Fracture healing occurs in 5 stages: 1) formation of a hematoma at the fracture site, 2) influx of inflammatory cells, 3) formation of a soft callus, 4) conversion to a hard callus as woven bone is deposited, and 5) remodeling where portions of the callus not under stress are resorbed until the original shape of the bone is restored. Factors like inadequate immobilization, local infection, malnutrition, or vascular issues can negatively impact the healing process.

1. FRACTURE HEALING

2. Fracture
Loss of the bone integrity due to
1. mechanical injury
2. diminished bone strength
Most common pathological condition affecting the bone

3. Types of fracture
1. simple
2.compound
3.comminuted
4.displaced
5.greenstick
6pathological
7.stress

4. Steps of Fracture healing
1. formation of hematoma
2.influx of inflammatory cell
3. formation of a soft callus
4. conversion to hard callus
5. remodelling

5. 1. Formation of Hematoma
Start immediately
Rupture of blood vessel that leads to the filling of fracture gap
and surrounding area of bone injury with blood

6. 2. Influx of inflammatory cell
- Clotted blood provides fibrin mesh
- Sealing of the fracture site
which creates framework for influx of inflammatory site.,
- and ingrowth of fibroblast and new capillaries
- Degranulated platelet and migratory inflammatory cell release PDGF, TGF-beta,
FGF and other factors that activates osteoprogenitor cell in the medullary cavity
and periosteum that result in the stimulation of osteoblastic and osteoclastic
activity

7. 3. Formation of a soft callus or procallus
- Takes place By the end of first week :
- It is mass of predominantly
uncalcified tissue that
provides anchorage between
the fracture bone
but not structural rigidity for
weight bearing

8. 4. Conversion to hard Callus
After 2 weeks
Soft callus transformed to bony callus
Activated osteoprogenitor cell deposit WOVEN Bone
In some cases, activated mesenchymal cell in soft tissue and bone surrounding
fractures line also differentiate into the chondrocytes that makes fibroblast and hyaline
cartilage.
- the newly formed cartilage undergoes endochondral ossification along the fracture
line which forms a contagious network in bone with newly deposited bone trabeculae in
the medulla and beneath the periosteum.
- In this way fracture ends are bridged

9. 5. Remodelling
As callus mature and gets subjected to weight bearing forces -
portion that are not physically stressed are resorbed.
This remodelling reduces the size of callus until shape and outline
of fractured bone re-established as lamellar bone

10. Factors affecting healing
1. Inadequate immobilization
2. Local infection
3. Malnutrition
4. Skeletal dysplasia
5. systemic infection
6. Diabetes
7. Vascular insufficiency
8. Vitamin deficiencies
9. Inadequate level of Calcium and Phosphorous