Introduction
Wound healing phases are the various stages in which the complete healing of a wound takes place. A healthy body is able to regenerate injuries by complete regeneration of tissue or formation of replacement tissue (scar tissue). A distinction is made between four to five phases of wound healing.
The healing process begins with the body’s own hemostasis, followed by the three main phases of wound healing, the cleansing phase, the granulation phase and the regeneration phase. Hemostasis is sometimes added to the cleansing phase. The beginning of wound healing is characterized by hemostasis, which occurs immediately after the injury.
Immediately after damage to the affected tissue, the blood vessels contract reflexively (reflex vasoconstriction). This stops the blood flow and allows the wound to close with a fibrin network. Fibrin is a protein that is produced by the body and, in the case of tissue damage, is released by various enzymes from its precursor fibrinogen, which circulates in the blood.
Many fibrin proteins accumulate at the site of the tissue injury to form a “plug” and thus close the wound. This first phase of wound healing is completed after only a few minutes (5-10). Now cells of the immune system migrate to the wound and trigger the cleansing phase (also exudative phase).
White blood cells (leukocytes) and macrophages remove the fibrin clot and any germs that may have penetrated. Classic signs of inflammation such as heat, redness and pain therefore occur mainly during this approx. 3-day phase.
During the subsequent granulation phase, new tissue and new blood vessels are formed at the site of the wound. First, connective tissue cells (fibroblasts) migrate and attach themselves to the remains of the fibrin network. There they begin to form collagen, the protein that is the main component of our skin and connective tissue.
However, the collagen formation is not completed, but rather a kind of filling tissue is created, the so-called granulation tissue. Like the cleansing phase, the granulation phase lasts up to 3 days. The last phase, the regeneration phase, follows after about a week. Collagen is now completely formed, as are new skin cells. Depending on the size and depth of the wound, this phase can last from days to months.
