3. Open injuries (wounds)

1. Definition

• Wound (vulnus) → breach of the integrity of skin or mucosa, with or without damage to deeper tissues, caused by a mechanical agent
• Cardinal signs:
  1. Pain
  2. Bleeding
  3. Gaping → separation of the edges by elastic tissue retraction
  4. Loss of function

2. Parts of a wound

• Edges
• Walls
• Floor (blind wound) or channel
• Entry and exit openings (through-and-through wound)

3. Pathological processes in the wound

Zones of damage

1. Wound defect (channel) → destroyed tissue, blood clot, foreign bodies, bacteria
2. Zone of primary traumatic necrosis → tissue killed directly by the agent
3. Zone of molecular concussion → damaged but viable tissue; becomes secondary necrosis with poor perfusion, oedema or infection
4. Width of zones 2 and 3 → greatest in gunshot, crushed and contused wounds; minimal in incised wounds

Microbial contamination

• Every accidental wound → primarily contaminated
• Bacteria stay on the surface for the first 6–8 h, then invade the tissue
• Golden period → 6–8 h; primary closure possible after debridement
• Face and scalp → up to 24 h because of the rich blood supply
• Infection threshold → > 10^5 organisms per gram of tissue
• Secondary contamination → later, from dressings, hands, hospital

Healing processes

1. Haemostasis
2. Inflammation → cleansing of the wound, days 1–4
3. Proliferation → granulation tissue, epithelialisation
4. Remodelling (maturation) → scar
5. Healing by primary or secondary intention → see Question 8

4. Classification

By agent (type of wound)

• Incised (vulnus scissum) → knife, glass; smooth edges, gaping, heavy bleeding, minimal necrosis, heals well
• Stab (vulnus punctum) → narrow, deep; small entry, risk of hidden organ injury and anaerobic infection
• Cut-stab (vulnus caesum) → axe, heavy sharp object; deep, with bone injury
• Contused (vulnus contusum) → blunt object; irregular edges, wide necrosis zone, little bleeding
• Lacerated (vulnus laceratum) → tearing force; irregular edges, flaps
• Crushed (vulnus conquassatum) → severe crushing; most tissue necrosis
• Bite (vulnus morsum) → animal or human; heavy oral flora, high infection risk, rabies risk
• Scalp (avulsion, degloving) → skin peeled off the deeper tissues
• Poisoned (vulnus venenatum) → snake or insect venom, chemicals
• Gunshot (vulnus sclopetarium) → bullet or fragment
  • Low velocity (< 600 m/s) → damage along the track
  • High velocity (> 600 m/s) → temporary cavity, damage far beyond the track
  • Entry small; exit larger and irregular
• Mixed → combined features

By course of the channel

• Blind → no exit
• Through-and-through (perforating) → entry and exit
• Tangential → grazes the surface

By relation to a body cavity

• Non-penetrating
• Penetrating → into the peritoneal, pleural, cranial or joint cavity

By origin

• Surgical (intentional) → aseptic conditions
• Accidental → always contaminated

By surgical contamination class

1. Clean → infection risk 1–2%; no viscus opened (hernia repair)
2. Clean-contaminated → < 10%; viscus opened under control (cholecystectomy)
3. Contaminated → 15–20%; spillage from bowel, fresh traumatic wound
4. Dirty → > 30%; pus, perforated viscus, old traumatic wound

By time

• Fresh → < 6–8 h
• Old → > 6–8 h, colonised
• Infected → clinical signs of infection

5. Clinical and surgical significance

• Examine for depth, foreign bodies, nerve, tendon and vessel damage
• Every wound → tetanus prophylaxis according to immunisation status
• Bite wounds → rabies assessment; not closed primarily, except on the face
• Penetrating abdominal or chest wound → assess for organ injury before closure
• Treatment → primary surgical treatment of the wound (Question 9)