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Foot orthotic terminology and classification

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Craig Payne, Oct 25, 2008.

  1. Craig Payne

    Craig Payne Moderator

    Articles:
    8

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    At PFOLA confernce , there was a couple of workshops on the attached document on the proposed terminology and classification of orthotic negative model production terminology and orthotic manufacturing terminology.

    I made some comment and will post them when get time away from mtg; PFOLA are seeking feedback.

    What say you?
     

    Attached Files:

  2. Craig Payne

    Craig Payne Moderator

    Articles:
    8
    PFOLA Technical Standards Document: Foot Orthotic Classifications, Definitions, and
    Summary of Manufacturing Processes Document.

    FOREWARD
    There is considerable confusion surrounding foot orthotic terminology and the various processes by which foot
    orthotics can be created. The purpose of this document is to serve as a reference for foot orthotic terminology, to
    provide for the classification and categorization of foot orthotics, to define the types of foot orthotics, and to
    provide a brief and concise description of the multiple processes by which foot orthotics are created.

    Standard terminology is essential for communication within and between disciplines, professions, occupations,
    agencies, and individuals who deal directly or indirectly with foot orthotics and foot orthotic therapy. Foot orthotic
    practitioners, manufactures, researchers, educators, as well as individuals who work in government, insurance, the
    legal profession, etc. and who have an interest in foot orthotic therapy must have a common language for effective
    communication to be possible. Unfortunately, effective communication about foot orthotics and foot orthotic
    therapy has been hindered by improper, inaccurate, inconsistent, poorly defined, or misunderstood terminology.

    In the performance of its mission, it is PFOLA’s desire that this document will serve to improve communication,
    increase understanding, and promote awareness of and within the prescription foot orthotic industry. This
    document must be both accurate and current and to that end PFOLA welcomes any and all comments on subject
    matter related to this document and will update this document as necessary for enhancement, correction,
    clarification and due to changes associated with changes or advancements in terminology, technology,
    methodology, materials, and processes, etc. Those who desire to provide comment or make recommendations to
    improve this document may do so by writing PFOLA directly or by e-mail addressed to the Technical Standards
    Committee at info@pfola.org.


    Foot Orthotic Classifications, Definitions, and Summary of Manufacturing Processes
    Document. Updated January 24, 2006

    Committee Members:
    Christopher Smith, DPM
    Mr. Scott Marshall
    Mr. Paul Paris
    Mr. Jeff Root

    Table of contents:
    Introduction
    Foot Modeling Definitions
    Orthotic Device Definitions
    Manufacturing Process Summaries PFOLA Technical Standards Definitions – DRAFT Revisions: January 24, 2006


    Foot Modeling Definitions
    Anatomical Volumetric Foot Model (AVFM). A digital or physical model that captures a person’s three
    dimensional plantar foot anatomy when the foot is non-weightbearing, semi-weightbearing, or fully-
    weightbearing.
    A digital AVFM must use actual 3 dimensional data points taken directly from the foot to duplicate
    plantar foot anatomy. The most common examples include laser 3D scanners, stereo-digital 3D imaging
    systems, and pin array systems.
    A physical AVFM captures foot anatomy through direct contact to duplicate plantar foot anatomy.
    The most common examples are plaster of paris casts or foam impressions taken directly from the foot.
    Any material or method that uses direct capture of the entire plantar foot anatomy creates an AVFM.

    Extrapolated Volumetric Foot Model (EVFM). A digital model that approximates a person’s three
    dimensional plantar foot anatomy through application of mathematical models that extrapolate pressure
    data, or extrapolate temperature data, or extrapolate light data to form the digital model when the foot is
    non-weightbearing, semi-weightbearing, or fully-weightbearing. The most common examples are pressure
    mapping systems, photographs and ink or carbon paper imprinting systems.

    Orthotic Device Definitions

    Foot Orthotic. An in shoe device that braces, supports, or protects the foot or part of the foot.

    Prescription Foot Orthotic. An in shoe device that is prescribed by a qualified healthcare professional to
    brace, support, or protect the foot or part of the foot.

    Anatomical Custom Foot Orthotic (ACFO). An in shoe device that is made directly from an Anatomical
    Volumetric Foot Model (AVFM). The AVFM is modified with the appropriate medial and/or lateral arch
    fill, lateral column expansion, heel expansion, and intrinsic forefoot and/or rearfoot corrections as defined
    by the prescribing physician. The entire dorsal surface of said custom device matches the surface of the
    modified, or corrected, AVFM.

