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USA Term 2 > Biomechanics *Gait/Balance/Posture* > Flashcards

Biomechanics *Gait/Balance/Posture* Flashcards

1
Q

What is Step Depth?

A

The distance between successive heel contacts of the two different feet

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2
Q

What is Stride length?

A

The distance between two successive heel contacts of the same foot

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3
Q

What is Step Width?

A

The lateral distance between the heel centers of two consecutive foot contacts and is on average around 8-10 cm

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4
Q

What is Foot Angle?

A

The amount of “Toe-Out”, is the angle between the line of progression of the body and the long axis of the foot

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5
Q

What is normal walking speed?

A

1.37 m/sec (3 mph)

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6
Q

What is normal step rate?

A

1.87 steps/sec (110 steps/min)

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7
Q

What is normal step length?

A

72 cm (28in)

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8
Q

What are the two major systems in gait?

A

Traditional vs. Rancho Los Amigos (RLA)

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9
Q

Unless noted otherwise, which leg starts the gait cycle?

A

The gait cycle begins at Right heel strike (initial contact) and ends with the next R heel strike (Initial contact)

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10
Q

Why is the RLA system preferred in research then the traditional?

A

The phases of gait (Except for initial contact) are durations of time, not points in time

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11
Q

What is the Percent of Cycle in the Heel Strike (Initial Contact) phase?

In the () is RLA, outside is Traditional

A

0%

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12
Q

What is the Percent of Cycle in the Heel Strike to Foot Flat (Loading Response) Phase?

In the () is RLA, outside is Traditional

A

0 - 10%

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13
Q

What is the Percent of Cycle in the Foot Flat to Midstance (Midstance) Phase?

In the () is RLA, outside is Traditional

A

10 - 30%

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14
Q

What is the Percent of Cycle in Midstance to Heel Off (Terminal Stance) Phase?

In the () is RLA, outside is Traditional

A

30 - 50%

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15
Q

What is the Percent of Cycle in the Heel Off to Toe Off (Pre-Swing) Phase?

In the () is RLA, outside is Traditional

A

50 - 60%

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16
Q

What is the Percent of Cycle in the Early Swing (Initial Swing) Phase?

In the () is RLA, outside is Traditional

A

60 - 75%

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17
Q

What is the Percent of Cycle in the Midswing Phase?

A

75 - 85%

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18
Q

What is the Percent of Cycle in the Late Swing (Terminal Swing) Phase?

In the () is RLA, outside is Traditional

A

85 - 100%

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19
Q

What is the kinematic analysis for the hip? (In terms of Hip joint motion in degrees and phases of gait)

A
  • In Initial contact the hip is flexed (0% gait cycle)
  • The hip extends from 10-50% gait cycle (heel off)
  • Flexes from 50-85% gait cycle
  • Stays flexed from 85-100% gait cycle
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20
Q

What is the kinematic analysis for the Knee? (In terms of Knee joint motion in degrees and phases of gait)

A
  • Knee is extended in Initial contact
  • Knee flexes till 15% of gait cycle
  • Extends till 40% of gait cycle
  • Flexes till 75% of gait cycle
  • Extends till 0% of gait cycle
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21
Q

What is the kinematic analysis for the ankle? (In terms of ankle joint motion in degrees and phases of gait)

A
  • Neutral at 0% gait cycle
  • Plan. Flexed till 10% gait cycle
  • Dorsi. Flexed till 50% gait cycle
  • Plan. Flexed till 65% gait cycle
  • Dorsi. Flexed till 80% gait cycle
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22
Q

How do the does muscle activity work by group?

A
  • Concentric contractions generate power
  • Eccentric contractions absorb power
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23
Q

When are the Hip Extensors activated in gait?

A
  • Concentric in early stance (Hip extension) for propulsion (0-50%, then 85-100%)
  • Slight eccentric activation at terminal swing for deceleration (50-85%)
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24
Q

When are the Hip Flexors activated in gait?

A
  • Firstly, Eccentric control of hip extension, after midstance (0-50%, then 85-100%)
  • Then Concentric to flex hip at toe off (50-85%)
  • Concentric during first half of swing
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25
Q

When are the Hip Abductors activated in gait?

