bone healing Flashcards

1
Q

What are the 3 phases of bone healing

A
  1. inflammatory
  2. restorative
  3. remodelling
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2
Q

Describe the inflammatory phase of bone healing

A
  1. fracture causes damages to bone structures & surrounding soft tissues
  2. at cellular level, lysis of osteocytes & cells of dead soft tissue leads to liberation of substances in fracture site that attract inflammatory cells & macrophages to clear away necrotic material
  3. blood clot forms at fracture site within few hours of injury
    - clot important in neovascularisation to fracture site
  4. phagocytes clean site of fracture
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3
Q

Describe the restorative phase of bone healing

A

characterised by formation of callus

  1. first soft callus produced is similar to hypercellular fibrocartilaginous tissue
  2. callus (though elastic) starts to stabilise fracture site

Process takes 4 days to 3 weeks

  1. as fracture is stabilised & blood supply is restored, newly formed cartilage is progressively substituted by bone tissue via endochondral ossification (osteoblasts)
  2. results in formation of hard callus

Begins 2 weeks after fracture & ends between week 6 & 12

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4
Q

What is compartmental syndrome?

A

a large bleed into the spaces between surrounding tissues => blood loss and hypovolaemic shock

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5
Q

Describe the remodelling phase of bone healing

A
  1. ends of bone are enveloped by a fusiform mass (callus)
  2. remodelling occurs involving osteoclasts

slow process - months to years

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6
Q

Label the stages of bone healing

A
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7
Q

In the restorative phase, what types of healing occur?

A

First intention (minimal bone callus formation)

Second intention (most common natural type of healing)

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8
Q

Describe healing by first intention

A

Direct bone formation at fracture line without callus

Faster than secondary healing but initially less stable

Requires:
- Immediate stabilization & good blood supply (esp. intraosseous)
- Perfect fracture reduction (reducible fracture)
- No micro-movements at fracture site
- Interfragmentary compression (Roux law)
- No infection

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9
Q

What can be used to provide interfragmentary compression to a fracture?

A

Patients own weight

Application of osteosynthesis systems that compress fracture lines

Placement of osteosynthesis systems that redistribute weight

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10
Q

What are the circumstances under which secondary intention healing occurs

A

late treatment

deficient reduction of fracture or loss of fragments

poor blood supply

infection

absence of forces of compression

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