Merck Manual

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Stages of Wound Healing

Stages of Wound Healing

Although there are many types of wounds, most undergo similar stages in healing. There are 3 major stages of wound healing after a full-thickness skin wound. The duration of each stage varies with wound type, management, and the individual's overall health.

Inflammation is the first stage of wound healing. It can be divided into several phases. Initially, blood vessels constrict to control bleeding, and then, within minutes, blood vessels dilate resulting in localized swelling. White blood cells migrate into the wound where they attack bacteria and clean up damaged tissue and foreign material. This cellular level debridement is essential to wound healing.

Proliferation is the second stage of wound healing. In a healthy wound, fibroblasts and capillaries (small blood vessels) migrate into the area and create a framework for other cells to grow on and rebuild missing and damaged tissues. In a surgically closed wound, skin, or epithelial, cells can cover the incision within 48 hours. In an open wound, the scaffold (granulation tissue) must fill the wound before epithelial cells can migrate in, so this type of healing takes longer. This process is hindered if the wound is too dry. Bandaging helps to maintain a healthy environment for healing open wounds.

Remodeling is the final stage of wound healing. During this period, the newly laid collagen fibers reorganize along lines of tension. This process forms a scar, and allows wound strength to increase slowly over a long period (up to 2 years). Most scars remain 15% to 20% weaker than the original tissue.