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MSK - 2 - Biomechanics > Biomechanics of Gait and Posture > Flashcards

Biomechanics of Gait and Posture Flashcards

1
Q

Biomechanics

What is Human Gait?

Gait and Posture

A

The translatory progression of the human body as a whole, produced by coordinated, rotatory movements of the body segments.

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2
Q

Biomechanics

How does reactive postural control differ from anticipatory postural control?

Gait and Posture

A

Anticipatory postural control identifies a patterned stimulus to change posture and premptively contact muscles to eliminate or diminish unwanted movement.

Reactive postural control responds to unanticipated proprioceptive input (movement) caused by an external force.

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3
Q

Biomechanics

Why is a person likely to resprain an ankle after the initial injury?

Gait and Posture

A

Due to injury to mechanoreceptors, propioceptive data going to the brain is absent or delayed. Under normal conditions, these signals would reflexively contract muscles to protect the ankle.

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4
Q

Biomechanics

Describe the postural Ankle Strategy.

Gait and Posture

A

During small perturbations, the trunk stays in neutral and the following muscles contract:
Posterior displacement: TA, quadriceps, abdominals
Anterior displacement: gastroc, hamstrings, paraspinals

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5
Q

Biomechanics

Describe the postural Hip Strategy.

Gait and Posture

A

During larger perturbations, the hips shift opposite the direction of the potential fall and the following muscles contract:
Posterior displacement: abdominals, quadriceps, TA
Anterior displacement: paraspinals, hamstrings, gastroc.

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6
Q

Biomechanics

Discuss consequences of the following major postural deviation:
Flexed Knee Posture

Gait and Posture

A
  • External flexion moment at knee and hip
  • Increased quad force required leading to joint compression and increased soleus activity
  • Requires more energy
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7
Q

Biomechanics

Discuss consequences of the following major postural deviation:
Genu Recurvatum

Gait and Posture

A
  • External extensor moment
  • Lengthening of cruciate and posterior ligaments of knee
  • Anterior knee compression
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8
Q

Biomechanics

Discuss consequences of the following major postural deviation:
Anterior Pelvic Tilt

Gait and Posture

A
  • Increased lumbar lordosis
  • Icreased external extension moment
  • Degeneration at facets and narrowing of foramen
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9
Q

Biomechanics

Discuss consequences of the following major postural deviation:
Forward Head Posture and Excessive Thoracic Kyphosis

Gait and Posture

A
  • Increased lower cervical lordosis
  • Increased upper cervical extension
  • Degeneration at facets and narrowing of foramen
  • Decreased subacromial space
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10
Q

Biomechanics

What is a Gait Cycle?

Gait and Posture

A

The interval of two consecutive initial contacts of the same foot.

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11
Q

Biomechanics

What is Stride Length?

Gait and Posture

A

The distance covered by one gait cycle
(144cm or 56in)

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12
Q

Biomechanics

What is Stride Duration?

Gait and Posture

A

Amount of time spent to complete one gait cycle.
(1.07s)

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13
Q

Biomechanics

What is Step Length?

Gait and Posture

A

Linear distance between two successive stepping point of opposite extremities.
(72cm or 28in)

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14
Q

Biomechanics

What is Step Width?

Gait and Posture

A

The measure of linear distance between paralel lines intersecting the mid-points of the heel on each foot
(8-10cm or 3.5in)

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15
Q

Biomechanics

What is Cadence?

Gait and Posture

A

Cadence is the number of steps per minute.
(108-118 steps/min)

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16
Q

Biomechanics

What is the Degree of Toe-out?

Gait and Posture

A

It is the angle of foot placement at loading respnse
(7°)

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17
Q

Biomechanics

What is toe clearance?

Gait and Posture

A

The distance between hallux and floor in swing phase.
(1.28-1.9 cm)

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18
Q

Biomechanics

What is gait speed?

Gait and Posture

A

The distance covered per unit of time - typically meters/second or miles/hour.
(1.3-1.4 meters/second)
(2.7-3.1 miles/hour)

19
Q

Biomechanics

What can gait speed predict?

Gait and Posture

A
20
Q

Biomechanics

At what speed does walking usually turn into running ?

Gait and Posture

A

The transition from walking to running is regulated by energy expenditure. The preferred transition occurs around the same point as when running becomes more economical than walking.
(4.5-4.8 mph)

21
Q

Biomechanics

What is base of support?

Gait and Posture

A

The area that bounds the outermost regions of contact between a body and the support surface

22
Q

Biomechanics

What is the Center of Pressure? (CoP)

Gait and Posture

A

The point at which most of the body weight is acting on the foot.

23
Q

Biomechanics

What are ways to increase stabilty?

Gait and Posture

A

1) Increasing body mass
2) Increasing friction between the body and the surfaces of contact
3) Increasing the size of the base of support
4) Vertically positioning the center of mass as low as possible

24
Q

Biomechanics

What are the phases of a gait cycle?

Gait and Posture

A

Stance phase - 60% | Swing phase - 40%

25
Q

Biomechanics

What are the five periods of stance phase?

Gait and Posture

A

1) Initial Contact (Heel Strike)
2) Loading Response (Foot Flat)
3) Midstance
4) Terminal Stance (Heel-off)
5) Pre-Swing (Toe-off)

26
Q

Biomechanics

What are the three periods of swing phase?

