Wound Healing Stages

There are four stages of wound healing.  The Inflammatory stage, the Proliferative stage, Epithelialisation and Maturation.The inflammatory stage is characterised by haemostasis, inflammation, phagocytosis and the clotting cascade.  Platelets seal off the blood vessel and coagulation normally occurs within hours.  The release of histamine leads to vasodilation.  The damaged tissue is infiltrated by white blood cells, mainly neutrophils and macrophages.  Growth factors and fibroblasts are released to fuel the re-growth of tissue.  This stage can take between 1-4 days to complete.The proliferative stage is characterised by angiogenesis, collagen disposition, granulation tissue formation and fibroplasia.  The wound will appear bright red in colour due to the formation of new blood vessels.  Fibroblasts accumulate at the edge of the wound, and proliferate and migrate across the wound bed, laying down a matrix of ground substance and collagen fibres.  Granulation tissue is formed, which is fibrous connective tissue that replaces a fibrin clot.  It contains macrophages and neutrophils.The epithelialisation stage is characterised by wound contraction and epithelial cells moving across the wound bed.  In contraction, the wound is made smaller by the action of myofibroblasts, which establish a 'grip' on the wound edges and contract themselves.  When the cells roles are close to complete, cells that are no longer needed are removed by apoptosis (cell death).The proliferative and epithelialisation stages are completed in approximately 4-21 days.The maturation stage is when the wound remodels and matures.  The wound is strengthened by the re-organisation of fibres.  Collagen is realigned along the tension lines.  The wound becomes less vascular.  Myofibroblasts cause increased contraction of the wound and further scar tissue.  This stage can take between 21 days to 2 years.

New Page