WOUND HEALING

WOUND- is a type of physical trauma wherein the

skin is torn, cut or punctured (open wound), or where blunt force trauma causes a contusion (closed wound).

- a break in the continuity of any bodily tissue due to violence is understood to encompass any action of external agency, including for example surgery.

HEALING- act or process of curing or restoring the

wound.

- prevents the egress of irritants may result in continued tissue disruption and/or infection

WOUND HEALING

- comprises a fundamental biological activity that involves both regenerative and reparative activities.

- functions to restore the disrupted or dead tissues to its normal state.

* An ideal repair can be achieved in tissues undergoing constant renewal but is least effective in nerve & muscle tissue.

* Nerve undergo repair only when cell bodies are intact.

* Muscle tissue is repaired by fibrous connective (scar) tissue, with permanent loss of function.

TYPES OF WOUND HEALING:

1. PRIMARY UNION

- healing by first intention- there is narrow space between the two cut surfaces of a wound- healing is completed in 2-3 weeks

2. SECONDARY UNION

- healing by second intention- the two cut surfaces cannot be appointed- granulation tissue tend to heal the wound from the base of wound contraction.

3. DELAYED UNION

- there is movement between the two fractured surfaces- infection- poor blood supply- pathogenic fractures

PHASES:

1. Hemostasis2. Inflammation3. Granulation4. Remodelling

STAGES:

1. Inflammation2. Proliferative

(Regeneration)3. Maturation

Factors Affecting Wound Healing:

1. Infection – promotes further inflammation & tissue destruction.

2. Foreign Bodies – stimulates inflammation, thereby impending the process of healing.

3. Old Age – due to nutritional & vascular deficiencies and deteriorating immune system.

4. Nutritional Status – Vitamin C deficiency has been associated with impaired healing

5. Concurrent Disease:

a. Vascular Disease – any disturbance to the blood supply of a tissue will result in delayed or impaired wound healing.

b. Diabetes Mellitus – impaired blood supply, impaired PMN leukocytes function & increased susceptibility to microbial agents.

c. Uremia – because of disturbance in inflammation response.

d. Blood Disease – hemorrhage at the site of tissue damage, resulting in large hematomas that predispose secondary microbial infection.

PRIMARY UNION

- Narrow space between the 2 cut surfaces.

- Undergoes hemorrhage prior to clotting.

SECONDARY UNION

- Large gap between the 2 cut surfaces that cannot be appointed.

- Initial degree of hemorrhage followed by blood clot formation.

PRIMARY UNION

- Margins of wound subsequently undergo mild inflammatory reactions releasing plasma and polymorphonuclear leukocytes into incised space.

SECONDARY

UNION

- Mild short-lived acute inflammatory reactions occur in the wound margins at the same time.

PRIMARY UNION

- After approximately 24 hours, capillary blood vessels from wound margins begin to bud into the wound space & then are followed by both macrophages and fibroblasts.

SECONDARY

UNION- Granulation tissue

subsequently begins to move into the wound base & sides. (These tissue comprising capillary buds, fibroblasts, macrophages, plasma cells & lymphocytes.

PRIMARY UNION

- Macrophages are primarily associated with phagocytosis of the wound debris & haemosiderin from hemoglobin breakdown.

SECONDARY

UNION

- Component cells ensure the removal of tissue debris, these cells include macrophages, fibroblasts & polymorphonuclear leukocytes.

PRIMARY UNION

- Fibroblasts begin to form ground substances.

SECONDARY

UNION

- Fibrous tissue is laid down in the deeper layers of the wound. Granulation tissue tends to heal the wound from the base.

PRIMARY UNION

- At the same time or a little earlier, epithelial cells from wound margins undergo mitosis & migrate toward center of wound thereby forming a complete but thin epithelial covering. (SCAB)

SECONDARY UNION

- Wound undergoes contraction, primarily reflecting fibroblastic activity. Thus edges of the wound is closed by granulation tissue & wound contraction thereby facilitating epithelial migration & mitosis. (SCAB)

PRIMARY UNION

- Epithelium undergoes progressive maturation to regain its full thickness.

SECONDARY

UNION

- Excessive granulation is formed so that recently healed wound may appear proud of the adjacent tissue usually resolved in a few weeks.

PRIMARY UNION

- Healing is usually complete by 2-3 weeks.

- A longer period may be required before there is complete restoration of the tissue architecture.

SECONDARY

UNION

- Complex interactions occur between epithelia & connective tissues:

CT formation – initially is essential for the restoration of normal epithelial continuity.

ET – subsequently may be responsible for the formation of connective tissue scar growth.

Secondary Healing differs from Primary Healing in several aspects:

1. Large tissue defects initially have more fibrin & more necrotic debris & exudates that must be removed. Inflammation reaction is more intense.

2. Much larger amount of granulation tissue is formed.

3. Phenomenon of wound contraction. That is, the defect is markedly reduced from its original size.