1. Gait Analysis: Technology and Clinical Applications
دکترامیر هوشنگ واحدی
متخصص طب فیزیکی و توانبخشی
قسمت 1

3. 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 is
where and when it is present
why it occurs

4. Humans are the only animals who characteristically have upright walking.
The fundamental goal of ambulation is to move from one place to another

5. 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

6. Types of Locomotion Types 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

7. Top-Down Approach

8. cortex: cerebellum
Brain stem basal ganglia
Spinal cord
peripheral nerves
NMJ
muscle

9. 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 tension 4. Generation of forces at, and moments across, synovial joints 5. 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

10. 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).

11. Gait analysis surgical planning
therapeutic interventions planning :botulinum toxin injection in the management of spasticity
optimization of lower extremity orthotic and prosthetic devices
sport movement analysis
analysis of musculoskeletal conditions, and outcomes measurement
quantitative assessment tool for movement generally and walking specifically. (the most important)

12. Normal Gait
Series of rhythmical , alternating movements of the trunk & limbs which result in the forward progression of the center of gravity
Intermittant : Propulsion movements & Restraining movements

13. Normal Gait

14. Gait Cycle
A 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
Stance phase : the weightbearing period
Swing phase: the non weightbearing period

15. This analogy of a wheel can be applied to human gait.

16. Support: 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

18. Gait parameters
Distance parameters
Time parameters
Speed parameters

20. step width (Walking Base)
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

22. Time parameters stride time step time stance time single support time
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

23. 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%

25. 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%)

26. Speed parameters Parameter Definition Significance cadence (step rate)
number of steps per minute
comfortable speed： 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

27. Cadence Number of steps per unit time Normal: 100 – 115 steps/min
_Cultural/social variations
Comfortable Walking Speed (CWS)
Least energy consumption per unit distance
Average= 80 m/min (~ 5 km/h)

28. 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

29. With increasing walking speeds:
Stance phase: decreases
Swing phase: increases
Double support: decreases
Running:
walking without double support
Ratio stance/swing reverses
Double support disappears. ‘Double swing’ develops

31. 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

33. 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

34. Path of the COG
Vertical
plane
Horizontal
plane

35. 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

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

38. Path of Center of Gravity
c- Overall displacement:
Sum of vertical & horizontal displacement
Figure ‘8’ movement of COG as seen from AP view

40. Elements of the Normal Pattern of Gait
Alignment
Gross Movements
Fine Movements

41. Alignment
Head is erect.
Shoulders are level.
Trunk is vertical.

42. Gross Movements
Arms swing reciprocally and with equal amplitude at normal walking speed.
Steps are of the same length and timing is synchronized.
Body vertical oscillations