    Extrapolation System Foot Orthotic (ESFO). An in shoe device that is made directly from an
    Extrapolated Volumetric Foot Model (EVFM). The EVFM is modified with the appropriate medial and/or
    lateral arch fill, lateral column expansion, heel expansion, and intrinsic forefoot and/or rearfoot corrections
    as defined by the prescribing physician. The entire dorsal surface of said custom device matches the surface
    of the modified, or corrected, EVFM.

    Library System Foot Orthotic (LSFO). An in shoe device that is made from a library of pre-
    manufactured shells, pre-manufactured corrected positive molds or pre-determined digital shape files (from
    which shells or molds are milled.) The foot orthotic shape is chosen by matching a library shape with either
    an AVFM or EVFM.
    Functional Foot Orthotic. An orthotic device that is designed to control abnormal motion or abnormal
    position of the foot and to control the abnormal motion or abnormal position of the lower extremity that is
    affected by the position and/or motion of the foot.

    Root Functional Foot Orthotic. A Functional foot orthotic made from an Anatomical Volumetric Foot
    Model (AVFM) that is taken with the foot non-weightbearing, the ankle joint dorsiflexed to resistance, the
    subtalar joint held in its neutral position, and the midtarsal joint fully pronated.


    Manufacturing Process Summaries

    The following summaries are generic descriptions of various foot orthotic manufacturing processes


    Anatomical Custom Foot Orthoses

    1. A physical AVFM – Manual Corrected Model -- Manual Orthotic Shell

    An AVFM is filled with plaster to create positive model > lateral and medial expansions and intrinsic
    corrections are added manually as per prescription > orthotic shell is vacuum formed over corrected
    positive model > shell is ground to fit shoe and patient’s foot > extrinsic components and top cover are
    added > orthotic device is finished.

    2. A physical AVFM -- CAD/CAM Corrected Model -- Manual Orthotic Shell

    An AVFM is digitized using a 3D scanner > digital 3D model is modified with lateral and medial
    expansions and intrinsic corrections using CAD software as per prescription > corrected positive model is
    milled using CAM software > orthotic shell is vacuum formed over corrected positive model > shell is
    ground to fit shoe and patient’s foot > extrinsic components and top cover are added > orthotic device is
    finished

    3. A physical AVFM -- CAD/CAM Corrected Model -- CAD/CAM Orthotic Shell

    An AVFM is digitized using a 3D scanner > digital 3D model is modified with lateral and medial
    expansions and intrinsic corrections using CAD software as per prescription > orthotic shell is milled
    directly from orthotic material to fit shoe and patient’s foot using CAM software > extrinsic components
    and top cover are added > orthotic device is finished

    4. A Digital AVFM – CAD/CAM Corrected Model -- Manual Orthotic Shell

    A digital AVFM is modified with lateral and medial expansions and intrinsic corrections using CAD
    software as per prescription > corrected positive model is milled using CAM software > orthotic shell is
    vacuum formed over corrected positive model > shell is ground to fit shoe and patient’s foot > extrinsic
    components and top cover are added > orthotic device is finished


    5. A Digital AVFM – CAD/CAM Corrected Model -- CAD/CAM Orthotic Shell

    A digital AVFM is modified with lateral and medial expansions and intrinsic corrections using CAD
    software as per prescription > orthotic shell is milled directly from orthotic material to fit shoe and patient’s
    foot using CAM software > extrinsic components and top cover are added > orthotic device is finished


    Extrapolation System Foot Orthoses

    1. EVFM – CAD/CAM Corrected Model -- Manual Orthotic Shell

    An EVFM digital file is modified with lateral and medial expansions and intrinsic corrections using CAD
    software as per prescription > corrected positive model is milled using CAM software > orthotic shell is
    vacuum formed over corrected positive model > shell is ground to fit shoe and patient’s foot > extrinsic
    components and top cover are added > orthotic device is finished

    2. EVFM – CAD/CAM Corrected Model -- CAD/CAM Orthotic Shell

    An EVFM digital file is modified with lateral and medial expansions and intrinsic corrections using CAD
    software as per prescription >orthotic shell is milled directly from orthotic material to fit shoe and patient’s
    foot using CAM software > extrinsic components and top cover are added > orthotic device is finished


