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Orthoses prescription variables

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Simon Spooner, Aug 17, 2009.

  1. Members do not see these Ads. Sign Up.
    Before we can determine which tests are needed to arrive at a foot orthosis prescription we first need to define what a foot orthosis is; then determine all of the possible prescription variables. Agreed?
  2. Agreed,

    Heres a list a variables in prescription that i can think of people can add or take away if they want.

    type of device.
    Modified Root
    Medial Skrive
    Lateral Skrive

    MaterialsEva - Different density
    Polypro -with Different thickness
    copolymer- with different thickness
    carbon fiber-

    Add onscuboid notch
    mortons ext
    rev mortons etc
    met dome
    ppt different thickness
    poron different thickness
    different top covers ie leather, senitex
    forefoot posting varus and valgus
    rearfoot posting varus and valgus
    rearfoot stabiliser
    plantarfascia grove
    cut out for 1st MTP

    thats a start of the top of my head of possibles even if some of the science is flawed I beleive we should test them ie morton ext.

    Michael Weber
  3. Craig Payne

    Craig Payne Moderator

    Michael - I would not call most of those prescription variables. They are all really design parameters.

    For eg.
    A clinial test would be supination resistance; the prescription variable would then be the need for a high, low or medium force from the foot orthotic; the design parameter would then be the orthotic design feature that delivers that presciption variable.

    eg if the prescription variable is the needed to deliver high force as supination resistance is high; then the design parameters that could do this are: kirby medial heel skive; more rigid material; medial wedging; DC wedge; MOSI; Blake inverted; etc

    I think the framework for this consensus project will go through, one by one, the clinical tests and what precription variable they indicate (or not); then seperatly (either afte that or in parallel), go through the design parameters and the indication/contratindication for them and reach a consensus that way.
  4. I might be confused and If so then feel free to take away my answer so the thread gets the discussion off on the correct foot (pun intended)

    I read it as prescription variable ie when writing a prescription how can it change from pat to pat.

    To come up with why I would define the tests as clinical tests or assessment.

    Simon was I off on the wrong foot?
  5. Craig Payne

    Craig Payne Moderator

    You not wrong...it just shows the challenges ahead for this project! I working away in the background trying to decide on the framework!

    for eg, even when it comes to the design parameters, which ones fit in the categories of:
    - negative model modifications or design parameters
    - positive model modifications or design parameters
    - shell modifications or design parameters
    - top cover modification or design parameters
    etc etc

    Maybe this is the thread to through them all into, then move to classify, then have a seperate thread for each prescritpion variable, clinical test and design parameter (assuming we can get a consensus on the terms 'prescription variable', 'clinical test' and 'design parameter' --- they just the terms and framework that I currently use)
  6. Atlas

    Atlas Well-Known Member

    I was thinking along Michael's line as well.

    Michael, what about shanks?; and devices that actually encourage the foot to pronate (aka valgus devices)?

    Physiotherapist (Masters) & Podiatrist
  7. I wrote the list quite quickly and missed a few other things such as prefab both shank dep and indep. heel lifts but did not think I should continue if it was not helping with what Simon was after.

    Have i missed the point Simon ?

    The way I was looking at the project was.
    1st what is an orthotic what variations can be made.
    2nd when and why should the be used
    3rd what clinicial tests should be used to determine when they should be used and how much.

    The 1st 2 areas would require less discussion and could help to keep the discussion going.

    The 3rd will the intersting with I beleive much heated debate.

    But will wait and see if we are off on the wrong path.

    Michael Weber
  8. I was thinking about orthoses prescription variables, in my view these are the things we ask the lab to do. So this might be how to pour the positive, arch fill etc, or it might be the material the top-cover is made out of etc.
  9. Graham

    Graham RIP


    Would it not be prudent to limit the initial discussion to a few. Say You, Simon, Kevin, Howard, Eric. You would more likely come up with a list of tests that way before taking it to the general Arena.

    Just a thought.
  10. How about making the prescription variable geographic? As in divide the foot into zones and consider what forces can be applied to each. So we have medial heel, lateral heel, proximal and distil midfoot medial and lateral and Plantar metatarsal area. Then divide force desired into high medium and low force. Perhaps also a catagory for vector of force...

