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Casting methods

Discussion in 'Biomechanics, Sports and Foot orthoses' started by cpoc103, Jan 12, 2011.

  1. cpoc103

    cpoc103 Active Member


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    Hi all happy new year to you all, I hope 2011 treats you well.

    I was casting the other day using a Cad/Cam system, and wondered what was the preferred choice of casting method people were using.
    Was interested to know how many people are still using conventional methods such as POP and foam box versus new technologies such as pin digitising and laser??? and if using newer tech.. what was the reasoning behind it??


    Cheers
    Col.
     
  2. Admin2

    Admin2 Administrator Staff Member

  3. Richard Stess

    Richard Stess Member

    I always find it very interesting to note that practitioners have jump from Foam to POP or POP to CAD/CAM without carefully examining the accuracy of the negative mold that is required for a particular use. Furthermore the number of devices that one is casting per month seems to be only one rationale for using CAD and CAD. The cost of these devices must be factored into the decision to employ one technology over another.

    As one of the originators and owners of the STS Company, that manufactures both tubular fiberglass material used for AFO's and prosthetic devices, polyester casting socks (fitted socks and slipper socks) used for both molding the foot/ankle I am continually surprised by the questions one asks and their responses. I often hear that a practitioner uses a foam box and does not use other methods only because it is faster than plaster of paris or it is cheaper. I often am told practitioners don't use, for example, the STS products because they cost a few dollars more per pair than plaster/foam while they will consider spending thousands of dollars for a cad/cam system. Often the two arguments don't add up to me. In the United States based on a study producted by Podiatric Management magazine approximately 30% of negative foot casts are made with foam boxes, 11 % STS Casting socks, 10% CAD/CAM with the remaining numbers made with POP.

    It seems to me that before one decides on one method over another they should decide on what is their main objective in obtaining mold (such as the type of orthotic device and material that is to be utilized), what method does their laboratory prefer and the degree of accuracy that is required. These decisions should be considered in addition to the overall cost of both material and practitioner time.

    Richard Stess, DPM
    President
    STS Company
     
  4. I'm old fashioned and low tech. Foam and POP for me, depending on what I want. I had a Laser scanner for a while but I never learned to love it.

    I agree.

    Although I would add that for me the MOST important element is which method the clinician can produce the best negative with. I find Foam easy to use because I am a large man, who likes pie. A slender and sylphlike being like twirly or blinda might struggle to exert the required force under any kind of control and produce a better cast with a non WB solution. Another might find foam easy to use, but have a bad back and not relish the idea of getting down on all fours to take the cast.

    Oh and the accuracy of the negative mould? I suspect this is shockingly poor regardless of the method, although I believe that casts have been shown to be more repeatable if Semi WB. I suspect this may be due to the presence of a reference plain. Chuter showed a range of 16 degrees RF to FF position in intertester variation from non weightbearing POP (from memory). This makes something of a mockery of the accuracy issue for me.
     
  5. footdoctor

    footdoctor Active Member

    Hi,

    Personally i'm a POP man. Why... Because it enables me to capture the foot in the shape that I desire.

    Used a optical laser scanner previously and got horrible image reproduction.

    Reasoning behind various casting methods

    1) Patients/customers are generally pretty impressed when clinicians use fancy technology. You might know jack sh*t about foot function/casting/image capture, but if you have the latest gadgets it may attract patients to your clinic. The marketeering approach.

    2) Potential time savings, POP casting might take 30 mins, laser scan or foam impression prob 2- 5 mins. Time saved, more patients, more profit .

    3) Ability to operate clinics from various locations. using foam boxes and portable scanners you can work pretty much anywhere. POP casting requires a plinth, a sink and prob a non carpetted area.

    4) Foot shape that you require to capture. This is probably the most important bit. pop casts, foam impression boxes, laser scans, pin matrix devices.......they all do one thing........ capture a shape. Decide what shape you wish to capture the foot in and select the method that works best for you in your environment.

    cheers

    Scott
     
  6. footdoctor

    footdoctor Active Member

    Richard.

    What is the advantage of me using a STS sock over pop bandage to produce a negative mold?

    Thanks

    Scott
     
  7. David Wedemeyer

    David Wedemeyer Well-Known Member

    Mainly POP casting and I use foam for certain patients. I have used the STS socks for FFO's, I like them personally. I'm probably cheap though...

