1. Classification of Wounds, Principles of Wound Treatment

I. Definition and Classification of Wounds

Definition

• Wound: damage to structure and function of epithelium and/or underlying tissue due to injury
• Cause: mechanical, physical, chemical, electrical or radiation injury
• Surgical wound: intentional and controlled
• Traumatic wound: accidental, often contaminated

Classification

1. Depth of penetration

• Superficial: epidermis only
• Partial thickness: reaches dermis
• Full thickness: reaches subcutaneous adipose tissue
• Deep: penetrates subcutaneous tissue and beyond

2. Severity

• Simple: skin and subcutaneous tissue
• Complicated: vessels, nerves, tendons, organs, bone/joint → check PMS
• PMS: pulse, motor function, sensation

3. Time scale

• Acute: sudden injury → heals at expected rate
• Chronic: non-healing wound persists beyond expected healing time
• Examples: diabetic foot, venous/arterial ulcer, pressure ulcer

4. Contamination

• Clean/sterile: low infection risk
• Contaminated: pathogens or foreign bodies possible
• Colonized: bacteria present without tissue invasion
• Infected: multiplying organisms + pain, erythema, warmth, swelling, pus/odor, fever

II. Mechanical and Non-Mechanical Wounds

Mechanical Wounds

1. Open wounds: internal tissue exposed

• Incision (vulnus scissum): clean sharp-edged object
• Laceration (vulnus lacerum): blunt trauma, irregular wound edges
• Abrasion (vulnus abrasum): epidermis scraped off on rough surface
• Avulsion: tissue forcibly detached
• Puncture wound (vulnus punctum): narrow deep wound → hidden contamination risk
• Gunshot wound (vulnus sclopetarium): deep tissue damage, possible entry + exit
• Bite wound (vulnus morsum): polymicrobial, high infection risk

2. Closed wounds: skin intact

• Contusion: blunt trauma to small vessels/muscle/tissue → painful bruise
• Crush injury: high external pressure → ischemia, necrosis, compartment risk
• Hematoma: collection of blood in a limited space

Non-Mechanical Wounds

1. Physical wounds

• Thermal/burn wound:
• 1st degree: hyperemia only
• 2nd degree: epidermis/dermis injury + blistering
• 3rd degree: full-thickness skin damage, black/white leathery discoloration
• Cold injury, irradiation, electrical injury

2. Chemical wounds

• Acid: coagulation necrosis
• Base/alkali: liquefactive necrosis → deeper penetration

III. Wound Healing and Closure

Phases of Wound Healing

1. Hemostasis: vasoconstriction → platelets → coagulation → fibrin clot
2. Inflammation: neutrophils/macrophages remove bacteria and necrotic tissue
3. Proliferation: angiogenesis + fibroblasts + collagen + granulation + epithelialization
4. Remodeling: collagen cross-linking + contraction → stronger pale scar

Factors Affecting Wound Healing

• Local factors: wound size, tension, poor blood supply, infection, foreign body, necrosis, hematoma, pressure
• Systemic factors: age, obesity, malnutrition, diabetes, anemia, shock, vascular disease, smoking, alcohol, steroids/immunosuppression

Types of Healing / Closure

• Primary intention: clean fresh wound → approximate edges with sutures/staples/adhesive

• Result: fast healing, good cosmetic result

• Secondary intention: infected, necrotic, tissue-loss or heavily contaminated wound → leave open

• Result: granulation + contraction → slower healing, larger scar

• Tertiary intention / delayed primary closure: contaminated wound left open first → close after 3-5 days if clean
• Bite, gunshot, deep puncture and grossly contaminated wounds are usually not closed primarily

Complications of Wound Healing / Closure

• Early complications: bleeding, hematoma, seroma, infection, dehiscence
• Late complications: hypertrophic scar, keloid, chronic ulcer, fistula/sinus, contracture

IV. Principles of Wound Treatment

Initial Assessment

1. Trauma priority: ABCDE + control major bleeding if severe injury
2. Local anesthesia / analgesia
3. Inspect and explore wound: depth, contamination, foreign body, necrosis, infection
4. Assess damaged structures: vessels, nerves, tendons, joint, bone, organ
5. Complicated limb wound → check PMS before and after treatment
6. Imaging if foreign body, fracture, joint penetration or deep injury suspected

Local Treatment

1. Microbiology sample if infected, pus, bite, chronic wound or high-risk contamination
2. Mechanical cleaning / irrigation: saline; remove dirt and foreign bodies
3. Debridement: remove necrotic/devitalized tissue and refresh wound edges if needed
4. Hemostasis: compression, ligation, cautery; avoid blind clamping near vessels/nerves
5. Closure decision:

• Clean wound → disinfection + edge refreshment if needed → primary closure
• Contaminated/infected/bite/puncture/gunshot → open treatment or delayed primary closure
• Large tissue loss → secondary intention, graft/flap or specialist reconstruction

6. Dressing, elevation/immobilization if needed, and follow-up

Antibiotics and Tetanus

• Antibiotics are not routine for every wound
• Indications: infected wound, bite, gross contamination, open fracture, puncture/crush wound, delayed presentation, diabetes/immunosuppression
• Bite wound first-line: amoxicillin/clavulanate if no contraindication
• Culture result → adjust antibiotic
• Tetanus prophylaxis: assess wound type + vaccination history
• Dirty/tetanus-prone: puncture, bite/saliva, soil/feces, burn, crush, frostbite, necrosis, compound fracture
• Unknown/incomplete vaccination → tetanus vaccine; add tetanus immunoglobulin (TIG) for dirty/major wounds
• Complete vaccination: booster if clean minor wound and last dose >=10 years; dirty wound and last dose >=5 years