SL1 - Bone Healing Flashcards

(28 cards)

1
Q

bone is composed of

A

minerals - Ca, P, Mg

Organic Matrix - type I collagen, proteoglycans, glycosaminoglycans

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2
Q

T/F there is separate venous drainage for cortex and medullary canal

A

true

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3
Q

osteoblasts

A

produce osteoid (unnmineralized bone matrix) on bone surface

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4
Q

osteocytes

A

osteoblasts that have been encased in mineral matrix

maintain bone matrix

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5
Q

osteoclasts

A

active in areas of bone remodeling

reside near bone surface

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6
Q

what are the 3 phases of bone healing

A

inflammation phase

repairative phase

remodeling phase

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7
Q

inflammatory phase

A

lasts about 2-3 weeks

death of osteocytes results in release of lysosomal enzymes

necrotic material at site of the fracture is source of inflammatory respose

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8
Q

repair phase

A

migration of osteoprogenitor cells - forms periosteal callus

angiogenesis - transient blood supply from surrounding soft tissue

deposition of Ca hydroxyapatite in matrix - callus mineralization

cartilage replaced by bone via endochondral ossification

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9
Q

remodeling phase

A

begins when fracture is bridged by callus

woven bone remodeled into lamellar bone via osteoclasts and osteoblasts

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10
Q

remodeling phase is directed by ______

A

stresses of weight bearing

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11
Q

types of bone healing

A

primary/direct

secondary/indirect

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12
Q

contact healing

A

primary bone healing

occurs with compression of bone ends under rigid fixation

no cartilaginous callus formed

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13
Q

gap healing

A

gap between fracture ends is < 1mm

granulation tissue at gap followed by transversely oriented lamellar bone

haversian remodeling occurs at ~ 3 weeks post stabilization

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14
Q

T/F primary bone healing outmoded in favor of secondary bone healing

A

True

exceptions: articular fractures and simple, stable fractures

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15
Q

secondary bone healing

A

fracture ends dont touch

micromotion at fracture promotes formation of callus

bone heals via mineralization of fibrocartilagenous callus into boney callus

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16
Q

biological osteosynthesis

A

secondary bone healing

fracture ends not compressed - protect surrounding soft tissue, protect blood supply

plates in bridging mode, external skeletal fixaition, interlocking nails

17
Q

average fracture healing time

18
Q

factors that affect bone healing

A

fracture configuration/severity

soft tissue damge

stability of repair

presence of infection

patient factors (age, weight, disposition, comorbities)

complience

19
Q

what is required to assess bone healing

A

orthogonal radiographs

20
Q

4 A’s of evaluation

A

alignment

apposition

apparatus

activity

21
Q

when does clinical union occur

A

when bone is strong enough that fixation is no longer necessary

22
Q

what is a delayed union

A

healing is prolonged beyond normal expected time course

fracture lines remains evident with feathery/wooly ends

callus is visible but lacks appropriate mineralization

no sclerosis of bone ends

23
Q

malunion

A

failure to re-establish normal function in face of healing

24
Q

which malunions are the lease tolerated

A

roatation and lateral translation

25
viable nonunion
biologically active fracture with cartilage and fibrous tissue between fracture ends
26
nonviable nonunion
fracture ends are sclerotic with rounded bone edges and visible fracture gap (bone have blood supply) ## Footnote *dystrophic, necrotic, defect, atrophic*
27
treatment options for delayed union
**pre-emptive treatment is ideal** - bone grafts, increased mechanical stiffness of implants, bone morphogenic protein ## Footnote *if delayed untion is anticipated - rechecks q 3-4 weeks*
28
treatment options for non-union
rigid stabilization removal of loose implants encourage biologically active environment - graft, marrow, demineralized bone matrix, bone morphogenic proteins remove non-viable bone +/- amputation