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Biomechanics > Exam 1: Hard Tissue and Cartilage > Flashcards

Exam 1: Hard Tissue and Cartilage Flashcards

1
Q

One of the most dynamic and metabolically active tissues

A

Bone

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2
Q

Bone remains active throughout

A

Life

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3
Q

Bone is highly ___ which means it has excellent capacity for ____

A

Vascular; self-repair

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4
Q

Bone can also alter its properties/configuration to respond/adapt to

A

Changes in mechanical demand

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5
Q

Examples of changes in bone properties

A

Bone density changes due to disuse

Shape changes during fracture/surgical healing

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6
Q

Cortical bone is ____ whereas trabecular bone is ____

A

Stiffer/brittle; tougher

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7
Q

Bone is anisotropic which means that it exhibits distinct mechanical properties when

A

Loaded along various axes

Because its structure differs in transverse and longitudinal directions

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8
Q

Cortical bone can withstand greater stress in ___ > ___ > ___

A

Compression > tension > shear

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9
Q

Cortical bone can tolerate _____ > ____

A

Longitudinal loads > transverse loads

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10
Q

Bone fractures can be produced by

A

Single load — exceeds ultimate strength

Repeated lower-magnitude loads

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11
Q

Wolff’s Law

A

Bone has ability to remodel to meet mechanical demands placed on it

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12
Q

Bone remodeling is due to _____ NOT ____

A

Responses to forces; degeneration

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13
Q

Bone is ____ when not needed

A

Resorbed

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14
Q

Load/demand can be placed on bone by _____ leading to _____

A

Muscle activity or gravity; bone deposition

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15
Q

Cartilage is essentially _____

A

Nonvascular

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16
Q

Cartilage is composed of

A

Collagen, chondrocytes and ground substance

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17
Q

3 types of cartilage

A

Articular
Hyaline
Fibrocartilage

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18
Q

Articular cartilage is ____ and subject to ______

A

Viscoelastic; creep and relaxation

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19
Q

During joint articulation, forces at the joint surface vary from

A

0 to >10x body weight

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20
Q

Cartilage is nearly ____ which is unlike any man-made material

A

Frictionless

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21
Q

Interfacial wear is caused by either

A

Adhesion or abrasion

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22
Q

Fatigue wear is caused by

A

Repetition of high loads over short period

Repetition of low loads over extended period

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23
Q

Articular cartilage has only limited capacity for

A

Repair and regeneration

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24
Q

The magnitude of stress sustained by articular cartilage is determined by

A

Total load and how it is distributed over articular surface contact area

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25
Q

Any intense stress concentration will play primary role in

A

Tissue degeneration

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26
Q

How many IVD in an adult

A

23 (numeric name for segment above)

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27
Q

Discs constitute ____% of entire height of vertebral column

A

20-33%

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28
Q

3 parts of the disc

A

Nucleus pulposus
Annulus fibrosus
Cartilaginous end plates

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29
Q

Disc to VB ratio

A

Height of IVD compared to height of VB

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30
Q

Greater disc:VB ratio means

A

Greater spinal segmental mobility

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31
Q

Disc:VB ratio is greatest in ____ spine

A

Cervical (2:5)

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32
Q

Disc:VB ratio is least in the ____ spine

A

Thoracic (1:5)

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33
Q

Disc:VB ratio in lumbar spine

A

1:3

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34
Q

Nucleus pulposus is a _____ with fine fibrous strands

A

Mucoprotein gel

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35
Q

Nucleus pulposus is ____% water

A

70-90%

  • 90 at birth
  • 80 at 20yrs
  • 70 old age
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36
Q

Bigger discs have ___ capacity to change size

A

More, because of creep

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37
Q

Lumbar nuclei fill ___% of total disc area and are located ____

A

30-50%; located more posterior

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38
Q

Cervical annulus is minimal on _____ and only a ____ in back

A

Lateral borders (uncinates reinforce)

Thin strip in back

39
Q

Annulus fibrosus is fibrous tissue in _____

A

Concentric laminated bands

40
Q

Concentric laminated bands appear to cross obliquely to each other at an angle of _____ to VB

A

30 degrees

41
Q

Annular fibers are firmly attached to _____

A

Cartilaginous endplates in inner zone

42
Q

Peripheral zone fibers attach to VB via

A

Sharpey’s fibers

43
Q

____ and ___ reinforce annular fibers

A

ALL and PLL

44
Q

The PLL ____ from cervicals to lumbars, only covering ___% of central portion of lower lumbar discs

