Hemostasis Phase — The Initial Response: The healing process begins immediately after injury with hemostasis, typically lasting 5-10 minutes. Blood vessels constrict to minimize blood loss, while platelets aggregate at the injury site to form a plug. The coagulation cascade activates, converting fibrinogen to fibrin to create a stable clot. This clot not only stops bleeding but also serves as a scaffold for incoming repair cells and provides a reservoir of growth factors essential for healing.
Inflammatory Phase — Cleaning and Preparation: The inflammatory phase lasts 2-5 days and is characterized by vasodilation, increased vascular permeability, and cellular infiltration. Neutrophils arrive first to fight infection and remove debris, followed by macrophages that orchestrate the healing response. Classic signs include redness, swelling, heat, and pain. This phase is essential for proper healing — attempts to suppress normal inflammation can actually delay recovery.
Proliferative Phase — Building New Tissue: Lasting 4-21 days, the proliferative phase involves angiogenesis (new blood vessel formation), collagen synthesis, and granulation tissue development. Fibroblasts migrate into the wound bed and produce collagen, creating the structural framework for healing. Epithelial cells multiply and migrate across the wound surface in a process called re-epithelialization. The wound contracts as myofibroblasts pull the edges together, reducing the surface area requiring repair.
Maturation Phase — Strengthening and Remodeling: The final phase can last months to years as the newly formed tissue strengthens and reorganizes. Type III collagen is gradually replaced with stronger Type I collagen, and collagen fibers align along stress lines to maximize tensile strength. However, healed tissue typically achieves only 70-80% of original strength. Proper wound care during earlier phases significantly impacts the quality of final tissue repair and functional outcomes.