    Library System Foot Orthoses

    1. Physical AVFM -- CAD/CAM Corrected Model -- Library of Pre-made Orthotic Shells

    A physical AVFM is digitized using a 3D scanner > digital model is modified with lateral and medial
    expansions and intrinsic corrections using CAD software as per prescription > corrected digital model is
    compared to a library of shell shapes and appropriate shell is chosen > library shell may be modified to fit
    shoe and patient’s foot > extrinsic components and top cover are added > orthotic device is finished

    2. Physical AVFM -- Library of Corrected Models -- Manual Orthotic Shell

    A physical AVFM is measured manually or digitized using a 3D scanner > measurements or digital 3D
    model is compared to a library of corrected model shapes and the appropriate model is chosen > orthotic
    shell is vacuum formed over library model > shell is ground to fit shoe and patient’s foot > extrinsic
    components and top cover are added > orthotic device is finished

    3. Physical AVFM -- Library of pre-made Orthotic Shells

    A physical AVFM is compared to a library of shell shapes and appropriate shell is chosen > library shell
    may be modified to fit shoe and patient’s foot > extrinsic components and top cover are added > orthotic
    device is finished

    4. Physical AVFM -- Library of Shell Shape Files -- CAD/CAM Orthotic Shell

    A physical AVFM is measured manually or digitized using a 3D scanner > measurements or digital 3D
    model is compared to a library of shell shape files and the appropriate file is chosen > orthotic shell is
    milled directly from orthotic material to fit shoe and patient’s foot using CAM software > extrinsic
    components and top cover are added > orthotic device is finished

    5. Digital AVFM -- CAD/CAM Corrected Model -- Library of Pre-made Orthotic Shells

    A digital AVFM is modified with lateral and medial expansions and intrinsic corrections using CAD
    software as per prescription > corrected digital model is compared to a library of shell shapes and
    appropriate shell is chosen > library shell may be modified to fit shoe and patient’s foot > extrinsic
    components and top cover are added > orthotic device is finished

    6. Digital AVFM -- Library of Corrected Models -- Manual Orthotic Shell

    A digital AVFM is compared to a library of corrected model shapes and the appropriate model is chosen >
    orthotic shell is vacuum formed over library model > shell is ground to fit shoe and patient’s foot >
    extrinsic components and top cover are added > orthotic device is finished

    7. Digital AVFM -- Library of pre-made Orthotic Shells

    A digital AVFM is compared to a library of shell shapes and appropriate shell is chosen > library shell may
    be modified to fit shoe and patient’s foot > extrinsic components and top cover are added > orthotic device
    is finished

    8. Digital AVFM -- Library of Shell Shape Files -- CAD/CAM Orthotic Shell

    A digital AVFM is compared to a library of corrected shell shape files and the appropriate file is chosen >
    orthotic shell is milled directly from orthotic material to fit shoe and patient’s foot using CAM software >
    extrinsic components and top cover are added > orthotic device is finished

    9. EVFM -- CAD/CAM Corrected Model -- Library of Pre-made Orthotic Shells

    An EVFM digital file is modified with lateral and medial expansions and intrinsic corrections using CAD
    software as per prescription > corrected digital model is compared to a library of shell shapes and
    appropriate shell is chosen > library shell may be modified to fit shoe and patient’s foot > extrinsic
    components and top cover are added > orthotic device is finished

    10. EVFM -- Library of Corrected Models -- Manual Orthotic Shell

    A EVFM digital file is compared to a library of corrected model shapes and the appropriate model is chosen
    > orthotic shell is vacuum formed over library model > shell is ground to fit shoe and patient’s foot >
    extrinsic components and top cover are added > orthotic device is finished


    11. EVFM -- Library of pre-made Orthotic Shells

    An EVFM digital file is compared to a library of shell shapes and appropriate shell is chosen > library shell
    may be modified to fit shoe and patient’s foot > extrinsic components and top cover are added > orthotic
    device is finished

    12. EVFM -- Library of Shell Shape Files -- CAD/CAM Orthotic Shell

    An EVFM digital file is compared to a library of shell shape files and the appropriate file is chosen >
    orthotic shell is milled directly from orthotic material to fit shoe and patient’s foot using CAM software >
    extrinsic components and top cover are added > orthotic device is finished
     
  3. joejared

    joejared Active Member

    I realize this post is more than a month old, but something strikes me as warranting encouragment of discussion on it. If this were your document, what would you exclude? What would you endorse? I didn't note much discussion on it but some of the terms concern me as they seem to reflect a lowering of standards from even a year ago.
     
