Forensic Wounds and Healing Processes

Medico-legal Aspects of Wounds

• A wound is a disruption of tissue continuity caused by external mechanical force.
• Wounds are legally classified according to healing time and resulting infirmity.
  • Simple wounds: heal in less than 20 days, no permanent harm.
  • Dangerous wounds: heal in more than 20 days, or cause permanent harm.
  • Fatal wounds: lead to death.

Permanent Infirmity

• Permanent infirmity is the loss of function in an organ.
• Detailed legal classifications of wounds exist:
  • Abrasions (scratches) -1
  • Contusions (bruises) -2
  • Incised (cut) wounds -3
  • Contused (lacerated) wounds -4
  • Stab wounds -5
  • Firearm wounds -6

Abrasions (Scratches)

• Abrasions involve superficial skin layers, sometimes the upper dermis, due to friction with a rough, blunt object.
• Grazes are linear abrasions made by a sharp object.
• Types include pressure abrasions (nails, ropes) and sliding abrasions (friction).
• Abrasions can indicate: smothering/throttling (nail marks), ligature marks (rope impressions), bite marks from humans or animals, or from car accidents (tire marks).
• The shape of the abrasion reflects the object or force that caused it, and can be used in investigations.

Medico-legal Importance of Abrasions

• Abrasions are frequently observed in assault investigations, aiding the identification of the attacker and the type of crime.
• Sliding and pressure fingernail abrasions are two types.
• Evidence, such as the age of an abrasion, can be compared to the date of a crime.

Age of Abrasions

• The age of an abrasion can be estimated by examining its appearance over time.
  • First 2 days: soft scab
  • After 3 days: dry scab
  • After 1 week: scab falls, red area remains, in 3 weeks, this red area will disappear.
• The scab is made up of serum, red blood cells, and fibrinogen.

Site of Abrasions

• The location of abrasions provides insight into the type of assault.
  • Smothering: around the mouth
  • Strangulation/hanging - around the neck
  • Rape: around wrists, mouth, thighs
• The position of abrasions helps identify the assailant.
• The shape of bite marks can help identify the culprit and identify if the person has a missing finger.

Bruises (Contusions)

• Bruises are extravasations of blood into tissues following blood vessel rupture due to blunt force.
• They are commonly found in the skin but can also affect deeper tissues such as muscle and internal organs.
• The shape and size of a bruise depends on the force and extent of the blow, and the location of the blow on the body (presence of tough/vascular tissue.
• Other factors like the disease of the person, sex( women tend to bruise easily) age group (large bruises are common among elderly and very young). All these factors should be taken into consideration when determining if the bruise is a result of trauma.

Medicolegal Significance of Bruises

• Bruises can indicate the direction of the assailant and differentiate between various types of wounds.
• Their presence can signal struggle or resistance.
• Bruises can occur after death, so differentiating between antemortem (before death) and postmortem (after death) bruises is important. The age of the bruise is an important factor when identifying the extent of the trauma.
• Color changes on the bruise are related to the age of the bruise ranging from bright red, to blue, green, yellow, and brown.
• The appearance and location of the bruise, and its shape, can point to the nature of the object causing the trauma.

Lacerations (Contused Wounds)

• Lacerations are wounds in which the skin and underlying tissues are torn or split due to heavy blunt force (car accidents/falling from heights).
• Characterized by: ragged/irregular edges, tissue bridges across the edges (blood vessels/muscle fibers). Crushed blood vessels and minimal bleeding, crushed hair stems/follicles, difficulty healing (secondary intention). Usually contaminated with foreign bodies/microorganisms.
• Common subtypes include crushed wounds, torn wounds, internal organ rupture, avulsion wounds, and split wounds

Incised (Cut) Wounds

• Incised wounds are made by drawing a sharp object over the skin and underlying tissues.
• Characterized by: clean, regular edges, no tissue bridges, profuse bleeding, and rapidly heal.
• Varieties include multiple small parallel cut wounds (hesitation marks), wounds on palms/forearms (defense wounds), and surgical incisions.
• Postmortem cut wounds exhibit no gaping and lack vital reactions.

Stab Wounds

• Stab wounds are deep wounds caused by forcing a sharp-pointed object into the body
• Characterized by: depth exceeds length, clean edges, potential for internal injury, hemorrhage, and sepsis.
• The shape, length, and depth of a stab wound give clues about the weapon used.
• Presence of a complete penetration or missing handle can indicate full weapon contact.

Factors influencing wounds

• Age of wounds can often be used to determine if a wound is antemortem or postmortem.
• Certain medical conditions can influence how a person bruises or responds to a trauma.

Fabricated/Self-Inflicted Wounds

• These are simple, superficial wounds inflicted by a person on their own body.
• They are typically in accessible areas and relatively non-threatening.
• The age of the wound does not always align with the claimed time of occurrence.

Defense Wounds

• Injuries sustained while protecting oneself, sometimes in response to an attack.
• Punches may cause abrasions/bruises on the outer forearm/back of the hands and fingers.
• Kicks may lead to bruises on the outer thigh to protect the genitals.
• Knife attacks can result in cut wounds across the fingers and palm.

Causes of Death due to Wounds

• Early causes:
  • Hemorrhage
  • Traumatic shock (parasympathetic/adrenergic reactions causing cardiac arrest, pulmonary edema, ventricular fibrillation)
• Late causes:
  • Sepsis
  • Surgical interventions
  • Suprarenal hemorrhage
  • Disseminated intravascular coagulation (DIC)
  • Adult respiratory distress syndrome (ARDS)
  • Acute renal failure