A
  • Eccentric on Initial contact to decelerate lower pelvis (BW) on same side (0-15%)
  • Then concentric to move BW up and help extend hip. Remains active for first 40% cycle to control pelvis.
    (15-65%)
  • 65-100% eccentric
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26
Q

When are the Hip Adductors activated in gait?

A
  • Hip adductors stabilize hip through co-contraction with abductors
  • May assist with hip extension at beginning of cycle, and with flexion after toe off

0-15%, then 65-100% Concentric

15-65% Eccentric

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27
Q

When are the Knee Extensors activated in gait?

A
  • Upon contact, eccentric to control slight degree of knee flexion in the first 10% (~0-10%)(Then eccentric ~40-85%)
  • Then concentric to extend knee to midstance (~10-40%)
  • Finally concentric to flex hip at toe off (~85-95%)
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28
Q

When are the Knee Flexors activated in gait?

A
  • Concentric in early stance (Hip extension)
  • May assist with knee flexion in swing (Keep leg up, early swing phase)
  • Eccentric at the knee in preparation for heel contact
    (Terminal Swing Phase)

Concentric at (0-15%, then 40-80%)
Eccentric at (15-40%, then 80-100%)

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29
Q

When are the Plantar Flexors activated in gait?

A
  • Active during most of stance except for first 10%
  • From 10% to heel off, eccentric control of Dors. Flexors
  • Concentric at push off (Between heel off and toe off)

Concentric at (0-10%, then 45-65%, then again at 85-95%)
Eccentric at (10-45%, then 65-85%, then again at 95- 100%)

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30
Q

When are the Dorsi Flexors activated during gait?

A
  • Strong eccentric at heel contact to avoid “Foot slap”
  • From heel contact to foot flat, eccentric deceleration of foot pronation
  • Concentric in swing to clear foot from ground
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31
Q

In gait, if there is an impairment of the ankle plantar flexion contracture, what would be the compensation?

A
  • Knee hyperextension (mid-stance)(Ipsilateral side) : Forward trunk lean (terminal stance)
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32
Q

In gait, if the patient has foot drop, what would be the compensation?

A

Excessive knee and hip flexion on ipsilateral side

33
Q

In gait, if the patient has reduced knee flexion, what would be the compensation?

A

Vaulting of contralateral ankle

34
Q

In gait, if there is an impairment of the knee flexion contracture, what would be the compensation?

A

Exaggerated knee and hip flexion of contralateral limb

35
Q

In gait, if the patient has reduced knee flexion and/or lack of ankle dorsiflexion, what would be the compensation?

A

Hip circumduction

36
Q

In gait, what would happens if the hip extensors are weak?

A
  • There will be a posterior trunk lean in early stance
  • Moves GRF (Ground Reaction Force) posterior to hip joint
37
Q

In gait, what would happen if the hip flexors are weak?

A
  • There would be rapid hip extension in stance
  • Circumduction during swing
38
Q

In gait, what would happen if the hip abductors are weak?

A
  • Contralateral pelvic drop or lateral lean during stance
39
Q

In gait, what would happen if the hip adductors are weak?

A
  • They become flexors when the hip is extended
  • They become extensors when the hip is flexed
  • They may demonstrate some combination of gait deviations typical of hip flexors and/or extensors
40
Q

In gait, what would happen if the knee extensors are weak?

A

No knee flexion during loading response

41
Q

In gait, what would happed if the knee flexors are weak?

A

There would be rapid knee extension during terminal swing (whip)

42
Q

In gait, what would happed if the Plantar Flexors are weak?

A

There would be a “Roll-off” instead of push off

43
Q

In gait, what would happen if the Dorsi Flexors are weak?

A

-initial contact with foot flat or foot slap during loading response
- Excessive hip and knee flexion during swing

44
Q

What is the Operational Definition of Posture?

A

Relative position of segments

  • Relative advantages and disadvantages
45
Q

What is the Operational Definition of Stability? What is Static Stability?

A

Defined as resistance to change in state

  • Balance is the ability to maintain an upright posture by keeping the Center Of Mass (COM) above the BOS
  • Sometimes called Static Stability

Static Stability is when the line of gravity falls within the BOS

46
Q

What is Line of gravity?

