4) Healing and Repair

Question 1

Describe the healing of a bone fracture.

Answer 1

• Haematoma forms from ruptured vessels within marrow cavity and periosteum
• Organising haematoma provides a framework for ingress of macrophages, endothelial cells fibroblasts and osteoblasts.
• These cells remove the necrotic tissue and capillaries develop (angiogenesis)
• Bone is laid down in an irregular woven pattern, sometimes with islands of cartilage (soft callus)
• Woven bone gradually replaced by more organised lamellar bone (hard callus)
• Lamellar bone gradually remodelled to the direction of mechanical stress