NEWSFLASHER Casting repeatibility

[robertisaacs]

I should probably have put this on the casting thread but since that one got waaaaay off topic i'll put it here.

Reliability of casting techniques

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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

Quote:

Background: We examined the ability of foot care professionals to consistently capture the forefoot-to-rearfoot angular relationship of a single-cast foot.

Methods: Eleven Canadian certified pedorthists each cast a single foot twice using the plaster of Paris and foam box techniques. Three independent raters subsequently measured the resultant casts. Statistical analysis of the data provided generalizability coefficient estimates (2) of the intracaster, intercaster, and rater reliabilities.

Results: Intracaster reliabilities were excellent when the plaster and foam box techniques were used (2 = 0.831 and 0.939, respectively). The casters were more intrareliable when foam was used (F = 2.755, P = .003). Intercaster reliabilities were poor for both techniques (2 = 0.410 and 0.425). Although, intrarater reliability was excellent (2 = 0.882), interrater reliability was poor (2 = 0.418).

Conclusion: Although plaster of Paris casting is widely perceived by the foot care community as the gold standard, other casting techniques may prove to be equally reliable.

[TimVS]

Ooh! Don't know if my uni can access that journal. I'll have a peep

[robertisaacs]

Why the sneaky little

And this, my friends, is why we must be careful drawing conclusions from abstracts!

On inspection of the full text it turns out

Foam.
The gait-referenced casting technique, developed by Edward Glaser, DPM (Sole Supports Inc, Lyles, Tennessee), attempts to cast the foot at its uncompensated midstance posture, where the maximal natural arch height is captured with the subtalar joint in its most stable position.

This is with the foot in the much dreaded MASS position!!!

[TimVS]

He he. I was worried, not being able to get hold of the full text, that there might be too many variables, but I wasn't thinking of that one.
Doing a critical analysis on that study would be quite fun, methinks.

Where did you get it?

[robertisaacs]

He he. I was worried, not being able to get hold of the full text, that there might be too many variables, but I wasn't thinking of that one.
Doing a critical analysis on that study would be quite fun, methinks.

We might start with the fact that it is comparing two different casting positions, STN for POP and MASS for foam. Considering that MASS involves inverting the stj to the end range then everting the MTJ until the 1st met hits dirt (ie a position reached from the end range of joints) whereas the STN is a position somewhere in the middle of the joint range it is not comparing like with like. I bet i could measure my height with my legs straight a good deal more repeatably than my height with my knees half bent. Its not comparing like with like.

Thats fine and dandy if they had said in the abstract that they were comparing two different casting positions. But you will look in vain in the abstract for any mention of this minor detail. They don't exactly shout about it in the full piece either! The abstract clearly implies a comparison.

And so as per my habit of offering giant smillies in the form of lolcats...