Wound healing Day 21 - 2yrs Remodelling Contracture Day 4 - 21 Proliferation Granulation Day 1 - 4 Inflammation Immediate Haemostasis Days post injury Phase of healing
Sealing of damaged blood vessels
Platelet –utility worker
Under the influence of the ADP, platelets aggregate and adhere to the exposed collagen. Intrinsic clotting cascade -> thrombin -> fibrinogen ->fibrin -> platelet aggregate into a stable haemostatic plug
Characterised by “ rubor et tumor cum calore et dolore” – 4 days.
Polymorphonuclear leukocytes - non skilled laborers – phagocytize debri and microorganisms, aided by local mast cells.
Macrophages – contractor – phagocytize bacteria –second line of defence and secrete IMs and growth factors like FGF,EGF,TGF beta, IL-1 which appears to direct the next stage.
Proliferative phase (4 – 21 days)
Involves proliferation, granulation and contraction
Framers build the framework of the new house – “framer” cells – fibroblasts secrete collagen network – specialised fibroblasts -> wound contraction
The “plumber” cells , pericytes and endothelial cells -> angiogenesis
The “roofer” and “sider”cells - keratinocytes -> epithelisation
Remodelling or Maturation phase
Interior finishing Ξ Remodeling or Maturation -> ↑Tensile strength
The cell -> fibroblast
Results in scar – active dynamic tissue
Stage I (upto 4 wks) – soft, fine&weak
Stage II (4 – 12 wks)–red, hard & strong
Stage III (12wks to 2 yrs) – soft, white& supple scar