Wound healing, like the body's response to injury, undergoes the three phases of inflammation, proliferation, and remodeling.
Inflammatory cell infiltration is a key step in wound healing, stimulated in part by endothelial cells, monocytes and cytokines.
The wound's fibrin plug brings collagen synthesizing fibroblasts to the wound, the cells that also stimulate the production of mucopolysaccharides.
“Scarless” fetal wound healing may relate to an altered inflammatory response, collagen composition and hyaluronic acid composition when compared to adult wound healing and scar formation.
Negative pressure is an important therapeutic adjunct for the treatment of delayed healing wounds.
Wound healing is a fundamental part of recovery from surgery. After tissue damage, the body responds in a predictable manner to repair and restore function. Wound healing involves blood clotting factors, inflammatory mediators, connective tissue formation, and remodeling processes. In the fetus some wounds will heal without a scar, but after birth scar formation is expected. Individuals respond to wound healing differently, resulting in differences in scar formation. Some chronic (eg, diabetes, malnutrition) and genetic (eg, Ehlers–Danlos) conditions negatively affect the healing of a wound.
The repair process after tissue injury from trauma or surgically created wounds has been divided into 3 phases: inflammation, proliferation, and remodeling (Fig. 12-1). These 3 phases overlap, but each has identifiable characteristics that will be discussed in more detail. Wound healing is the tissue's ability to restore function after injury. There is an urgency to restore function, minimize loss of fluid, and avoid infection. This may explain why perfect repair, or regeneration, is not possible. Regeneration is a term used for restoration of the tissue without a scar or signs of previous injury. It is found to take place only in fetal tissue and in certain organs such as liver and bone.
Schematic timeline of the events involved in wound healing.
All wounds undergo the same 3 steps (inflammatory, proliferative, and remodeling phases) progressing toward repair and restoration of function. Acute wounds heal in a predictable fashion, progressing through these 3 phases. Chronic wounds do not proceed past the inflammatory phase.
The inflammatory phase starts immediately after injury or incision and lasts for approximately 6 days. This phase represents the body's attempt to limit blood loss by creating a seal over the wound and is followed by removal of necrotic tissue and debris. During the inflammatory phase there is an increase in vascular permeability. Cells migrate into the tissue stimulated by chemotaxis. These cells release several cytokines and growth factors which activate migrating cells (Fig. 12-2).
The inflammatory phase of wound healing with neutrophil cellular infiltration.