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Semester 2 FS Exam 10 > Normal and Pathological Gait > Flashcards

Normal and Pathological Gait Flashcards

1
Q

Define Gait

A

the manner or style of locomotion involving the use of two legs, alternatively, to provide support and propulsion, while at least one foot being in contact with the ground at all times.

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2
Q

Important aspects of gait - definition info

A

During gait you are always in double or single support (one leg is in contact with ground at all times) (running = one foot off the ground)
normal gait has general characteristics but is specific to how you walk (unique)

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3
Q

two purposes of the legs during gait

A
  1. prevent collapse

2. propel yourself in the direction of motion

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4
Q

What is the purpose of gait?

A

to transport the body safely and efficiently across the ground (from point a to point b)
efficiency is key! walking for exercise = goal to walk to burn calories; not efficient

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5
Q

Purpose of gait on different surfaces

A

level: how much mass is transported how far? (mass x distance = work)
Uphill/downhill: consider change of altitude, PE = mgh
uneven terrain: safety (NM control, prevent from collapse, balance of upper body, foot trajectory clearance)

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6
Q

5 Major motor functions during gait

A
  1. Support of upper body
  2. Dynamic balance
  3. Foot trajectory control
  4. Generation of mechanical energy
  5. Absorb mechanical energy
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7
Q

Support of upper body

A

prevent collapse of lower limb during stance

upper body needs to be controlled so visual and vestibular systems can work during gait

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8
Q

Dynamic balance

A

maintenance of upright posture and balance of the entire body
important because sensory information can override locomotive system

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9
Q

Foot trajectory control

A

to achieve safe ground clearance and gentle toe or heel landing (toe off to heel contact)

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10
Q

generation of mechanical energy

A

maintain or increase forward velocity
mechanical energy required for every step of gait
generating energy = concentric contraction

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11
Q

absorb mechanical energy

A

shock absorption and stability or to decrease forward velocity of the body (occurs at every joint, especially the knee)
absorbing energy = eccentric contraction

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12
Q

Spatial and temporal descriptors on level walking include what two things?

A

time and distance parameters

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13
Q

Time parameters of walking on level ground

A 
stance time = 0.5 seconds
single support time
double support time
swing time
stride or step time
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14
Q

Double support

A

22% of gait cycle total
decreases when speed of walking increases
increases in elderly or those with balance issues
0 time spent in double support while running

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15
Q

stride vs step time

A

stride time is not very useful

step time is important! It will decrease on the affected side (limping)

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16
Q

Distance parameters of walking on level ground

A

stride length
step length
step width
degree of toe-out

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17
Q

Stride length

A

decreases in elderly

increases as speed of walking increases

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18
Q

step width

A

increases in those with balance issues

medial lateral direction

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19
Q

Rate (distance/time) variables

A

cadence: steps per min

walking/gait velocity: distance/unit of time

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20
Q

Cadence

A

comfortable speed = 80-110 steps/min
fast = 120 steps/min
40-55 strides/min = 80-110 steps/min
1 stride = 2 steps

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21
Q

Can two people walk at the same speed and have different cadences?

A

yes: kid walking with parents
kid has much higher cadence than parent
parent has larger stride length
cadence and stride length contribute to speed
pathologies cause decreased stride length

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22
Q

Walking/gait velocity

A

(0.9 - 1.7 m/s)
increases w/ increased cadence and stride length simultaneously
decreases w/ decreased angle of toe out and limb length or weight
increased speed = decreased duration of all stance phase components (sub phases)
avg walking gait/velocity = 1.3 m/s
walking at 1 m/s = slow

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23
Q

Other kinematic variables

A

center of mass position and velocity during gait
linear position, velocity and acceleration of the COM, pelvis, and head during gait
linear position and velocity of the toe during gait
angle change of each joint during gait

