable is time dependent and as such variations in the orthosis morphology along its length (from heel to toe) is potentially capable of changing the centre of pressure pathway from heel strike to toe-off.
  17. joejared

    joejared Active Member

    In another thread, I noted pressure readings at different stages of gait, which easily argues there's room to improve on simplly casting of a patient's foot. casting an obese patient's foot is often not too different than scanning a 2x4, especially in a weight bearing condition. More than one lab has requested multiple types of scans per patient within a single order, from non-weight to full weight bearing. For now, they have to be treated individually. A cavus foot might benefit from weight bearing, if only to see how the foot twists (and mid-tarsals) under load, but much of this is actually quantifiable.

    Fair enough. There's a little bit of preference on my side, but has more to do with the tools available from my side of the fence. Changes/deforms tends to deflect the surface that makes what's under the deformation less readable. Repeatablity has value, as does precision. One note in terms of casting, one lab now has different fill codes for plaster vs biofoam casts, simply because of the newer resulting data being more evenly distributed, or more complete than waving a wand. Intuitively, I'm pretty much of the opinion that there should have always been different fill relationships, in much the same manner as non-weight bearing vs. weight bearing scans should.
  18. Joe, I'm tired and once again I'm struggling to keep up with you, for example: "I noted pressure readings at different stages of gait" Yeah? "casting an obese patient's foot is often not too different than scanning a 2x4" a 2x4 what?

    I think what you are trying to say above is that in essence a scan or a cast captures an instant in time and that by taking multiple scans in multiple positions we get a better picture of the foot during gait (provided the scans are weightbearing and during gait-right?) Ultimately, technology will allow a 4D model of the foot and lower limb to be captured. In the mean-time...

    Consider this:

    Lets say we can identify the tissue under stress and the very moment that the stress in that tissue reaches pathological levels with a given activity. Should we capture the foot in this position or in some other position?
  19. joejared

    joejared Active Member

    Sorry, I forgot you're on a metric system. Two by four piece of wood.

    For the multiple scans, not during gait, but rather as a tool to determine expansion. As for pressure maps, and not for making the orthotic so much, but as a tool to know where the orthotic will likely incur the most stress and adapt the design accordingly, I see a potential to integrate the two technologies.

    Good question, and it easily argues for multiple types of casts per patient, I think, at least to get a better idea of the dynamics of the foot. By computer, it's relatively easy, but I doubt a practitioner would take the time by plaster.
  20. DaveCOL

    DaveCOL Member

    [Check4SPAM] RE: URL Attempt

    non-weight bearing, and or Semi weight Bearing casts have been widely taken in from most legitimate laboratories in North America.

    In my opinion we chose the Sharp Shape scanner for use in our laboratory.

    The more you discuss WEIGHT BARING casts, the more you legitimize pressure scanners as a means to making custom orthotics.

    Last edited by a moderator: Sep 22, 2016
  21. corndolly

    corndolly Member

    HI everyone , just want to know if anyone has any details on what labs use the sharp shape foot scanner. I have been using this very happily for about 5 years but the lab I used has gone out of business and I am left with a scanner which is standing idle catching dust in the corner of my surgery. or does anyone want to buy my scanner?!!
  22. Craig Payne

    Craig Payne Moderator

    That is the problem I have with closed source scanners. What happens if you no longer like the product from the lab or (as in this case), the lab goes out of business?

    Would it not make more sense for there to be open source scanners that you can buy from the traditional medical or podiatry supply houses. You scan the foot, then go to a drop down menu and choose which lab to send it to. Does that not make more sense not to be tied to one particular lab with what could be a white elephant?
  23. Agreed, Craig. You don't even need the drop down menu, just a scanner that can save files in a variety of formats.
  24. I'm not sure how the hardware / software locks you in to using only one lab although it is probably via some form of encryption. The only thing I can think of that might help to get around this is if you can import the scanned data into something like Meshlab and then save it in another format. This may or may not work, but as it's free it might be worth a try.


    Joe can probably tell you more as I think he runs a pay per scan type system.
  25. joejared

    joejared Active Member

    Granted, my scanner is very proprietary to OreTek products only, and has encryption features, but to be honest, I just respect the routing preferences between client (remote Scanning system) and Client/Server (Lab manufacturing for client). My software is only locked into OreTek, which comes free with the scanner, and is crippled or otherwise only limited in features at the Client/Server's request. Should a Client site actually want something more than scan and ship, they just ask, but in most cases, the intent is to eliminate shipping expenses for the casts, so it's really no big deal, and any customer can schedule a visit for free training. The lab technicians are generally more experienced with the intricacies of OreTek as well as the scanner data, and the aim is to make it simple for casting of patients. As long as the data looks like a foot, it should be good enough for the lab technicians to work with, whether it is non-weight bearing or semi-weight bearing, and in rare cases, full weight bearing.

    For reference, there are more client/server sites than listed and until they're ready to go public I'm content to forward leads to them privately. My kiwi client/server site will be publicly listed shortly, and my Aussie Client/Server customer will be visiting first week of November.

    The only fees I charge for my product are what they've been for the past 9 years, which are royalties, effectively translating to $0.50/surface. Routing of client data is free, and of key importance, respecting the agreements between both parties, paramount. When a potential customer comes to me for my product, I consider them open to all labs until they settle on a provider. When a lab buys a scanner for one of their customers, I start with the assumption that the new client site has an agreement with that lab and the new client understands that my product is for OreTek only, and that I will not interfere with any agreement between them and their supplier until both parties are amicable to the change.

