principles of bone healing

Question 1

What are the 3 phases of bone healing

Answer 1

inflammatory
restorative
remodelling

Question 2

Describe the inflammatory phase of bone healing

Answer 2

lysis of osteocytes and cells of dead soft tissues => liberates inflammatory mediators that attract inflammatory cells and macrophages to remove debris and bacteria etc.
Blood clot is formed at fracture site (within few hours)
Phagocytes clean site of fracture

Question 3

Why is the blood clot formed in the inflammatory phase of bone healing important?

Answer 3

It is important to the process of the neovascularisation to the fracture site

Question 4

What is compartmental syndrome

Answer 4

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

Question 5

Describe the soft callus formation in the restorative phase

Answer 5

First callus is similar to fibrocartilaginous tissue (soft)
Callus starts to stabilise fracture site
4 days - 3 weeks

Question 6

Describe the hard callus formation in the restorative phase

Answer 6

fracture is stabilised and blood supply restored
newly formed cartilage is substituted by bone tissue via endochondral ossification (osteoblasts)
=> formation of hard callus
This relies on the fracture site being stabilised
begins 2 weeks after fracture and finished between 6th and 12th week

Question 7

Describe the remodelling phase of bone healing

Answer 7

ends of bones are enveloped by fusiform mass (callus)
remodelling occurs via osteoclasts
months - years

Question 8

What types of healing occur in the restorative phase?

Answer 8

first intention (minimal bone callus formation - occurs after surgery)
Second intention (most common natural type of healing)

Question 9

Describe first intention healing of the bone

Answer 9

direct formation of bone tissue in a fracture line without the production of bone callus

Question 10

What conditions are required to cause first intention bone healing

Answer 10

immediate stabilisation
good blood supply
prefect reduction of fracture edges
absence of micromovements at fracture line
Interfragmentary compression (Roux law)
Absence of infection

Question 11

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

Answer 11

The patient’s own weight
Application of osteosynthesis systems that compress the fracture lines
Placement of osteosynthesis systems that redistribute the weight

Question 11

What causes second intention bone healing?

Answer 11

late treatment
deficient reduction of the fracture or loss of fragments
poor blood supply
infection
no compression