3: Principles of Bone Healing - Carnevale Flashcards Preview

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Flashcards in 3: Principles of Bone Healing - Carnevale Deck (26)
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1
Q

breakdown of bone

A
  • 35% organic

- 65% inorganic

2
Q

matrix of bone

A

95% collagen type I

5% non-collagenous prtns

3
Q

unmineralized bone =

A

osteoid

4
Q

pluripotent mesenchymal cell that can form osteoblasts

A

osteoprogenitor

5
Q

cells that initiate mineralization

A

osteoblasts

- synthesize and transport prtn (like type 1 collagen) and osteoprotegerin

6
Q

what receptor on osteoclasts stimulates osteoclastic bone resorption

A

RANK receptor

- RANK ligand is produced by osteoblasts

7
Q

become osteocytes when surrounded by matrix

A

osteoblasts

- osteocytes are matured osteoblasts that regulate daily serum calcium and phosphorus

8
Q

responsible for bone resorption

A

osteoclasts

  • mutliple nuclei
  • live in howship lacunae
9
Q

osteoprotegerin

A

acts as decoy on RANK receptor on osteoclast

10
Q

what are osteoclasts derived from?

A

hematopoietic progenitor cells

11
Q

role of estrogen in bone growth

A
  • increases bone formation by increasing collagen synthesis by osteoblasts
  • prevents bone resorption by inhibiting osteoclast differentiation
12
Q

when is woven bone normal?

A
  • fetal skeleton
  • growth plates
  • pathologic in adults almost always
13
Q

only type of normal bone in adults

A

lamellar bone

- highly orderly

14
Q

terms

  • end of long bone
  • growth plate
  • next to growth plate
  • shaft
  • bone covering (blood vessels, nerves)
A
epiphysis
epiphyseal plate
metaphsis
diaphysis
periosteum
15
Q

describe bone remodeling cycle

A
  1. osteoclast precursors recruited to bone surface, where thy fuse, differentiate, and mature
  2. osteoclasts resorb both organic and inorganic bone matrix
  3. resorption phase ends with osteoclast apoptosis
  4. in reversal phase, osteoblasts differentiate from mesenchymal precursors, under influence of factros from osteoclasts, and secrete new bone matrix (osteoid)
  5. at end of cycle, some osteoblasts have been incorporated into bone as osteocytes and others remain on the surface as quiescent bone-lining cells
16
Q

why do we need vit C for bones?

A
  • maintenance of normal connective tissue
  • synthesizes collagen
  • responsible for bone formation –> synthesizes organic matrix
  • inorganic calcified portion of capillary walls
17
Q

clinical syndrome related to problems with osteoid synthesis AND collagen support of blood vessels

A

scurvy (vit C deficiency)

  • note hemorrhages found around corkscrew hairs
  • poor wound healing
  • subperiosteal hemorrhage
18
Q

three phases of fracture healing

A

1 = organization of hematoma at fracture site –> soft, organizing PROCALLUS (hematoma organizing by end of 1st wk, anchorage, no structural rigidity)

  1. conversion of procallus to FIBROCARTILAGINOUS CALLUS : reactive mesenchymal cells (deposition of woven bone and new cartilage); 3rd wk; max enlargement
  2. replacement of mesencymal cells by OSSEOUS CALLUS; eventually remodeled along lines of weight bearing; completes repair (endochondral ossification forms bony networl; fractured ends bridged by bone callus)
19
Q

“callus”

A

orderly progression of cartilage into microtrabecular new bone

20
Q

inhibitory factors to fracture healing

A
  • infection
  • non union
  • inadequate immobilization
  • poor circulation, poor nutriton
  • drugs (corticosteroids, immunosuppressives, cytotoxic therapy)
  • systemic abnormality
21
Q

mechanisms of avascualr necrosis (infarction of bone and marrow resulting from ischemia)

A
  • fracture
  • corticosteroids
  • uncertain cause idiopathic
  • sickle cell disease
22
Q

most common route of osteomyelitis

A

hematogenous

23
Q

most common agents of osteomyelitis

A

pyogenic (staph aureus) agents or mycobacterium tuberculosis

24
Q

cause of osteomyelitis in sickle cell patients

A

salmonella

25
Q

sequestrum

A

residual necrotic bone post osteomyelitis - may be resorbed or surrounded by rim of reactive bone called involucrum

26
Q

brodie abscess

A

when well-defined rim of sclerotic bone surrounds residual abscess - viable organisms may persist

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