the
axis
the
ters
two
ting
the
lyis
the
f its
orce
eme
mal
orce
ts, a
tion
f the
was
nore
the
and
cts.
tion
f the
ring
rmal
"CP
erful
ntact
11 of
bute
f the
are
rmal
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rious
, the
dif-
Normal
+ 40| Adducilon
E
zZ
tL
€
®
E
o
=
€
39 -40| Abduction
0.0 0.2 0.4 0.6 0.8 1.0 1.2
= Internal rotation 4
z 20
il
= 10
E
o
= 0
5 External rotation
0.0 0.2 0.4 0.8 0.8 1.0 1.2
~— 80] Extension
E 60
= 40
4 20
-20
= -40
wn —90
M 80 Flexion
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Time [s]
Swing Phase Stance Phase
Net Knee Moment
arret Inertial Moment of the Shank-Foot
Fig. 3: Reactive knee moments (normal) calculated from
ground reaction, inertial properties of thigh and shank-foot
segments as well as from rotational and translational
acceleration.
DISCUSSION
Two recommendations for further studies became readily
apparent following this pilot study. The customized analysis
of body shape leading to the mass distribution parametric
description is extremely desirous, but nevertheless, very
operator intensive. To have these data available, the
reduction of the stereometric data must be greatly optimized.
Promising developments are seen in the field of image
analysis, but the image matching techniques still fall short of
satisfactory levels of accuracy when applied to the surface of
the human body, because of its monochromatic
characteristics of low contrast and structural differences. For
the kinematic analysis, the tracking algorithms of marker
identification must be improved to include large numbers of
markers to increase the accuracy of the three-dimensional
motion recording. Finally, the kinematic and kinetic analysis
of gait should be expanded to include the study of both legs
simultaneously in order to include the influence that the
contralateral body has on the entire gait cycle. The total gait
analysis should include the contributions of the upper
extremities to the locomotion of individuals with pathologic
gait.
Knee Moments
Spastic Diplegia
~— 40] Adductilon
E 30
= 20
> 10
S -0
—10
$ -20
n -30
& -40{_ Abduction
0.0 0.2 0.4 0.8 0.8 1.0 1.2
= Internal rotation
E
z
td
Ge
c
©
E
o
=
vo
8g External rotation
0.0 0.2 0.4 0.6 0.8 1.0 1.2
— 80| Extension
E
z
L—
Wm
c
©
E
o
=
v
m 790] Flexion
0.0 0.2 0.4. 0.6 0.8 1.0 1.2
Time [s]
Swing Phase Stance Phase
"es Moment due to Ground Reactions
-—-— nertial Torque of the Shank-Foot
Fig. 4: Reactive knee moments (spastic diplegia) calculated as
in Fig. 3.
The usefulness of gait analysis to orthopedic surgery and
rehablitation would should be enhanced, if forces and
moments at the hip and knee were regularly measurable. This
requires the transfer of kinematic measurements in laboratory
space to anatomical coordinate systems. In many instances,
individual determination of segmental body volume and mass
with segmental mass center location is required to calculate
the dynamic components of such reactive forces and
moments in addition to information from dynamic 3D force
plates. Photogrammetry using information from CCD still
and movie-video cameras together with digital image
processing could deliver the required information in a fast
and economically acceptable manner. In addition it would
permit graphic demonstration of the results of measurements
within the context of particular phases of total body
movements, thus enhancing much needed understandability.
The pilot study on 20 test persons presented here was
performed with conventional film and photogrammetric
equipment. The results have provided medically valuable
new information on joint forces and moments at the hip and
knee during walking in presence of spastic cerebral palsy
and normal subjects. The results provide better understanding
of the development of secondary bone and joint deformities
such as femoral anteversion, loss of acetabular sphericity and
deformities around the knee joints in presence of spastic
musculature. They are of help to decide on the most suitable
plan for treatment.
