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