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Di. Josef Kollmitzer
09-06-1994, 08:01 PM
This is the SUMMARY of the QUERY of FRONTAL KNEE ANGLES:
Original TEXT:

>Dear Biomch-L readers:
>We are starting a project in measuring gait of patients with knee
>endoprotheses (one degree of freedom). We concentrate on the
>variability of the frontal knee angle to detect movements with a small ROM in
>the knee due to fixation loss. We are trying to estimate the noise level of
>frontal knee angle plots measured by a videometry system.
>My questions are:
>1. Is there any publication available dealing with frontal knee angles?
>2. Do You have any suggestion which other parameter (kinetic, kinematic, EMG,
>temporal, spatial, angular velocity....) might show relevant changes in this
>case?
>I would be grateful if you could send me any information on this topic and I
>would then post a summary of the responses.

>Josef Kollmitzer
>Univ.Clinic PMR Gaitlab
>Waehringer Guertel 18-20
>A-1090 VIENNA, AUSTRIA
>Tel: +43-1-40400-2308
>Fax: +43-1-40400-5281

============================= ANSWERS ==================================

From: H_E_J_Veeger@fbw.vu.nl
Do you know dr. Thomas Kienbacher, PM&R surgeon, also from Vienna? He spent a
year working in the gait lab at Mayo in Rochester MN. His research was on
gait in stair climbing, and I know he spent quite some time in analysis of
the frontal plane.

From: ikirtley@info.curtin.edu.au (Chris Kirtley)
We are studying a related problem - the small angular motions in the leg
joints during quiet standing. I think these are about the same magnitude
(one degree or so) as the ones you will be measuring, however.
We have found that the signal/noise ratio in kinematic analysis of these
motions is acceptable only if we filter at very low cut-off frequencies,
for example at 3Hz or less. Even then there is a lot of noise.
In order to improve the signal/noise ratio, we have used an optical lever
method (which will shortly - hopefully! - be published in MBEC). With this
we get a very clean signal, but it is quite time-consuming to set up, then
we can only record for a short time (10-30 seconds). Of course, this method
would be no use for gait, but at least you can use it to check the fidelity
of your data after filtering, to show that you are not missing any higher
frequency components.
I recorded frontal plane knee angles and moments in 1984, when I was with
Mike Whittle in Oxford, using a Vicon system (reported in Journal of
Biomedical Engineering 1985, 7(4):282-288 "Influence of walking speed on
gait parameters"). I confess, I was new to biomechanics at the time, and
didn't even look at the noise level! I presume now that it must have been
quite bad! Mike Whittle would know for sure - he's done quite a lot of
frontal-plane kinematics and kinetics, and is now in Chattanooga, USA
(email MWHITTLE@UTCVM.UTC.EDU).
ORGANISATION: School of Physiotherapy, Curtin University of Tech. Australia

From: "Robert Soutas-Little"
We have been measuring all three knee angles for five years in patients
using Euler or Cardan angles. The thigh and shank are targeted with a
minimum of three targets each and segment coordinates systems formed for
each segment. Our targeting protocol uses two markers to extablish a sement
anatomical axis and the third to form an anatomical plane. This requires
only simple vector calculations. The angles are based on a "Joint
Coordinate System" as outlined in Grood and Suntay 1983 paper in the Journal
of Biomechanical Engineering. I would be happy to supply more details is
needed. We collect data using a 4 camera Elite or Motion Analysis System
and have gotten good results from both.
Organisation: Biomechanics Evaluation Laboratory, Michigan State University

From: Rahamim.Seliktar@cbis.ece.drexel.edu (Rami Seliktar)
Although this does not answer your questions, it may be of some value to you.
R.S.
Seliktar R. and Mizrahi, J., "Partial Immobilization of the Ankle and Talar
Joints Complex and its Effect on the Ground-Foot Force Characteristics,"
Engineering in Medicine, 13 (1), 5-10, 1984.
Organisation: Drexel University,Pennsylvania