Post on 11-Jan-2016
Gait Analysis: Technology and Clinical Applications
واحدی هوشنگ دکترامیرتوانبخشی و فیزیکی متخصصطب
1قسمت
The goal of this chapter is to introduce and familiarize the clinician with the terminology, the biomechanics, and the complex interaction that exists between the body and the physical factors that impact human gait
the clinician must be able to produce a hypothesis and then attempt to understand
what the problem iswhere and when it is presentwhy it occurs
Humans are the only animals who characteristically have upright walking.
The fundamental goal of ambulation is to move from one place to another
locomotion the act or power of moving the body
from place to place by means of one's own mechanisms or power
ambulation one type of locomotion which is
characterized by moving the body on the level surface
Types of LocomotionTypes Examples
on feet · walking (ambulation, level walking) · race walking
. ascending or descending ramp
· running
· ascending or descending stairs · jumping
on wheels · bicycling · roller skating
· ice skating · wheelchair propelling
on hands · walking on hands · crutch walking
· stunts
on hands and knees · creeping
· crawling
on hands and feet · bear walking
· ropewalking
rotary locomotion · cartwheels · handsprings
· rolls
Top-Down Approach
cortex: cerebellum
Brain stem basal ganglia Spinal cord
peripheral nerves
NMJ
muscle
The sequence of events that must take place for walking to occur may be summarized as follows:
1. Registration and activation of the gait command in the central nervous system
2. Transmission of the gait signals to the peripheral nervous system
3. Contraction of muscles that develop tension4. Generation of forces at, and moments across,
synovial joints5. Regulation of the joint forces and moments by the
rigid skeletal segments based on their anthropometry
6. Displacement (i.e., movement) of the segments in a manner that is recognized as functional gait
7. Generation of ground reaction forces
Clinical Usefulness of the Top-Down Approach understand pathology determine methods of treatment decide on which methods we should use to
study patients gait. For example, a patient.s lesion could be central nervous system (as in cerebral palsy)peripheral nervous system (as in Charcot-
Marie-Tooth disease)the muscular level (as in muscular dystrophy)the synovial joint (as in rheumatoid arthritis).
Gait analysissurgical planningtherapeutic interventions
planning :botulinum toxin injection in the management of spasticity
optimization of lower extremity orthotic and prosthetic devices
sport movement analysisanalysis of musculoskeletal conditions,
and outcomes measurement quantitative assessment tool for
movement generally and walking specifically. (the most important)
Normal GaitSeries of rhythmical , alternating
movements of the trunk & limbs which result in the forward progression of the center of gravity
Intermittant : Propulsion movements & Restraining movements
Normal Gait
Gait CycleA single sequence of functions of one limb is
called a gait cycle. It is essentially the functional unit of gait.Gait Cycle:There are two basic phases in
the full cycle of a step
1. Stance phase : the weightbearing period
2. Swing phase: the non weightbearing period
This analogy of a wheel can be applied to human gait.
Support:1) Double-limb support :
period during which both feet are in contact with the floor.
2) Single- limb support:
period starts when the opposite foot is lifted for the swing phase
Gait parameters
Distance parameters Time parametersSpeed parameters
Spatial (Distance) parameters
Step Length– Distance between corresponding successive points of heel contact of the
opposite feet
Rt step length = Lt step length (in normal gait)
Stride Length– Distance between successive points of heel contact of the same foot
Double the step length (in normal gait)
144 cm in healthy adults
step width (Walking Base) – lateral distance between both heel centers of 2 consecutive foot contacts
7-9 cm in healthy adults
foot angle angle (degree of toe-out)– between the line of progression of the body and the longitudinal axis of the
foot
7º in healthy adults
Time parameters
Parameter Definition Significance
stride time the duration for the completion of a full gait
cycle
slightly > 1 sec
step time the duration for the completion of a right or
left step
= the reciprocal of cadence for
a symmetric gait
stance time the duration when the foot is on the ground
during one gait cycle
60% of one gait cycle
single support
time
the duration when only one foot is on the
ground during one gait cycle
double support
time
the duration when both feet are in contact
with the ground simultaneously during one
gait cycle
~20% of one gait cycle
as walking speed á
in the elderly
in patients with balanced
disorders
swing time the duration when the foot is in the air
during one gait cycle
40% of one gait cycle
as walking speed
Time Frame:A. Stance vs. Swing:
Stance phase = 60% of gait cycle
Swing phase = 40%B. Single vs. Double support:
Single support = 80% of gait cycle
Double support = 20%
1.Initial contact (0%)2. Loading response (0-15%)3. Midstance (15-40%)4. Terminal stance (40-50%)5. Preswing (50-60%)6. Initial Swing (60-70%)7. Midswing (70-85%)8. Terminal swing (85-100%)
Speed parameters
Parameter Definition Significance
cadence (step rate) number of steps per minute comfortable speed : 80-
110 steps/min
slow speed : <70
steps/min
fast speed : >120
steps/min
walking speed distance per unit of time Speed in duration of all the
component phases,
especially double support
phase
as cadence, stride length,
or both
as angle of toe out or limb
length
Cadence– Number of steps per unit time– Normal: 100 – 115 steps/min
_Cultural/social variationsComfortable Walking Speed (CWS)
– Least energy consumption per unit distance
– Average= 80 m/min (~ 5 km/h)
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)
Velocity = stride length x cadence 120
With increasing walking speeds:Stance phase: decreasesSwing phase: increasesDouble support: decreases
Running:walking without double supportRatio stance/swing reversesDouble support disappears. ‘Double
swing’ develops
Line of gravity The line of gravity through the center of
mass of the body
Note center of mass (COM): the weighed
average of the center of mass of each body segments
center of gravity (COG): the vertical projection of the COM to the ground
The Center of Gravity (COG)
COG located at S1 - S2
During preferred rate walking the COG approximates a sinusoidal curve from the:
Center of gravity (COG)—located 5 cm anterior to second sacral vertebra. The COG is displaced 5 cm (< 2 in.) horizontally and 5 cm vertically during an average adult male step
Path of the COG
Verticalplane
Horizontalplane
Path of Center of Gravity
A-Vertical displacement:Rhythmic up & down movementHighest point: midstanceLowest point: double supportAverage displacement: 5cmPath: extremely smooth sinusoidal curve
Path of Center of Gravity
B-Lateral displacement:Rhythmic side-to-side movementLateral limit: midstanceAverage displacement: 5cmPath: extremely smooth sinusoidal
curve
Path of Center of Gravity
c- Overall displacement:Sum of vertical & horizontal displacementFigure ‘8’ movement of COG as seen from
AP view
Elements of the Normal Pattern of Gait
Alignment Gross Movements Fine Movements
Alignment
1. Head is erect.
2. Shoulders are level.
3. Trunk is vertical.
Gross Movements
1. Arms swing reciprocally and with equal amplitude at normal walking speed.
2. Steps are of the same length and timing is synchronized.
3. Body vertical oscillations