Wound Healing Lecture Notes PDF

Semester 7- level 4-academic year 2024-2025 By Dr/ Saleh Saleh El Balka Lecture of Surgical Oncology 2024  Definition of wound Break in the integrity of tissue which leads to disruption of structure and/or function. Tissue injury...

Semester 7- level 4-academic year 2024-2025 By Dr/ Saleh Saleh El Balka Lecture of Surgical Oncology 2024  Definition of wound Break in the integrity of tissue which leads to disruption of structure and/or function. Tissue injury caused by external force.  wound Rank and Wakefield classification: A) tidy wounds. B) untidy wounds.  Types of wounds 1) open vs closed Clean incised wound Lacerated wound Crush injuries Abrasions Contusions & Bruises  Healing Def: The normal body response to injury (surgical/traumatic) to restore the normal structure and function. Healing Types of Wound Healing  Timing of suture application: 1-Primary sutures: Applied at the time of injury when dealing with a clean surgical wound or recent wound. 2-Delayed primary sutures: Are applied to doubtful or contaminated wounds or in late presentation after injury. The wounds are left open after surgical excision with delayed primary suture applied 5 to 7 days later. 3-Secondary sutures: Are used where an infected wound is left open to granulate and only when it gets clean, sutures can be applied. 4-Reconstruction: If there is skin or tissue loss to be replaced and gaps to be bridged skin covers and different types of grafts may be needed at any stage of management.  Phases of Wound Healing These phases are not sequential but overlap. Meaning that the next phase starts before the previous phase ends: 1. Inflammatory phase (Days 1 to 6) 2. Fibroproliferative phase (Day 4 to Week 3) 3. Maturation/remodeling phase (week 3 to 1 Year)  Inflammatory Phase (Day 1 to 6) Aim: To establish hemostasis and mobilize the immune system that will complete the healing process. This phase is composed of a vascular response and a cellular response represented by the following: Inflammatory Phase (Day 1 to 6) Fibroproliferative Phase (Day 4 to Week 3) Fibroproliferative Phase (Day 4 to Week 3)  Contraction ✓ This process involves movement of the wound edge toward the center of the wound. ✓ ⎚ It’s facilitated by the action of myofibroblasts (Specialized fibroblast with contractile ✓ cytoplasmic microfilaments) ✓ Act in concert to contract entire wound bed. Maturation/Remodeling Phase (Week 3 to 1 Year) 1. After 3-5 weeks: Equilibrium reached between collagen breakdown & synthesis. 2. ↑↑ Collagen organization & stronger cross-links. 3. type I collagen replacement of type III collagen, restoring normal 4:1 ratio 4. ↓↓ in GAGS, water content, vascularity & cellular population. 5. Peak tensile strength at approximately 60 days = 80% pre-injury strength )%100  Collagen synthesis I. Starts 3-5 days post injury II. Primarily by fibroblasts III. Maximum synthesis rate is 2-4 weeks IV. Declines after 4 weeks V. Type 3-Collagen is seen in early phases of wound healing  Systemic Factors affecting wound healing 1) Genetic: Predisposition to hypertrophic or keloid scarring 2) Skin type Pigmentation, elasticity, thickness (thin vs thick), sebaceous quality, and location (e.g., shoulder, sternum, ear lobe) 3) Age Affects healing rate (Children VS Elderly) 4) Chronic diseases I. Diabetes II. Renal failure III. Nutritional deficiencies IV. Atherosclerotic disease V. Immunodeficiency Systemic Factors affecting wound healing 5) Vitamins a. Vitamin A:  Reverses delayed wound healing from steroids. b. Vitamin C: Vital for collagen synthesis. c. Vitamin E: Antioxidant 6)Zinc: Cofactor for many enzymes. 7)Smoking : Constricts blood vessels & ↓↓ oxygen delivery Systemic Factors affecting wound healing 8) Drugs: 1. Steroids: ↓↓ Inflammation Inhibit epithelialization ↓↓ Collagen production 2. Antineoplastic agents. 3. Anti-inflammatories. Local factors affect wound healing 1. Type of wound (tidy Vs untidy) : Mechanism (incision Vs crushing). Environment (dry Vs moist*, temperature, pH, infection). Tissue loss. 2. Vascularity: A good blood supply (e.g. in the face & scalp leads to nice healing while in a poor blood supply (wounds below the knee) causes delayed healing. Local factors affect wound healing 3) Irradiation: It impairs wound contraction & granulation tissue formation as it causes ischemia due to EAO. 4) Immobilization: It helps healing, because movement damage the blood supply of granulation tissue. 5) Tension: increased tension in the wound …ischemia.. impaired healing. Sutures under tension , hematoma and infection increase tension inside the wound. Local factors affect wound healing 6) Infection: It delays healing. A. Fibroblasts compete with bacteria for O2 &nutrition. B. Moreover, bacteria secrete collagenolytic enzymes, which destroy collagen fibers. 7) Foreign bodies & necrotic tissue impair wound healing. 8) Adhesion of the wound to a bony surface It prevents wound contraction (chronic venous ulcers, wounds on chin of tibia).. Local factors affect wound healing 9) Impaired venous drainage As in post-phlebitic limbs, impairs wound healing 10) Bad surgical technique: Rough tissue handling, excessive cauterization, blood clots, tight sutures. tissue ischemia and subsequent necrosis extend the inflammatory phase Factors which favor wound infection include: ❑Presence of foreign bodies. ❑Dead tissues. ❑Ischemia. ❑Suturing under tension. ▪ After 1 week è the wound has only 3% of its final strength. ▪ After 3 weeks è the wound has 20% of its final strength. ▪ After 3 months è the wound has 80% of its original strength. NB: The tissues never regain their original tensile strength.  Complication of wound healing a. General: 1) SHOCK (hypovolemic, septic, neurogenic) 2) Infection (specific or nonspecific) 3) Crush injury and syndrome b. Local: 1. Wound failure (wound dehiscence): It can be a result of any general or local factor affecting wound healing. Failure to an abdominal wound is called burst abdomen. 2. Stretching of the scar Complication of wound healing 3. Hypertrophied scar: There is increased collagen production over breakdown with collagen deposition but the scar tissue never extends beyond the limits of the original wound. A hypertrophic scar is itchy. It appears red, raised above the skin surface and tender. With spontaneous maturation the scar becomes pale and flat. ▪ The process of maturation of a hypertrophic scar can be accelerated by application of pressure to its surface by silicone gel sheets → causes ischemia of the small blood vessels leading to diminished activity of the fibroblasts & collagen synthesis. Complication of wound healing 4. Keloid formation:  It occurs more frequent in oriental races and Africans. May occur in any wound after healing which could be perfect with no complication. It is extreme over growth of scar tissue that grows beyond the limits of original wound and showing no spontaneous tendency to subside. Local steroid injection may help in some cases of keloid formation. The best result can be achieved with surgical excision and postoperative interstitial radiotherapy otherwise recurrence in inevitable.  Complication 4. Contracture: This is a patholgical shortening of the scar tissue resulting in deformity in scar ovelying joints. Proper positioning of the joint during healing can minimize the Deformity  Complication 5) Surgical site infection 6) Injury and ischemia 7) Lymphedema/ hematoma/ seroma 8) Disfigurement (Ugly scar) 9) Chronic ulcer 10) Malignant transformation (Marjolin ulcer)