Wound healing
Wound healing or wound repair is the body's natural process of regenerating dermal and epidermal tissue. When a wound occurs, a set of complex biochemical events take place in a closely orchestrated cascade to repair the damage.
Healing steps
Healing by primary intention
First-line healing concerns surgical wounds or surgically sutured traumatic wounds. The first healing phase is reconstruction of skin continuity and corresponds to the time during which the surgeon leaves the suture in place.
The sutures are removed after a period of 5 to 15 days. The duration of this period depends on the skin thickness and the tension applied to the edges.
Healing is still not complete when the sutures are removed, because an inflammation phenomenon is observed that can last for up to two months. After two or even three months, the scar will progressively reduce although it will not disappear entirely.
Healing by secondary intention or directed healing
First stage: DEBRIDEMENT (read more...)
Wound debridement will help to eliminate all necrotic necrosed tissue. Natural debridement occurs through macrophages but mechanical debridement is required if devitalised tissue is present (wet necrosis or dry necrosis).
The clinicial will remove all waste using tongs, compresses or a scraper.
Debridement is a compulsory step and healing cannot begin unless the wound is debrided.
The risk of infection within the wound is high when there is any devitalised tissue present. Debridement will quickly eliminate necrosis and fibrin.
There are 3 types of debridement :
Surgical/Sharp debridement
Surgical debridement is performed under local or general anaesthetic. It eliminates a maximum amount of devitalised tissue in a single step.
It can be performed using tongs, scissors or a surgical scalpel. This process must begin by cutting out the centre of the necrosis and working towards the edges.
Enzymatic or natural/autolytic debridement
Enzymatic or natural/autolytic debridement is performed by means of protolytic enzymes secreted by macrophages or the action of some of the bacteria which colonise the wound.
Debridement using external therapeutic means (dressings such as: Alginates (wet necrosis), hydrogels (dry necrosis), maggot therapy and negative pressure therapy).
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Second stage: GRANULATION (read more...)
Once the devitalised tissue has been removed and the pathological process has been brought under control, neo-vascularisation creates buds that progressively fill the wound bed.
Granulation tissue contains fibroblasts, collagen and elastin.
Granulation normally stops when the volume of lost tissue has been replaced. However, there are occasions when overgranulation occurs. Hypergranulation should be restricted limited so as not to hinder the next phase, which is epithelialisation.
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Third stage: EPITHELIALISATION (read more...)
Once granulation is complete and lost tissue has been replaced, terminal epithelialisation which is the last phase of the healing process can begin.
There is no longer a basement membrane, and epithelialisation will take place from skin edge to skin edge.
Marginally, the basal cells slide over the surface of the granulation buds through multiplication and generate a neo-epidermis on the surface of the healed wound.
The final scar is not identical to normal skin (no hair, no sebaceous glands, no sweat glands) and sensitivity is impaired.
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