Dear all,
The sheer amount of data for the latest case is somewhat overwhelming,
isn't it!
I thought that might be a good place to start - what variables can we
pick off the curves to summarise the data in a meaningful way?
I have selected a few, the changes in which I present in the following
graphs:
/archives/10-4-00/tempspat.gif
/archives/10-4-00/kinem.gif
/archives/10-4-00/kinet.gif
Here's my summary of what happened:
1. There was a 20% increase in walking speed entirely due to
an
increased stride.
2. There was a very large reduction in left double support (down
to 9%
cycle).
3. Most kinematic changes were in the left leg: increased hip
extension,
straightening of the knee at initial contact, and increased ankle range
of motion.
4. The right ankle is now generating much more power, and absorbing
less. The right stance knee moment and left ankle moments have
normalised.
So, all in all, this was a very successful case. The only residual
problem appears to be a slightly flexed right knee at contact,
and
slightly weak left ankle. I think these could well improve with time
and
a little physical therapy.
Congratulations to Andreas and the rest of the Speising team (I guess
the surgeon deserves a little credit too!). I'd be interested to hear
what the rest of you think.
Chris
Just a quick addendum - I realise that I carried over the terminology
on
the automated printout and used the phrase "left double support".
According to Jim Wall, the double support phase can be usefully split
into "braking" and "thrusting" parts - I think in this case it is the
thrusting phase which is short. This might be a point for discussion,
since it's of note that the left stance phase has shortened to 56.7%.
I
wonder why?
Does anyone else split up the double support phase in this way?
--
Dr. Chris Kirtley MD PhD
Associate Professor
HomeCare Technologies for the 21st Century (Whitaker Foundation)
NIDRR Rehabilitation Engineering Research Center on TeleRehabilitation
Dept. of Biomedical Engineering, Pangborn 105B
Catholic University of America
2.06 Double support (DS): The period of time
when
both feet are in contact with the
ground. This occurs twice in the gait cycle,
at
the beginning and end of the stance phase.
Also referred to as left and right double
limb
stance or LDLS and RDLS respectively.
For example, LDLS refers to the DS after left
initial contact.
Kind Regards
Kamiar Aminian
James C. Wall, Ph.D.
Professor
Department of Physical Therapy
University of South Alabama
1504 Springhill Avenue, Room 1214
Mobile AL 36604
Phone: (334) 434 3575
Fax: (334)
434 3822
e-mail: jcwall@jaguar1.usouthal.edu
Thanks to Kamiar Aminian for his contribution to the double support
debate. Just so everyone is clear what we're talking about, I've colored
in a journal figure to show the double support periods:
As you can see, the right initial double support is the same as the
left
terminal double support, and vice versa. I have often wondered whether
the relative size of these phases conveys any useful information. As
I
mentioned, Jim Wall refers to them as the braking and
thrusting
double
support periods, which I think is a much more functional terminology.
So, a reduction in initial (braking) DS of one limb is associated with
a
reduced terminal (thrusting) DS on the contralateral side. In this
case
(12mo post-op):
Right Stance = 63.18
Left Stance = 56.73% (weaker side)
Right Swing = 36.82
Left Stance = 43.27%
Right Initial (braking) DS = Left Terminal (thrusting) DS = 11.6%
Left Initial (braking) DS = Right Terminal (thrusting) DS = 9.3%
These figures are quite noticeably different, so I wonder if they tell
us anything? It would be nice if they did, because this sort of
information is (relatively) easy to measure. For eample, is it simply
a
compensation for weak push-off - in this case the left side
is weaker
and so its thrusting DS is therefore increased. Is this a general rule?
Chris
--
Dr. Chris Kirtley MD PhD
Associate Professor
HomeCare Technologies for the 21st Century (Whitaker Foundation)
NIDRR Rehabilitation Engineering Research Center on TeleRehabilitation
Dept. of Biomedical Engineering, Pangborn 105B
Catholic University of America
The double support phase results when both feet are in contact with
the ground. My latest results using a 2m pressure plate actually
allows us to determine exactly which parts of the feet are in contact
at the same time during double support.
In the normal foot it is clear that during walking the parts of the
heel (initial support) match exactly the parts of the opposite foot
(terminal support). The matching is so perfect that the combination
produces a "third footprint" that is difficult to distinguish from
a
normal footprint. As the heel "rolls on" during initial support, the
forefoot of the other foot exactly "rolls off" during terminal
support.
Superimposing the two in time produces a normal footprint. At any
instant any anatomical point taken from either footprint is always
in contact with the ground. At any instant one anatomical point
taken from either footprint is always in contact with the ground. But
the amazing thing is that the same point from both feet is seldom
ever in contact simultaneously.
At least for the normal foot at 100hz.
The differences between left and right will reveal a lot. Aristotle
long ago (384 BC) pointed out that the left and right feet fulfilled
different roles.
Craig Nevin
Anatomical Engineer.
University of Cape Town