A

Narrows; 50%

45
Q

Weakest area of annulus

A

Posterolateral aspect

46
Q

Most likely spot for disc herniation in lumbar spine

A

Posterolateral aspect

47
Q

Outer portion of cartilaginous end plate is ____

A

Impermeable

48
Q

Diffusion of nutrient occurs in ___ portion of cartilaginous end plate

A

Central

49
Q

The end plate supplies ____ with most or all of its nutrition

A

Nucleus pulposus

50
Q

How many blood vessels go directly to disc

A

NONE

51
Q

Annular fibers get blood supply from

A

Adjacent soft tissues

52
Q

Nucleus pulposus get blood supply from

A

VBs

53
Q

IVD is an ______ and _____ tissue which means it undergoes rapid degeneration and has limited _____

A

Avascular; aneural; self repair

54
Q

During degeneration discs become _____ and _____

A

Vascularized and innervated by sensory fibers

55
Q

Overnight what happens to disc

A

Fluid volume inc

Disc expands

56
Q

Result of disc expansion overnight

A

Inc resistance to forces

57
Q

During the daytime fluid exits the disc which lead to ___ tension of ligs and ___ ROM

A

Dec tension; inc ROM

**lumbar flexion inc up to 50%

58
Q

_____ of nucleus pulposus results in ____ of annular fibers

A

Compression; tension

59
Q

Flexion results in compression of ____ and tension on ____

A

Anterior disc; posterior disc

60
Q

With age and biomechanical stress exposure chemical nature of disc changes to

A

Become more fibrous

61
Q

As a result of disc becoming more fibrous ______ is diminished

A

Flexibility

62
Q

And injured disc ___ more than a healthy

A

Deforms

63
Q

Hysteresis is the

A

Absorption or dissipation of energy by a distorted structure

64
Q

Hysteresis varies with

A

Age
Level
Repetitive load

65
Q

Relation to level and hysteresis

A

Less in lower T and upper L

66
Q

Hysteresis ____ when successively loaded

A

Decreases

67
Q

Nucleus resists _____ forces and pushes out against _____

A

Compressive; annular fibers

68
Q

Annular fibers resist ___ forces

A

Tensile

69
Q

3 types of loads imposed on the disc

A

Compressive
Tensile
Shear

70
Q

Examples of compressive loads

A 
Gravity
Muscle co-contraction
Flexion
Extension
Lateral bend
71
Q

Examples of tensile stresses

A

Flexion
Extension
Lateral bend
Traction

72
Q

Examples of shear stresses

A

Axial rotation of torso
A — P
L — R

73
Q

The disc is more susceptible to failure in area of _____ not ____

A

Tension; compression

74
Q

Mechanical failure occurs first in ______ and causes _____

A

Cartilaginous endplate; nuclear herniation

75
Q

Nuclear herniation AKA

A

Schmorl’s node

76
Q

Compressive loads in extension are transmitted through the ____ leading to ___

A

Facets; capsular injuries

77
Q

Compressive loads applied with torque can produce

A

Circumferential tears in annular fibers of IVD

78
Q

90% of resistance to torque of a motion segment is provided by

A

IVDs

79
Q

____ provides majority of torsional resistance

A

Annulus

80
Q

Axial rotation can strain the annulus in torsion but ______ protect it

A

Zygapophyseal joints

81
Q

Biomechanical behavior is dependent upon

A

State of degeneration

82
Q

State of degeneration is dependent upon ____

A

Age of the disc

83
Q

Most degenerated segments in spine

A

L3/L4
L4/L5
L5/S1

84
Q

4 stages/types of disc herniation

A

Nuclear herniation
Bulge/prolapse
Extrusion
Sequestration

85
Q

Nuclear herniation

A

Nucleus pulposus migrates outward

Stays within confines of IVD

86
Q

Bulge/prolapse

A

Migration outside confines of IVD but NO rupture of outer annular fibers

87
Q

Extrusion

A

Outer annular fibers tear, nucleus pulposus move into epidural space

88
Q

Sequestration

A

Discal fragments break loose from IVD, float freely in CSF

89
Q

Disc herniation usually occurs w/ full flexion or lateral bending because of

A

Excessive forces through PLL

90
Q

________ also associated w/ disc herniation

A

Repeated loading

91
Q

Common postural habits that inc lumbar flexion

A

Crossing legs
Squatting down on heels
Lifting light weights
Rapid lunging

92
Q

Contraindication to adjust patient w/ herniated disc?

A

NO

93
Q

Adjunct treatment option for disc herniation

A

Axial traction
- 70-85% effective

McKenzie extension

Biomechanics (15 decks)

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