Saturday, October 5, 2024

Hydracadence Part II

Frances Berg

1. The foot was not a SACH foot. SACH is “Solid Ankle Cushion Heel”.
This one had a solid heel. It was made of wood with a Crepe sole and a
crepe toe from the met heads forward. It did not need a cushion heel for a
soft heel strike because of the plantarflexing ankle, which provided the
“cushion” or damping effect at heel strike.

2. I don’t recall the weight, but it was probably considered fairly
heavy at the time, but I don’t think it was any heavier than current
microprocessor prostheses.

3. There was no actual predecessor. It was pretty revolutionary.

4. I don’t know the cost off hand.

Good luck, Jon

It was little before my time actually. We have a few old ones here in our
storeroom so I have seen and played with them. I only have worked on one
patient that actually used one. The main claim to fame is the fact that
the ankle motion (active dorsiflexion) is coordinated with the swinging of
the knee to provide the user better toe clearance during swing phase. As
non-amputees we do this subconsciously to help with toe clearance. This is
the only knee ankle complex to date to do this for the amputee. The
downside was it was heavy. I know that Ossur is looking to integrate their
Rheo knee with their Proprio foot which would do a similar function.

Stan Vydrzal

Frances,

I am a Prosthetist from the Philadelphia area. I started in the field in
the 70’s and used to see the Hydracadence in clinics especially thru the
VA. Since then I worked primarily with kids but have a friend/patient who
has worn a Hydracadence since the 50’s. He has 2 units which he
interchanges as necessary. He always carries the extra when he travels. He
was once stuck in Europe with mechanical failure. When Trulife in Seattle
was still servicing those units, I had his rebuilt. I believe they have
since discontinued that service. I tried unsuccessfully to convert my
friend to a RHEO five years ago, he always goes back to his tried and true
Hydracadence.

My opinion was always they require too much maintenance and are heavy but
the believers can not be swayed.

If you need specific info about them, let me know.

Ed Moran

Stuff I found out:

1. Currently made by Proteor, France. I believe they
have made some improvements esp. regarding swing clearance. New Patent
2009.

www.youtube.com/watch?v=G2sMBrxpMiY watch this! Fun!

2. Knee flexion above 20 degrees causes foot
dorsiflexion. This aids in foot clearance during swing. (much deeper
discussion of this in works sighted below. It is more complicated than it
may seem…)

3. Sitting: with the knee bent at 90 degrees, the foot
dorsiflexes and can be tucked under the chair. Reduces torque on limb and
cosmetic benefit.

4. Users petitioned the gov’t (unknown date) for better
reimbursement to keep knee in production/distribution.

5. Practitioners and patients Love/Hate this knee. It
evokes passion.

6. 3 useful articles (out of many good ones…)
– A Cappozzo, T Leo, A polycentric knee-ankle mechanism for above-knee
prostheses
. *Journal of Biomechanics*, 1980 (biomechanical study)

-Sapin E,
Goujon H,
de Almeida F,
Fodé P,
Lavaste F.
Functional gait analysis of trans-femoral amputees using two different
single-axis prosthetic knees with hydraulic swing-phase control: Kinematic
and kinetic comparison of two prosthetic knees.

*Prosthet Orthot
Int.*2008
Jun;32(2):201-18.
(insight into the Hydracadence II)

-Staros A MSME. Murphy EF. Properties of Fluid Flow applied to Above-Knee
Prostheses. *Prosthetics and Sensory Aids Service*, Veterans
Administration, New York, NY. 1960’s. (awesome description of the
hydraulics)

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