Kinematic gait analysis 1

2/10/2018 duraiphysio rrajadurai007@yahoo.in 1

Definitions
Kinematics is the science of motion. In human movement, it is the study of
the positions, angles, velocities, and accelerations of body segments and
joints during motion.
Use of kinematic measurements
Kinematic measurements are limited in what they can tell us about the
causes of motion is - for this we need to look at the kinetics.
However, they do provide a description of the motion which can be valuabl
for assessment purposes

DEFINATION
 The Gait defined as forward
propulsion of body by lower limbs in a
systemic ,coordinated semi-rotatory
movements of trunk , arm and head.

Determinants of Gait
 6 specific features that increase the
efficiency of walking and running gaits
 All reduce unnecessary movement of
the upper body, either vertically, or
horizontally in the lateral axis
52/10/2018 duraiphysio rrajadurai007@yahoo.in

DG1: Pelvic tilt

The pelvis lists downward
(obliquity) to increase the
effective leg length at toe-off and
heel-strike:
 Reduces the vertical movements
of the upper body, and thereby
increases energy efficiency.
 The pelvis slopes downwards
laterally towards the leg which is
in swing phase. i.e. rotation about
an anterior-posterior axis
 Only anatomically possible if the
swing leg can be shortened
sufficiently (principally by knee
flexion) to clear the ground.
 Where this is not possible (e.g.
through injury), the absence of
pelvic tilt and pronounced
movements of the upper body are
obvious.

Pelvic rotation
 Pelvic rotation
The pelvis rotates
anteriorly at heel-strie,
and posteriorly at toe-
off to increase the
effective leg-length at
these times:
 Rotation about a
vertical axis enables a
given step length to be
achieved with less
vertical excursion of
the trunk.
 Alternatively, longer
step lengths can be
achieved for the same
vertical movement.

Knee flexion in stance phase
 Stance Phase knee
flexion
A slight flexion of the
knee lowers the CoM
during stance:
 As the hip joint
passes over the foot
during the support
phase, there is some
flexion of the knee.
 This reduces vertical
movements at the hip,
and therefore of the
trunk and head.

Ankle mechanism
 Ankle rockers
The ankle is
dorsiflexed at heel-
strike and plantar-
flexed at toe-off. Both
these actions
increase the length of
the leg(see pictures
above).

Forefoot mechanism

During the final part
of the support phase,
the forefoot serves to
increase the effective
length of the leg lever.
 This is brought about
by plantarflexion at
the ankle

Reduced lateral pelvic
displacement
 Is minimised by having
a narrow walking base
i.e. feet closer together
than are hips.
 Therefore less energy
is used moving hip
from side to side (less
lateral movement
needed to balance
body over stance foot.
 Enabled by valgus
angulation at the knee

Swing-phase kinematics
An essential pre-requisiste for gait is to be able to shorten the swing
leg before propelling it foward.
The main way this is achieved is by flexion of the knee. This amount of
swing-phase knee-flexion is proportional to the stride length, and thus the
gait velocity (Kirtley et al, 1985):
Many gait pathologies (e.g hemiplegia, diplegia, knee osteoarthrosis) impair
swing-phase knee flexion, causing compensatory mechanisms to be used,
such as hip-hiking, lateral-tilting and circumduction.

Parameters:
1. Spatial parameter: (Distance)
1) Step length.
2) Stride length.
3) Stride length to lower extremity length
ratio.
4) Base of support.
5) Step or stride width.
6) Foot angle (degree of toe out.)

2. Temporal parameter: (Time)
1) Step time.
2) Stride time.
3) Stance duration.
4) Swing duration.
5) Swing / stance ratio.
6) Speed, distance time.
7) Cadence, steps / min.

Spatial parameter
(Distance dimension)
Evaluation:
 It can be done via foot print using tape measurement,
water, protractor, marks.
 Then draw a line of progression which is a hypothetical
line corresponding with the direction of walking.

