Re: Casting for viscoelastic liners
Randall McFarland, CPO
Description
Collection
Title:
Re: Casting for viscoelastic liners
Creator:
Randall McFarland, CPO
Text:
Chris Burdette's discussion about possible shortcomings of reducing a
cast for the OWW Alpha liner reminded me of something I've wondered about
when casting over a viscoelastic liner. It seems to me that two things occur
when you put a liner over the stump.
First, it seems that the snug liner over the fleshy stump would tend to
distort the natural contours of the stump towards a rounded shape.
Secondly, it seems that during the casting, the viscoelastic material itself
would flow away, stretching thinner over prominent, bony areas to further
deviate from the original shape.... and then we manually reduce the cast (as
Chris described) to as to put the viscoelastic liner under pressure to
utilize the flow characteristics.
It seems that if you casted over a non-distorting spacer that was
slightly thinner than the intended viscoelastic liner (to give the desired
pressurization), you would more closely capture the true contour of the stump
with fewer necessary cast modifications. (As we know, the more accurate the
original cast and the less you have to modify, the better.) I wonder if the
correct number of plys of thick elastic stump socks (protected from the
plaster by Saran wrap) would work for a uniform liner. Has anyone
experimented and developed such a low tech system that consistently gives
the proper volume for the liner to work as intended?
Randy McFarland, CPO
Fullerton, CA
cast for the OWW Alpha liner reminded me of something I've wondered about
when casting over a viscoelastic liner. It seems to me that two things occur
when you put a liner over the stump.
First, it seems that the snug liner over the fleshy stump would tend to
distort the natural contours of the stump towards a rounded shape.
Secondly, it seems that during the casting, the viscoelastic material itself
would flow away, stretching thinner over prominent, bony areas to further
deviate from the original shape.... and then we manually reduce the cast (as
Chris described) to as to put the viscoelastic liner under pressure to
utilize the flow characteristics.
It seems that if you casted over a non-distorting spacer that was
slightly thinner than the intended viscoelastic liner (to give the desired
pressurization), you would more closely capture the true contour of the stump
with fewer necessary cast modifications. (As we know, the more accurate the
original cast and the less you have to modify, the better.) I wonder if the
correct number of plys of thick elastic stump socks (protected from the
plaster by Saran wrap) would work for a uniform liner. Has anyone
experimented and developed such a low tech system that consistently gives
the proper volume for the liner to work as intended?
Randy McFarland, CPO
Fullerton, CA
Citation
Randall McFarland, CPO, “Re: Casting for viscoelastic liners,” Digital Resource Foundation for Orthotics and Prosthetics, accessed November 4, 2024, https://library.drfop.org/items/show/215872.