  4. Craig Payne

    Craig Payne Moderator

    Articles:
    8
    I have on my ever expanding 'do list' (in the context of the Arena'ettes being more than their usual high maintainence) to respond to PFOLA with my views, as I do not think the classification adequately covers the prefabricated foot orthotics and the pathway to their prescription. However, I do acknowledge that these are the Prescription Foot Orthotic Laboratory Association terminology guidelines.

    I will post my feedback when get to it.
     
  5. joejared

    joejared Active Member

    Attn Jeff Root

    As you are the current vice president of PFOLA, and as you yourself admitted to being on the committee that wrote this, how about if you took the time to share how this document was put together, and the rational for various definitions? For example, the term
    extrapolation

    Extrapolation implies deriving data from a given set of known points, in one unit of measure, and predicting points outside an array of known points in the same unit of measure. I don't see this to be the case in its use any more than if I were to say, "Every 3 feet I find an apple. There must be a pear in 20 yards". Do you see how it would make so much sense that that pear really is 20 yards away, forgetting the fact that I'm actually in a an orange grove?

    Also, how is a libraried product ever to be considered a prescription orthotic, and why would it even be recognized as a prescription orthotic if in fact it is not directly or through an automated process, made from the patient's foot?

    Why has Pfola expanded its definition of orthotics to include prefabs?

    In another thread, you mentioned apathy. In that same thread, you basically said you didn't have time to participate, and yet, you had time to post, and would have time to respond to an email. Does this mean you also use a different unit of measure when typing an email than you do typing a response in a forum?

    These concepts come to mind as glaringly different than pfola's attitude years earlier.
     
  6. Craig Payne

    Craig Payne Moderator

    Articles:
    8
    Joe

    The purpose of the document is not to support or defend any particular type of foot orthotic or production method. It was to define them.

    You and I might not like the use of some of the extrapolation systems (eg Footmaxx) or the use of library shells, but they are being widely used and need to be defined (we can debate the merits of different production pathways elsewhere).

    This is especially the case for 3rd party reimbursement. For eg, if a lab is using a library system are they passing the cost saving on to the prescriber (most that I know of are), but more importantly is the prescriber passing that cost saving on to the patient (or 3rd party payer)? .... probably not.

    SO the document was the first step in showing 3rd party payers what a true volumetric model is and the different production pathways options, so that payment can be scaled appropriatly.

    Imagine the scandel if a lab is using a library system, but is "secretive" about it and it gets out that they are doing this --> this will hurt the whole industry (there was a lab that used to doing this secretly -- but guess what?...you hear very little from them these days and they not a big lab any more..). I do not have a problem with the use of libarary systems, but expect that lab to be open about it; to inform me; and to give me a choice (I may choose not to use it)

    The problem I mentioned above is the need for the document to cover prefabricated orthotics that are prescribed without any volumetric or extrapolated modelling .... a prefab is really just a libarary system that the prescriber uses "off the shelf" without modelling (unless you call guessing the arch height, modelling before you use a different type of prefab device) - I think that needs to be better defined in the document to educate 3rd party payers about that pathway.
     
    Last edited: Dec 11, 2008
  7. joejared

    joejared Active Member

    I have to remember to stay objective on topics like this. Being more the purist at least when it comes to prescription devices, and as pfola by definition at one time portrayed itself or appeared to be an organization of prescription foot orthotic manufacturers, I was inflamed by this change from years back.

    I agree with you on this point completely. I have at least one customer that is prefab milling some of their orthotics, but at least from their side, they are selling them as prefabs, which I respect, although I don't much like prefabs.

    I'm trying to determine who is the preacher and who the choir is. ;-) As for libraried systems, I believe that concept will or should evaporate once the cost to both the labs and podiatrists are driven down to affordable levels, at least for those who wish to use automation. I can't speak for prefabs, as it may well be a good decision to use a prefab for a patient, but that's none of my business. I don't think I would go to a podiatrist however who prescribed an off the shelf product but I doubt most patients can tell the difference.

    I think this is where our paths diverge. I don't believe non-prescription devices should be documented nor recognized, but rather a concise and clear definition of what a prescription foot orthotic is, and what is recognized technically as acceptable as such. How many individuals know that extrapolation (as loosely used in this document) and libraried parts are only loosely based on the patient's foot, and of them, how many will misinterpret the document to mean that if the document references a technology or method, it has technical merit as a prescription device? Misinterpretations, even by degreed professionals are common, and to even recognize techniques other than that which is based on something quantifiable is dangerous to this community.
     
