Thanks to all. Will look into new foot option 1st as his previous provider gave him a foot one size too small (?!) My 2nd choice & one I had been considering is using the OB torsion adaptor w/signed waver.
Original post:
Does anyone know of an axial rotation option for a 332 lb, 6’1″ gentleman with a TTA & a long history of dysfunctional gait due to 25 years of various surgical attempts at limb salvage. Someone put him in a HD Harmony which he reports being unable to tolerate & refused to use it… so a week after receiving the device, the prosthetist just disconnected it…leaving this gentleman lugging the extra weight around, no valve, a gel knee sleeve & limb pistoning. Oh, & he absolutely crushes the vertical shock in the unit. I digress…
We have discovered that he needs the axial rotation available in the harmony due to no pelvic rotation & odd trunk movement from years a habitual & compensatory movements. Every tube clamp arrangement tried ends up with the prosthetic foot internally rotated & huge genu varus moment. The torque in his biomechanics from mid-stance on prosthetic side to initial swing just overwhelms the tube clamps and the foot internally rotates. Using a fused clamp on proximal or distal end of the pylon…the other clamp turns. Tried same manufacture tube & clamps, varied manufacturers tubes & clamps, HD products & always torqued to spec’s. Tried roughing up the non-fused end of the tube (tough to get into/out of clamp), but still turns.
The gentleman suggested spot welding the clamps to the tube, but then he’ll have a static prosthetic situation resulting in all his torsional forces affecting him proximally. Not an option.
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Responses:
Maybe a diet is in order? He is 8 pounds over the Ossur Reflex Rotate.
CPO
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I had a similar situation once, with a slightly larger patient who was suffering severe back pain for similar reasons, although his gait was not as abnormal as your patient’s gait sounds. What we ended up using was the Otto Bock 4R40, which as far as I know is the highest weight-rated torsion adapter available (275 lbs), informed the patient that it would likely break frequently, and had him sign waivers of liability and warranty. He was surprisingly active for his size (5’11” and about 355 lbs, if I recall correctly), and the adapter usually lasted 8-12 months before the torsion spring broke, although once it lasted only two months. It was worth it to him in any case, because it resolved about 90% of his back pain. It is worth noting that the structure never broke, just the torsion spring, although when that does break, the foot then flops from end to end of the available range with no resistance at all. After a few years he always bought a
spare to have on hand, and when the spring broke, he would bring in the spare, we would replace it, and order another. His insurance paid for a few of them, again if I recall correctly.
CPO
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Try the Triumph foot from Trulife. The weight limit is 366# and it has significant axial rotation and shock absorption built into the foot design. Not to mention it’s inversion/eversion is best in this category foot. Plantar/dorsi flexion is superior as well!
CPO
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Every tube clamp has a small radius at the end of the compression
slit, forms essentially 3/4th of a circle. Select the largest
diameter drill bit that easily fits in this hole, may need to be
metric or even a number bit, but it should be snug. Before proceeding
you need to insure you can obtain a roll pin in that diameter. After
alignment and sure of the toe-out setting, securely affix the tube
clamp with pipe in your drill press making sure the drill bit is
perpendicular to the hole in both planes. Let off the tension of the
tube clamp screw and drill a hole through the wall of the tube. Do
not drill through the opposite wall. Remove pipe from clamp and using
a small deburring bit clean the outside of the hole in the pipe. With
a round fine file, or sandpaper on on dowel, clean the inside of the
drilled hole. Cleaning and deburring the tube hole on both sides is
very important. Your tube and clamp are now indexed and can be
repeatedly reassembled to the same setting. Select a roll pin in a
length that will bottom out on the inside wall of the tube and project
past the clamp about 1/4″, this projection allows you to remove the
pin in the future. Drive in the roll pin when ready to deliver
prosthesis, cover pin projection with small piece of firm pelite and
wrap with tape. This protects the pin and the patient from the sharp
end of the pin.
Spot welding sounds easier, but remember you can’t weld dissimilar
metals, you must be a hell of a welder to spot on the thin tube wall,
run risk of weakening the tube and clamp, void any manufacturer
warranty, and disassembly is a bitch.
Have you tried a torsion coupler like the Fillauer that uses a heavy
urethane plug? His weight and size may destroy sooner then ideal, but
unless he is prepared to lose weight he’ll have to endure the expense.
CPO
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We use green loctite on the tube and it keeps it from turning.
Unknown certification
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Rick Milen, CPO, PTA
NEXSTEP, Inc.
Prosthetic Specialists
West Lawn, PA
http://www.iwalknexstep.com/
