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Reliability of casting techniques

Discussion in 'Biomechanics, Sports and Foot orthoses' started by NewsBot, Jan 17, 2008.

  1. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
    1

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    Ability of Foot Care Professionals to Cast Feet Using the Nonweightbearing Plaster and the Gait-Referenced Foam Casting Techniques
    Leslie C. Trotter and Michael Raymond Pierrynowski
    Journal of the American Podiatric Medical Association
    Volume 98 Number 1 14-18 2008

     
  2. Admin2

    Admin2 Administrator Staff Member

  3. Craig Payne

    Craig Payne Moderator

    Articles:
    8
    Its now obvious that negative model production methods that have a reference plane (ie the floor) are more repeatable than negative model production methods that do not have a reference plane (ie the traditional NWB plaster casting).

    HOWEVER, just because a method is repeatable, does not necessarily make it the correct method ... it could just be reliably repeating the wromg position of the foot with incredible accuracy.
     
  4. So foam MIGHT be getting right all the time OR might be getting it wrong all the time.

    And POP, at least in the subjects who showed less intra tester repeatibility are DEFINATELY getting it wrong SOME of the time.

    And possibly the casts we take so lovingly and with such exquisite attention to detail and repeatibility get sent off to a lab where they get "cast corrected" to within an inch of their lives to make them virtually identical to all the others anyway.

    A study i'd like to see would be a scan of the anterior surface of a bunch of different lab made shells of feet the same size but different ff/rf relationships, arch heights etc. THAT would be an interesting bit of data!

    Regards
    Robert
     
  5. davidh

    davidh Podiatry Arena Veteran

    :pigs:

    (in my case......):eek:.
     
  6. It appears, having looked at the full text, that all is not what it seems....

    From methodology

    The MASS position is studiously not mentioned however it looks much like if from the description.

    Sneaky little ******

    So it appears that this study shows only that the Ed glaser school of casting is more repeatible.

    Hmmmmmm.

    Regards
    Robert
     
  7. Craig Payne

    Craig Payne Moderator

    Articles:
    8
    Exactly. It not just foam, its the negative model methods that have a reference plane (ie the floor) which could inculde semi-weightbearing plaster cast that are really good at repeatably getting the same position ...that does not mean it the correct position.

    We have done a study on both:
    Chuter V, Payne CB, Miller K: Variability of neutral position casting. Journal of the American Podiatric Medical Association 93:1-5 2003

    Payne C, Chuter V, Oates M, Miller K: Evaluation of a weightbearing neutral position casting device. Australasian Journal of Podiatric Medicine 35(3)65-71 2001
     
  8. Craig Payne

    Craig Payne Moderator

    Articles:
    8
    In fairness to the researchers and Ed, the declaration of this interest is at the end of the paper.
     
  9. I agree with Craig here. However, IF the uncompensated forefoot to rearfoot alignment is significant, it cannot be captured using weightbearing techniques.

    A note regarding the methodology. For the intra-observer reliability I would have liked to have seen far more repeated trials than just two, better to have fewer "observers" and more repetitions for intra-observer. And for the inter-observer, I would have liked to have seen more observers.
     
  10. Mac

    Mac Member

    If Figure 1 is at all accurate, I am concerned with the thumb and forearm positioning that was employed during the non-weightbearing plaster of paris casting. This hardly looks like proper neutral suspension technique!

    Mac
     
  11. Chris,
    For those who don't get JAPMA can you attach the image please?

    The other point here is that in a clinical situation these patients could have been cast by any of the individuals who performed the casting. The rubbish inter-rater performance, suggests that a wide variety of "prescriptions" could have resulted. But the million dollar question is.... would it have made any difference?
     
  12. Admin2

    Admin2 Administrator Staff Member

    Ask and ye shall receive Matthew 21:22
    [​IMG]
     
  13. Mac

    Mac Member

    Simon:

    To address your previous question,

    "But the million dollar question is.... would it have made any difference?"

    In my opinion, it depends on the magnitude of the differences, the method of manufacture and prescribed materials. Certainly when using thermoplastics and composite materials, you have less room for error. The devices will probably not be tolerable and comfort will be compromised.

    Mac
     
  14. How do papers like this get published in JAPMA where there is a clear conflict of interest with the researchers being consultants for the lab where the technique is used and promoted as the "only correct casting technique". Lucky for these authors that I wasn't the reviewer for this paper.
     
  15. The bit which frightens me about this is that there is no mention whatsoever in the abstract that they are comparing casting repeatibility in two different positions. The implication is that we are comparing like with like, that the study shows foam may prove equally reliable as POP.

    My bike travels as fast as my car... when my car is in first gear!

    If they said they were comparing fully WB in foam and STN in POP we would not consider it a fair comparison. MASS is a position based on finding the end range of joints rather than a point somewhere in the middle. I'm not surprised it was more repeatible.

    I know we should not draw conclusions from abstracts but the truth is that there are a large number of podiatrists who don't have access to full texts, or lack the time to read every article they see in full. As such i think a misleading abstract is a very serious issue.


    It does'nt exactly shout about the different positions in the full text either.

    Regards
    Robert
     
  16. PodAus

    PodAus Active Member

    Which begs the question, even with good casting repeatability/ reliablity using any preferred method, how does it statistically relate to the reliability of achieving a predicted outcome for any individual prescribed orthotic therapy? Particularly without any orthotic modification upon review...
     
  17. Craig Payne

    Craig Payne Moderator

    Articles:
    8
    We see this all the time in drug trials. I do not necessarily have a problem with it, provided that:

    1. The conflict is explictly acknowledged (which in this case it was)

    2. It is explicit in the methods what was put in place to eliminate the potential for bias (which in this case, not enough information was given for us to make a judgement; eg were the 3 raters who measured the casts 4 times aware of the source of funding and the purpose of the study? Was the employee of the sponsor one of the raters?)

    It would be wrong to exclude company supported research by company employees from the literature. it would be worse to disguise it and not be explicit about what was done to eliminate potential biases because of the potential conflict.
     
  18. Craig Payne

    Craig Payne Moderator

    Articles:
    8
    This is worthy of a whole new thread. There is no doubt casting is variable. There is also no doubt that rigid custom made foot orthotic work. :dizzy:
     
  19. Simple:
    1. Patient would have got better anyway.
    2. Placebo/ Hawthorn effects.
    3. The orthosis reduced the stresses to within the zone of optimal stress.
    4. Foot orthoses aren't precision objects and don't need to be precision objects to achieve 1, 2 or 3.
     
  20. PodAus

    PodAus Active Member

    New thread started and completed in one line. That about covers it.

    It's how efficiently the patient gets better - time, cost, user-friendliness. Positive outcomes keeps us all happy :empathy:
     
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