Presentation in a seminar

1. Objective Analysis of Kinetics and
kinematics parameters in Gait
Dr. P.K.Lenka, NIOH, Kolkata
Email: lenka_pk@yahoo.co.uk

2. Outline
• Introduction to Gait
• Subjective and Objective Analysis of Gait
• Interpret kinematic and kinetic of gait
• Measure of Kinematic Parameters
• Measure of Kinetics Parameters
• Case study
• Discussion
• Conclusion

3. • It is a key activity of daily living
• It is an excellent functional test of many systems
– It involves the interaction of multiple joint movements
– It is a test of sensory-motor integration
• Provides insight:
Surgical decision making, Prosthetic design, Orthotic
design, Rehabilitation strategies, Objective tracking of
progress, Biometrics, Milestone Profiles
Gait: The study of Human Walking.
The objective of Gait Analysis is the ability to answer a
few clinical questions related to human motion
Clinical Gait Analysis is the investigation of the pattern of walking
that would be used for diagnosis and treatment of diseases

4. Gait

5. • It is the "manner of moving the body from one place to another
by alternately and repetitively changing the location of the feet"
(Smith, 1990)
"a translator progression of the body as a while produced by
coordinated rotary movements of body segments”
• The sequences for walking that occur may be
summarized as follows
– Registration and activation of the gait command within the
central nervous system
– Transmission of the gait systems to the peripheral nervous
system
– Contraction of muscles
– Generation of several forces
– Regulation of joint forces and moments across synovial joints
and skeletal segments
– Generation of ground reaction forces

6. Gait & Posture Terminology
• Temporal and spatial measures
• Phases of gait
• Center of Gravity(COG,COP,COM)
• Determinants of gait
• Gait Physiology
• Kinetics and Kinematics

7. Why Gait is important to P&O ?
• During Locomotion, more than 1000 muscles are
synchronized to move over 200 bones around 100
moveable joints in Human Body.
• A healthy person walking at self selected velocity,
performed this task at a minimal energy cost.
• It differs from individual to individual depending on age,
sex, activity, mood or due to diseases or use of P&O
devices.
• Decline in economy of mobility indicates that more
physical work is required and may suggest an abnormal
gait pattern

8. Temporal and spatial measures
• Stride Duration (cycle duration, cycle period)
• Stance Time (stance duration)
• Swing Time (swing duration)
• Single Support Time
• Double Support Time
• Stride Length
• Step Length
• Base of Support Width
• Degree of Toe Out
• Cadence
• Velocity

9. Steptimes:

10. Gait Parameters (Time Distance)
Step Length
Stride Length
Base of Support

11. Step time
Swing time

12. Stance Time
Single Support Time
Double Support Time

13. Degree of Toe Out- Foot
Progression Angle

14. speed = average length of the stride
average duration of the stride
or,
speed = stride length x steps per minute (cadence)
120
• Cadence= number of steps/Minute

15. • Initial Double Support(0-12%)
• Single Limb Stance(12-50%)
• Second Double Support(50-62%)
• Initial swing(62-75%)
• Mid-swing(75-85%)
• Terminal swing(85-100%)
• Initial Contact
• Loading Response
• Mid stance
• Terminal Stance
• Pre swing
• Initial Swing
• Mid Swing
• Late Swing
HS/IC FF/LR MS HO/TS TO/PS IS MS TS

17. Path of Center of Gravity
• Center of Gravity (CG):
– midway between the hips
– Few cm in front of S2
• Least energy consumption if CG travels in
straight line

18. CG

19. Path of Center of Gravity
A. Vertical displacement:
• Rhythmic up & down movement
• Highest point: midstance
• Lowest point: double support
• Average displacement: 5cm
• Path: extremely smooth sinusoidal
curve

20. Path of Center of Gravity
B. Lateral displacement:
• Rhythmic side-to-side movement
• Lateral limit: midstance
• Average displacement: 5cm
• Path: extremely smooth
sinusoidal curve

21. Path of Center of Gravity
C. Overall displacement:
• Sum of vertical & horizontal
displacement
• Figure ‘8’ movement of CG
as seen from AP view
Horizontal
plane
Vertical
plane

22. Determinants of Gait :
• Six optimizations used to minimize excursion
of CG in vertical & horizontal planes
• Reduce significantly energy consumption of
ambulation
• Classic papers: Sanders, Inman (1953)

23. Determinants of Gait :
 (1) Pelvic rotation:
 Forward rotation of the pelvis in the horizontal plane approx. 8o
on the swing-phase side
 Reduces the angle of hip flexion & extension
 Enables a slightly longer step-length w/o further lowering of CG

24. Determinants of Gait :
 (2) Pelvic tilt:
 5o in the swinging side
 In standing, this is a positive Trendelenberg sign
 Reduces the height of the apex of the curve of COG

25. Determinants of Gait :
 (3) Knee flexion in stance phase:
 Approx. 20o
 Shortens the leg in the middle of stance phase
 Reduces the height of the apex of the curve of COG