    One point to clarify. My charges do NOT increase because someone has purchased a scanner, and there are NO routing click charges. The royalties I refer to are the same as they've always been, and relate to the number of units sold using OreTek. It costs no more to route data from client to Client/Server, and no charges are assessed for such automation. In rare occasions, clients have preferred to pay their own royalties (Savings for paying early), but most clients never see an invoice from me, other than for hardware.
    Last edited: Oct 14, 2009
  26. joejared

    joejared Active Member

    If the tool provides what you want, multiple formats are unnecessary. This particular issue is easy solved. I give OreTek away along with all software and hardware updates. Operating from a service model, my success is symbiotically that of my customers. It is actually to my benefit to give whatever I design away, especially if it improves performance and quality.

    Last week, I removed support for anything .raw, simply because it was an unnecessary and troublesome distraction. Piedmont Orthotics is looking for a buyer for his $6500.00 cast scanner and $8000.00 wand digitizer, if anyone is interested. :rolleyes:
  27. joejared

    joejared Active Member

    I believe Believe there are several sharpeshape systems out there. Within my own network of laboraties, earthwalk orthotics and NewGen Advanced Orthotics also have sharpeshape. The only other labs I know of that use sharpeshape are Better Forms and Jeff Root. There are many others out there, and perhaps they'll chime in. You could easily find a supplier from Pfola as many of the labs there are sharpeshape.
  28. DaveCOL

    DaveCOL Member

    [Check4SPAM] RE: URL Attempt

    We take all Sharp Shape scan files. We are located in Canada; but have the cheapest rates around. We are hopefully not going out of business as we have been established for over 30 years. Our American rates are only about $70.00 US.. and with already having a scanner we could probably do it for less. Check us out at www.canadianorthotics.com


  29. joejared

    joejared Active Member

    Re: [Check4SPAM] RE: URL Attempt

    It's refreshing to see competitors actually referencing their prices publicly. Earthwalk and NewGen recently gave me a quote in the below $20.00/pair range for cut and ship orders, and obviously finishing work such as top covers would be extra + royalties, naturally. While Sharpeshape products are outside the scope of my support and royalties, either way, I'm pretty sure there are plenty of sources out there. Per plate charges (4 1/2 pairs per plate) are typically in the $50.00+material expenses range for most of my client/server sites. This reminds me though that I don't have a quote from my canadian client/server site for my client pricing spreadsheet.
  30. LER

    LER Active Member

    There is a company that I came across at APMA and most recently, PFOLA. Techmed3D provides true open architecture to any lab that accepts STL files. They only sell the digital equipment, not the end product. Something to consider.
  31. joejared

    joejared Active Member

    Price tag, probably in excess of $15K if not $20K or higher, not counting software. From the looks of things, it's a spinoff of the Polhemus Fasttrak Digitizer and their optical system, if not a polhemus itself repackaged. I believe their accuracy statement based on what I know of Polhemus technology. However, ferrous metals are it's kryptonite, distorting its position any time ferrous materials are in close proximity. 40 seconds is pretty slow for to scan for an orthosis.
  32. ddemetrius456

    ddemetrius456 Welcome New Poster

    [Check4SPAM] RE: URL Attempt

    Well, There are several sharpe shape systems out there.And we chose the Sharp Shape scanner for use in our laboratory. In my opinion the more you discuss WEIGHT BARING casts, the more you legitimize pressure scanners as a means to making custom orthotics. Anyway nice post.

    Thanks a for the information.....keep posting..............

    Managed Services
  33. joejared

    joejared Active Member

    Re: [Check4SPAM] RE: URL Attempt

    The labs now using my foot scanner quickly have been preferring the non-weight bearing method as the rule, not the exception. It's actually an inversion of a pressure map, providing arch only data, as seen below, with the only consistantly usable data being the non-contact regions. Subjectively, as there is a tendency for the fill to match the surface, making an orthosis from a window or pressure plate, I think to be a bad idea. The lack of repeatability in non-weight bearing scans is partly due to whether pronation or supination is involved, as the mid-tarsals would obviously twist and move longitudinally given these conditions. Casting neutral is the standard the labs are using.


    Other examples here after I blank out actual patient data.

    Loss of usable data.In the last example, it's still possible to intuitively find the cuboid, but much more difficult than in a non-weight bearing scan and much of the "natural" shape of the foot is lost. In discussions with 2 labs, having both types of scans combined is useful in determining fat pad expansion, and will be available in coming versions, but I myself prefer non-weight bearing scans. In non-weight bearing scans, one of my codes has no difficulty in finding the arch from medial to lateral, and plotting a nonlinear curve through the mid-tarsal joints. This method becomes considerably less reliable in semi or full weight bearing scans, but I still have one person doing standing full weight bearing scans. God only knows why. :deadhorse:
  34. joejared

    joejared Active Member

    Recently, a customer who insists on using my scanner for weight bearing casting sent me an example of a full weight bearing scan of his foot. As I've written earlier, it's like the inverse of pressure mapped system, providing only usable data in the arch and perimeter regions, everywhere but where contact is made. Personally, I have little confidence in weight bearing scans, and perhaps that is simply because it no longer has much resemblance to a foot. Quantifiably, the greater majority of the input data is actually a solid representation of the window, and not the foot.


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