Blunt Force Injuries

BFT Basics & Bruises - The First Impact

• Blunt Force Trauma (BFT): Injury by non-penetrating impact. Mechanisms: compression, traction, shearing.
• Abrasions (Grazes/Scratches):
  • Superficial epidermal damage.
  • Types: Scratch, Graze, Imprint/Patterned (e.g., ligature, tyre).
  • MLI: Site of impact, direction (skin tags).
• Contusions (Bruises):
  • Subcutaneous hemorrhage from ruptured vessels; skin intact.
  • MLI: Site, weapon pattern, comprehensive assessment (color changes unreliable for precise dating), violence degree.
  • ⚠️ Bruise Dating Limitations: Color changes offer only general estimation - highly variable due to individual healing rates, skin tone, depth, location.
    • Modern forensic practice: Color-based dating unreliable for precise medico-legal conclusions
    • Comprehensive assessment considering mechanism, clinical presentation crucial
  • ⚠️ Delayed Appearance: Bruises may appear hours to days post-injury; can manifest distant from impact site due to blood tracking
  • 

⭐ Bruises over lax tissues (e.g., eyelids) are often larger than over bony prominences for the same force.

💡 Absence of visible bruise at initial examination does not rule out blunt force injury - re-examination after time often prudent.

Lacerations & Fractures - Tears, Snaps, & Cracks

• Lacerations: Skin/tissue tears from blunt force.

  • Margins: Irregular, abraded, bruised.
  • Tissue bridges: Pathognomonic. 📌 Differentiates from incised wounds.
  • Undermining common. Foreign bodies often present.

• Fractures: Bone discontinuity.

  • Skull Fractures:
    • Linear: Most common.
    • Depressed: Bone pushed inwards.
    • Comminuted: Multiple fragments.
    • Diastatic: Sutural separation (children).
    • Basal: Signs 📌 "BRC" - Battle's sign (mastoid), Raccoon eyes (periorbital), CSF leak.
  • Ring fracture: At foramen magnum (e.g., fall from height).

⭐ Lacerations are caused by crushing or stretching forces leading to tearing of tissues, characteristically showing bridging strands of tissue across the wound gap.

Head Trauma - Cranial Catastrophes

• Scalp Injuries:
  • Abrasion, Contusion (subgaleal haematoma 'Goose egg'), Laceration (commonest).
  • Black Eye (Raccoon eyes/Panda eyes): Periorbital ecchymosis with tarsal plate sparing; Anterior cranial fossa fracture.
  • Battle's Sign: Mastoid ecchymosis; Middle/Posterior cranial fossa fracture.
• Skull Fractures (#):
  • Linear (most common), Depressed (Pond/Ping-pong in infants), Diastatic (suture separation), Basal (CSF leak: rhinorrhea, otorrhea).
  • Ring #: Around foramen magnum (fall from height/blow to vertex).
• Intracranial Haemorrhages (ICH):
  • Extradural (EDH):
    • Source: Middle Meningeal Artery (pterion fracture).
    • Lucid interval (classic).
    • CT: Biconvex/Lenticular, hyperdense. Does not cross sutures.
  • Subdural (SDH):
    • Source: Bridging veins.
    • Acute (trauma, shaken baby) vs. Chronic (elderly, alcoholics).
    • CT: Crescent/Sickle-shaped, hyperdense (acute). Crosses sutures.
  • Subarachnoid (SAH):
    • Source: Trauma (most common overall); Ruptured Berry aneurysm (non-traumatic).
    • "Worst headache of life". Nuchal rigidity.
    • CT: Blood in sulci/cisterns. LP: Xanthochromia.
  • Intracerebral/Contusions:
    • Coup (at impact site) & Contrecoup (opposite impact).
    • Commonly affects Frontal/Temporal lobes.

⭐ Lucid Interval: A period of consciousness between initial unconsciousness (due to concussion) and subsequent deterioration (due to haematoma expansion) is a classic feature of Extradural Haemorrhage (EDH).

Torso Trauma & Telltales - Body Blows & Beyond

• Thoracic Injuries:

  • Rib # (Flail chest: ≥3 cons. ribs, ≥2 places each - focus on respiratory compromise)
  • Lung: Contusion, Laceration
  • Heart: Commotio cordis, Cardiac rupture. Aortic rupture (isthmus).
  • Diaphragmatic rupture
  • CT scan gold standard for thoracic trauma assessment

• Abdominal Injuries:

  • Solid organs: Spleen & Liver (most common), Kidneys, Pancreas.
  • Hollow viscus: Intestines (Seatbelt sign → Chance #), Stomach.
  • Retroperitoneal hemorrhage

• Patterned Injuries: Imprint of weapon (e.g., tram-line bruise).

• Bruise Differentiation (Ante-mortem vs. Post-mortem):

  📌 BILiVeR: Blue/Black → Green → Yellow → Brown/Resolved (Variable timing - requires histology + clinical correlation)

• Complications: Hemorrhage, Infection, Fat embolism, ARDS.

⭐ Rupture of the aorta in blunt thoracic trauma most commonly occurs at the aortic isthmus.

High‑Yield Points - ⚡ Biggest Takeaways

• Blunt force trauma manifests as abrasions, contusions, lacerations, and fractures.
• Abrasions: Superficial; patterned abrasions can identify the impacting object.
• Contusions: Age estimated by color changes; ectopic bruises (e.g., Battle's sign) indicate underlying fractures.
• Lacerations: Characterized by irregular margins, tissue bridges, and surrounding bruising.
• Patterned injuries, like tram-track bruises, are vital for weapon identification.
• Key head injuries: Coup-contrecoup mechanism; ring fractures at skull base from falls.