Knee Extension Orthosis - Summary of replies - Part 2

Knee Extension Orthosis - Summary of replies - Part 2

Mark Raabe

7/18/2001

Fellow OandPers,
Please find following the responses Part 2 to the original question...
> Dear Colleagues,
> Have received a Rx for a knee orthosis with extension assist for a male
with
> removal of necrotic patella. Have been told that there is no extension
> mechanism of the knee left. Doctor wants an orthosis that will provide
> extension and stability during gait without being locked...ie. Allowing
knee
> flexion during gait! I am unaware of a suitable functional knee orthosis
or
> joint that would accomplish this. Does anyone know of possible solutions??
I
> know there has been numerous inquiries regarding a weight activated
locking
> joint on this server, have we discovered such an animal? And if so what
are
> people's experiences of it?
Most mentioned the Otto Bock 17B3 offset joints with extension
rubbers,(17Y35), with mention of the Scott Extension Orthosis as well (maybe
a bit bulky), but what I think I will try initially is a GRAFO - by
utilising the ToeOFF orthosis I think we will be able to ascertain if this
approach will be successful for our patient/client. The replies are
separated by blank line...

Sounds as if you need a UCLA, functional KAFO. It's never been a very
popular orthosis, but it will fill your needs to a T
It was taught at UCLA throughout the 1960s. I don't know if the ball
bearing, offset knee joints are still in production. Maybe you could find a
pair at U.S. Mfg. or Hosmer Dorrance. They were the only manufacturers of
that joint that I know of. Tim Staats, who teaches at U. Cal. Dominguez
Hills, might still have a copy of the manual, as he was the last director of
the UCLA program.

Otto Bock makes two extension assist devices which attach to their offset
knee joints which work very effectively in extending a patients knee without

locking. I am not sure of the part numbers, but they are both listed in
Bock's orthotics catalogue. I have used these on numerous occasions with
great results.

Otto Bock makes/made a knee extension assist attachment for their 18mm
offset
knee joints. I have used it on a woman with a similar condition that you
describe. My patient had partial extensors but lacked the final 30 degrees
of
extension. The offset joints will allow knee stability during stance and the

extension assist mechanism will help extend the knee during swing. I've
also
used the combination on polio patients.
There isn't much to choose from commercially. I have used criss-cross
elastic webbing attached above and below the knee joints anterior to the
knee, but these get very tight when sitting. A bale to hold the elastic off
the knee helped somewhat but caused cosmetic problems.

Becker makes a (somewhat bulky) knee joint with extension assist called the
Tricknee (Trick Knee). I've held it in my hand and it appears sound, but I
haven't used it yet.

I have worked with a knee orthosis from Scott Orthotic labs. It is
available from them directly of from Becker Orthopedic. I would say that it
is functional, although a bit bulky. It uses latex surgical tubing as the
extension assist. It does not lock in extension, and it does allow full
flexion. I use this more as a diagnostic tool than a definitive orthoses,
however, when appropriate, I find that it can work long term. As long as
the patient/client is content or at least accepting of the size and shape.
I have custom fabricated similar devices in an attempt to reduce the bulk of
the orthoses, but none of these worked quite as well as I would have liked.

Mark, contact Scott Orthopedic Labs...they have a number of knee extension
orthosis' available. Good Luck.

Just from my gait analysis experience, couldn't you try to aply a
GRF-AFO in order to stabilse the knee in extension during stance,
herefore removing any need to use knee extensors?

Otto Bock used to make 22mm offset knee joints with extensist rubber (or
synthetic) bands. The joint provides stance stability because of the
offset. The bands provide extension assist and attach to the exterior of the
joints using the normal mounting screws. You should be able to use
aluminium uprights but guard against rapid flexion (such as could occur in a
fall). Be sure the design won't cause a fracture of the femur if violently
flexed. I generally used an anterior thigh section with straps in the
posterior for attachment and security.

You may wish to consider a KAFO with unlocked posterior offset knee joints
and free ROM ankle. The posterior offset knee joints will provide excellent
stability in stance by the patient maintaining his center of gravity
anterior to the mechanical joint. Additional stability at the knee will be
provided by the hip extensors and plantar flexors. As an example of this
compensatory gait pattern will be found in the post polio patient with a
functional ambulation pattern in spite of absent knee extensors. I have
tried and rejected any number of extension assist mechanisms over the years.

Check out the Trick Knee joint manufact by OTS in Barnardsville, NC. Call my

office Monday if you can't find the number.

please let me know if you have any luck. This is an area of weakness in the
Orthotic field. The only brace I'm aware of is by Scott Labs in the U.S. It
has a latex tubing - style extension assist. I have seen some knee joints,
with extension assist, but can't remember where. Have you thought about an
Ultraflex style K.O.? You can adjust the ext. assist to be very strong. I've
used it for K.F. contractures with very good success. It is somewhat bulky,
however.
Best of luck,

Thank you one and all for the multitude of answers, it was much appreciated
Best regards,
Mark Raabe, Dip. App. Sci. P&O
Orthotist/Prosthetist
OrthoSynergy Pty. Ltd.