  8. Jeff and Colleagues:

    Like Craig, I was going to respond to the PFOLA paper of orthosis definitions but until now, never found the time.

    Here are my suggestions:

    Don't use the term "volumetric" to describe a three dimensional (3D) image of the foot. Volume only defines a quantity of material not a shape. A sphere, flat-sided box and an egg-shaped object may all have the same volume, but have very different 3D shapes. Also, suggesting that 2D data can be "extrapolated" to approximate a 3D shape is tenuous, at best. With these ideas in mind, the new classifications would be:

    Anatomical Volumetric Foot Model = True 3D Foot Model

    Extrapolated Volumetric Foot Model = Extrapolated 2D to 3D Foot Model

    The term "orthosis" not "orthotic" should be used throughout the document.

    Here are the only two orthosis definitions that you definitely need:

    Pre-made foot orthosis definition: A pre-made foot orthosis is an in-shoe medical device that is not made from a custom mold of the plantar foot and which is intended to alter the magnitudes and temporal patterns of the reaction forces acting on the plantar aspect of the foot in order to allow more normal foot and lower extremity function and to decrease pathologic loading forces on the structural components of the foot and lower extremity during weightbearing activities.

    Prescription foot orthosis definition: A prescription foot orthosis is a custom fit in-shoe medical device that is made from a custom mold of the plantar foot, prescribed by a qualified health-care professional and which is designed by that professional to alter the magnitudes and temporal patterns of the reaction forces acting on the plantar aspect of the foot in order to allow more normal foot and lower extremity function and to decrease pathologic loading forces on the structural components of the foot and lower extremity during weightbearing activities.

    I don't know if we need definitions for "functional foot orthosis" and "Root functional orthosis" since they would both be considered to be included under the heading of "prescription foot orthoses".

    If "library system foot orthosis" needs to be defined, make certain it is understood that this type of orthosis should be included under the heading of pre-made foot orthoses, nothing more, nothing less. This is very important to maintain the credibility of this document.

    That is all I have time to write on during my lunch break. Hopefully others can give some good suggestions also.
     
  9. joejared

    joejared Active Member

    Alternatively, Topographical foot model would work as well, as topographical would imply quantifiable altitude measurements and would also imply topical surface calculations.

    I don't think the word extrapolated truly belongs. Interpreted would probably be more accurate, simply because extrapolation assumes constant units of measure between input data and output approximated data. I know I was being rediculous and immature in my post on this term, but seriously, a different term should be applied. Pressure != (is not equal to) altitude, especially when the pressure value is 0, nor is there an exact science to date that will make an arch out of thin air, which is what is currently being done, so someone is doing some intuitive and subjective estimations, at best, from where the actual pressure is applied. To me, it seems like guess-timation but estimation would also apply, however loosely.

    One of my customers uses the plural term, orthoses. (Or-tho-sees) It would be acceptable to use that term as well, in my opinion. Both orthotics and orthoses are redundant and pleonasms. ;-) We could follow the english traditions and add more synonyms, such as foot-things, as one of my customers calls them. The best we can hope for, however, is to start a trend, ultimately making Orthosis/Orthoses the more popular term, but it's probably going to be about as religious a debate as would be casting methods.

    I like this definition. Either they are making an orthotic from a cast or they aren't, and templated or libraried equates to prefab as well it should.

    I think the style of casting is a dialog between the doctor and lab. I'm going to guess that discussion of casting techniques could be a chapter or two all by itself.

    I've heard various terms that all point to the same subset of data, and the only reason for these terms is inadequacy of technology to meet the original specification of taking a cast and manufacturing an orthotic from the cast, using conventional casting methods. My own software can take a size 3 orthotic and make one that closely resembles an orthotic for Michael Jordon, but it's still not made from the patient's foot. Had I known why one customer had asked for the ability to resize orthotics, I would have redoubled my efforts to make a better product for them and their customers, but by now, it's moot and will likely also be seldom used or at worst, be used only for minor adjustments, as was originally intended. While libraried or templated products are closer than prefabs, they are still just estimations of what's needed for the patient. It is not molded from a cast corrected mold of the foot and shouldn't be considered in the same light as conventional methods.
     
    Last edited: Dec 12, 2008
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