26. Determinants of Gait :
 (4) Ankle mechanism:
 Lengthens the leg at heel contact
 Smoothens the curve of COG
 Reduces the lowering of COG

27. Determinants of Gait :
 (5) Foot mechanism:
 Lengthens the leg at toe-off as ankle moves from
dorsiflexion to plantarflexion
 Smoothens the curve of COG
 Reduces the lowering of COG

28. Combination of 4 & 5
• Heel-strike:Knee is extended and ankle is
plantar flexed to lengthen the leg
• Loading response (HS to FF): knee flexes,
ankle plantarflexes, and foot pronates
• Midstance to terminal stance (FF to HO):
Knee extends, ankle dorsiflexes
• Preswing (HO to TO): ankle plantarflexes to
lengthen the leg

29. Determinants of Gait :
 (6) Lateral displacement of body:
 The normally narrow width of the walking base minimizes
the lateral displacement of CG
 Reduced muscular energy consumption due to reduced
lateral acceleration & deceleration

30. Gait Physiology
• Muscles contract when body alignment creates a
torque antagonistic to weightbearing stability – (I.e.
the body vector is aligned to create instability)
• • The intensity of muscular responses are proportional
to the magnitude of the torque demand that must be
restrained – as soon as alternate means are available
the muscles relax
• • There is a continual exchange between the external
torque demand and the controlling mechanisms
(muscle action,momentum, passive tension of
ligaments and fascia, etc.) to resist that demand

31. Determining muscle function via the ground reaction
force vector method
• Phase GRFV torque Muscle torque
• Initial contact (the GRFV is anterior to hip)
Attempts to produce hip flexion. This force is
resisted by the hip extensors
• Terminal stance - Ankle dorsiflexion - Ankle
plantar flexion.

32. GRFV

34. Initial Contact (Heel strike)
• Hip stabilized by extensor
activity of hamstrings and
gluts
• Knee stabilized by
cocontraction of quads and
hamstrings
• Ankle pre-tibial muscles
dorsiflex ankle, positioning
foot for initial contact.
●HIP: 25° flexion ●KNEE: 0° -5 ° ●ANKLE: 0° (90 °)

35. Loading Response (HS to Foot Flat)
• Hip abductors stabilize pelvic drop
in frontal plane
• Hip extensors counteract trunk
and hip flexion
• Quads control knee flexion
providing shock absorption
• Ankle dorsiflexors decelerate foot
drop
• Tibialis anterior and posterior
eccentrically decelerate
pronation.
• HIP: 25° flexion ●KNEE: 0° → 15° flexion (Lowers CM)
●ANKLE: 0° → 10° plantar flexion

36. Mid-stance (FF to Midstance)
• Hip abductors continue to
minimize pelvic drop in the frontal
plane
• Quads resist knee flexion until
COG passes over base of support,
then quads are silent
• Soleus and gastroc eccentrically
control forward tibial progression
●HIP: 25° flexion → 0° ,●KNEE: 15° flexion → 0° flexion
●ANKLE: 10° plantar flexion → 5° dorsi flexion

37. (Midstance to Heel off)
• Brief burst from hip flexors resisting
hyperextension of the hip
• Tensor fascia latae active throughout
stance to resist pelvic drop
• Minimal to no quad or hamstring
activity
• Ankle plantar flexors prevent forward
tibial collapse and contribute to heel
rise through passive tension.
●HIP: 0° flexion → 20° extension ,●KNEE: 0°
●ANKLE: 5° dorsi flexion → 10° dorsi flexion

38. Pre-swing (Heel to Toe off)
• Femur flexes forward due to
gravityand momentum, may be
facilitated by adductor longus and
rectus femoris
• Adductors stabilize weight shift
across midline to other foot
• Rectus femoris may restrain rapid
passive knee flexion, otherwise
quads silent
• Passive tension in ankle plantar
flexors facilitates knee flexion and
then decreases to zero in
preparation for toe off
●HIP: 20° extension → 0° ,●KNEE: 0° → 40° flexion
●ANKLE: 10° dorsi flexion → 20° plantar flexion

39. Initial Swing (Toe off to Early Acceleration)
• Hip flexors flex hip
• Adductor longus brings leg
toward midline
• Ankle pre-tibials initiate
dorsiflexion to clear toes
●HIP: 15 ° ,●KNEE: 60°
●ANKLE: 10° plantar flexion

40. Mid-swing
• Hip flexors and momentum
flex hip
• Hamstrings begin to
decelerate knee extension –
Knee extension created by
tibial forward momentum
• Ankle pre-tibials
concentrically contract to
clear foot
• HIP: 25 ° ,KNEE: 25°,ANKLE: 0°

