CONTINUED
First thought is the type of surface. Most folks that I have met consider
K2 ambulators more ‘hard surface’ walkers, i.e., they would probably not be
able to walk safely on loose type surfaces such as soil, sand, gravel,
unpaved stone, etc. Another consideration is being able to walk on a hard
surface that moves such as a boat, ship, and/or perhaps airplane. It is
doubtful that a K2 ambulator would be able to traverse such environments
easily (without assistance) whereas a K3 ambulator should.
2. I have yet to see any amputee walk ‘normally’ as has been defined by
Perry and others. Furthermore, I don’t think the technology is
commercially available yet for such a feat although I’m sure DARPA is
working on it. That said some K3 ambulators do walk briskly and would meet
the standard for normal cadence just as there are able bodied people who do
not. Amputation level does play a role. So does the outcome/type of
amputation surgery, the rehabilitation approach, the individual’s personal
goals for that rehab, and the number of amputations a person has. Higher
level amputations require more joints and hence more energy to ambulate.
So I doubt single TP and short Tfs can. I would also find it amazing to
see a bilateral Tf perform at that level regardless of limb length. I work
with a long Tt, long Tf patient who can and often does walk at this speed.
I have met single and bilateral Tts in various countries that can as well.
Bottom line – I do not think it is logical to assume that Medicare
classification levels should be based on the normal cadence (or other
parameters of gait) of an able bodied person that is unless or until normal
kinetics can be re-established.
3. Perhaps a better question to ask is how often does a K3 ambulator
display variable cadence while performing his/her activities of daily
living. The sports minded might jog, play tennis or perhaps engage in team
sports such as soccer, basketball, softball where there would be a
noticeable difference between gait speeds. Without further research, I
would not be able to assign a specific percentage to the difference but ask
yourself, how often does your cadence change throughout the day? Mine, not
so much unless I am dodging a fast moving motorcylce, car, or bus on the
street. I do face slow moving lines on occasion and sometimes I have to
run to catch a bus or stop a taxi. For me the line is daily activities.
1. Sometimes a person needs to traverse uneven ground / rocky terrain,
or climb upon equipment such as a tractor, or a fire truck. A detailed
knowledge of the person occupation/ADLs would reveal what he/she needs to
traverse.
2. Same number of steps per minute as an ‘average’ able bodied person
should not be a K3 qualifier because we don’t have any data about the
person’s cadence pre-amputation to compare. I use the amputee mobility
predictor to validate my K level assessment. In my opinion, most K3
ambulators are stable walking up and down a staircase.
3. I don’t use a count of steps per minute to determine K level so noting
an increase of 5 or 10 steps per minute doesn’t add value to my assessment.
If I think about the reason K level assessment is done, it is to get paid.
Having data such as that client X walks 105 steps per minute normally and
can increase to 120 for a duration of 5 minutes then slows back to 105,
doesn’t really help. To inform me about the type of prosthesis a person
would benefit from, I get to know them, by talking with them and observing
them ambulate. Unfortunately, these are subjective measure and aren’t
recognized by payers so much. If you are successful in determining how many
steps per minute a person must increase their cadence in order to be a K3,
then the next step would be to get payers to regard that as an acceptable
standard. Otherwise it doesn’t help.
In response to #1.
Ladders, higher objects to step over than curbs, ie. Logs, brush,
fences, work place objects, creeks, pipes, cables. Any of they types of
objects that would be encountered by fully able bodied individuals in the
normal course of daily ambulation beyond just curbs and steps.
In response to #2.
Personally, I do not expect an amputee to meet this criteria as in my
experience, all amputees adopt a “self selected†walking speed to
essentially not expend any more energy than they have to. This obviously
produces different normal gait speeds for each individual which is also
affected by length of amputation and associated co-morbidities.
Additionally, recognition of this can form the basis for justification for
K3 as when walking alone a patient may use their self selected walking
speed and feel the need to adjust walking speed with walking with friends,
cohorts, etc who may walk at a faster pace and they just want to keep up.
In response to #3
I am not sure at this point that any preselected percentage would
render any improvement in predicitive accuracy. As the selection of K2 vs
K3 is at the heart of the issue, any need for variable cadence should be
measured somewhat by the safety issues related to circumstances. We
currently do not assess falls, risk of falls, or any of the normal
measurement instruments used by PT to assess risk of fall. As I review
claims nationally by our industry now, I rarely see any history recorded or
used to justify component selection. I believe the differentiating factors
that are starting to show up as differentiating factors to consider when
trying to assess the rationale for a microprocessor knee versus a non
microprocessor fluid control knee may rely more heavily on this factor in
the near future. Also, how to assess cognitive load necessary to expend by
a patient may be a necessary consideration especially in the work place
where there attentions may need to be focused on their tasks more than when
their next step is going to land for safety reasons. All fodder for future
consideration.
*Dr. Stephan R. Manucharian, CP, BOCO, LP(NJ), FAAOP*
*Doctor of Health ScienceClinical DirectorOrthopedic Arts Laboratory,
Inc.141 Atlantic Ave., Brooklyn, NY 11201718-858-2400; Fax:
718-858-9258;http://www.OrthopedicArts.net
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