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basic sciences > Bone and Bone Injury/Repair > Flashcards

Bone and Bone Injury/Repair Flashcards

1
Q

What tcx factor directs mesenchymal cells to the osteoblast lineage?

A

RUNX2

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2
Q

What maintains the ionic milieu of bone?

A

“Entrapped cells” of osteoblasts = disruption of the active-lining cell layers activates these cells

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3
Q

Example of woven bone?

A

Embryonic skeleton, fracture callus

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4
Q

What produces RANKL? What expresses RANKL receptor?

A

Osteoblasts and tumor cells produce it, osteoclasts express receptor for it = stimulates differentiation into mature osteoclasts, increases bone resorption

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5
Q

What produces osteocalcin?

A

Osteoblasts

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6
Q

Intermittent (pulsatile) PTH releases stimulates what?

A

Osteoblasts

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7
Q

What does TNF-a do to osteoblasts?

A

Inhibits it

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8
Q

How does osteocalcin and PTH affect osteocytes?

A

Osteocalcin stimulates it, PTH inhibits it

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9
Q

Howship’s lacunae?

A

Where bone resorption occurs by osteoclasts

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10
Q

What does osteoprotegerin do?

A

Inhibits binding of RANKL = decreases bone resorption

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11
Q

How does calcitonin affect osteoclasts?

A

Inhibits it

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12
Q

What interleukin is found in membranes surrounding loose total joints?

A

IL-1 = potent stimulator of osteoclasts (IL-10 inhibits osteoclasts)

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13
Q

Bisphosphonates?

A

Inhibit osteoclasts, have direct anabolic effect on bone

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14
Q

Which bisphosphonates are assoc with osteonecrosis of jaw?

A

Non-nitrogen-containing bisphosphonates

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15
Q

Ortho implications of bisphosphonate use?

A
  1. Reduced rate of spinal fusion in animal model (recommend withhold prior to surgery)
  2. Safe for cementless hips and cemented knees, may decrease subsidence rate in acetabular component
  3. No data on fracture healing
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16
Q

Osteoprogenitor cells and strain conditions?

A

1) Low strain = osteoblasts
2) Intermediate strain = cartilage
3) High strain = fibrous tissue

17
Q

Type of collagen in bone?

A

Type I

18
Q

What is the most abundant noncollagenous protein in bone?

A

Osteocalcin = can be measured in serum or urine as a marker for bone turnover

19
Q

Peizoelectric remodeling?

A

Remodeling occurs in response to electrical charge

1) Compression side = electronegative, stimulating osteoblasts
2) +ension side = electropositive, stimulating osteoclasts

20
Q

Hueter-Volkmann law?

A

Remodeling occurs in small packets of cells known as basic multicellular units (BMUs) = compressive forces inhibit growth, tension stimulates growth
1) May play role in scoliosis and Blount’s dz

21
Q

Bones with tenuous blood supply?

A

Scaphoid, talus, femoral head, odontoid

22
Q

Long bones receive blood supply from 3 sources?

A

1) Nutrient artery = inner 2/3, high BP
2) Metaphyseal-epiphyseal system
3) Periosteal system = outer 1/3, low BP

23
Q

Normal blood flow to bone? What happens to blood flow with a fracture or in immature bone?

A

1) Normal = centrifugal (inside to outside)

2) Fracture/immature bone = centripetal (outside to inside), periosteal system predominates

24
Q

What is the major determinant of how well a fracture heals?

A

Bone blood flow

25
Q

Blood flow and fracture healing?

A

1) Initial response = decrease in blood flow
2) Within hours-days = flow increases (regional acceleratory phenomenon)
3) Peaks = 2 weeks
4) Return to normal = 3-5 months

26
Q

How reaming affects blood supply to bone?

A

Devascularizes inner 50-80% of cortex and delays revasc of endosteal blood supply

27
Q

Inner vs. outer periosteum?

A

1) Inner (cambium) = loose, vascular, form periosteal callus during fracture healing
2) Outer (fibrous) = less cellular, contiguous with joint capsule

28
Q

Types of bone formation?

A

1) Enchondral = bone replaces cartilage
2) Intramembranous = mesenchymal cells differentiate into osteoblasts which form bone
3) Appositional = osteoblasts lay down new bone on existing bone

29
Q

Fracture callus is what kind of bone formation?

A

Enchondral

30
Q

Examples of diseases with abnormal ossification?

A

1) Enchondral = achondroplasia
2) Intramembranous = cleidocranial dysostosis
3) Appositional = Paget’s, infantile hyperostosis (Caffey’s dz), melorheostosis

31
Q

Physis?

A

2 growth plates exists in immature long bones

1) Horizontal (physis)
2) Spherical (growth of epiphysis)

32
Q

Major source of nutrition of growth plate?

A

Perichondral artery

basic sciences (2 decks)

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