Thanks to all who responded. Your ideas helped me to decide what to do with some challenging legs I’m working with. I’m needing to accomodate Bilateral knee flexion contractures of 40 degrees and I’m wanting to get some energy return from a knee extension assist later in stance phase. After consulting with the psysiatrist, I learned that the contractures would not be reduced until the child is full grown- that way he would not need to undergo surgery twice. That presents a dilema, especially with the lack of quadricept strength. In addition to the responses listed below, ideas I got from other collegues included using the step lock joints, the Becker polycentric with scott cam lock and extension assist, laminating the thigh cuffs to the BK sockets, and attaching anterior thigh cuffs with neoprine posterior straps. If anyone is curious what I ended up doing, contact me later and hopefully, because of your help, I will have come up with a good result…
Original question: Dear list,
I have a 9 year old Bilateral Congenital BK I’m
working with. He presents with knee flexion
contractures of about 40 degrees and he lacks knee
extension but has fair knee flexion. Hip ROM and MMT
are normal. He currently wears sockets with thigh
cuffs attached with dial locks permanently fixed in
flexion. He walks without crutches and it looks as if
he were climbing up a steep hill just walking on flat
ground. He circumducts and laterally leans. I plan
to fit him with dynamic response feet and new sockets
and thigh cuffs.
My question is: Does anyone have experience using a
extension assist knee joint of some kind in a similar
situation? I’m thinking that if he could get some
spring back out of loading the thigh cuffs, it would
help propel him forward. Thanks for your ideas, Zach
Harvey, CPO
Responses:
sounds like a great idea. Will you use a Scott style knee extension
joint
(tube rubber to pull him into extension)?
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call Townsend and ask their experience
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what you are doing is noble, a 9year old congenital bk should
not be held back by his prostheses. The prostheses should give him every
opportunity to to live and appear normal.
If I follow your post correctly, it sounds like he is and has been
locked at the knees during ambulation. Yes Does he sit with his legs
straight forward? No, they’re permanently locked in flexion.
I would expect that he would have little chance of
gaining a fuller range of motion at the knee and increased strength with out
encouraging some sort of load throughout the knee. The thigh cuffs
and locks have to go. How much extension is he able to get, (i SHOULD
ASK IF YOU EXPECT OR DESIRE TO INCREASE ROM AND STRENGTH OVER TIME?) 40 degrees
max extension. This is as far as he can go w/o surgery is
it reasonable to set him up with transitional prostheses that are
flexed, then straighten them as his strength and range improve. I have done
this with adults in the past. A foot that is planter flexed slightly
will help with this also. This way when they stand the heel will only
touch the ground when the knee extends beyond it’s current end point. I
have had a few patients that I have had success with in doing this. I
adjust their prosthesis so that the heel doesn’t quite touch when they
leave the office. A week of the stress on the quads and constant
stretch on the gastrocs and hamstrings will increase ROM and strength.
I should tell you that these patients that most of these patients
have been patients in the early stages of regaining their ability to
ambulate (so they are standing and walking in the parallel bars with the
supervision of a rehab professional). Your patient’s independence may
actually work against him.
I have used the Otto Bock, Townsend , and Scott style of dynamic
knee extension assist joints. i don’t know what else may exist. None of
these will be terribly useful to you in this situation.
Those are my 2 cents.
Have you tried using a SACH foot (oversized), set in some degree of
plantar
flexion? This will extend the knees. An old fashioned fork strap with
closed
patella section, extension aid and waist belt may also help some.
Your little boy is in for a world of trouble if he can’t get full
extension
out of his knees sometime soon. Agressive physiotherapy or surgery is
definitely indicated here. Why can’t muscle/tendon releases be done?
Progressive knee flexion contracture, femoral deformity and enormous
energy
expenditure while ambulating will be his lot if he can’t straighten his
knees. Good luck in this respect.
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