Responses to Seal-in liners and atrophy

Responses to Seal-in liners and atrophy

Christopher Hoyt

3/16/2009

Dear List:

Thanks to those friends and colleagues who responded to my comments
concerning limb changes after Seal-in liner use. I was awaiting a
statement from Össur before sending the responses to the list serv.

INITIAL POSTING:
I was wondering if anyone has experienced significant muscle atrophy
in their client's residual limb after using a Seal-in liner. Unsure
if this is incidence or coincidence, but I have noticed two patients
(one male, 51 years of age, one female 53 years old) with mature knee
disarticulation residual limbs, who after switching from true suction
and physiological suspension to wearing the Seal-in liner for two
years, present with noticeably atrophied thighs and lack of muscle tone.
Input regarding the seal-in liner and any and all amputation levels
is appreciated.
In addition: the atrophy observed was most noticeable proximally,
not at the location of the sealing ring. Both patients were using
single ring seal-in liners.


RESPONSES:
Only one experience, but, I concur. My patient is a 61 y.o. male.

I don't use a lot of seal in so I can't help you there, but your
letter is
very interesting. Atrophy does not surprose me as muscle tone since
tone
is relatedto the health of the mucsle and the use of the mucle. I wonder
why tome would be affected?

Interesting question Chris,
I haven't noticed the atrophy ( because I haven't fit that many ) but
the placement of the seal would be similar to the compression of an
agressive sc fit, which I believe often will create atrophy.
I've been an advocate of a higher seal placment and wonder if that
would make a difference.
Just curious to your thoughts.

Limb shrinkage is an interest of mine, but all I can share are some
thoughts. I do so a little hesitantly because I'm a tad
intimidated . . .
I assume that you made the suction sockets previously for these
patients? I suspect that it is all in the socket design. A retired
prosthetist (in Denver, no less) once told me: A tight socket will
shrink the limb until it isn't tight anymore. With the advent of
roll on liners, it seems to me that we are placing the limbs tighter
and tighter on the stump (percentage reductions as per liner
manufacturer's rec.). With the seal in liner on an AK or a KD,
aren't we placing socket circumferential reductions far tighter
distally than ever before (as opposed to a traditional suction
socket)? In the AK suction design, isn't the reduction tighter
proximally and less so distally, creating both a suspension seal as
well as a slight bottleneck constrained by the walls of the socket,
which might create homeostatic volume maintenance in these limbs?
Therefore, it seems to me that with using liners (and manufacturer's
socket rec.) we are shrinking the limbs with compression. These are
just some thoughts from a prosthetist with far less experience than
you! One day a proper study will be done on this issue . . .

Interesting situation. Could it be that it is too tight where the rings
are? How are you compensating for the anatomical shape and the rounded
end of the seal in. Actually I was visualizing the 5 ring seal in, but
the last question remains if not.
  I just wanted to let you know about a technique I have used which
works
well. A custom Alpha liner with the edge rolled over the top and a
sleeve suspension rolled over that. (that is from Jeff Deneune-OWW) Now
you have true suction throughout the whole limb. It works best,
obviously, with low trim lines, and ability to bear weight

I can't say that I have seen it, Chris. But it does make some sense.
Any compression from the liner is going to have a result different from
the true suction socket. Part of that could be atrophy. Compression
from the liner could cause the Tensor Fascia Latte(don't drink that) to
not have to fire as much. I tend to believe that people in true suction
sockets retain/use more muscle and muscular grasp to control their
prostheses. I believe this is due to the more direct feedback that they
get from socket-skin interface. Anything between that, like a liner,
makes the feedback fuzzier. Give the patient the false impression that
they do not need to work as much.(subconscious) Just my theory. FYI,
I went to school @ NCP many moons ago. My AK instructor always
showed videos of your TF mods. Good stuff.

