Gait Cycle Analysis PDF

 Biomechanics of gait Overview Gait cycle Kinamatics  Ankle  Knee  Hip Kinetics  Ankle  Knee  Hip  GAIT CYCLE  Series of rhythmical, alternating movements of the trunk & limbs which result in the forward progression of the center of gravity....

 Biomechanics of gait Overview Gait cycle Kinamatics  Ankle  Knee  Hip Kinetics  Ankle  Knee  Hip  GAIT CYCLE  Series of rhythmical, alternating movements of the trunk & limbs which result in the forward progression of the center of gravity. GAIT CYCLE – TERMINOLOGY  Step length  Stride length  Walking base  GAIT CYCLE - TERMINOLOGY  Cadence  Number of steps per unit time  Normal: 100 – 115 steps/min  Cultural/social variations Velocity  Distance covered by the body in unit time  Usually measured in m/s  Instantaneous velocity varies during the gait cycle  Average velocity (m/min) = step length (m) x cadence (steps/min) GAIT CYCLE - PHASES GAIT CYCLE - PHASES  Stance Pha  Swing phas  Support STANCE PHASE Stance phase: 1. Heel contact 2. Foot-flat 3. Midstance 4. Heel-off 5. Toe-off SWING PHASE Swing phase: 1. Acceleration 2. Midswing 3. Deceleration Time Frame A. Stance vs. Swing B. Single vs. Double support With increasing walking speeds Running  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  Path of Center of Gravity Vertical displacement:  Rhythmic up & down movement  Highest point: midstance  Lowest point: double support  Average displacement: 5cm  Path: extremely smooth sinusoidal curve  Path of Center of Gravity Lateral displacement:  Rhythmic side-to-side movement  Lateral limit: midstance  Average displacement: 5cm  Path: extremely smooth sinusoidal curve  Overall displacement Sum of vertical & horizontal displacement Figure ‘8’ movement of CG as seen from AP view  Determinants of gait 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  Determinants of gait Pelvic tilt 5o dip of the swinging side (i.e. hip adduction) In standing, this dip is a positive Trendelenberg sign Reduces the height of the apex of the curve of CG  Determinants of gait Knee flexion in stance phase Approx. 20o flexion Shortens the leg in the middle of stance phase Reduces the height of the apex of the curve of CG  Determinants of gait Ankle mechanism Lengthens the leg at heel contact Smoothens the curve of CG Reduces the lowering of CG  Determinants of gait Foot mechanism Lengthens the leg at toe-off as ankle moves from dorsiflexion to plantarflexion Smoothens the curve of CG Reduces the lowering of CG  Determinants of gait Foot mechanism Normal walking base 5cm to 10cm Maintain stability at mid-stance Minimize lateral displacement of CG Gait Analysis – Biomechanics  Gait Analysis – Biomechanics  The force that the foot exerts on the floor due to gravity & inertia is opposed by the ground reaction force  Ground reaction force (RF) may be resolved into horizontal (HF) & vertical (VF) components.  Understanding joint position & RF leads to understanding of muscle activity during gait Sagittal Plane Motion  Stance Phase (Kinamatics & kinatics)  Swing Phase (Kinamatics & Kinatics)  Kinamatics Motion Heel Contact To Midstance  Kinetics (External Forces) Motion Heel Contact To Midstance  Kinetics (Internal Forces) Motion Heel Contact To Midstance  Kinamatics Motion Midstance To Toe-Off  Kinetics (External Forces) Motion Midstance To Toe-Off  Kinetics (Internal Forces) Motion Midstance To Toe-Off Motion During Swing Phase Frontal & Transverse Plane Motions  Stance Phase  Swing Phase  Early Stance Heel Contact To Foot Flat Continue…..  Mid Stance Foot Flat To Heel Off  Late Stance Heel Off To Toe-Off Swing Its All About Gait 