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DPT Biomechanics > Biomechanical Properties and Behaviors of Bone > Flashcards

Biomechanical Properties and Behaviors of Bone Flashcards

1
Q

which bone can absorb a lot of energy (shock absorbing), more flexible

A

cancellous bone (trabecular, spongy)

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2
Q

What kind of force is cortical bone strongest in?

A

compression

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3
Q

which bone fails at low deformation

A

cortical bone

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4
Q

When is cortical bone weakest

A

shear

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5
Q

Which bone can sustain large deformation

A

cancellous

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6
Q

debonding of cement lines, microfracture

A

tension

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7
Q

cracking of osteons

A

compression

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8
Q

how do muscles attenuate tensile stress?

A

they produce counteractive compressive stress

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9
Q

muscle fatigue can lead to a _____ fracture

A

transverse

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10
Q

resorption of older bone and formation of new bone

A

remodeling

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11
Q

_____ of the body’s trabecular bone is remodeled each year

A

25%

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12
Q

younger bone is more ductile or brittle

A

ductile

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13
Q

higher loading speed results in more _____ behavior

A

brittle

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14
Q

regarding bending, stresses are higher ______ from the neutral axis

A

further

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15
Q

Where will the structure break in a 3 point bend

A

point of application

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16
Q

Where does the fracture begin in a 3 point bend

A

on the tensile side (weaker in tension than compression)

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17
Q

Where will the structure break in a 4 point bend?

A

weakest point

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18
Q

an oblique fracture will occur when there is _____ compression and _____ failure

A

high, slow

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19
Q

stiffness and load to failure increase with

A

loading rate (30% stronger during brisk walk than slow walk

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20
Q

comminuted or multiple fragment fracture usually occurs in what kind of an environment

A

high energy

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21
Q

with low repetitive forces, osteoclast activity ______ osteoblast activity, leaving no time for body to repair microdamage

A

outpaces

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22
Q

Bone responds to mechanical stresses by increasing/decreasing mass according to magnitudes and directions of forces that are applied

A

Wolff’s law

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23
Q

formation of new bone without resorption

A

modeling

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24
Q

resorption of older bone and formation of new bone (osteoclasts and osteoblasts)

A

remodeling

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25
Q

what contributes to bone hypertrophy or increase of mass

A

osteoblast

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26
Q

What are the three parts of the female athlete triad?

A

eating disorders, amenorrhea, osteoporosis

affects 1-10% of all adolescent and college age women

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27
Q

mineralization peaks at what ages for women and men respectively

A

25-28

30-35

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28
Q

What does higher mineralization (larger crystals) mean for older adults?

A

decreased plastic deformation and energy absorption

increased brittleness

29
Q

side effects of osteoporosis drugs

A

decreased toughness, increased microdamage accumulation

30
Q

Three most common fracture sites in the aging individual

A

femoral neck
radius/ulna
spine

31
Q

Which bone can transmit a lot of force, very strong in compression, and very stiff(does not deform much before fracturing)

A

cortical

32
Q

cancellous bone is able to deform a lot before it fractures. this is primarily due to its

A

high collagen content

33
Q

During isometric contractions the internal moment is ____ to the external moment

A

equal

34
Q

During concentric contractions the internal moment is ____ than the external moment

A

greater

35
Q

During eccentric contractions, internal moment is ____ than external moment

A

less

36
Q

in the biomechanical muscle model, the sarcomere and passive components (endo-, peri-, and epimysium)

A

are parallel

37
Q

The maximum torque generated by the hip abductors occurs when the muscles are in a ____ position which corresponds to the functional task of _____

A

lengthened, single leg stance phase of gait

38
Q

An important function of the acetabular labrum is

A

it deepens the acetabular cup for increased stability

39
Q

The right lower extremity posture that would be observed in a person who has a dramatic retroversion of the right hip? Anteversion?

A

duck foot, pigeon toe

40
Q

The right lower extremity position that would be observed in a person who has a dramatic coxa vara of the right hip would be

A

right genu valgum (knock kneed)

41
Q

a newborn has increased

A

coxa valga (150 degrees)

42
Q

T or F During 2-legged stance, the hip muscles are primarily responsible for stability of the coxafemoral joint

A

F - NO muscle activity is required to maintain upright, neutral posture at the hip, ligaments and joint capsule provide stability

43
Q

3 primary functions of the hip

A

1 support HAT
2 static erect postures
3 dynamic postures

44
Q

What is the loose (open) pack position of the hip

A

35 degrees flexion/abduction, slight external rotation

45
Q

What is the closed packed position of the hip

A

maximum extension/int rot/abduction

46
Q

What are the two articulating surfaces of the hip

A

acetabulum of Os Coxae and head of Femur

47
Q

Which ligament of the hip is known as the Y

A

iliofemoral (anterior)
the others are pubofemoral (ant/inf)
ischiofemoral (post)

48
Q

a ring of fibrocartilage that encircles the acetabulum and its functions include shock absorption and pressure distribution; joint lubrication; enhances joint stability

A

acetabular labrum

49
Q

which portions of the acetabular labrum is most innervated

A

anterior and superior

50
Q

what finishes the acetabular labrum

A

transverse acetabular ligament

51
Q

What structure deepens the acetabulum by 20 or more percent

A

acetabular labrum

52
Q

Where is the articular cartilage thickest for femoral head and acetabulum

A

superiorly

53
Q

What is the only part of the femoral head that is not covered in articular cartilage?

A

fovea (attachment of the ligamentum teres)

54
Q

What happens if there is a disruptions of the ligamentum teres?

A

avascular necrosis

55
Q

Angle of inclination in
Infants
adults
elderly

A

150
125
120

56
Q

females can have a greater pelvic width, which will do what to their angle of inclination?

A

lessen it

57
Q

when angle is greater than 125, it is called

when it is less than 125, it is called

A

coxa valga

coxa vara

58
Q

coxa valga corresponds with genu….

coxa vara corresponds with genu….

A

vara - bowleg

valga - knock-kneed

59
Q

The typical angle of torsion for adults is _____ degrees

A

12

60
Q

Anteversion causes _____ rotation of the femur when the angle of torsion is ______

A

internal

greater than 12 degrees

61
Q

Retroversion causes _____ rotation of the femur when the angle of torsion is

A

external, less than 12 degrees

62
Q

forces in the hip are transmitted to the femoral shaft through the femoral neck. this is what kind of system

A

cantilever

63
Q

accordion-like folds are found on the inferior and superior aspects of the joint capsule. these are called

A

frenula (synovial folds)

64
Q

What do the frenula permit

A

full abduction and adduction range of motion

65
Q

Why do humans have extremely limited hip hyperextension

A

the three dense and strong ligaments wrap around the hip joint capsule in a clockwise direction

66
Q

T or F The ligamentum teres supports the hip joint

A

F, its primary purpose is to serve as a guid for oburator artery branch traveling to fovea on head of femur

67
Q

What are the primary muscles involved in unilateral stance

A

hip abductors, opposite lumbar erector spinae

68
Q

What happens to the right femur if you can see Trendelenburg Sign in right unilateral stance?
pelvis?
lumbar spine?

A

adducts
left lateral tilt
right lateral flexion

DPT Biomechanics (6 decks)

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