I haven't noticed this but have only done a couple of through knees
with seal-in liners and that was relatively recent (excellent results
too as I could get rid of half pelite slip liners). However I would
think that with true suction there is an element of muscle flexing
going on to maintain the suction and with the seal-in because the
suction is guaranteed if you like, then they relax thigh muscles and
there is no concern (conscious or unconscious) about the suction
letting go.
On a side note, I have noticed less atrophy with AK's using seal-in
liners as I believe the liner pulls the stump back out continuously
to the size of the liner.?
Also experimenting a bit with older new amputees on interims and
getting much better outcomes (quicker rehab progress and higher
physical ability and safety) than conventional fitting with waist
suspension, even for vascular amps.
I really like the seal in. It has made fitting Ak's much easier and
because the seal is low down there is no danger of loosing suction
when making distorted movements and you can pul the socket away from
the top of the stump and there is no sudden loss of suction. The
silicon also helps to alleviate any skin friction type issues and
protests the skin and keeps it supple.

I have several people using the seal in liners but have not seen the
any dramatic atrophy of their limbs as of yet. I just fit an Iran
veteran who has ossification of the RL and said at delivery was the
most comfortable limb to date. Time will tell. He has a running
prosthesis with a 5 Seal in liner OB 4 bar Hydraulic knee and a
Sprint flex.

I read your enquiry about Seal-in on the O&P list and would
appreciate it if you would us know what feed back you get. We have
noticed that there is almost always a reduction in volume a few
months after changing to Seal-in. Even if previous prosthesis was
silicone with pin, but it is still to early for me to say if this
will present as atrophy later.

Just a thought: do you think that patients are more confident in the
seal-in suspension, thus reducing the amount of isometric contraction
of the limb? This might account for the atrophy. Simple patient
feedback could give you the answer. {C. HOYT: I did ask both
patients if they felt more confident in the seal-in rather than true
suction and they said as long as the limb suspended well they were
confident, and both could not discern if they were working harder in
one system over the other...they just walk.}

Good observation. It may be that your patients are not activating
their residual limb musculature as vigorously when wearing the seal-
in liners, whereby the liners do the 'work' of maintaining suction
integrity for them.

I would love to see a single or double sample with these two patients
wearing their respective suspensions using EMG to determine the
differences
in muscle use with each suspension.
I had a Transtibial patient (real estate surveyor) with a fused knee
convert
from a conventional strap and waist belt to a custom urethane liner
and he
developed the same problem. It did not affect his external gait
parameters
but he felt that he had less stamina with respect to his thigh
musculature
when on his feet for long days in the field.

Atrophy of musculature in the thigh of knee disarticulation patients
may be related to the reduced need to “grip” the socket with muscular
contractions. This may or may not be a negative so long as the hip
power is unaffected and if there is still good socket control. This
is possibly a subconscious reaction and might reduce the energy
expenditure from the individual. Perhaps there is a study in this?
Differential volume changes are observed in TT and TF fittings,
typically we see some overall reduction, slightly accentuated over
the distal 1/3. This is typically a rapid reduction in the first
weeks of use, we recommend staying on a check socket for this period
and only moving to a definitive when the limb has re-settled into the
new socket environment.
I checked with my counterpart in Germany, there are a high number of
KD amputees in Germany and the Seal-In (single and multiple seals)
have become a preferred treatment for these users. I will forward a
presentation from the clinical team in Germany when I receive it.

DISCUSSION:
Hopefully we can ask this same question a few years down the road to
see how certain interface designs affect the residual limb, long
term. I feel it it important to note that both of these patients
were educated on possible volume fluctuations and the use of sock(s)
to maintain their fitting, however they were unaware that their limbs
had atrophied due to the positive suspension / rotation seal. Both
developed painful bursae distally which brought them in to my
office. Since then, they have both been fitted with custom silicone
liners / suction suspension and within three months time both limbs
have regained muscle firmness seen in classic knee-disarticulations.
Hope this information is useful.

Chris
Christopher Hoyt, C.P.
BioDesign, Inc.
Denver, Colorado