    So a foot with a medially deviated STJ and a pathology linked to high residual pronatory moments would do better with higher supination force in the proximal medial zone.

    Just brainstorming. Is that the sort of thing you have in mind?

  11. ok on to the list we should add.

    type of device
    shank indep and depent off the shelf device

    casting pour
    different angles of pour

    modification of negative cast
    amount of arch fill
    intrinsic ff posting varus/valgus
    increased medial/lateral flange

    add ons we should add
    heel lift
    full length top covers with and without different density material combo´s
    varus and valgus shank

    thats all for now

    kind of takes away from the consensus part don´t you think ?

    Michael Weber
  12. Graham

    Graham RIP


    It is not unusual to have a working group of experts develop the plan and then take it to the masses for their in-put. Then they would likely be able to indicate why certain tests/measurements have been included or excluded.

    The smaller the working party with as wide an accademic expertise in the area will result in progress far more efficiently than if we all wade in from the start.

  13. Bruce Williams

    Bruce Williams Well-Known Member

    I think Craig is exactly right in his comments above. You really need to understand when a specific physical exam determinant or test indicates a specific orthotic prescription modification, not the other way around.

    Further you want to decide what to do for patients with hypermobility of the 1st ray and or lesser rays - dorsiflexion stiffness for those who prefer that.

    What about for patients who have limb length differences functional / structural.

    If i'm off target, let me know Craig, but it seemed that this was what you were shooting for.

    I would also add as modifications to the supination resistance test, ie the patient is too compliant and requires additions or modifications to their cast positioning, the need for a cluffy wedge or digital pad as I call it. Basically a modification for extending the toes to preload the plantar fascia. A lateral Forefoot wedge, or cuboid pad, helps in these instances often as well in regards to the medial band of the plantar fascia.

  14. Atlas

    Atlas Well-Known Member

    I don't know about this. Often an identical physical exam result doesn't necessarily agree with the similar intervention.

    Evidence based practice (EBP) is in our psyche; but with orthotics, it should be results-based-practice (RBP). This process should have loops that allow you to go back and change an aspect of the orthotic prescription...and then judge its effect. There is a place for trial and error here.

    Clinical tests are important, but they are still the small picture. The big picture is how we are influencing the patient's main problem, and whether overall they are better/same/worse.

    What we as a profession do when they are the same or worse (after intervention) is what we need the most help with IMO.

    Physiotherapist (Masters) & Podiatrist
  15. Adrian Misseri

    Adrian Misseri Active Member


    I think this a great way to address teh concepts. This may also make it easier to demonstrate how each of the orthotic variables affect the intrinsic mechanisms of the foot. I like this. Ties back to one of the fundamental ideas I learned back in undergraduate uni 'how much force do you need and where do you want it?' (and yes it came from Craig...)

  16. Dean Hartley

    Dean Hartley Active Member

    I think this is a good idea.
  17. Adrian Misseri

    Adrian Misseri Active Member


    Perhaps opinions are open on the provisor they are backedup with appropriate evidence?
  18. Bruce Williams

    Bruce Williams Well-Known Member


    I agree with you. I see this project as the start of a large orthotic flowchart.
    Having utilized in-shoe pressure to aid my orthotic prescribing over teh last 8-9 years I can definitely agree with your comments on trial and error.

    What I have come to greatly appreciate during that time is that there are certain orthotic modifications that work due to certain biomechanical parameters that patients feet have.

    I think if we can identify some of the foot types, via testing etc, then we can start to get a decent flow chart moving along that will give most physicians a very good line on how to handle many or most foot problems via orthotic treatment. We can also give them several modification ideas with descriptors on what might work despite what EBM or studiesmay indicate otherwise.

  19. Jeff Root

    Jeff Root Well-Known Member

    I would refer to them as prescription options. A true prescription form should have different types of orthses plus options for the practitioner to choose from. Prescription defaults can be used or options can be selected to change the defaults to further customize the Rx.

  20. Chris Gracey

    Chris Gracey Active Member

    I'd like the psychedelic Tissue Stress black light poster please! 19.95 available exclusively through Podiatry-Arena...

