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ngryfakis68
12-12-2003, 12:33 AM
Thanks to all who replied to my original posting. Here is the summary of
replies.







Oliver Rettig [Oliver.Rettig@ok.uni-heidelberg.de]



1. What type of activities/motions are you capturing with this upper

extremity model?

motions of daily work and arm movement while walking of ICP-patients and
probants



2. Are you having any problems with the model that you are using i.e.

flipping, etc.?

Yes, lots of problems with the models I have found in the

literature: supination/pronation of wrist: deviations of maximum of 20
degrees in the range of motion compared with gonimetric measurements, also
elbow flexion/extention especially if the elbow is near stretched position:
deviations from goniometer measurement of maximum of 15 degrees



3. (Vicon users only) Is your model the standard Plug-in-Gait upper

extremity model? If not, what are you using?

I have testet the models from Raab, Vicon, Disselhorst-Klug and a italien
group I have forgotten the name and then I have developed my own model with
wand markers. I will validate the model in the next year. I have a
formulation of the model in BodyBuilder language but I have started to
formulate it with Matlab/Java.



In the Vicon model especially the markers to describe wrist
supination/pronation are not good enough for our research and also I want to
have access on all the parameters - I do not like the model as a black box.



We are working for two different applications with two different models: 1.
arm swing while walking of children with cerebral palsy. For this
appplication I use a model similar to the Raab model. This is the work of my
doctoral research. This time validation of this model is not the primary
thing I will do the next months. 2. arm movements of daily work. For this I
am using a model with more markers and validation is the current work. We
have made lots of markerplacements on the same proband places from different
people and soon we will start to place the markers on different probands
from the same researcher.



Movements of the hand: We are only interested in wrist supination/pronation.
Clinical: We want to make measurements with patients who can not rotate
radius around ulna. Excuse me I do not know the medical term for it.



4. What kind of transformations are you using with your current model

that you plan to validate?

I am not sure what you mean with transformations. For validation we make a
set of normalized movements and make parallel to the marker based
measurements goniometric measurements. To compare them we transform the
segments in sagital, coronal etc. planes - the planes the clinical looks
for. These calculations we make with a Java/Matlab program. We use static
measurements and calculates some segments with transformations relativ to
these measurements.



5. What are your marker placements and why do you feel that these will

solve flipping problems, etc.

We are using 9 cameras and we do not have lots of flipping problems. Our
model is using wand markers. So perhaps it is not good for fast movements. I
think I will write an abstract in december where I describe the marker
placement. Than I can send it to you.





Arnel Aguinaldo, MA, ATC

Director, Center for Human Performance

Bioengineer, Motion Analysis Laboratory

Children's Hospital San Diego | San Diego, CA USA



1. What type of activities/motions are you capturing with this upper

extremity model?

Pitching, golf swing, hitting



2. Are you having any problems with the model that you are using i.e.

flipping, etc.?

We developed a model based on the JCS system. The challenging aspect, of
course, is in the definitions of shoulder joint motion as the clinical
interpretations of such movements are mathematically "ambiguous." I thought
Dr. Jim Richards described it best at last year's GCMA meeting that most
models used for shoulder motion have inherent flaws and advantages, you
simply select the one most appropriate for the application you're measuring.





Michelle B. Sabick, PhD
Assistant Professor
Department of Mechanical Engineering
Boise State University



I have been using upper extremity motion capture models for several years
now, mainly to study motions in throwing and wheelchair propulsion. There
are nearly always quadrant issues in UE models unless the motion you are
looking at is very restricted, e.g. wheelchair propulsion. However, if you
are dealing with very general motions, quadrant flipping is a very difficult
problem to address.



I am a new Vicon user and have not yet developed my own UE model in
BodyBuilder yet, although I plan to soon. I only use the Plug-In-Gait model
when the motions I am interested in do not concentrate on the upper
extremity. All the programs that I use are currently in Matlab, and are
more sophisticated than the PIG model, with three markers per segment so all
necessary degrees of freedom are accounted for. A couple of articles
regarding the use of this marker set to study wheelchair propulsion will be
coming out in the next few months. However, none of these focuses
specifically on the methodology, they are more clinically oriented. The
kinematic model that I use is similar to that used by Kulig et al.



Kulig K, Rao SS, Mulroy SJ, et al.: Shoulder joint kinetics during the push
phase of wheelchair propulsion. Clin Orthop(354): 132-143, 1998



Regards,



Michelle Sabick













Nicholas J. Gryfakis, M.S.

Manager/Biomedical Engineer

Motion Analysis Center

Children's Memorial Hospital

2515 N. Clark Suite 705

Chicago, IL 60614

773.327.1936

773.327.1937 (fax)



For mail inquiries only:

2300 Childrens Plaza Box 92

Chicago, IL 60614





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