Question about intrinsic rearfoot posting

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Hi all!


im a 3rd year podiatry student and just have a *stupid* question that i wanted to ask about orthoses to you podiatrists .

(this is for a semi rigid modified root )
When making an "intrinsic rearfoot posting heel grind at 0 degrees", i would have to grind the positive cast is ground flat at the heel.
The dilemma is this - How much DO i grind ??? i mean its already at 0 degrees when i put that nail in the bisection of the 1st MTPJ and made the anterior platform. do i grind down so that theres a 10mm squared flat area? or grind it down by 3 mms? how does it work??

any help would be appreciated!
thanks in advance!

 

Every lab would probably do it and interpret the prescription instructions differently, so its not a *stupid* question (thats why the title of the thread has been edited).

If I understand you correctly, then I am not sure why you want to modify the positive cast (ie i would have to grind the positive cast is ground flat at the heel. ). Again, if I understand you correctly, you just get the calc bisection to vertical (ie 0 degrees); mold the shell, then grind the plantar surface of the shell under the rearfoot flat to create an "intrinsic rearfoot post" to hold the calc bisection of the cast at 0 degrees. As its intrinsic to the shell, and extrinsic post is not needed.

Hope this makes sense.

 

thanks for the reply Craig.
hmm, if i understand you correctly, do you mean that i should grind the plantar surface fo the rearfoot of the polypropylene? (or whatever material that is the shell of my device) and NOT the actual plaster cast (positive cast)?

 

Yes for an intrinsic rearfoot post (ie its intrinsic to the device)

There are other reasons you might want to grind the plaster cast (eg Kirby Skive)

 

cool
yup its for modified root device, so i dont grind the plaster, got it.
thanks a lot Craig!

be expecting a lot of questions coming from me in the near future hehe

cheers!