Chapter 6 - Gait and Posture Analysis

Question 1

Main functions of Lower Kinetic Chain

Answer 1

• to provide a stable BOS in standing

- to propel body through space with gait (gait is controlled instability)

Question 2

What are the 3 essential requirements for gait?

Answer 2

1) Progression
2) Postural Control
3) Adaptation

Question 3

Progression

Answer 3

The “fall” that occurs at initiation of gait controlled by CNS, CNS computes in advanced the required size and direction of this fall

Question 4

Postural Control

Answer 4

Dynamically maintained to properly position the body for efficient gait

Question 5

Adaptation

Answer 5

Achieved by adjusting the central pattern to meet task and environmental demands

Question 6

Stance Phase

Answer 6

60-65% of gait cycle

Foot is in contact with ground and the limb is bearing weight

Question 7

Swing Phase

Answer 7

35-40% of gait cycle

Foot is not in contact with the ground

Question 8

Weight Acceptance

Answer 8

Initial contact and loading response (first 10% of gait cycle)
Double support at this time, both feet are on the floor

Question 9

Single Leg Support Intervals

Answer 9

Midstance, terminal stance, preswing

Question 10

Midstance

Answer 10

• first half of single-leg support

- begins as one foot is lifted and continues until the body weight is aligned over forefoot

Question 11

Terminal Stance

Answer 11

• second half of single-leg support

- begins with heel of weight-bearing foot lifting and continues until contralateral foot strikes ground

Question 12

Preswing

Answer 12

-begins with initial contact of contralateral limb and ends with ipsilateral toe-off

Question 13

Swing Phase Intervals

Answer 13

Initial swing, midswing, terminal swing

Question 14

What are the primary sources of motion during swing phase?

Answer 14

Gravity and momentum

Question 15

Initial Swing

Answer 15

-begins with lifting of the foot from the floor and ends when swinging foot is opposite the stance foot

Question 16

Midswing

Answer 16

-begins as swinging foot is opposite stance limb and ends when swinging foot is forward and the tibia is vertical

Question 17

Terminal Swing

Answer 17

-begins with vertical tibia of swing foot and ends the moment the foot strikes the floor

Question 18

Step Width

Answer 18

Distance between both feet, normally 5-10 cm (2-4 in). Forms BOS (COG must be over BOS for equilibrium)

Question 19

Step Length

Answer 19

Distance between point of initial contact of one foot and initial contact of other foot (average is 28 inches)

Question 20

Stride Length

Answer 20

Distance between successive points of foot to floor contact of same foot (step length + step length = stride length) normal is 56 inches

Question 21

Cadence

Answer 21

number of steps taken in a certain time (normal is 90-120/min)

Question 22

Velocity

Answer 22

Distance a body moves in a given time

V = d/t

Question 23

What causes the Vertical Ground Reaction Force?

Answer 23

• gravity
• body weight
• firmness of the ground

Question 24

Where does the Vertical Ground Reaction Force peak during gait?

Answer 24

1st = maximum limb loading during loading response
2nd = during terminal stance

Question 25

Why do women experience greater Ground Reaction Forces?

Answer 25

- shorter leg length than men (51.2% of body height vs 56%) - women must strike ground more often to cover same distance - women complete heel to toe gait in a shorter time than men

Question 26

Gait involves...

Answer 26

- displacement of body weight in desired direction | - coordinated effort between joints of the trunk/extremities and the muscles that control or produce these motions

Question 27

Five priorities for Normal Gait

Answer 27

1) Stability of weight bearing foot throughout stance phase 2) Clearance of NWB foot during swing phase 3) Appropriate prepositioning of foot during terminal swing 4) Adequate step length 5) Energy conservation

Question 28

How to ensure that energy is conserved during gait

Answer 28

* COG must undergo MINIMAL displacement - any displacement that elevates, depresses or moves COG beyond normal will waste energy - any abrupt/irregular movement will waste energy

Question 29

Six ways to reduce energy loss during gait

Answer 29

1) Lateral displacement of pelvis (1 to 2 inches) 2) Forward pelvic rotation on swing side 3) Vertical displacement of pelvis (no more than 2 inches) 4) Knee flexion in stance 5) Ankle mechanism (10 DF/20 PF) 6) Foot mechanism

Question 30

Explain how trunk, thoracic and lumbar spine, pelvis and shoulders rotate during gait

Answer 30

-trunk twists about vertical axis -t spine and pelvis rotate opposite -l spine and pelvis rotate together -shoulder and trunk rotate out of phase with each other (if arm swing prevented, upper trunk and pelvis rotate same way)

Question 31

What is the hips function during gait?

Answer 31

Extend the leg during stance phase | Flex the leg during swing phase

Question 32

When is the force on the hip the greatest?

Answer 32

Midstance

Question 33

What occurs at the hip during swing phase?

Answer 33

- adducts early in swing phase - 30-35 degrees of hip flexion in late swing phase - slight hip abduction at end of swing phase

Question 34

What occurs at the hip during normal stride?

Answer 34

rotates 40-45 degrees

Question 35

What occurs at the hip during toe-off?

Answer 35

10 degrees of extension

Question 36

What are the functions of the knee during gait?

Answer 36

- bear weight and absorb shock - reduce vertical displacement of the COG - maintain the stride length - allow the foot to move through its swing

Question 37

What motions occur at the knee during gait?

Answer 37

Loading Response = 20 flexion Terminal Stance = almost fully extended Swing Phase = flexes again Heel Strike = extends 60 degrees of motion required for clearance