Longer fibula amputation RESPONSES part 1

Longer fibula amputation RESPONSES part 1

Randall McFarland, CPO

Original question:
We saw a 75 y.o. female client, weight 90 lbs. who presents with an
amputation where the tibia is cut about 2 shorter than the fibula. Does
anyone have experience with this unconventional shape? I'd like to hear
from those who have actually had experience with this successful or not.
Thanks,
Randy McFarland, CPO

Thanks to all who took the time to send the following
RESPONSES. (each separated by a blank line):

I have successfully fitted several patients with a fibula slightly longer
than their tibia but none anywhere close to 2 inches longer. Good luck!

We did a tec on all three patients we saw. The resolution was re-education of
the surgeon.

I had great success with many of these amputations. I used a trilateral
shape, locking in well(gently) on each side of the tibia and flattening the
posterior popliteal area (no walnut cut out). Molded this shape into the
initial cast using the 2 part casting system. The first is a preshaped
anterior splint extending from the distal edge of both the Medial and
Lateral femoral condyles and the tibial tubercle to center of distal end
(anteriorly) and extending to the posterior edge of the condyles and of the
fibula on the lateral side and just passed the midline on the medial side.
This splint is about 7 layers thick of fast setting 8' rigid plaster
bandage. I mold the splint to have the shape I want the final cast to have.
Don't press too hard or it will pop away from the limb every time you take
your hands off it. When it is good and hard wrap the remainder of the limb
with elastic plaster bandage about 2 to 3 layers thick and keep the anterior
splint in place while flattening the posterior proximal area. If you are
doing a supracondylar socket you'll need a 3 piece cast. Use 8 layers of
rigid plaster extending from hamstring anteriorly to hamstring. When
modifying your AP to what you want flatten the posterior proximal are and
don't allow a large bulge distal to that, dress up (remove any bumps and any
protrusions where the splint ends) and remove a slight amount of plaster
along each side of the tibia (on the shaft medially and in the antertibialis
channel laterally). Do everything else as always. Do not pay any further
attention to the shaft of the fibula. If your hand cast was molded correctly
you'll have a very comfortable socket in that area and lateral stability
will be provided by the molding in the anteriortibialis channel.
Good luck,
Bob Brown, Sr, CPO, FAAOP

It has been years since I have dealt with this type of incompetence.
However I have in the past seen this type of amputation done overseas and
dealt with the consequences with a reasonably good degree of success. I am
not particularly a proponent of silicone foam distal end pads but that is
what I used to maintain good distal contact and a reasonable margin of
comfort. The fibula can be highly sensitive but it can be worked around.
The best case scenario is revision but in order to spare your patient the
additional surgical insult you could try a silicone foam distal end pad. I
recommend that if you add a firming component to you foam be judicious and
keep the foam soft. The problem with foam in my mind is one of durability,
it starts off well but has a short life depending on the activity level.
Fitting a case like this can be done but it is certainly a travesty for your
patient, and no doubt will increase the fitting difficulty for you as well
as reduce your fitting options. Best of success in your endeavor. By the
way you may need to relieve the foam slightly where the fibula contacts it
directly by removing a small portion in order to decrease pressure to a
tolerable level.

Unfortunately, the few that I've treated required custom-made
injection-molded silicone liners. Tried commercial liners with distal gel
pads (highest elevation under the tibia) but the pads tended to migrate and
roll. Poured pads were also problematic.
    In lieu of a custom liner, I suggest that you mold a distal pad of
Playdoe and hand-shape to roughly acommodate the patient's unusual distal
end, then cover lightly with Saran Wrap and place into liner. 5 minutes (or
less) of walking will convert the Playdoe into a custom pad. With care, the
pad may last for 1-2 months.
    You may also make a 2 piece urethane mold, over this finished Playdoe Pad
in order to get a permanent mold for this patient. Then merely pour or inject
liquid silicone into the mold chamber to create a one-piece, soft gel distal
end pad ... with a perfect fit to the walls of the liner and to the distal
end of the limb. Use an acetoxy type RTV silicone adhesive to bond the
silicone pad to the silicone liner. Let set at least 24 hours. If you need
more specifics or materials, contact me.
Hope this helps.
Lou Haberman CPO

The third patient that I fitted at UCLA had a similar situation. His tibia
was about 2 3/4 and his fibula was about 4. Not quiet the same but
close.Although I will not pretend that a successful fitting at school is the
same as a successful fitting in real life, the point is that this man had
been a patient-demonstrator at UCLA for several years and continued for
several years after I finished (1963). He wore a prosthesis continually and
appearantly did well. He was probably 50-55 years old and a traumatic
amputee, not dysvascular.The modifications that I did were straight forward,
with the exception of a distal relief under the fibula. I would not consider
fitting this lady without foaming a silicone pad distally.Good Luck
Jim Fenton

I have one patient with a similar situation, and the fitting has been a
problem. I think we have finally gotten a good result, but prior to that,
there was a lot of skin breakdown on the distal end of the fibula. The way
we achieved a successful result is as follows:
I first made a splint cast of the distal 4 inches of the limb. This was done
over gipsisoliercreme, (otto bock's version of Vaseline....) to get a good
and accurate impression of the distal anatomy. Prior to making this cast
VERY IMPORTANT I made a small build up on the distal fibula, using 1/4, or
3/8 soft pelite. This created a relief in the mold for the distal fibula.
This relief is a circle of material, skived on the edges, and warmed and
formed over your fingertip. This little cup is then adhered to the distal
fibula with medical adhesive, or doublestick tape. I then used greenlabel
splints, about 3 or 4 thick to make the mold.
This small cast was then filled with straight plaster, no vermiculite.
I then sealed this smooth mold with shellac and lacquer, for a parting layer
for the next step.
I then took more plaster, and built up on the distal end of my mold to a
thickness of about 1, and carefully smoothed this to blend it to a smooth
transition to the original mold. (now what I have is a mold of the patient's
distal limb, with a distal buildup)
I took this mold and pulled a socket of diaclear over it.
I drilled a small hole distally in the diaclear and blew it off the mold.
Then I knocked the distal buildup of plaster off the mold.
I coated the mold with vaseline, and replaced diaclear over it. The diaclear
now formed a void over the distal end of the mold.
I injected this void with blue silicone from Uco (I think) Make sure you
have enough of it, it takes quite a bit.
When I was confident this was set, I again blew off the diaclear socket,
and was left with a very nice custom molded distal pad with a relief for the
distal fibula.
I then had the raw materials to get my BK cast. I placed the silicone pad
over the distal end of the limb, and rolled an Alpha liner, 6 mm over it. I
took my mold in the conventional way after that, and made the prosthesis.
I instructed the patient on placing the silicone pad on his limb prior to
rolling on the liner, and he has been abrasion free ever since, about nine
months so far.
Good luck. THis is a particularly challenging fitting, and I will be pleased
to hear how you finally resolve it.
Take care.
Mark Bondurant, CPO