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24
Q

Displacement of COM in vertical and lateral directions

A

vertical displacement of COM = 5cm

lateral displacement of COM = 4cm

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25
Q

Vertical displacement of COM

A

30% of gait cycle (end of midstance) is the highest point of trajectory
55% of gait cycle (middle of double support) is the lowest point of trajectory (preswing)
at the same time of the highest trajectory = COM is closest to the foot that is in contact with the ground

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26
Q

Energy cost of gait

A
  1. muscles affect the rate of energy expenditure during gait
  2. the overall metabolic cost of walking can be assessed by measuring O2 consumption and CO2 production
  3. Oxygen rate at average walking speed is 80 m/min or 1.3 m/s or 3 miles per hour. or 12 ml/kg/min (energy cost of walking)
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27
Q

how do muscles affect the rate of energy expenditure during gait?

A 
increase/decrease speed of motion
lift body against gravity
decelerate different body segments
stabilize joints so they don't move (co-contraction)
lower BW
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28
Q

Compass vs normal gait

A

normal gait is more efficient than compass gait because vertical excursion is much smaller

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29
Q

Purpose of 6 determinants of gait

A

minimize COM movement, therefore minimizing energy consumption

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30
Q

6 determinants of gait

A
  1. pelvic rotation about the vertical axis
  2. pelvic tilt about AP axis
  3. knee flexion in stance phase
  4. ankle mechanism
  5. foot mechanism
  6. lateral displacement of body
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31
Q

Pelvic rotation

A

pelvic rotation decreases COM vertical displacement anteriorly at heelstrike and posteriorly at toe-off

32
Q

Pelvic tilt

A

decreases COM vertical displacement

33
Q

Knee flexion

A

decreases COM vertical displacement

34
Q

foot/ankle mechanism

A

decreases COM vertical displacement during stance

35
Q

Lateral displacement of body

A

normal leg = valgus, meaning knee joint centers closer than hip joint centers, allowing me to put feet closer together, meaning my COM does not displace/move as far in M/L direction during gait

36
Q

Toe kinematics

A

max toe clearance is 1.3 cm (??)
max horizontal velocity of foot during walking is 4.6 m/s (??)
fast velocity of foot during swing with little toe clearance = high trip/fall risk
lowest toe clearance occurs at max horizontal velocity of the foot!!!!

37
Q

What happens to the head and pelvis M/L acceleration with age?

A

although acceleration in ml direciton of pelvis decreases slightly, the head motion increases and is more than the pelvis. head motion should be smaller than pelvic!

38
Q

what happens to step width with age?

A

step width increases – wider BOS – safety mechanism – more stability

39
Q

Kinetic variables

A 
(causes of motion)
GRF
center of pressure
joint moment (torque)
joint power
40
Q

Foot kinematics at heel strike

A

vertical GRF = “M pattern/shape” of graph

spike in graph at IC = Heelstrike Transient

41
Q

Heelstrike transient

A

abnormal spike in graph at IC
coordination issue with IC of heel on ground, landing should be smooth. Knee is still in screwhome mechanism, so force from hitting ground will be transferred to knee

42
Q

Forces that control walking

A

gravity (BW)
air resistance
internal muscles forces
GRF

43
Q

GRF

A

normal component = vertical forces
shear component = AP and ML friction forces
direction of GRF changes during gait

44
Q

Vertical GRF

A

double peaks:
1st at heel strike (action of body momentum)
2nd peak at push off - contraction of calf muscle
these peaks are higher than BW because you are creating more force
IC = creating more force from ground. force is greater than BW to prevent COM from dropping

45
Q

peak value of vertical GRF

A

120% BW at peaks (push off and heel strike)

46
Q

When is the vertical GRF lower than your BW?