A

Force vector of gravity
- Always vertical in a static model

47
Q

What is BOS?

A

A polygon formed by the most peripheral contact points of the body with the ground

48
Q

What is Center Of Pressure (COP)?

A
  • The average location of foot to floor forces
  • The point of contact between the GFR and the ground
49
Q

How can a cane increase Static stability?

A
  • Increase size of BOS
  • Increase “Margin of stability”
    (The distance from COP to nearest edge of BOS)
50
Q

How can a cane decrease stability?

A
  • Might be used incorrectly; if provides no help if its pulled not pushed
  • Increases computational load; may result in deterioration of motor control
51
Q

What are the components of neurological system for balance? (3)

A
  1. Visual
  2. Vestibular
  3. Sensory-Motor
52
Q

What is the difference between Feed-Forward vs. Feed-Back?

A

Feed-Forward: Is based on previous learning
- Basis for ‘anticipatory’ strategies

Feed-Back: Is based on current sensations
- Basis for ‘reactive strategies’

53
Q

For Posture and Balance, Feed-back control of balance requires 3 steps, what are the steps?

A
  1. Sensing
  2. Processing
  3. Responding
54
Q

What takes part in the ‘Sensing’ step for Feedback control of balance?

A
  • Sensors-Mechanoreceptors (proprioceptors): Joint capsules and ligaments, muscles, skin (especially feet), and fastest subsystem to respond
  • Sensors-Vision: Relationship to surface geometry, head position, reports to visual cortex
  • Sensors-Vestibular:Orientation of the head, coordinates with visual system, reports to cerebellum
55
Q

What takes part in the ‘Processor’ step for Feedback control of balance?

A
  • CNS
  • Though experiment
    “Walking while chewing gum”
56
Q

What takes part in the ‘Responding’ step for Feedback control of balance?

A
  • Muscle activation
    (This is dependent of ROM, strength, joint structure and function)
    (Often impaired by: pain and inflammation)
57
Q

What are Perturbations? What are strategies to respond to perturbations?

A

Perturbations are sudden mechanical changes threatening stability

(Stratagies)
- Proactive (anticipatory)
Feedforward Control

  • Reactive
    Feedback Control
58
Q

As perturbations become greater, what is the feedback based strategy?

A

In approximate order:
- Fixed BOS: Ankle strategy and Hip strategy

  • Changing BOS: Stepping and Grasping
  • Changing Height of COM: Squatting

*Feedback strategies are automatic in people free of impairments

59
Q

What is the Romberg’s Test? What are the different variations of Romberg’s? What is used to assess this test?

A
  • Checking balance in bilateral stance with eyes closed for 1 min.

variations:
- Tandem (1 foot in front of the other)
- Single limb
- With perturbations
- With and without vision
- With and without proprioception

  • Force Plate
60
Q

What is the difference between Static Posture and Dynamic Posture?

A

Static posture is the condition of staying in the same posture or position for extended periods

Dynamic posture for examples is walking and running

61
Q

Ideal Posture is considered ideal because it is optimized for what?

A
  • Minimal muscle force
  • Minimal stress on joints and CT
  • Maximal stability
62
Q

If a person is sitting slumped, what happens to their LOG relative to the axes of rotation?

A

In the slumped position, the LOG is relatively distant from the axes of rotation of the head, neck and trunk

63
Q

What would anyone choose less than idea posture?

A
  • Atypical bony shape
  • Pain avoidance (antalgic posture)
  • Weakness
  • LOM
  • Difficulty maintaining balance
  • Psycho-social issues
64
Q

What is Ideal standing Posture?

A

(Sagittal Plane)
- Location of the combined action line formed by the ground reaction force vector (GRF) and line of gravity (LoG) in the optimal standing posture

  • The location of the LOG relative to
    Apex of spinal curves and Joint centers
  • Minimal Distance of LOG
    (Minimal moment arm length and minimal external moment.)
65
Q

What is External Moment?

A

This is due to gravity re-counteracted via internal moments from ligaments or large muscles

66
Q

In terms of alignment is the sagittal plane of standing posture, what is the LOG, External moment, Passive Opposing forces and Active Opposing forces for the Atlanto-Occipital Joint?

