response Summary: Northvane and valve leakage

response Summary: Northvane and valve leakage

Ted Trower

3/19/2003

My question was:

We've been using the Northvane Semi-Flex medium along with the valves from
Thermal Techniques for AK sockets with generally good results. One recent
client has proved to be difficult. He uses lotion to create a wet
fit. This seems to result in the lotion lubricating the surfaces under
the valve seat and allowing the plastic to creep out from under the locking
ring. Once this occurs (it seems to take two-three days to get started)
the valve seat leaks air and suspension is unreliable. Has anyone one else
encountered this or a similar problem? What solution have you found? I've
experimented with various adhesives without much success. Is there a valve
available with a wider locking ring?


Responses follow:
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Ted, if he is using niva cream as the lotion, it is causing the problem.
For some reason the plastic reacts to the niva cream and changes shape. At
least that's what one of my upper limb patient discovered and what the
company verified at the ISPO meeting in Scotland.
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We use the Lyn valve from ESP. They have a metal ring for locking the flex
plastic onto the valve. We use Thermolyn super soft from OB (and some others
depending on client needs) and do a share of wet fits with no problems (if
fabricated properly) yet...
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We have had the same problem. I have found 2 solutions. One is to use the
Otto Bock valve, it has a better seal with a wider flange. Use silicone
adhesive between the seat and the plastic to get the best seal. It will
require a new socket however to get the seat correct.
If you want to try to fix the existing valve go to the hardware store and
get a vacuum break for a dishwasher. Take the domed metal piece and open
up the center hole and reduce the outer diameter to fit it over the plastic
under the outer ring. It will grab the plastic and keep it from sliding out
from under the ring. It is a little hard to make but it worked on the last
2 Thermal Techniques valves I used.
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You might try the Lynn VAlve from ESP. We have had good luck with it.
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ESP has a valve that uses a Grip Ring I think this should solve your
problem.
Its called the Lynn Valve with Flex connect.
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I use Proflex w/ silicone and Thermal Technique valves. Many of my
fittings are wet. I have found that the smaller diameter valves maintain
stiffer rigidity around the valve and the problem of the plastic slipping
out of the housing is greatly reduced. Not a cure all but it has
certainly minimized the problem for us.
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Thanks to all who responded. I found the idea of using the small valve
especially intriguing.


Ted A. Trower C.P.O.
A-S-C Orthotics & Prosthetics
Jackson, Michigan, USA

www.amputee.com