Gait and Posture

A

1) Initial Swing
2) Mid-swing
3) Terminal Swing

27
Q

Biomechanics

Define the first period of gait.
Initial Contact

Gait and Posture

A

The first period is defined as the instant the foot contacts the ground

28
Q

Biomechanics

Define the second period of gait:
Loading Response

Gait and Posture

A

The second period of gait begins with foot contact and will end with opposite limb toe-off

29
Q

Biomechanics

Define the third period of gait:
Mid-stance

Gait and Posture

A

The third period of gait begins with opposite limb toe off and ends with ipsilateral heel rise

30
Q

Biomechanics

Define the fourth period of gait:
Terminal Stance

Gait and Posture

A

The fourth period of gait begins with ipsilateral heel rise and ends with opposite limb foot contact

31
Q

Biomechanics

Define the fifth period of gait:
Pre-swing

Gait and Posture

A

The fifth period of gait begins with opposite limb foot contact and ends with ipsilateral toe off

32
Q

Biomechanics

Define the sixth period of gait:
Initial Swing

Gait and Posture

A

The sixth period of gait begins with ipsilateral toe off and ends when the medial malleoli are aligned

33
Q

Biomechanics

Define the seventh period of gait:
Mid-swing

Gait and Posture

A

The seventh phase of gait begins with the medial malleoli aligned and ends when the ipsilateral tibia is perpendicular to the ground.

34
Q

Biomechanics

Define the eighth period of gait:
Terminal Swing

Gait and Posture

A

The eighth and final phase of gait begins with the tibia perpendicular to the floor and ends when the ipsilateral foot strikes the floor.

35
Q

Biomechanics

Explain the difference between external and internal moments in gait.

Gait and Posture

A

External moments are created when the line of gravity passes at a distance from the axis of rotation. An internal moment must be muscularly created to counteract this motion.

36
Q

Biomechanics

For each period give the GRF, external moment direction, and muscle activity at each major lower body joint:
Initial Contact

Gait and Posture

A

HIP:
GRF: anterior
EM: flexion moment
Muscle: Hip Extensors

KNEE JOINT:
GRF: anterior
EM: Extension
Muscle: Quads

ANKLE JOINT:
GRF: posterior
EM: plantar flexion
Muscle: dorsiflexors

37
Q

Biomechanics

For each period give the GRF, external moment direction, and muscle activity at each major lower body joint:
Loading Response

Gait and Posture

A

HIP:
GRF: anterior
EM: flexion
Muscle: Hip Extensors

KNEE JOINT:
GRF: posterior
EM: flexion
muscle: Quads

ANKLE JOINT:
GRF: posterior
EM: PF
Muscle: dorsiflexors

38
Q

Biomechanics

For each period give the GRF, external moment direction, and muscle activity at each major lower body joint:
Midstance

Gait and Posture

A

HIP:
GRF: anterior to posterior
EM: flexion to extension
Muscle: Only extensors during flexion moment

KNEE JOINT:
GRF: posterior to anterior
EM: flexion to extension
Muscle: Only quads during flexion moment

ANKLE JOINT:
GRF: anterior
EM: DF
Muscle: Plantar flexors

39
Q

Biomechanics

For each period give the GRF, external moment direction, and muscle activity at each major lower body joint:
Terminal Stance

Gait and Posture

A

HIP:
GRF: posterior
EM: Extension
Muscle: none

KNEE JOINT:
GRF: anterior then moves posterior before contralateral initial contact
EM: extension to flexion before contralateral initial contact
Muscle: No muscle activity

ANKLE JOINT:
GRF: anterior
EM: DF
Muscle: plantar flexors

40
Q

Biomechanics

For each period give the GRF, external moment direction, and muscle activity at each major lower body joint:
Pre-swing

Gait and Posture

A

HIP:
GRF: posterior
EM: Decreasing extension secondary to knee flexion
Muscle: adductor longus and rectus femoris

KNEE JOINT:
GRF: posterior
EM: flexion
M: Rectus Femoris

ANKLE JOINT:
GRF: anterior
EM: DF
M: Elastic recoil of plantar flexors

41
Q

Biomechanics

For the following rockers give the period of gait, GRF involved, and active or passive structures involved:
1st Ankle Rocker - Heel

Gait and Posture

A

Period: IC- LR
GRF: posterior PF
Structures: pretibials control PF

42
Q

Biomechanics

For the following rockers give the period of gait, GRF involved, and active or passive structures involved:
2nd Ankle Rocker - Ankle

Gait and Posture

A

Period: LR- TS
GRF: anterior DF
Structures: PF’s eccentrically control DF

43
Q

Biomechanics

For the following rockers give the period of gait, GRF involved, and active or passive structures involved:
3rd Ankle Rocker - Forefoot & Toe

Gait and Posture

A

Period: TS-PreSw
GRF: anterior DF
Structures: PF stretch-shortening cycle

44
Q

Biomechanics

Compare gait differences between a young child and an older adult.

Gait and Posture

A

Child: short steps, uneven step length, Initial contact with flat foot, decreased stride length and cadence, no reverse pendulum

Older adult: decreased velocity, strides, and step length, wide BoS, may need AD

MSK - 2 - Biomechanics (16 decks)

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