Measurement of spatial parameters:
1- Step length:
It is the linear distance in the plane of progression between
two successive points of heel floor contact of the opposite
heel
(Approximately = 70 cm + or - 10 cm)
2- Stride length:
It is the linear distance in the plane of progression between
two
successive points of heel floor contact of the same heel
(Approximately = 150 cm + 15 cm)
One stride = 2 steps in one gait cycle)
3- Stride length/ Lower Extremity length ratio SL/ LEL
ratio: It is the ratio between stride length and lower extremity
length. (Nearly = 1.7 ± 0.12)

 Lower extremity length:
is measured by tape measurement from greater
trochanter to lateral maleollus.
4. Stride or step width:
It is the distance between two lines cutting feet equal
halves (8 cm ± 3.5 cm = 10 – 15 cm)
5. Base of support: (BOS)
It is the area over which the body is supported or
assumed.

Dimensions
a- Longitudinal dimension:
The longitudinal distance between the two furthest points of two
opposite feet from heel of right foot to toes of left foot.
b- Horizontal dimension:
The horizontal distance between the two furthest points of two
opposite feet from lateral border of right foot to lateral border of
left foot.
6. Foot angle:
It is the angle between 2 lines:
First line is extending from second toe to the heel center.
Second line is the line of progression or parallel to it
(7o -10o up to 20o.

2, Temporal Parameter
(Time dimension)
Evaluation: can be done by using a stop watch.
Measurement of temporal parameters:
1. Step time:
It is time interval between successive instant of foot floor contact of
the opposite feet. (0.8 sec.)
2. Stride time:
It is the time interval between successive instant of foot floor contact of the
same foot. (1.09 o.o6 sec = 1.6 sec)
3. Stance duration:
It is the time while the foot is in contact with the floor.
4. Swing duration:
It is the time while the foot is not in contact with the floor. (0.4 sec.)

5. Swing / stance ratio:
It is the ratio between swing time and stance time (57 + 0.02)
6. Speed: It is distance / time.
In male: 89 meter/min.
In female: 74 meter/min. (45 cm / sec)
7. Cadence:
It means number of steps per unit time.
(11o + 6 steps /min)
Slow: 60 – 70 Steps / min.
Medium: 80 – 90 Steps / min.
Fast:120 Steps / min.

Temporal Analysis
 Stride time (s)
 Stride rate = 1/time (/s)
 Stride cadence = 120 × rate (b/min)
 Instrumentation
◦ Photocells and timers
◦ Videography (1 frame =
1/30 second)
◦ Metronome

Electromyography
Delsys electrodes Mega system
Noraxon systemBortec system

 Linear position
◦ Ruler, tape measure, optical
 Linear velocity
◦ radar gun, photo-optical timer
 Linear acceleration
◦ Accelerometry, videography
miniature
accelerometers
radar gun

Motion Capture
 Cinefilm, video or
infrared video
 Subject is filmed and
locations of joint
centres are digitized
Panasonic
videocamera
Basler charge-coupled device
(CCD) camera
Vicon
infra-red
camera

Motion Capture
(e.g., SIMI or Vicon)
3D motion
data
EMG data
F-Scan
data
Force platform
data
Video
data

Passive Infrared Motion Capture
(e.g., Vicon or M.A.C.)
Infrared
video
camera
s
Kistler force platforms
M.A.C.
system

Active Infrared Motion Capture
 NDI’s Optotrak
Infrared
video
camera
s
Infrared
emitting
diodes

Gait and Movement
Analysis Laboratory
 Motion capture
system for marker
 Force platforms for
ground reactions
 Electromyography
for muscle activity
 Pressure mapping
systems for in-
shoe pressure
patterns

REFERENCE:
joint structure and function - cynthia c norkin
gait analysis an introduction michael w.whittle
Web sources:
www.physiopaedia.com
www.alterg.com
www.clinicalgaitanalysis.com

THANK YOU

Kinematic gait analysis 1

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