    I have an optical system that was good but not excellent (and went to a proprietary lab, which sunk it). The same company is debuting a laser system very soon, holding my breath. Difficult to get the entire calcaneus with flatbed systems though. Ultimately if I could do away with POP casting I would be pleased.

    Regards,
     
  8. Rosso

    Rosso Member

    I have a Lab and most of my clients use Plaster about 5 % use impression boxes
    We have most of the Plaster clients use our method of casting with 3 layer of bandage and smooth the heel to the toes but not make a boat of the plaster as we scan the exterior of the cast with our 3D Scanner. This method defines the foot and naturally allows for some expansion.
    We also accept the 3 D Scans from Pods however they should have some experience and a method to check the Scans before sending to us.
    There is a new Laser scanner on the market around AU$15K and is quite good. It is a semi weight bearing which has its limitations as well. The best scanners we feel are the tripod mounted Precision Scanner Classed as hand held and they come up very well.
    We have played with Pin Digitizing however the Precision hand held scanner makes PD results look amauterish.
    As to technique pros and Cons of different methods I'll leave that for you Pods to sort out
     
  9. Out of interest Rosso, as a lab, what type do you prefer to work with and why?
     
  10. Rosso

    Rosso Member

    Both both have advantages and disadvantages
    Recieved scans from non weight bearing scanner, if completed correctly and checked before the patient leaves the clinic are very good. No issues for a reasonable foot. Feet with complications some times we need to clarify with the Pod what we are seening.
    Plaster cast scanning, we have a process for our casting method and one for the traditional method. It seem the Training organisations in Australia do not know about Cad/Cam 3D scanning nor are they training in the tradional method as every new grad we see make very poor Casts even for the Plaster pour method.
    It boils down to good skills in both methods make our life easier.
    We have some minor issues with impression boxes mainly heels not wide enough but again this is a skill issue and our intrepretation of the Pod skills.
    Most Pod who use them never have an issue as the script is filled out correctly.Others have issue because the foot is fat and they dont ask for extra heel width.
    I sometimes tread on delicate Toes when I communicate, better to do that than speak with fork tongue.
    :bash:
     
  11. Sounds fair.

    It comes back to what I said earlier. Each method can produce a good cast if done well, and a bad one done badly. Skill is paramount.
     
  12. cpoc103

    cpoc103 Active Member

    So Rosso, you scan the outside of the negative cast? how well does this come out in relation to foot shape?

    Its interesting to see how many pods still use POP and impression boxes, agree with Robert, it comes down to the practitioner and what best works for them. no matter what method of casting you use, if you take a bad cast it wont matter what casting method you use the end result will be the same!!

    cheers for the responses guys.

    col.
     
  13. PowerPodiatry

    PowerPodiatry Active Member

    Without getting too off track...

    Ran my own in-house LAb for 1st 18 yrs then through lack of sleep and bandsaw through finger decided it time to outsource for the last 7yrs.

    When casting for own construction a level of intuition is allowable so the method of casting becomes a preference because the inherent problems in the chosen system gets ironed out because..."that's right Mrs Blogs has a fat heel".

    Using a Lab requires accurate and definable instruction.

    My question often revolves around VALUE and integrity.

    POP/Foam costs me $XXX to sit on the shelf
    Scanner costs me $YYY per month even when I am on Holidays.

    Will I make unnecessary orthoses just to cover the increased cost of Technology?

    Will the patient have to pay more so that I retain my profit margin?

    What % of patients that needs orthoses be unable to accept the higher charge(same profit)?

    All for technology that increases VALUE to myself and patients.

    Interesting Topic Ladies & Gentlemen
     
  14. Rosso

    Rosso Member

    Lock the foot in place do your usual procedure pre plastering.
    If you use 3 layers of 100mm (4 inches for the backward countries) plaster bandage, with the patient layed prone, drape the bandage over the heel ( up the heel say 75mm and smooth it over the arch and planter, and wrap it back up the toes, there is no need to make a boat of it and roll over the top sides of the foot ( this makes it easier to remove). re Lock the foot in place then smooth over leaving a smooth surface on the exterior of the cast as well as emulating the foot shape exactly. You wait less time to remove the cast from the patient, leave the cast to dry normally ( Its faster drying time ) You can smooth out your indent where you locked the foot or just leave it. The guys tell me less mess and quicker, that got to be PLUS PLUS
    One of the big issues we see is the process of plastering many many layer and trying to remove the cast end up distorting the cast any way. If I can work out how to upload a photo here in the next few days I will.:morning:
     
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