Responses: Knee Disarticulation Socket Design 2

Responses: Knee Disarticulation Socket Design 2

Ultrapedics/Eric Schwelke, C.P.O.

7/13/2001

7/2/01, I posted the following:

To all:
>
> We are working with a 42 yo female w/ ho Rt. KD 2nd to trauma almost 1
year
> ago. (Subway accident). Residuum is in excellent condition, well healed
> clean suture line, well defined with no edema. Excellent end bearing
> possibilities. We are leaning toward using a gel cushion liner
> (specifically the new ALPS moldable cushion thermoliner). Two questions
for
> colleagues who have experience w/ KD’s: How practical have you found end
> bearing to be?? Further, along with end bearing, have you always used
> either IC or Quad brims?? No brim at all?? As for socket design for
> suspension, aside from the various doors and/or bivalved sockets, have you
> found other configurations successful utilizing flex inner sockets w/
> frames?? All responses will be posted to the server in a timely manner.
>
> Thanks in advance.
>Eric Schwelke, C.P.O.

Here are additional comments and suggestions up to today, 7/13/01. The
consensus for brim style/type is no brim at all as long as it is a true end
bearing residuum. Some trim just distal to greater trochanter with others
using minimal heights. Some other interesting ideas for suspension include
* Air bladders just proximal to condyles
* Suction liners/valves



Responses:

I have recently fit a KD patient who is very active. He can tolerate end
bearing so the socket design I chose was one that was developed by TEC.
Using
a TEC distal end cup I cast the PT just distal of the GT. Reduce the mold by
1% where the distal end cup is. The socket shape covers the distal end and a
2 lateral wall extends proximally to distal of the GT where it becomes a
cuff with a 2 medial opening secured by a strap. Suspension is achieved by
means of suction using a TEC VC4 valve and a Tec profile suspension sleeve.
The socket will be very light. Combine it with a polycentric knee and
variflex foot it should weigh no more than 5-6lbs
Hope this helps.

Eric,
I had a 15 year old female KD secondary to ewing sarcoma. She wore a tec
custom with a medial pelite pad that she guided in to the socket when
donning. Not my design. When she came to me for her definitive she was still
a little tender distally. I fabricated a bio-elastic liner with carbon
braided frame. I thought with no door this would be a stretch. She had been
using a wet fit with her temporary. She used ultralite lotion from Cascade
and had grown accustomed to using it. I tried an easy pull bag from
Fillauer, but she was not very receptive to this. We went back to the wet
fit and that is how she continues to donn her prostheses. I used as Ipos IC
brim to to distribute some of the weight bearing on the ischium. I used a
small green dot valve posterior distally also. In three months time as she
was able to bear more weight, I ended up cutting the frame down little by
little until there was no posterior frame. Of course there was still some
frame left distal posterior just proximal to the condyles. I thought this
process worked out great, but it does require some time. She said with the
bio, it felt like she had a lot more control and it made a difference
cosmetically. She is a level 4 ambulator now. Hope this helps. Forgot, when
cut away the posterior, I added a dacron backed
hook and pyle strap to keep the inner socket in place. If the frame is thin
and strong enough it may help with increased volume.

I've done several sockets on my client so far and what I ended up with is a
simple laminated socket; even though she has prominent condlyles and a
skinny leg (this defied my logic). I guess the nylon cover on the dermo
liner allows the condyles to slide past the narrow part of the socket
without any resistance. If your client has real prominent codyles consider
a flexible inner socket with medial and lateral windows; with the dermo
liners nylon cover and the flexible inner socket she'll have no problem
getting her
condyles past the narrow part of the socket.
Admittedly, I had a problem with he notion of lowering the socket as much as
I had too to get enough skin exposed for the band of dermo liner, for fear
that it would compromise her stability with the shorter lever arm. But my
client stated she felt no loss of stability. She really liked the shorter
socket too, most will.
If you can grasp the concept I've described the suction socket is
ridiculously easy to fit, you'll like it.
Let me know how it goes. I have to give credit to the person who taught me
this suction system for KD's: Tad Meyer, CP. He works for Hanger here in
Omaha, NE.

Hi Eric,
    End bearing, good leverage and good muscle strength are advantages of
the
TK level. The brim of the socket may only need to go up 2/3 the length of
the
femur, so you don't need to go with quad or IC. A end pad like viscoelastic
or 1/2 inch PPT is advisable but I don't think a gel liner is necessary. A
push-in pelite liner utilizing the bulbous shape for suspension could do the
trick. Stay simple, strong, light and low maintenance whenever possible.

Eric, I believe that if a knee disart can tolerate end bearing then forego a
brim-type socket. For knee disartics I fit what I call a 50/50 socket where
I get 50% weight bearing on the distal end and the other 50% on the girth of
the thigh. Recently I fit a lady with a suction socket by using a dermo
(non-pin) liner that extended all the way up the thing. To create suction I
used a leak-rate valve in the distal end and then used a 4-6 piece of dermo
liner (much like a knee sleeve for TTs) to seal off the proximal end of the
socket. This is essentially the same way people are fitting total suction
sockets on TT prostheses. The patient commented that the suction was
excellent, no pistioning or movement at all. She likes it so far.