A

midstance - result of knee flexion

47
Q

AP GRF component

A

magnitude and direction of AP shear force depends on position of COM relative to location of foot
peak value = 20% BW
sufficient friction force btwn foot and ground is needed to prevent slipping
propulsive force of one limb is applied simultaneously to the braking force of the other limb when the weight is transferred from one limb to the other

48
Q

AP GRF

A

magnitude and direction of AP shear force depends on position of COM relative to foot location:

  • in the posterior direction at heel strike for slowing the progression of the body
  • in the anterior direction at toe off for propelling body forward
  • larger the step length = greater shear forces
49
Q

AP GRF during push off

A

during push off, tendency of motion is for foot to go backwards but friction applies force forwards (prevents slipping)
1st step = high positive on graph because you are gaining speed
to slow down you have to create more negative force than positive

50
Q

The magnitude of the ML shear force depends on the position of the COM relative to the foot:

A

lateral direction at heel strike
medial direction during rest of stance phase
larger step width = greater shear forces b/c of greater angle btwn LE and floor
peak value = 5% BW
wide variety depending on foot type
peak value will increase if BOS increases
medial force from ground helps transfer weight to opposite side during gait
ML = friction force

51
Q

Trajectory of COP during gait

A

at heel strike, COP is located lateral to midpoint of heel
mid stance, COP moves more laterally
from HO to TO, COP moves medially from MT heads to big toe
pronated foot = COP shifted over medially

52
Q

COP at LR

A

heel

53
Q

COP at mid stance

A

heel and midfoot

54
Q

COP at terminal stance

A

forefoot only

55
Q

COP at pre swing

A

medial forefoot

56
Q

Joint Moment at heel strike

A

at heel strike, the line of action of the GRF passes post to ankle joint, post to knee joint, and anterior to hip = ankle PF, knee flexion, hip flexion torques
to prevent collapse of LE, these external torques are counterbalanced by internal joint moments that are created by ankle DF’s, knee extensors, and hip extensors

57
Q

Internal moments do not: (2 things)

A
  1. do not indication the direction of motion
  2. do not indicate co-contraction of agonists and antagonists
    a muscle being active doesn’t mean the joint will move in that direction of contraction
58
Q

Joint moment notes

A

at IC we have PF torque, but TA is active
at knee = external flexion torque, but quads are active
muscles create internal torques/moments to counter GRFs
GRFs create external torques on joints

59
Q

Torque + motion = ?

A

joint power

60
Q

Definition of joint power

A

the rate of work performed by controlling muscles

the product of the net joint moment and the joint angular velocity

61
Q

significance of joint power

A

indicating the net rate of generating or absorbing energy by all muscles and other connective tissues crossing the joint
- positive value = power generation = concentric contraction
- negative value = power absorption = eccentric
motion and torque can be in the same or opposite directions

62
Q

First rocker occurs when during the gait cycle?

A

IC thru LR

63
Q

first rocker fulcrum

A

fulcrum = heel - DF moment

PF controlled by DF muscles to counter balance the PF torque of GRF

64
Q

second rocker occurs when?

A

mid stance

65
Q

fulcrum of second rocker?

A

fulcrum = ankle - PF moment
DF controlled by PF muscles to counter balance DF torque of GRF
rotation around ankle joint (fulcrum)

66
Q

third rocker occurs when?

A

terminal stance

67
Q

third rocker fulcrum

A

fulcrum = MT heads - PF moment
PF produced by PF muscles
heel rotates around MT heads
occurs from RHO to LIC

68
Q

Limitations of Kinematic data

A

kinematics can mislead w/ respect to determining how motion is coordinated by the muscles groups that created the motion (sprinter example)

69
Q

Hip joint power peak at mid stance

A

extensor generation of power during mid stance

70
Q

hip joint power peak at terminal stance

A

flexor absorption of power

71
Q

hip joint power peak pre swing

A

flexor generation of power during pre swing

72
Q

hip joint power peak loading response

A

abductor absorption of power during loading response

73
Q

Knee joint power peak LR

A

extensor absorption of power during LR

74
Q

knee joint power peak pre swing

A

extensor absorption of power during pre swing

75
Q

Ankle power peak LR

A

DF absorption of power during LR

76
Q

ankle power peak terminal stance

A

PF absorption of power during terminal stance

77
Q

ankle power peak pre swing

A

PF generation of power during pre swing

Semester 2 FS Exam 10 (2 decks)

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