bone

Question 1

what are some gross functions of bone?

Answer 1

protection for internal function
rigid levers for attachment of muscles to allow motion
harbors hemopoietic tissue for production of blood cells
serves as a reservoir for calcium, phosphate and other ions

Question 2

where is blood made

Answer 2

BONE

Question 3

what are key features of bone structure?

Answer 3

highly vascular, innervated, dynamic CT, capable of repair and remodeling

Question 4

what are osteocytes?

Answer 4

mature bone cells

Question 5

what are osteoblasts?

Answer 5

young cells-growth

Question 6

what are osteoclasts?

Answer 6

phagocytic (break down bone-eat it)

Question 7

applying wolff’s law to bone after a period of immobilization what would be expected with casting and NWB status following 8 weeks of immobilization?

Answer 7

may see a 3 fold decrease in load to failure, stiffness and energy storing capacity

Question 8

applying wolff’s law to bone after a period of immobilization why are plates/screws impanted?

Answer 8

to reduce stress at fracture site but they may reduce/slow healing, but the fixation site strength may increase

Question 9

which is stiffer: cortical/compact bone or cancellous bone?

Answer 9

compact bone is stiffer because steeper slope of stress/strain curve

Question 10

what is the point of cancellous/trabecular bone’s porous structure?

Answer 10

great capacity for energy storage

Question 11

T/F bone becomes brittle with age?

Answer 11

True

Question 12

is bone more brittle with increasing or decreasing velocity of laoding?

Answer 12

increasing. increasing velocity increases severity of fracture

Question 13

bone demonstrates what mechanical behavior? and what does it mean?

Answer 13

anisotropic. tissue responds to direction of force applied

Question 14

which direction is strength greatest in for bone?

Answer 14

the direction in which loading is most common

Question 15

T/F strength decreases as direction of loading changes from compression to transverse loading?

Answer 15

True

Question 16

what is the best loading for bone to resist?

Answer 16

compression

Question 17

what is the second best loading for bone to resist?

Answer 17

longitudinal tension

Question 18

what is the third best loading for bone to resist?

Answer 18

obliwue tension

Question 19

what is the worst loading for bone to resist?

Answer 19

transverse loading

Question 20

which is stiffer: cortical bone or cancellous bone?

Answer 20

cortical bone is stiffer

Question 21

Pick the correct pair to complete the sentence: cortical bone can withstand (greater/lesser) stress but (more/less) strain than cancellous bone.

Answer 21

greater, less

Question 22

what percent of cancellous bone can sustain strains before failing?

Answer 22

75%

Question 23

what percent of cortical bone can sustain strains before failing?

Answer 23

2%

Question 24

what is compression?

Answer 24

when the structure “shortens and widens”

Question 25

what does compression commonly produce in vertebrae?

Answer 25

fractures

Question 26

T/F constant compression may hinder growth?

Answer 26

true

Question 27

what may unequal loading produce with compression?

Answer 27

valgus or varus deformity

Question 28

which is the best loading parameter to facilitate growth and repair?

Answer 28

cyclic

Question 29

what is the piezo electric effects of bending forces?

Answer 29

negative charge on side of compression and positive on side of tension

Question 30

for healthy bone where do osteoblasts and osteoclasts tend to migrate with load?

Answer 30

osteoblasts tend to migrate toward negative electrode while osteoclasts tend to migrate toward positive electrode

Question 31

which side is bone deposition increases on when loaded?

Answer 31

side of compression

Question 32

which side is bone reabsorption increased on when loaded?

Answer 32

side of tension

Question 33

what is the effect of muscle contractions on bone?

Answer 33

usually oppose antagonist or gravity to counterbalance bending
acting independently create bending of bones
create tension at tendon-bone junction
create tuberosities/trochanters developmentally
pathologically may create avulsion fractures

Question 34

T/F yielding in bone under tension occurs by debonding of osteons at cement lines

Answer 34

true

Question 35

what does this mean: constant compressive loading produces increase in endosteal diameter and increase in intracortical porosity

Answer 35

constant compressive loading makes bone porous which is bad because it makes them weak example with braces

Question 36

is intermittant loading good and why?

Answer 36

good because produces increased bone mass

Question 37

what kind of fractures are common with torsion loading forces?

Answer 37

spiral fractures

Question 38

what is most sensitive to torsion forces and why?

Answer 38

epiphyseal plate. under torsional load, newly forming bone will grow away from epiphysis in a spiral fashion

Question 39

for a cross sectional area greater are leaders to…

Answer 39

stiffer and stronger bne

Question 40

what do healing fractures begin with?

Answer 40

large callus. first soft then hard

Question 41

what do we do to stabilize fracture sites and what does this do to them?

Answer 41

screw holes. it initially weakens the bone then in 8 weeks returns to normal strength due to the remodeling

Question 42

what intervention tactics should we use to facilitate growth with regard to intensity?

Answer 42

loading within tissue structural tolerance
move carefully into the plastic zone
pain free loading

Question 43

what intervention tactics should we use to facilitate growth with regard to duration or frequency?

Answer 43

many repetitions cyclical loading

Question 44

what intervention tactics should we use to facilitate growth with regard to mode?

Answer 44

attempt to mimic functional loading characteristics