Bone Modeling and Remodeling

Question 1

what does load predictability like with bones?

Answer 1

long bones that are slightly curved

Question 2

what is the periosteum?

Answer 2

outer fibrous layer: supportive function
inner osteogenic layer: adaptive response

Question 3

what is the cellular component of bone?

Answer 3

osteoblats
osteocytes: osteoblasts in bone matrix
osteoclasts

Question 4

what makes up the organic extracellular matrix of bone?

Answer 4

collagen
proteoglycans
glycosaminoglycans

Question 5

what makes up the inorganic portion of bone?

Answer 5

calcium
phosphate
hydroxyapatite crystals

Question 6

what does the unique design of bone allow?

Answer 6

animal to adapt to its mechanical environment

Question 7

what does loading lead to?

Answer 7

deformation, stress, and then strain

Question 8

what is stress?

Answer 8

amount of force per unit area that develops on a plane surface within a structure in response to an externally applied load

Question 9

what is strain defined as?

Answer 9

localized change in dimension that occurs within a structure as it responds to externally applied loads

Question 10

what is wolff’s law?

Answer 10

bone changes shape and strength, modeled and remodeled, in response to the magnitude and direction of strain

Question 11

what does high strain cyclic fatigue do with cortical bone?

Answer 11

decreases stiffness and leads to bone strengthening

Question 12

what is modeling?

Answer 12

bone formation along periosteal and endosteal surfaces

Question 13

what is remodeling?

Answer 13

formed bone, normal lamellar or abnormal fiber bone, is replaced
resorption and bone formation

Question 14

what properties of the bone change during resorption?

Answer 14

porosity increase
stiffness decreases

Question 15

what does microtrauma of bone culminate in?

Answer 15

clinical injury that is sudden in onset and substantial in extent

Question 16

what are some bad bone changes in response to exercise?

Answer 16

subchondral sclerosis can result from intense remodeling
microdamage/microfracture, intense resorption, and inferior subchondral bone and possible fracture
maladaptive or non-adaptive bone remodeling

Question 17

what is being done in the thoroughbred industry to improve safety?

Answer 17

shoeing regulations
anabolic steroids banned
track approval process
synthetic tracks
training techniques

Question 18

where is cancellous (trabecular) bone?

Answer 18

ends of long bones

Question 19

where is compact (cortical) bone?

Answer 19

shaft of long bones

Question 20

what cells make up the transport and communication system within bone?

Answer 20

osteocytes: osteoblasts trapped in bone matrix

Question 21

how much of the bone wet weight is organic extracellular matrix?

Answer 21

21%

Question 22

what makes up the strain environment?

Answer 22

strain magnitude
strain rate
strain frequency
strain distribution
number of loading cycles
rest-recovery periods

Question 23

does wolff’s law involve both cortical and cancellous bone?

Answer 23

yes

Question 24

what might cyclic loading during the resorption phase lead to?

Answer 24

bucked shins
dorsal cortical fracture

Question 25

what are bucked shins?

Answer 25

periosteal new bone formation and inflammation

Question 26

what adaptive changes occur in cancellous/trabecular bone?

Answer 26

micromodeling: trabecular bone in subchondral region strengthens
remodeling: resorption and deposition of lamellar bone