Fracture healing

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Fracture healing

Five basic recognised overlapping stages of fracture healing:
Stage 1 Haematoma
Stage 2 Periosteal and endosteal cellular proliferation
Stage 3 Callus
Stage 4 Consolidation
Stage 5 Remodelling

Following fracture  tearing of blood vessels in medullary cavity, cortex and periosteumhaematoma at fracture site; periosteum is stripped away from surface of bone. Neutrophils and macrophages migrate into the haematoma  phagocytose haematoma and necrotic debris. Capillaries in-grow from surrounding tissue and with fibroblasts  form granulation tissue. New osteoprogenitor cells develop from mesenchymal precursor cells  from osteoblasts  migrate into granulation tissue  synthesis osteoid  layered in a haphazard/random way to produce a woven bone pattern  external callus (stabilises/bridges fracture site external to bone) and internal callus (stabilises/bridges fracture site in medullary cavity). Ossification of fracture ends begin when bone ends are closely opposes. Callus remodelling takes place over several months by osteoclastic erosion and osteoblastic synthesis  woven bone replace with the compact organised bone.

General fracture healing time frame:
• first 12 hours – bleeding reaches maximum and clot develop in fracture site
• first 24 hours – acute inflammation locally
• 2nd day – early granulation develops
• 5th day – osteogenesis begins
• 3 weeks – fibrous union has developed and some callus formed
• 6 weeks – external callus well developed
• 4-5 months remodelling completes (can last for several years)

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