Gait Flashcards
Gait analysis
measure temporal spatial, kinematic, kinetic, and EMG data to get complete picture of how an individual walks
disadvantages of gait analysis
reliability of some measurements are questionable
dependent on expertise of observer and quality of tool
gait cycle
starts when one foot contacts the ground and ends with the next contact of the same foot with the ground
stride
synonymous gait cycle
step
sequence of events that occurs within successive ground contacts of opposite feet
step length
distance from a point of contact with the ground of one foot to the following occurance of the same point with the other foot
step width
the horizontal distance between the feet
foot angle
angle between the line of progression of the body and the long axis of the foot
cadence
the number of steps per minute
stride time
the time required for a full gait cycle
velocity
measures the time it takes to cover a given distance covered in a given amount of time
-best functional measure of someone’s walking ability
normative value for velocity
1.3 to 1.4 m/s or 3 MPH
normative value for cadence
110-120 steps/minute
normative value for step length
0.7 m or about 28 inches
Stance Phase of Gait Cycle
approx 60% of gait cycle
- when foot hits the ground until it lifts
- supporting body weight
single leg support of stance phase
one leg on ground
-occurs from 10-50% of gait cycle
double leg support of stance phase
both legs on ground
-occurs from 0-15% & 50-60% of gait cycle
swing phase
approx 40% of gait cycle
- foot leaves ground until it hits ground again
- goal: advance foot to go forward
subphases of stance phase
- initial contact
- loading response
- mid-stance
- terminal stance
- pre-swing
initial contact
when foot touches ground
0% of gait cycle
loading response
initial contact w/ one foot until the opposite foot leaves the ground
-approx 8% of gait cycle
mid stance
begins when swing foot leaves the ground- ends when body weight is directly over stance leg
approx - 10-30% of gait cyccle
terminal stance
begins when body weight is directly over the stance leg and ends when swing leg contacts ground
-approx 30-50% of gait cycle
(heel off occurs at 40%)
pre-swing
begins when the (previous) swing foot contacts the ground and ends when the (previous) stance foot leaves ground
approx 50-60% of gait cycle
(toe off occurs at 60%)
acceleration phase (swing phase)
toe off to mid swing
deceleration phase (swing phase)
mid swing to initial contact
early swing phase
occurs from toe off until swing foot is next to stance foot
approx 60-73% of gait cycle
Mid-swing phase
occurs from feet adjacent until the tibia of the swing leg is vertical
approx 73-87% of gait cycle
Late swing phase
occurs from tibia vertical until just before foot hits ground
(87%-100% of gait cycle)
Gait
forward progression is achieved by successive and alternating steps forward
center of mass & gait
COM moves in 3 directions during gait
Vertical (view from side)
Medial-Lateral (view from front/back)
minimum height of vertical COM movement
occurs at the midpoint of both periods of double limb support
5% and 55% of gait cycle
maximum height of vertical COM movement
occurs at midpoint of both period of single leg stance
30% and 80% of gait cycle
medial lateral COM movement
shifts back & forth from left & right
-maximum movement occurs at midstance
30% for one leg & 80% for the other leg
Kinematic strategies to minimize energy expenditure
minimize vertical displacement of COM
minimize medial lateral displacement of COM
determinants of gait
-reduce significant energy consumption of ambulation
- pelvic rotation
- pelvic tilt
- knee flexion in stance phase
- ankle mechanism
- foot mechanism
- lateral displacement of body
pelvic rotation
forward rotation of pelvis (8% of swing phase)
- reduces angle of hip flexion and extension
- longer step length w/o further lowering of COM
pelvic tilt
5 degree dip of the swinging side (hip abduction)
- in standing, this dip is a + Trendelenburg sign
- reduces height of apex of the curve of COM
knee flexion in stance phase
approx 20 degree dip
- shortens the leg in the middle of stance phase
- reduces the height of the apex of the curve of COM
ankle mechanism
lengthens the leg at heel contact
- smoothens the curve of COM
- reduces the lowering of COM
foot mechanism
lengthens the leg at toe-off as ankle moves from dorsiflexion to plantar flexion
- smoothens curve of COM
- reduces lowering of COM
lateral displacement of body
the normally narrow width of walking base minimizes the lateral displacement of COM
-reduced muscular energy consumption due to reduced lateral acceleration & deceleration
Why is COM important?
- critical for energy expenditure during gait (changes energy back & forth from potential energy to kinetic energy)
- determines where the ground reaction force is applied to a joint (body needs to control GRF by activating muscles)
The trunk in gait
important for maintaining balance and minimizing energy expenditure during gait
- trunk rotation is about 7 degrees
- restriction of trunk motion may increase energy expenditure by 10%
Trunk anterior/posterior position - COM and GRF
if someone is leaning forward, the GRF is anterior to the knee
- may be a compensation for weakness: hang on the posterior capsule for the knee
shoulder motion
out of phase with the hip
increased arm swing = increased speed
used for maintenance of balance
pelvis movement during gait
anterior and posterior pelvic tilt/rotation
- pelvis is considered rigid during gait
- movement is small (2-4 degrees of motion)
pelvis at heel contact
pelvis is neutral
-goes into slight posterior tilt/rotation at 10% of gait cycle (double support)
pelvis at mid stance
moves into anterior tilt/rotation
pelvis at toe off
moves back into posterior tilt/rotation until toe off
double support
pelvis at mid swing
back to anterior tilt/rotation at mid swing
helps hip advance
Patient w/ hip flexion contractures (effect on pelvis)
show an exaggerated anterior pelvic tilt and lordosis during the second half of the stance
pelvis motion & velocity
increases with velocity
-increase functional step length
pelvis in frontal plane
look from front or back
- watch the iliac crest rise/fall
- pelvic obliquity
-moves about 10 degrees due to adduction/abduction of the hip
Pelvis (frontal plane) on stance
during weight acceptance onto the stance leg, the pelvis drops on the swing side
pattern repeats itself inverse after the opposite foot strike
pelvis : horizontal plane @ initial contact
pelvis is rotated four degrees internally
pelvis (horizontal plane) during swing
pelvis ER
- first returning to neutral position and then continuing to externally rotate an additional 4 degrees
(rotation lengthens the t trailing and advancing limbs)
prevents 0.95 cm of downward displacement of COM
The hip in sagittal plane
hip is flexed about 30 degrees at initial contact
but as the body moves over foot, it extends
when does maximum hip extension occur
right before toe-off (10 degrees)
When does hip flexion start? & when is maximum hip flexion?
(sagittal plane)
right before pre-swing
max = just before initial contact (35 degrees)
- but the hip is ready to extend to get ready for weight acceptance
when is the hip at neutral (sagittal plane)
neutral at toe-off
when is the hip at neutral (frontal plane)
at initial contact
hip adduction occurs (frontal) & max
as weight goes on stance foot
max hipp adduction is 5 degrees around 20% of gait cycle
