Fracture healing

Question 1

What is primary and secondary bone healing?

Answer 1

Primary - minimal fracture gap, gap bridges with new bone from osteoblasts
Secondary - gap which needs to be filled in temporarily to act as scaffold for new bone to be laid down

Question 2

Describe the events in secondary bone healing

Answer 2

Fracture occurs
Haematoma with inflammation from damaged tissues
Macrophages and osteoclasts remove debris and resorb bone ends
Granulation tissue forms from fibroblasts and new blood vessels
Chondroblasts form cartilage (soft callus)
Osteoblasts lay down bone matrix
Calcium mineralisation produces immature woven bone (hard callus)
Remodelling occurs with organisation along lines of stress into lamellar bone