A

LOG: Anterior
External Moment: Flexion
Passive Opposing forces: ligaments that limit flexion
Active opposing forces: Neck extensors

67
Q

In terms of alignment is the sagittal plane of standing posture, what is the LOG, External moment, Passive Opposing forces and Active Opposing forces for the Cervical spine?

A

LOG: Posterior
External Moment: Extension
Passive Opposing forces: ALL and lig. that limit Ext.
Active Opposing forces: Deep flexor muscles

68
Q

In terms of alignment is the sagittal plane of standing posture, what is the LOG, External moment, Passive Opposing forces and Active Opposing forces for the Thoracic spine?

A

LOG: Anterior
External Moment: Flexion
Passive Opposing forces: PLL, surpa and interspinous lig.
Active Opposing forces: Erector Spinae muscles

69
Q

In terms of alignment is the sagittal plane of standing posture, what is the LOG, External moment, Passive Opposing forces and Active Opposing forces for the Lumbar spine?

A

LOG: Posterior
External Moment: Extension
Passive Opposing forces: ALL and Iliolumbar lig
Active Opposing forces: Abdominal muscle (EO,IO,RA)

70
Q

In terms of alignment is the sagittal plane of standing posture, what is the LOG, External moment, Passive Opposing forces and Active Opposing forces for the Sacroiliac Joint?

A

LOG: Anterior
External Moment: Nutation
Passive Opposing forces: Sacrotub. and spinous, iliolumbar and ant. SI lig.
Active Opposing forces: Transverse abdominis

71
Q

In terms of alignment is the sagittal plane of standing posture, what is the LOG, External moment, Passive Opposing forces and Active Opposing forces for the Hip Joint?

A

LOG: Posterior
External Moment: Extension
Passive Opposing forces: Iliofemoral lig
Active Opposing forces: Iliopsoas

72
Q

In terms of alignment is the sagittal plane of standing posture, what is the LOG, External moment, Passive Opposing forces and Active Opposing forces for the Knee Joint?

A

LOG: Anterior
External Moment: Extension
Passive Opposing forces: Posterior joint capsule
Active Opposing forces: Hamstrings, gastroc

73
Q

In terms of alignment is the sagittal plane of standing posture, what is the LOG, External moment, Passive Opposing forces and Active Opposing forces for the Ankle Joint?

A

LOG: Anterior
External Moment: Dorsiflexion
Passive Opposing forces: n/a
Active Opposing forces: Soleus and gastroc

74
Q

In terms of alignment, what are some possible effects of an Excessive Anterior Pelvic Tilt Deviation? (Compression, Distraction, Stretching, and shortening)

A

Compression: Posterior aspect of vertebral bodies
Distraction: Lumbosacral angle increased; shearing at L5-S1
Stretching: Abdominal muscles
Shortening: Iliopsoas, lumbar extensors

75
Q

In terms of alignment, what are some possible effects of an Excessive Lumbar Lordosis Deviation? (Compression, Distraction, Stretching, and shortening)

A

Compression: Posterior vertebral bodies and facet jts.
Distraction: Anterior Annulus fibers
Stretching: ALL
Shortening: PLL and interspinous lig.

76
Q

In terms of alignment, what are some possible effects of an Excessive Dorsal Kyphosis Deviation? (Compression, Distraction, Stretching, and shortening)

A

Compression: Anterior vertebral bodies
Distraction: Facet joint capsules and posterior annulus fibers
Stretching: Dorsal back extensors, posterior ligaments
Shortening: ALL, upper abdominal muscles

77
Q

In terms of alignment, what are some possible effects of an Excessive Cervical Lordosis Deviation? (Compression, Distraction, Stretching, and shortening)

A

Compression: Posterior vertebral bodies and facet jts.
Distraction: Anterior Annulus fibers
Stretching: ALL
Shortening: Posterior ligaments and Neck extensors

78
Q

What is Scoliosis?

A
  • Curvature of the spine in the frontal plane
    –Almost all deviations in the frontal plane result in or are caused by scoliosis
79
Q

What are the effects of a Longer lower extremity?

A

If its the right:

  • Right pelvic elevation
  • Increase in amount of lordosis and kyphosis
  • Scoliosis

USA Term 2 (45 decks)

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