Principles of Bone Healing

Question 1

What are the 3 phases of bone healing?

Answer 1

1. Inflammatory
2. Restorative
3. Remodelling

Question 2

In simple terms what is the process of remodelling?

Answer 2

1. Hematoma forms
2. Fibrocartilaginous callus forms
3. Bony callus forms
4. Bone remodelling occurs

Question 3

What is the Inflammatory phase?

Answer 3

First phase of bone healing
1. lysis of osteocytes and dead soft tissue cells attracts inflammatory cells to site
2. Blood clot forms at fracture site (hematoma) within a couple of hours
3. Phagocytes ‘clean’ the site of fracture
this is important to neovascularisation at the site

Hematoma may be within periosteum or spill out if it is breached

Question 4

What is the restorative phase?

Answer 4

Formation of soft callus at the start
Relatively soft
Movement can still occur between fragments of fracture site
Stabilises fracture
Lasts 4 days to 3 weeks
As fracture becomes stabilised this is substituted for bony tissue
Endochondral ossification
Hard callous formation and bony union
Occurs about 2 weeks after fracture and ends between 6th and 12th week

Question 5

What are the types of healing within the restorative phase?

Answer 5

First Intention
Seen after surgical repair of fracture
Minimal bone callus formation
Faster than secondary intention

Second Intention
Most common
Natural type of healing
Unmanaged fracture

Question 6

Describe First Intention Healing

Answer 6

Caused by surgical intervention
Direct formation of bone tissue in a fracture line without production of bone callus
Occurs when:
Immediate stabilised
Good blood supply
Perfect reduction of the fracture edges
Absence of micromovements at the level of the fracture line
Interfragmentary compression
The patient’s own weight
Application of osteosynthesis systems that compress the fracture lines
Placement of osteosynthesis systems that redistribute the weight
Absence of infection

Question 7

Describe Second Intention Healing

Answer 7

Most common
Natural type of healing
Unmanaged fracture
Achieved when the following occurs:
Late treatment
Deficient reduction of the fracture or loss of fragments
Poor blood supply
Infection
Absence of forces of compression