[Avodah] Aftura

[Jonathan Baker]

Query for the collected knowledge here, which came up in our shul's
Shaleshudis shiur in Hilchos Shabbos:

What is "aftura"?

SA OH 328:28 talks about lancing and bandaging a boil on Shabbos. 
MB sk 90 refers to a related procedure called "an aftura on the arm",
which is some kind of hole that one might want to keep open over
Shabbos, particularly by stuffing beans (kitnis) into it.  This comes
from the Magen Avraham.  M"A discusses the "aftura in the arm" as a
separate issue from the lanced boil (which presumably could be anywhere
on the body?) 

Since it's a "hole", "aftura" would seem to be a transliteration of
"aperture".  The KSA at 91:13 offers "fontanelle, imperatur" as possible
synonyms for "aftura".  But I don't understand how either of those might
fit either, as a "fontanelle" is the soft spot on an infant's skull, and
"imperatur" sounds like an "emperor".

It's clear from the texts that this is a refuah, a remedy or part of a
medical procedure, not an accidental injury, hence the desire to keep
it open and/or protected.  Magen Avraham says it's from the Raavan
(13th century), and if both the MB and the AhS discuss it, it was still
a current procedure in the Early Modern period.

RD Josh Backon and I have been trying to figure this out, but no go. 
Josh has sent it on to R' Seth Mandel, who has the necessary linguistic
background, but I figured I'd throw it to the assembled masses, and see
if someone might know medical or surgical history.  

--
        name: jon baker              web: http://www.panix.com/~jjbaker
     address: jjbaker at panix.com     blog: http://thanbook.blogspot.com