Kinetics and Kinematics Paramters in Gait
- 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
- 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.
- 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.
- 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)