In this step we will look at the current understanding of wound healing and its phases, types, and factors involved in the process.
Generally, wound healing consists of the following four steps:
Haemostasis: vascular constriction, platelet aggregation, degranulation, and fibrin formation or thrombus.
Inflammation: neutrophil infiltration, monocyte infiltration, macrophage differentiation, and lymphocyte infiltration.
Proliferation: re-epithelialisation, angiogenesis, collagen synthesis, and extracellular matrix formation.
Remodeling: collagen remodeling, vascular maturation, and regression.
A simpler way of classifying wound healing is by the classic clinical phases:
Inflammation Phase (exudation): 2 - 4 Days.
Fibroplasia Phase (proliferation): 10 - 12 Days.
Maturation Phase (scar formation): > 1 Year.
The images below depict the inflammation phase. The wound is red, painful, and produces exudate.
As a result of this phase, surgical wounds show oedema (30% increase in all dimensions of the tissue). If a wound is sutured too tight, ischaemia can occur as well. Below, you can see a diagrammatic representation of a nail embedded in skin and the consequences of this, as well as an image of the skin after the nail has been removed. You can see the swelling in the wound region as well.
Types of wound healing:
Erosion and blisters require regeneration to heal. The tissue lost is replaced by the same type of tissue.
Using the principle of regeneration, split skin transplantation and bone repair procedures are carried out.
In repair, scars are formed, and these may be of various different types (as seen above). The tissue lost is replaced by new (scar) tissue.
Factors of importance for wound healing/infection:
After reading this section, try to answer the following questions in the comments section below.
How do you detect the inflammatory phase of a wound? What are the signs observed?
In you opinion, which is the most important patient factor and techno-surgical factor contributing to wound healing? Why do you think this?
© BSAC & EWMA