Answer
The 4 phases of fracture repair are the following:
1. Hematoma formation
2. Fibrocartilage callus formation
3. Bony callus formation
4. Bone remodelling
Work Step by Step
1. Hematoma formation: When the fracture occurs, several blood vessels rupture causing a swelling called hematoma. This hematoma clots and forms the basic structure for further repair.
2. Fibrocartilage callus formation: During this phase, new capillaries grow and the dead tissues are disposed of by phagocytes. Fibrocartilage callus is formed by various types of internal and external repair tissues.
3. Bony callus formation: When more osteoblasts and osteoclasts enter the area, fibrocartilage callus is replaced by bony callus mainly consisting of spongy bone.
4. Bone remodelling: After this, the bony callus is gradually remodeled according to mechanical stresses in the bone, and it forms a strong patch at the site of the fracture.
