Wound healing and scar Dr . SAAD Muwafaq Attash 2017

-Wound healing is a mechanism whereby the body attempts to restore the integrity of the injured part Factors influencing healing of a wound A-Local factors 1- Site of the wound 2- Structures involved 3- Mechanism of wounding 4-Incision -Crush -Crush avulsion 5- Contamination (foreign bodies/bacteria)a 6- Loss of tissue 7- Other local factors -Vascular insufficiency (arterial or venous) - Previous radiation -Pressure

B- Systemic factors 1-Malnutrition or vitamin and mineral deficiencies Disease (e.g. diabetes mellitus) 2-Medications (e.g. steroids) 3-Immune deficiencies [e.g. chemotherapy, acquired 4-immunodeficiency syndrome (AIDS)] 5-Smoking

NORMAL WOUND HEALING This is variously described as taking place in three or four phases, the most commonly agreed being: 1- the inflammatory phase; 2- the proliferative phase; 3 -the remodelling phase (maturing phase). Occasionally, a haemostatic phase is referred to as Occurring before the inflammatory phase, or a destructive phase following inflammation consisting of the cellular cleansing of the wound by macrophages

The inflammatory phase : begins immediately after wounding and lasts 2–3 days. Bleeding is followed by vasoconstriction and thrombus formation to limit blood loss. Platelets stick to the damaged endothelial lining of vessels, releasing adenosine diphosphate (ADP), which causes thrombocytic aggregates to fill the wound. Macrophages remove devitalised tissue and micro-organisms while regulating fibroblast activity in the proliferative phase of healing.

The proliferative phase: lasts from the third day to the third week consisting mainly of fibroblast activity with the production of collagen and ground substance , the growth of new blood vessels as capillary loops (angioneogenesis) and the re-epithelialisation of the wound surface. Fibroblasts require vitamin C to produce collagen. the early part of this phase is called granulation tissue. In the latter part of this phase, there is an increase in the tensile strength of the wound due to increased collagen

The remodelling phase: is characterised by maturation of collagen (type I replacing type III until a ratio of 4:1 is achieved). is a realignment of collagen fibres along the lines of tension, decreased wound vascularity and wound contraction due to fibroblast and myofibroblast activity.

A classification of wound closure and healing: 1- By primary intention Wound edges opposed. Normal healing. Minimal scar 2- By secondary intention Wound left open. Heals by granulation, contraction and epithelialisation Increased inflammation and proliferation Poor scar 3- By tertiary intention (also called delayed primary intention) Wound initially left open Edges later opposed when healing conditions favourable  

Incised Crushed or avulsed Tidy Untidy Incised Crushed or avulsed Clean Contaminated Healthy tissues Devitalised tissues Seldom tissue loss Often tissue loss The surgeon’s aim is to convert untidy to tidy by removing all contaminated and devitalised tissue. Primary repair of all structures (e.g. bone, tendon, vessel andnerve) may be possible in a tidy wound, but a contaminated wound with dead tissue requires debridement.

Managing the acute wound ■ Cleansing ■ Exploration and diagnosis ■ Debridement ■ Repair of structures ■ Replacement of lost tissues where indicated ■ Skin cover if required ■ Skin closure without tension ■ All of the above with careful tissue handling and meticulous technique

The final appearance of a scar depend on many factors : 1-differnce between individual patients . 2-the type of skin and location on the body 3-tension on the closure 4-direction of the wound(langer or relaxed skin tension line). 5-both local and systemic condition -Crush wound healed with bad scar - Vascular disease and nutritional disorder provide factor for bad scar 6-surgical technique A traumatic technique and tension free suture line will provide a good line scare Important techniqual factors affected the result a-suture type and time of removal example face 3-5 days b-wound edge eversion

scars The maturation phase represents the formation of what is described as a scar . it mature over a period lasting a year or more. - At first pink, hard, raised and often itchy. - The collagen becomes denser, the scar becomes acellular as the fibroblasts and blood vessels reduce. scar becomes paler, softer, flattens and its itchiness diminishes( first 3 months) -( 1–2 years) Tensile strength will continue to increase but will never reach that of normal skin

Types: 1-Atrophyic scar: pale, flat and stretched in appearance, on the back and areas of tension. easily traumatised,thinned. Excision and resuturing may only rarely improve such a scar. 2-Hypertrophyic scar: excessive scar tissue that does not extend beyond the boundary of the original incision or wound. results from a prolonged inflammatory phase and unfavourable scar siting (i.e. across the lines ofskin tension). In the face, these are known as the lines of facialexpression.

3-Keloid scar: excessive scar tissue that extends beyond the boundaries of the original incision or wound.\ - aetiology is unknown, - associated with elevated levels of growth factor, deeply pigmented skin, inherited tendency certain areas of the body (e.g. a triangle whose Points are the xiphisternum and each shoulder tip). -Histology of both hypertrophic and keloid scars shows excess collagen with hypervascularity, but this is more marked in Keloids . -Treatment of both is difficult -Hypertrophic scars improve spontaneously with time, whereas keloids do not.

Treatment of hypertrophic and keloid scars ■ Pressure – local moulds or elasticated garments ■ Silicone gel sheeting (mechanism unknown) ■ Intralesional steroid injection (triamcinolone) ■ Excision and steroid injectiona ■ Excision and postoperative radiation . ■ Intralesional excision (keloids only) ■ Laser ■ Vitamin E or palm oil massage (unproven)

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