    Bruce has the right idea. Sounds like we're developing a protocol and after all, you have to begin with a particular school of thought and what is considered WNL for the foot within that doctrine. Classify Bone vs. soft tissue. Then derive a Dx based on that thought using known tests and measures that will adhere to that ideal. Throw out the ones that do not mesh with that particular philosophy. What are the possible outcome measures? Are you looking to improve ROM? Reduce pain? Subjective reports of comfort? Which orthotic elements will bring about the desired change? Which methods of fabrication should be used to produce those elements? Which retest is best to determine structural/functional outcome?
    Did it work? Yes. You're done. No. Where to flow back to? Philosophy? Dx? Fabrication? etc.

    1) Define the Ideology
    2) Define Fields
    3) Define Items within those fields
    4) Define a method for prioritizing items to go in fields
    5) Propagate defined fields with defined items
    6) Define outcomes
    7) Define tests for outcomes (True/False, +/-, Worked/Didn't work, etc)
    8) Define true/false weight in the case of multiple scenarios (did this, but not that)
    9) Determine level of target field to return to in case of False based on weighted priority.
    10) Run a feasibility study, get it published in the literature to disseminate it to the masses.
    11) It goes to 11! So put on some Grateful Dead (2/11/70 Filmore East comes to mind) Turn out the lights and just smile, smile, smile!

    So, to make this more tangible, I propose we design a flowchart using 1 school of thought. Work it to completion and make the mistakes we are going to make on that one. THEN, we can introduce a new Philosophy and plug it into the system. Most of the work is already done so we should have a foot orthotic consensus in no time!
    I volunteer to design an Excel Spreadsheet but since I'm new, perhaps it's inappropriate. I'll bet someone else already has one.

    Peace and Props,


    Admin: Should this post go in the "genesis of" thread? I just realized Spooner set this up to define orthotics and their parameters and discussion should revolve around that specifically and not project format. Thanks.
    Last edited: Aug 20, 2009
  21. SimYardley

    SimYardley Welcome New Poster

    I have a few thoughts on design, as a process, in relation to the communication of conceptual design to manufacturers, and how accessibility of prescription tools needs to account for podiatrists of all levels of expertise. I’ll try and explain by describing a well-known engineering cartoon.

    Imagine a number of swings, all different, hanging from the branch of a tree. The first swing has four extra-heavy duty ropes and a reinforced aluminium seat. Underneath it, there is written, ‘As the health and safety team wanted it’. The next one has a sparkling paint job and a big company logo engraved on the seat, accompanied by the text, ‘As the advertising department wanted it’. Subsequent seats all show different designs that represent the embodiment of single-minded solutions for the multitude of parameters involved in the design process e.g. design for manufacture, performance, safety, reliability etc. The last swing is a simple swing with two plain ropes. It says, ‘As the customer wanted it!’. The morale of the story then is simple – it is clear that such competing design parameters need to be balanced against each other if a good, quality (an engineering term that says it all) product is to be made.

    In bringing this analogy to bear in terms of orthotic design and manufacture, I would start by saying that the customer in this illustration represents the patient and a measurable therapeutic effect is what the customer wants! So, and I am stating the obvious here, it is clear that an effective therapeutic device is the principal goal for patient, podiatrist and manufacturer. However, all the ‘swings’ represent design parameters that require equal consideration for good design. As such, I consider the terminology of functionality of the product (for therapeutic effect) to be just one of many design parameters in a total design process. However, as clinicians, I will make a bold statement in saying that whilst most podiatrists have a working knowledge of materials etc, they are even better skilled in creating a conceptual design of the device for effective therapeutic outcome. In short, a conceptual design encapsulates the forces you would want to apply to the patient for best therapeutic effect (or what Craig P refers to above as a prescription variable). I feel that this is the starting point for communicating a design to a manufacturer, and is indeed the starting point in the design process as a whole.

