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amirseif
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Posted: Fri Jul 7th, 2006 04:30 am |
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Walking retraining requires dynamic posture and balance to be maintained while gait is practiced. LiteGait is designed to allow the clinician to provide the postural stability needed.
Rigid support above the patient's shoulders allows very involved patients to be treated by LiteGait supportive environment. As the patient progresses the therapist dials the desired range of movement of the support structure.
FlexAble Yoke allows a gradual increase in the support as the position is changed (a loss of posture and balance) within the dialed range of movement. Any furhter change in position outside of the dialed range is prevented.
Constant support in a rope pulling on a user - or unloading - allows indefinite change in position and hence has no real affect on posture or balance.
Last edited on Fri Jul 7th, 2006 04:31 am by amirseif
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Rich
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Posted: Thu Jul 6th, 2006 03:28 am |
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| I think you have answered this in one of your previous postings but for the sake of clarity please tell me how the Flexable Yoke compares to something that provides constant support?
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shanna
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Posted: Fri Jun 9th, 2006 07:37 pm |
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(FROM A. SEIF) Your assertions are perfectly in concert with the task specificity of
practice. The vertical displacement though small in slower rates, is part
of what needs to be practiced to make the practiced motor behavior a closer
to the intended function (namely free gait).
Your second observation of the fact that the amount of weight supported
changes less with increased flexibility is correct and with it a more
comfortable ride for the non-involved participant.
Two words of caution. One is that the support is not constant
throughout the cycle even with the flexibility added. If it were constant,
you would have some of the problems of unloading devices (namely lack of
ability to help with balance and posture). The amount of change from top of
the cycle to the bottom, however, is greatly reduced. A rigid yoke will
quickly bottom out, increasing to force to as-much-as-needed to hold
position. A FlexAble will have a spring much lower spring constant and will
allow movement with increasing support. The non-involved individuals can
use the unit with near constant support.
The second point to consider is that the positional control is turned
partially over to the patient and if the level of patient function does not
warrant that you would be getting either less ability to forward the limbs
or worse the PT will have to work harder to provide some of what the machine
is no longer doing.
The case of your runner is the best example to accentuate the
difference. Without the FlexAble yoke, During running the first 1/2 inch of
his vertical adjustment of COM will max out any support provided at the top
of the cycle and beyond that no lowering of COM happens which results in
less than desired outcome. The FlexAble yoke continues to increase the
support during the entire COM fall without maxing out (if fully open) and
hence though assistance maybe minimal at the top of the COM cycle and a lot
more at the bottom, its continuously varying force has no sudden increase
and hence more comfortable and closer to constant.
How do you standardize FlexAble function?
You can turn it all the way open and then make the adjustment for the
support you want with BiSym. SO let say you have a FA200 on your unit fully
open and you have given 60 pounds of support in static standing to the
patient. As long as the patient walks normally(no falls or loss of balance)
depending on their speed which decides the amount of adjustment the 60 pound
support might change up and down by 10 pounds during a allow walk and 20
pounds a faster walk and 40 pounds with even faster (more COM adjustment).
However the static measure and fully FlexAble yoke could be a standard you
use with your higher functioning patient and a way to control your protocol.
However, it is your call what you want to do to your lower functioning
patient when the COM not as part of normal gait but as a result of their
inability to support themselves on one side or the other falls outside of
normal gait cycle vertical deviation of COM. I would assume you want the
machine to help them more rapidly with added support as to prevent a COM
lowered to a point of patient's inability to recover from(I call those near
fall in LG) If so, you can decide how much COM movement below the static
position is good to allow after which point the old rigid yoke will kick in
and prevent a near fall. You can set with some limitation the number of
inches below the static support you would allow the patient to go by merely
closing(tightening) the knob to have the desired bottom.
One more monkey wrench for you! we have mulitple cartridges. The one
you have is probably an FA200 which suggest a certain (I can give you
technical details) Spring Constant, we have FA100 and also FA300. Depending
on the weight range the patient fall in you may need to change your
cartridge in order to allow their specific weight to benefit from
flexibility. To understand this, take a child of 50 pound weight, open the
FlexAble knob all the way and support them 10 pounds. You won't get much
movement for even all of their weight if the spring is too rigid. On the
other hand if you had a 500 pound patient hanging from you present Yoke,
they will max out the range the required support never goes in the range
that spring works.
