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PHTH 517 > BIOMECHANICS 2 > Flashcards

BIOMECHANICS 2 Flashcards

1
Q

sit to stand is a good test of what 3 things

A
  • muscle strength
  • joint range of motion
  • balance
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2
Q

4 types of linear forces

A
  • compression
  • tension/distraction
  • shear
  • torsion
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3
Q

will compression ever generate rotation? why?

A

no - its moment arm is acting right through the joint axis

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4
Q

Shear force is always _____

A

perpendicular

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5
Q

Muscles generate forces along…

A

their muscle bodies

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6
Q

What dictates relative compression/tension/shear

A

angle of insertion

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7
Q

moments cause ____due to _____ when once end of a linkage is fixed

A

angular rotation

linear force production

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8
Q

define angular rotations

A

kinematic movements occurring about cardinal planes of movement

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9
Q

What is the moment arm for compression forces

A

0

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10
Q

Linear force exerted at a distance from an axis of rotation generates a tendency to rotate. How that results in motion depends on ____-

A

its inertia

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11
Q

What is the key determinant of moment magnitude

A

joint angle

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12
Q

The effect of joint angle on moment is ____ and ___ specific

A

joint and direction

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13
Q

Force of gravity acting through center of mass creates a moment tending to ….

A

drop pelvis towards contralateral side

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14
Q

What is the glute med role in pelvis alignment when walking

A

rotate pelvis counterclockwise (reverse OI), without this action you get pelvis drop towards opposite side

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15
Q

What is knee osteoarthritis

A

Degenerative disease affecting the whole joint

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16
Q

What is external knee adduction moment

A

every time you take a step force travels from foot through COM force does not travel through knee joint. resulting in moment arm and a tendency for the knee to rotate causing adduction of the tibia with respect tot the femur and compressing the medial compartment

17
Q

knee adduction moment correlates with…

A

implantable load measurements

18
Q

knee adduction moment is higher in OA or no-OA?

A

OA

19
Q

What is knee adduction moment related to

A

disease severity and symptoms

20
Q

what does knee adduction moment predict?

A

Tibial BMD
Disease progression
Treatment success

21
Q

What are physiotherapist implicantions to reduce the GRF causing the adduction moment at the knee

A
  • Body mass
  • Walking speed
  • Footwear
  • Shock absorbing insoles
  • Cane
  • Muscle strength
22
Q

What are the two external forces that contribute to moments

A
  • Gravity (limb weight)

- External forces (GRF)

23
Q

What are 4 things that internally contribute to moment

A
  • Muscle forces
  • Ligaments
  • Bone
  • Other soft tissue
24
Q

___% of load while walking goes through the medial compartment

A

80-85%

25
Q

Is the medial or lateral compartement of the knee more prone to OA ? why?

A

Medial - because 80-85% of load travels through it while walking

26
Q

What is the relationship between walking speed and GRF

A

faster you walk/run the greater the GRF

27
Q

How do you alter walking speed

A

by altering stride length, width, and cadence

28
Q

In what type of shoes do you have the highest adduction moment

A

high heels

29
Q

What was the result of wearing insoles in people with knee adduction moment

A

less pain following 1 month and reduce knee adduction moment

30
Q

What was the result of all the studies looking at increasing muscle strength to decrease knee adduction moment

A

following training programs there was no decrease in knee adduction moment and many even saw an increase. however there were improvements in pain and quality of life

31
Q

What are the physiotherapist implications for reducing moment arm in knee adduction moment cases

A
  • Alignment
  • Wedged insoles
  • Varus thrust
  • Foot position
  • Trunk position
32
Q

How is alignment altered in knee adduction moment cases

A
  • Use of a brace to try and realign lower limb

- Surgery - medial opening wedge

33
Q

What occurs in the medial opening wedge surgery

A

cut bone on medial side and take lower leg and swing it out lateralizing where foot is to promote more neutral aligment and then fill the space with bone graphs

34
Q

What does the lateral wedge insole do

A
  • Increase heigh on lateral aspect of foot
  • Realigns lower limb
  • Shock absorption
35
Q

What is the result of the lateral wedge insole

A
  • 6-8% decrease in knee adduction moment
36
Q

What is varus thrust

A

when you only have varus in dynamic situations - xrays appear normal

37
Q

How can you change foot position to change knee adduction moment. explain

A
  • Toeing out - changes the orientation of GRF force making it pass more laterally in knee joint and reduces size of moment arm
38
Q

How does changing trunk position lead to a reduction in the knee adduction moment - what is the consequence of doing this

A

Lean over stance limb brings COM closer to the knee and reduces the magnitude of the moment arm

  • Concern about hip and back in doing this
  • Clunky gait
  • Additional energy expenditure

PHTH 517 (10 decks)

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