Biomechanics of gait

1. Kinetics and Kinematics of
Gait
Sukanya Dandekar (MPT student )
Dr. Suvarna Ganvir ( PhD,Prof & H.O.D)
Dept. of Neurophysiotherapy
D.V.V.P.F.’s College of Physiotherapy,
Ahmednagar

2.  Introduction
 Kinematics
 Determinants of Gait
 Kinetics
 Kinetics and kinematics of trunk and upper extremities
CONTENT

3.  Gait : “ Translatory progression of the body as a whole,
produced by co-ordinated , rotatory movements of body
segments”
INTRODUCTION

4.  Phases of gait cycle
 Gait terminologies
 Joint motion
KINEMATICS

5.  Begins – heel of reference extremity contacts the supporting
surface
 Ends- heel of same reference extremity contacts the ground
again
 Phases :
1. Stance - reference extremity contact with the ground
constitutes 60%
2. Swing – reference extremity not in contact with the ground
Constitutes 40%
3. Double support- 2 intervals where the weight is transferred
from one extremity to another
GAIT CYCLE

6. STANCE PHASE

7. SWING PHASE

8. Approx ROM needed in normal gait and time of occurrence of
maximum flexion and extension positions for major joints
determined by joint angles.
1. Sagittal plane joint angles
2. Frontal plane joint angle
3. Transerse plane joint angles
JOINT MOTION

10.  Determinant is a various movement occurs in the body
including pelvis, knee and ankle to maintain center of
gravity of the body in a horizontal plane and ensure the
smoothing pathway of gait.
 Factors responsible for minimizing the displacement of
center of gravity
DETERMINANTS OF GAIT

11.  6" Determinants of gait:
 Major determinants:
1. Pelvic rotation.
2. Pelvic tilting.
3. Knee flexion in stance phase.
4. Foot mechanism
5. knee mechanism.
6. lateral displacement of the body.
 Minor determinants:
 Neck movement.
 Swinging of arms

12.  pelvis rotates alternatively to right and to left in
relation to the line of progression in transverse
plane about the vertical axis.
 magnitude : 4 degrees on either side of the central
axis.
 Associated hip movement: Internal and external
rotation during stance phase.
1. Pelvic rotation

13.  The pelvis tilts downward on swing leg (on the side
which is opposite to that of weight bearing leg) along
the frontal plane around sagittal axis.
 magnitude: 5 degrees.
 Associated hip movement: hip adduction in stance
phase and hip abduction in the swing phase.
2. Pelvic tilting

14.  At initial contact, the knee is almost (0 ±5deg).
 At loading response, the knee begins the first excursion of
flexion after the heel strike ( = 15deg – 20deg )
 It has 3 functions:
1. Shock absorption.
2. Minimize displacement of COG.
3. Decrease energy expenditure.
3. Knee flexion in the stance phase:

15.  At mid- stance, the extension of knee reaches (5 deg) in
flexion.
 At terminal stance, the knee joint reaches 0 degof extension
to start the first excursion of knee extension.
 At pre-swing, the knee joint flexes up to 10deg flexion to
start the second excursion of knee flexion

16. Early in the stance phase:
 Foot dorsiflexed ,knee extended extremity max
length COG reaches lowest point in a downward
displacement.
Late in the stance phase:
 Foot plantar flexed knee slight flexion maintain
COG in its beginning of progression with minimum
displacement.
4. & 5. Foot and knee mechanism:

17.  COG displaced laterally over the weight bearing
extremity twice during the cycle of motion in the
horizontal plane.
 The motion is produced by the horizontal shift of pelvis
and relative adduction of hip.
Magnitude: 4.5 cm each stride
6. Lateral displacement of body and COG

18. 1. Increase the efficiency and smoothness of pathway of
gait.
2. Decrease the vertical and lateral displacement of
centre of gravity to two inches excursion.
3. Decrease the energy expenditure.
4. Make gait more graceful.
Function of the 6 detrminants of gait

19.  Moments produced by muscles, ligaments and bones
 Are called as “flexor/ extensor “, “abductor/ adductor”,etc.
 Sagittal plane
 Frontal plane
 Transverse plane
MUSCLE ACTIVITY
 Concentric and eccentric according to the internal moment of
the joint
INTERNAL MOMENT

22.  Walking accomplished by -
1. Bursts – concentric contraction – positive work
2. Eccentric contraction- negative work
 Body saves energy by passive exchange of potential and
kinetic energy
 Initial contact – lowest potential energy
 As the leg moves into midstance potential energy
rises exchange for kinetic energy
ENERGY REQUIREMENTS

23.  Potential energy curve drops at the same time as the
kinetic energy rises
 Sum of potential and kinetic components energy
saving
 Kinetic and potential energy not matching energy
conservation reduced

24.  Trunk remains in erect position during normal free
speed walking on normal ground, varying only 1.5
degrees.
 Sagittal plane: Heel strike flexion of HAT
opposing moment provided by hip extensors
 Frontal plane: COM medial to hip joint moment
balanced by hip abductor moment of the supporting
extremity
KINEMATICS AND KINETICS OF THE
TRUNK

25.  Initial contact pelvis rotates counter clock wise
trunk rotates clock wise
 Vice versa
 Trunk motion prevents excess body motion and
balances rotation of the pelvis
 Mediolateral translations(side to side motions):
Trunk to right-right heel strike to left toe off

26.  Arm swinging – opposite to legs and pelvis but similar
to trunk
 Counter balances forward swinging of the leg and
decelerates rotation of the body
 Forward swing :supscapularis, teres major and
lattissimus dorsi
 Backward swing :middle and post deltoid, teres major
and latissimus dorsi
 Forward swing medial rotators eccentrically
control rotation
 post deltoid eccentrically to restrain forward swing
KINEMATICS AND KINETICS OF THE
UPPER EXTREMITIES

27.  Joint Structure and Function :A Comprehensive
Analysis- Fifth Edition by Cynthia C. Norkins
 Physical Rehabilitation – Fifth Edition by Susan B O’
Sullivan
 Kinesiology The Mechanics and Pathomechanics of
Human Movement – Second Edition by Carol A. Oatis
REFERENCES