I received a number of questions and responses to my previous post in which
I commented on lowering the trim lines in an elevated vacuum socket. I was
asked what I meant specifically when I said that with elevated vacuum the
fit must be “dead on”.
I am posting a copy of one of the questions and my reply to it below:
If there are more questions fire away,
Jon Batzdorff, CPO
Good Morning Jon,
I’m watching with interest the increase in popularity of the elevated vacuum
systems, having first cut my teeth with the OWW system. I’m curious about
your final statement relative to the ‘dead-on’ socket fit given that the
trim lines are inferior to the pelvic anatomy. Short of tension values, and
having no anatomical construct to the femur/soft tissue matrix distally, how
do you define this ‘dead-on’ concept. To date it appears more of a
reflection of the vacuum containment/strength and residual muscular
integrity. Just thought I’d ask you personally. Thanks.
—————————–
Hi David,
The “dead on” has to do with several things. Here are the primary elements.
1. Liner fit: It is my feeling that most of the problems associated with
“milking” and distal edema with lanyard and pin fit transfemoral liners is
because they are off the shelf liners. Therefore the tension
they apply to the soft issue is uneven and random unless you
happen to have either a residual limb that perfectly matches
the conical liners. You can imagine how most of them re-shape the soft
tissue
to fit the liner, rather than the other way around. The reason there are not
even more problems than we see is because they are typically not suction
sockets. If you take a non-custom liner and apply suction, the possibilities
for problems increase and if you increase the vacuum to 27 inches, you are
creating a dangerous system, depending on the fit of the liner. Therefore, I
recommend that you pay particular
attention to the fit of the liner and either make a habit of using custom
liners on elevated vacuum as I do religiously, or be darn sure the ordered
liner fits with even tensions throughout the limb.
2. The fit at the distal one half of the socket and distal end: If you are
using a double walled socket, which I recommend for transfemoral elevated
vacuum, you cannot visually see the distal fit of the socket. There is a
liner and then a “wick” which is a cotton sock, and a vacuum cap made of
carbon. Even if you made a clear test socket initially,
there are so many layers of things that it is hard to get an accurate
eyeball view of the fit down there. The vacuum cap must be cast, modified
and constructed to provide total contact with some compression both
circumferentially and distally, and the patient must be trained in applying
the liner, wick, the distal end cap, and the outer socket properly to
assure proper fit.
I hope this helps specify the concerns. As I begin the next elevated vacuum
socket next week I will try to post each step of the process on the blog
as I am doing the steps of the process. So check that out for
more details: http://elevatedvacuum.wordpress.com/
Jon
