Pathophysiology
Clinical meaning
Wound healing progresses through four overlapping phases: hemostasis, inflammation, proliferation, and maturation (remodeling). Understanding these phases is essential for selecting the appropriate wound dressing. During hemostasis (immediate to minutes), damaged blood vessels constrict and platelets aggregate to form a platelet plug, which is stabilized by a fibrin mesh to create a clot. This clot serves as a provisional matrix for cell migration. During the inflammatory phase (1-6 days), neutrophils migrate to the wound within hours to combat bacteria and remove debris through phagocytosis. Macrophages follow at approximately 48-72 hours and are considered the most critical cells in wound healing because they coordinate the transition from inflammation to proliferation by releasing growth factors including platelet-derived growth factor (PDGF), transforming growth factor-beta (TGF-beta), and vascular endothelial growth factor (VEGF). During the proliferative phase (4-21 days), fibroblasts migrate into the wound and begin synthesizing collagen, the primary structural protein of new tissue. Angiogenesis (new blood vessel formation) creates a granular, beefy-red tissue called granulation tissue. Epithelial cells at the wound edges divide and migrate across the wound surface (epithelialization), and wound contraction occurs...