Laceration - Definition and Types

Definition

• Underlying rigidity: Where bone lies just beneath thin skin (e.g., scalp, eyebrow, shin), blunt force readily produces a laceration - which may even simulate an incised wound.
• Underlying flexibility: Where tissue is soft (e.g., cheek, abdomen, limbs), the same force more often produces only a bruise or contusion.

Classification of Lacerations (by Mechanism)

1. Split Laceration

• Mechanism: Blunt, near-perpendicular impact compresses skin between the object and the underlying bone.
• Appearance: Linear split, often closely resembles an incised wound ("incised-looking laceration"). On close examination (with magnifying lens), hair follicles are crushed rather than cleanly cut, and tissue bridges are present - confirming its lacerated nature.
• Sites: Scalp, eyebrow, face, cheek bone, lower jaw, shin, iliac crest, perineum - areas where skin overlies bone with little subcutaneous fat.
• Medicolegal note: The most common type encountered and the one most likely to be confused with an incised wound.

2. Stretch Laceration (Tangential Laceration)

• Mechanism: A blunt, glancing or tangential impact causes the skin to overstretch until it tears, producing a skin flap.
• Appearance: A flap of skin partially detached from underlying bone or deep fascia. The direction of the flap indicates the direction of the applied force.
• Common causes: Head striking a vehicle windscreen, run-over injuries by motor vehicle, compound fracture (bone deformity tears overlying skin), glancing kicks.
• Foreign material may be found in the wound depth.

3. Avulsion (Shearing/Horizontal Laceration)

• Mechanism: A shearing/grinding force delivered at an acute horizontal angle detaches or tears off a portion of skin or tissue from its attachments.
• Appearance: Degloving of skin over a large area ("flaying"). Underlying muscles are crushed; bones may be fractured.
• Common causes: Lorry/truck wheel running over a limb, machinery injuries, hair caught in machinery (scalp avulsion).
• Special variant: In shearing injuries, the skin surface may appear intact while soft tissue is avulsed from underlying fascia, creating a pocket filled with blood (common on back of thighs in pedestrians struck by vehicles).

Avulsion (degloving) laceration of the lower leg - Parikh's Forensic Medicine

4. Tears (Irregular Laceration)

• Mechanism: Impact against irregular or sharp-edged blunt objects (e.g., motor car door handles, broken bottles, earthenware pots, falls on rough surfaces).
• Appearance: Irregular tearing of skin and deeper tissues. Foreign material in the wound may provide a clue to the causative object.

5. Cut Laceration

• Mechanism: Caused by a heavy, relatively sharp-edged instrument (axe, hatchet, chopper). Combines features of both laceration and incised wound.
• Appearance: Margins are abraded with surrounding bruising. This term is considered somewhat ambiguous and best avoided in formal reporting (Essentials of FMT, 2026).

6. Internal Laceration

• Mechanism: Blunt force exceeds the tensile strength of an internal organ without necessarily producing external injury.
• Causes of visceral laceration: (1) Direct injury by bone fragments, (2) traction/strain shears within viscera, (3) stretching of visceral attachments, (4) hydrostatic forces.
• Example: Liver laceration from blunt abdominal trauma; there may or may not be surface bruising/abrasion.

Sub-classification by Associated Features

Characteristic Features of a Lacerated Wound

Shape of Laceration and the Weapon

• Crescentic laceration - hammer head (blunt object with an edge)
• Stellate laceration - blunt round end (e.g., rod end)
• Linear with split/Y-end - stick or rod
• The convexity of the laceration curve points in the direction of force.

Medicolegal Importance

1. A laceration is produced by blunt force - identifying the type helps reconstruct the weapon and direction of injury.
2. Split lacerations on the scalp can mimic incised wounds - always examine carefully and shave hair around the wound.
3. The flap direction in stretch lacerations and the undermined side in angulated impact both indicate direction of force, which is important in assault reconstruction.
4. Internal lacerations (e.g., liver, spleen) can cause fatal hemorrhage with no external wound - important in medicolegal autopsies.

• [Parikh's Textbook of Medical Jurisprudence, Forensic Medicine and Toxicology](Q.16.5, p. 253)
• [The Essentials of Forensic Medicine and Toxicology, 36th edition (2026)](Chapter 8, p. 195)
• [P.C. Dikshit Textbook of Forensic Medicine and Toxicology](Chapter 13)