    Before I get any rebuttals, obviously podiatrists vary in levels of skills and expertise in terms of orthotic design. Specialist BMX/researcher clinicians are able to conceptualise all the ‘swings’ on the tree when considering the design and manufacture of an orthotic. As such, they have the ability to embody the conceptual design into a total design that balances all of the design parameters, thus providing an immense advantage in producing good quality products. In such cases, I would argue that the podiatrist is involved in a process which fulfils the role of both design consultant and clinician, and I would imagine a standard prescription form could be quite limiting. However, not all podiatrists have such specialist knowledge/experience, even though all podiatrists design orthotics to some extent. Consequently, the prescription has to somehow communicate effectively the design intent of the podiatrist to the manufacturer. Here, I feel, is where problems in producing an effective prescription system are most felt i.e. interprofessional communication. If we assume that podiatrists are best at conceptualising design for therapeutic effect and manufacturers are best at design engineering for quality products (again, not always the case!), then bridging the gap between the two parties with a one-off written prescription sounds like a big task. Are we expecting too much of the written prescription, in terms of closing this gap? More importantly, if the final device isn’t exactly what we had in mind when we had that first conceptual design, how much does that variation in tolerance really matter in clinical terms?! I digress...:rolleyes:

    In relation to prescription protocols, as a communication tool within a design process, I would say that we need to accept that there are differing levels of experience in our podiatric community. Some advanced clinicians are able to consider all the design parameters concurrently when producing a design specification for an orthotic. Some less-experienced clinicians cannot. However, there is a common parameter that is shared by all, that is the conceptual design of a device for therapeutic effect. Assessing the patient and applying an understanding of the evidence-base for application of forces (rate/magnitude/direction) in treatment of diagnosed pathologies, this is where the podiatrist is the expert and it is the starting point for the design process. In terms of communicating this conceptual design into instructions for the manufacture of a device, I would argue that written prescriptions should reflect a design process that begins with the conceptualisation of therapeutic intent, in order for it to remain accessible to all clinicians.

    Thanks all for an interesting thread, S.
  22. Nothing new under the sun, I was just reviewing this old text in relation to another thread: Allan M. Spencer: Practical Podiatric Orthopedic Procedures. Ohio College of Podiatric Medicine 1978
    "The actual devices made have many different configurations, dependent upon who fabricates them and which of the various theories of biomechanical control and evaluation the fabricator utilizes. These controversies exist because of the various foot types dealt with and the many styles of foot gear used with the devices. The best device is the one that is suited to the needs of the patient; above who, how, or why it was made."

    An astute observation.
  23. joejared

    joejared Active Member

    Define modified root. I also think your typolock is stuck and should mean Skive.

    Control over thickness assumed, but just where? Along the lateral column, distal trimline, medial trim line, overall thickness, heel thickness, and lateral.

    Add onscuboid notch
    mortons ext
    rev mortons etc
    met dome
    Do you mean transverse met pad?

    Web, as in web feet or ?

    Otherwise... covered. ;-)
  24. joejared

    joejared Active Member

    "And then a miracle happens"

    I say, document well what you want, so that at first, some of us blindly assume, create a few likenesses from barely functional to pretty close, and then finally read the fine manual (rtfm) and ultimately do it right. Kirby Skive #3 in my own system well, will be just like that, as per the manual. I sorta wish I had more than a visual effect from one of my customers as he filed into a plaster cast to acheive a Kirby Skive, but it's never too late to change.
  25. Peter1234

    Peter1234 Active Member

    hi all,

    this is a little outside the variable question....but can i ask if anyone can recommend an orthotic lab in the uk ??

    pretty please with sugar on top..
  26. Ian Linane

    Ian Linane Well-Known Member

    Hi Peter
    Try Philip Wells at Salts Techstep, based in Birmingham. Good bloke and I've always found the products good. Phil is on here somewhere as well.
  27. Peter1234

    Peter1234 Active Member

    Thank you Ian,

    I was considering asking you personally but you beat me to it!!
  28. 7Pod7

    7Pod7 Active Member

    I think this brainstorming is onto something. It certainly seems to point to that we make orthotics to counteract excessive forces and their directions on the foot. A geographic systematic approach can help us visualise what we are focusing on.
  29. Lab Guy

    Lab Guy Well-Known Member

  30. Freeman

    Freeman Active Member

    Having read through some of these threads recently, I would think this is in constant need for resurrecting ...perhaps PFOLA could consider a project of this.
    Freeman Churchill
  31. Dennis Kiper

    Dennis Kiper Active Member


    Before we can determine which tests are needed to arrive at a foot orthosis prescription

    What is a ?foot orthosis prescription? mean to you? Maybe then we can work backwards to establish the needs of the pt?

    we first need to define what a foot orthosis is;

    This is why I'm asking the above question

    then determine all of the possible prescription variables. Agreed?

    What are all the Rx variables you are concerned about?

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