Friday, March 29, 2024

Summary of responses: Expulsion valves why?…3

grantxw8

Probably the last reply on this subject. If anyone wants to contact the

respondent then email me and I will forward enquiries. Enjoy.

Cheers,

Grant

Dear Grant,

Been reading with interest yours and other thoughts on

air expulsion valves in TT’s. Some of the responses seem to have some

understanding of the negative pressure concept, but most appear to be

practitioners with very little experience or insight into the “concept”.

One of the underlying principles in negative pressure fit is the dramatic

reduction in motion between residual limb and socket. When incorporating

this reduction in motion with an interface where the modulus differential

between residuum and socket is reduced, skin/liner stresses are minimized

(a critical comfort/residual limb health objective). Dr. Joan Sanders

studies (JRR&D 92-96) suggest stump/socket forces are increased by

acceleration (whether in stance or swing). She goes on to suggest the

best mode of suspension is one with little or no displacement. She

further adds the negative pressure fitting eliminates distal displacement

and most importantly skin distraction. Her research on interface

concepts is worth studying.

One further rather esoteric consideration is proprioception provided by

specific suspension modes. Proprioception is critical when the Pacinian

corpuscles in the ankle are lost (primary lower limb proprioceptors) and

amputees rely very heavily on the residuum for proprioceptive feedback

for their compensatory strategies. Negative pressure fittings appear to

enhance proprioceptive accuity. It’s interesting to note that many

clients who utilize negative pressure fit comment that “it feels like the

socket is directly connected to their skeleton” and that they have

greatly improved fine control. This increased proprioception generally

leads to an increase in spatial awareness and confidence in the

prosthesis.

I have attached a few images of one of our patients who uses negative

pressure setups. As you will see, he presents with significant scarring

on his residuum. The patient is a butcher who is on his feet 12 hours

per day, and an A grade golfer who walks his rounds. We would not have

been able to produce a similar outcome without negative pressure fitting.

I hate to propose subjective matter, however we have numerous similar

clients who demonstrate similar outcomes (clients with and without

heavily scared residual limbs). We’ve fitted in excess of 100 clients

with this mode over the last 24 months, and would be happy to share our

experiences.

RECENT NEWS

Get unlimited access!

Join EDGE ADVANTAGE and unlock The O&P EDGE's vast library of archived content.

O&P JOBS

Welcome Back!

Login to your account below

Retrieve your password

Please enter your username or email address to reset your password.

The O&P EDGE Magazine
Are you sure want to unlock this post?
Unlock left : 0
Are you sure want to cancel subscription?