Bone

Question 1

Origin of osteoblasts

Answer 1

Undifferentiated mesenchymal stem cells

Question 2

Multifunctional transcription factor that directs mesenchymal cells osteoblast lineage

Answer 2

RUNX2

Question 3

Products of osteoblasts

Answer 3

OSTEOCALCIN
Alkaline phosphatase 
Type I collagen 
Bone sialoprotein
RANKL

Question 4

Origin of osteoclasts

Answer 4

Hematopoietic cells in macrophage lineage

Question 5

Actions of RANKL

Answer 5

Bind to receptors on osteoclasts
Stimulates differentiation into mature osteoclasts
Increase bone resorption

Question 6

Action of bisphosphonates

Answer 6

Inhibit osteoclastic bone resorption

Question 7

Types of bone

Answer 7

Normal
Lamellar
Cortical
Cancellous

Immature/pathologic
Woven

Question 8

Origin of osteoclasts

Answer 8

Hematopoietic cells of macrophage lineage

Question 9

Produced by osteoblasts, stimulates differentiation of osteoclasts to active mature osteoclasts

Answer 9

RANKL

Question 10

Inhibits bone resorption by binding and inactivating RANKL

Answer 10

Osteoprotegerin

Question 11

Directly inhibit osteoclastic bone resorption. Nitrogen containing (answer) are 1000 fold more potent

Answer 11

Bisphosphonates

Question 12

Associated with osteonecrosis of jaw

Answer 12

Bisphosphonates

Question 13

Bone matrix components

Answer 13

60% inorganic, 40% organic
Calcium hydroxyapatite majority of inorganic
Type 1 collagen majority of organic

Question 14

Most abundant non collagenous protein in bone

Answer 14

Osteocalcin

Question 15

Remodeling occurs in response to mechanical stress

Answer 15

Wolff’s law

Question 16

Compressive forces inhibit growth, tension stimulates it

Answer 16

Heuter-Volkmann Law

Question 17

Types of bone formation

Answer 17

Enchondral ossification
Intramembranous ossification
Appositional ossification

Question 18

Bone formation. Bone replaces cartilage model

Answer 18

Enchondral ossification

Question 19

Bone formation. No cartilage model. Aggregates of undifferentiated mesenchymal differentiate into osteoblasts which form bone

Answer 19

Intramembranous ossification

Question 20

Bone formation. Osteoblasts lay down new bone on existing bone

Answer 20

Appositional ossification

Question 21

3 stages of fracture repair

Answer 21

Inflammation, repair, remodeling

Question 22

Fracture healing type in closed treatment

Answer 22

Periosteal bridging callus

Question 23

Fracture healing type. Compression plate treatment

Answer 23

Primary cortical healing

Question 24

Why do NSAIDS affect fracture healing?

Answer 24

COX-2 activity needed for normal enchondral ossification

Question 25

properties of bone grafts

Answer 25

Osteoconduction - scaffold for bone growth
Osteoinduction- growth factors that stimulate bone growth (BMP in tibial fractures)

Osteogenic grafts

Question 26

Highest compressive strength of any graft material

Answer 26

Calcium phosphate based grafts

Question 27

Primary homeostatic regulators of serum calcium

Answer 27

PTH

1,25(OH)-vitamin D3

Question 28

Bone mass peak age range

Answer 28

16-25

Question 29

Most common cause of hypercalcemia

Answer 29

Malignancy

Question 30

Definition of osteoporosis (WHO)

Answer 30

Lumbar bone density 2.5 or more SD less than peak bone mass of a healthy 25 year old

Question 31

Tx of osteoporosis

Answer 31

Calcium supplements 100-1500mg/day

Bisphosphonates