The measure of FlexAble is the distance the yoke travels below the set
static standing point under patient full weight. If you are using the right
combination of patient and cartridge you would be able to set the range to
be just outside of normal gait cycle and hence not allow them to fall beyond
the point that is in the normal COM range, or you could restrict it further.
This may be needed for a patient who you know will not recover from a COM
change near normal range!
I hope this is what you had in mind but if not let's talk about it some
more.
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shanna
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Posted: Fri Jun 9th, 2006 07:36 pm |
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(FROM TRAINER)That is an interesting view, not one I had
really considered. Another thought that Ellen and I have tossed around
considering the rigid vs. flexible yolk is that the flexible yolk allows
for the normal vertical rise and fall throughout the gait pattern, which
if you are focusing on retraining a normal pattern of walking, more
closely represents normal overground gait. With the rigid yolk when you
adjust BWS it seems to us that at the lower portion of the gait cycle
(double limb stance or full stride) there is more support than was
orginally provided when the BWS was established prior to walking (while
that patient was in static stance) because the center of gravity is
actually lower. We have spent some time playing with the new yolk and
have found that if we adjust BWS with the yolk rigid (to say 30%) and
then provide some flexibility, that the BWS does not increase beyond the
30% during full stride (like it does if we leave the yolk rigid) but it
does provide a level of BWS (up to 30%) throughout the entire gait cycle.
It is actually more comfortable to the participant as well. I also think
that you have a good point about the rigidity of the yolk especially for
those patients who need more stabilty and additional unloading. But from
my standpoint I think you are on the right track with the flexible yolk
because it more closely represents normal gait. I would like to have a
method of standardizing the amount of flexibility?? Any thoughts??
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shanna
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Posted: Fri Jun 9th, 2006 04:38 pm |
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(FROM A.SEIF)I will try to give you an answer for this. The easiest way is going back to common sense and say When the patient is going faster than 1.5 mph (when the center of mass is going to need more vertical adjustment) or when the patient needs to be challenged with more of their own balance control, then you should begin to increase the flexibility in the hope of making the most out of the training for the patient. In this manner of thinking along the lines of motor learning the task-specficity of the practiced motor behavior can be increased with the added flexibility when appropraite.
If I have a CVA with no useful motor on the right side, the rigidity is needed to prevent the fall to the bottom of the support every time the right knee is loaded. On the other hand as that patient regains the control of the knee at least during locomotion, it is prudent to use the flexibility (though not at the cost of quality of the practiced gait) in order to bridge the gap between supported walking and free walking.
Most researchers using reduced weight bearing devices (not LiteGait) have used therapist and/or patient own upper body strength to stablize the posture - this is what LiteGait with its rigid arms above the patient helps accomplish. So BWS is kind of a catch-all terms when it comes to published articles. (It would be great to colaborate on a real definition based on articles together!)
What my take on all the work, I have seen is that somehow posture has been assisted beyond the stated weight bearing reduction and that has persisted in some cases throughout the study and in some as long as the patient has required it.
Increased speed which in clinical terms should correspond to improved patient function(though not in some studies from UCLA) demands the release of some of that rigidity( LG is used to accomplish this by reduction of weight bearing assistance). In addition to reduction of the support now when appropraite clinician can release the rigidity and hence produce a more task specific environment for the practice of the motor behavior. When PWB/BWS is applied according to SCI model of high speed while the support may be at 40 % or more the only means to accomplish more realistic gait is to increase the flexibility of the yoke.
From a sensory point of view, you will be increasing gait related the sensory input to the patient as the rigidity is decreased, however you may accomplish it. Keep in mind, that in my view reducing the support or the rigidity and replacing it with a harder working PT or with a poorer gait quality does not match the ultimate goal of many repetitions of a well formed gait behavior which in turn generates good afference inputs to excite locomotor centers.
Long winded, yes. Complete, I do not think so! Let me know if this helps at all or if you would like to chat about it more.
Last edited on Fri Jun 9th, 2006 04:39 pm by shanna
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shanna
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Posted: Fri Jun 9th, 2006 04:33 pm |
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When establishing
BWS with the flexible yolk, is it best to set it with the desired
flexibility or without any flexibility? I was not sure how to answer
this question, as I am new to using this new component myself.
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