20/10/2024
Normal wound healing
The inflammatory phase of wound healing lasts for 2 to 3 days. Normal wound healing occurs
in three phases – the inflammatory phase lasts for the first 2 to 3 days, the proliferative phase
lasts for 3 days to 3 weeks and, finally, the remodelling (maturation) phase lasts from the end
of the third week to years.
The inflammatory phase, also called the exudative phase, has no tensile strength to
the wound. It consists of vascular, cellular and enzymatic processes. As a result of the
wound, bleeding, vasoconstriction and thrombus formation occurs. Platelets stick to
the damaged vessel endothelium, releasing adenosine diphosphate (ADP), cytokines,
serotonin, prostaglandins and histamine. This causes vascular permeability, resulting in the
migration of inflammatory cells and macrophages, the latter removing devitalised tissue and
microorganisms. Fibrinogen produces fibrin, which forms the framework for the fibroblastic
activity, which is the second phase.
The proliferative phase lasts from 3 days to the end of the third week. The principal
feature of this is fibroblastic activity with the production of collagen and new capillaries
(angiogenesis) and re-epithelialisation; this is called granulation tissue. This increased
collagen gives the wound almost one-third of its original tensile strength. The third phase of
remodelling constitutes re-arrangement and cross-linking of collagen fibres, which can go on
for years while the wound regains 80% of its original tensile strength.
