Wounds: classification, healing phases, and surgical debridement principles

1. Definition and classification

A wound (vulnus) is a mechanical tissue injury accompanied by a breach in the integrity of the skin or mucous membranes. It fundamentally differs from an erosion and an abrasion by the depth of the lesion (reaching at least the dermis).

By the nature of the injury

• Incision (cut) wound — caused by a sharp object, smooth edges, profuse bleeding.
• Puncture wound — narrow wound track, small opening, risk of damage to deep structures.
• Chopped wound — a combination of cut and contused wounds, often accompanied by bone damage.
• Contused wound — caused by blunt trauma, bruised edges, moderate bleeding.
• Crush wound — extensive tissue damage, high risk of necrosis.
• Lacerated wound — uneven edges, tissue defects, often seen in agricultural injuries.
• Bite wound — high bacterial contamination (oral cavity flora), risk of rabies.
• Gunshot wound — bullet or shrapnel; three zones of damage: wound canal, contusion, and molecular concussion.
• Poisoned wound — caused by a chemical substance or venom.
• Mixed wound — a combination of several mechanisms.

By the degree of contamination

1. Clean (aseptic) — surgical wound without contact with the lumen of hollow organs.
2. Clean-contaminated — during elective gastrointestinal/respiratory tract surgery without significant contamination.
3. Contaminated — open trauma up to 6 hours, elective surgery with gross violation of asepsis.
4. Dirty — delayed > 6–12 hours, purulent, with necrotic tissues.

By depth

• Superficial — within the bounds of the skin.
• Penetrating — damages a body cavity (abdominal, pleural, cranial).
• Non-penetrating.

2. Phases of the wound healing process

Inflammatory phase (1–5 days)

• First subphase — vascular changes: vasoconstriction → vasodilation, plasma leakage, platelet plug formation, release of mediators (histamine, bradykinin, serotonin).
• Second subphase — clearing the wound of necrotic tissues: migration of neutrophils (0–2 days), followed by macrophages (2–5 days). Macrophages are key regulators of the transition to the proliferative phase.

Proliferative phase (5–21 days)

• Angiogenesis — formation of new capillaries.
• Fibroblasts synthesize type III collagen, fibronectin, and glycosaminoglycans.
• Granulation tissue is formed (bright red, granular, easily bleeding).
• Epithelialization from the wound edges and skin appendages.

Remodeling phase (21 days – 1 year or more)

• Replacement of type III collagen with type I collagen.
• Organization of fibers along lines of tension.
• The scar gradually fades and decreases in size.
• Scar strength: 20% at 3 weeks, 70–80% at 3 months, maximum — 80% of normal tissue.

3. Types of healing

4. Primary surgical debridement (PSD)

Goal — to convert an accidental infected wound into a conditionally aseptic one and create conditions for primary intention healing.

Timing

• Early — up to 24 hours. The standard, often sufficient without antibiotic prophylaxis.
• Delayed — 24–48 hours against the background of antibiotic therapy.
• Late — > 48 h, usually with already developed suppuration.

Stages

1. Wound toilet — cleansing with an antiseptic, removal of foreign bodies.
2. Incision — expansion of the wound for revision.
3. Excision of non-viable and crushed tissues (conservatively on the face and hands).
4. Hemostasis.
5. Restoration of anatomical structures (tendons, nerves, vessels).
6. Suturing (primary, delayed primary, early/late secondary).
7. Drainage if necessary.

5. Secondary surgical debridement (SSD)

Performed when wound suppuration has developed:

• Opening of pockets, removal of pus and necrosis.
• Washing with antiseptics (chlorhexidine, povidone-iodine, dioxidine).
• Drainage.
• Treatment in the secondary phase — moist-to-dry dressings with antiseptics, water-soluble ointments (Levomekol) until cleansing; then regeneration stimulators (Actovegin, Solcoseryl).

6. Prevention of tetanus and rabies

• Tetanus prophylaxis: in case of a "dirty" wound — tetanus toxoid ± tetanus immunoglobulin depending on vaccination status.
• Rabies prophylaxis: in case of bites by wild or unknown animals — KOVAB + rabies immunoglobulin into severe wounds / bites to the head, neck, hands.

7. Management of chronic wounds

Chronic wound — not healing for more than 4 weeks. Causes: impaired blood supply (venous ulcers, diabetic foot), prolonged pressure (pressure ulcers), infection, chronic diseases.

TIME principles

• Tissue — removal of necrosis (surgical, enzymatic, autolytic).
• Infection — control of biofilms, local antiseptics, systemic antibiotics for cellulitis.
• Moisture — maintenance of a moist environment (hydrocolloids, alginates, hydrogels).
• Edge — stimulation of epithelization from the edges (moisture retention, sometimes growth factors).

Additionally: treatment of the underlying disease (compensation of DM, compression therapy for venous ulcers, offloading for pressure ulcers), nutritional support (protein > 1.2 g/kg, vitamin C, zinc).

8. Pathological scars

• Hypertrophic — enlarged, but within the boundaries of the wound. Forms in the first 3–6 months, partially regresses after 1 year.
• Keloid — extends beyond the wound, does not regress. More common in individuals with dark skin; typical localization — earlobes, sternum, shoulders.
• Treatment: silicone sheets, glucocorticoid injections (triamcinolone), compression, laser, surgical excision + radiotherapy for keloids.

9. Systemic factors delaying healing

• DM (hyperglycemia ↓ leukocyte chemotaxis).
• Smoking (↓ microcirculation).
• Protein and vitamin deficiency.
• Taking GCs, cytostatics.
• Chronic renal, hepatic failure.
• Age > 70 years.

10. FAQ

After how many hours is a wound considered infected?
After 6 hours of contact with the external environment in standard locations. On the face and hands (rich blood supply) — up to 24 hours.

When are delayed primary sutures placed?
4–7 days after primary surgical debridement on a clean wound without signs of inflammation. Tactics for high risk of suppuration.

What should be used to treat a wound at home?
Surrounding skin — 5% iodine, brilliant green, or chlorhexidine. Inside the wound — chlorhexidine or saline. Hydrogen peroxide damages granulation tissue — not used during healing.

What is "tertiary intention"?
An obsolete synonym for delayed primary suture — when the wound is left open for 4–7 days, then sutured in the absence of suppuration.

When are systemic antibiotics indicated?
In case of pronounced contamination, bites, deep penetrating wounds, cellulitis around the wound, immunodeficiency.

See also: Burns · Peritonitis · Antibiotics · Acute abdomen · Surgery catalog · Clinical scales