41. Terminal Swing
(Midswing-Deceleration)
• Hamstrings continue to
decelerate forward swing of leg
• Quadriceps may contract to
extend knee in preparation for
initial contact
• Ankle pre-tibials contract to
prepare foot for initial contact
●HIP: 25 ° ,●KNEE: 0°
●ANKLE: 0° plantar flexion

42. Gait Analysis: Techniques and
Recognition of Abnormal Gait
April 30, 2007
Kinematics

43. Kinematics Parameter
• Position of joint centers
• Center of mass
• Joint angles
• Angular velocities

44. Gait Kinematics
• Hip angle
– between thigh & trunk
– flexion positive
• Knee angle
– between thigh & leg
– flexion positive
• Ankle angle
– between foot & leg minus 90°
– DF positive

50. Kinetics
Linear Forces Dynamic Forces Fast Dynamic Forces

51. Gait Analysis: Techniques and
Recognition of Abnormal Gait
April 30, 2007
Force Platform
The reaction force produced
by the ground is called the
Ground Reaction Force (GRF),
which is basically the reaction
to the force the body exerts on
the ground.
Kinetics

52. Kinetic Parameter
• GRF, JRF
• COP, COM
• GRFV method
• Rigid Body Dynamics method (5/7 segment)
• Joint power
• Muscle Torques
• Muscle Power

53. Kinetics: Moment
Moment Profiles tell us
about the net torque
about a joint from the
muscles and therefore
we can speculate which
muscles are contributing
to this torque
(i.e.: what is the net
muscle torque at any
one point in time?)

54. Gait Kinetics: Power
• Power is rate at which work is performed
P = M 
Power – time graphs are obtained by calculating
the product of the angular velocity and the
resultant muscle torque
• The energy for walking is generated by
concentric contraction and absorbed by
eccentric contractions

55. Kinetics: Power
power production
– concentric contraction
power absorption
– eccentric contraction
Power profiles tell us
about the
contribution of
muscles to gait

56. Dynamics
• Forward Dynamics:
• How forces cause movements. We use dynamics to
estimate the movements that result from forces and
moments.
• (a=F/m).
• Inverse Dynamics:
• How movements require forces. We use inverse
dynamics to estimate the forces that cause the
motions we measure.
• (F=ma).

62. GAIT Measurement Instruments
• Force Plates/Mats/Walkway
• Motion Analysis/Simulation/Modeling /Video Analysis/Image
Processing /Instrumented Trade mills /Biomechanics Software
• EMG/ECG/EEG
• Energy/PCI

63. NIOH Set up
Power Lab
Cosmed-K4b2

64. Measuringshoes:

65. ULTRAFLEX
4-in-1 Gait analysis system:
1. 16 channels of CDG
(CDG=Computer Dyno Graphy,
recording the dynamic force distribution
under the foot during gait)
2. 16 channels of EMG
(Electromyography)
3. 16 channels Gonio
(angle measurement of any joint,
in two planes per joint)
4. 4 Channel Video

66. The digital datalogger unit:
•Exchangeable
memorycard for multiple
measurements.
•Very light weight.
•Easy to use.
•Glasfibre highspeed
datatransfer.

68. Forcegraphics details:

69. Mean values Sum:

70. HISTOGRAM:

71. GAITLINE:

72. Gaitline-mean:

73. CYCLOGRAM:

74. Cyclogram-mean:

76. Case study
A Prosthetist wants to examine the joint loadings and
Moment at knee of a person with trans-tibial prosthesis
of body weight 57.6 kg walking at a speed of 4 km/hour
in a plane surface.

77. Approach-inverse dynamics

82. value Location term value
Body Mass 56.7kg Foot BSP 0.822kg
Gravitational Constant 9.8 MI Proportional
segment length,
Radius of Gyration
0.0026kg/
sqm.
Acceleration X 9.9 m/s Fx-Ankle -107N
Acceleration Y 5.3m/s Fy-Ankle Fay +530-
0.822(9.8)=M(5.3)
-517
GRF x 113 Moment
at Ankle
M=Iα=>
107(0.05)+517(0.0
4)+115(0.09)-
530(0.008)
-78.7
GRF y 530

84. value Location term value
Body Mass 56.7kg Foot BSP 0.822kg
Gravitational Constant 9.8 MI Proportional
segment length,
Radius of Gyration
0.0026kg/s
qm.
Acceleration X 9.9 m/s Fx-Ankle -107N
Acceleration Y 5.3m/s Fy-Ankle Fay +530-
0.822(9.8)=M(5.3)
-517
GRF x 113 Moment
at Ankle
M=Iα=>
107(0.05)+517(0.04
)+115(0.09)-
530(0.008)
-78.7
GRF y 530

85. Calculation
Known variables: Moment at distal part of
Prosthesis, Force in X direction , Force in Y
direction, length of prosthesis, weight of
prosthesis, MI of Prosthesis, CG of Prosthesis
To Derive: Moment, Rx and Ry at proximal part of
rigid segment (Moment at Knee and Joint Loading)

86. Thank You
Thanking You