Autopsy & forensics

• Sharp force injuries: injuries produced by sharp objects
• Sharp object: an object that has a sharp edge or pointed extremity
  • Numerous objects can produce sharp force injuries; knives are the most commonly used weapons (Int J Legal Med 2000;113:259, J Forensic Sci 2020;65:833)
    • Typical knife contains:
      • Handle: the portion that can be gripped; it can be used as a blunt force weapon, producing patterned injuries
      • Guard (or finger guard): a metal bar at right angles between the blade and the hilt; the guard may include the quillon, protuberances extending perpendicularly to the long axis of the knife that stop the fingers from sliding forward onto the knife blade and cutting edge; the quillon may produce patterned skin injuries (Italian Journal of Legal Medicine 2012;1:4)
      • Blade: can have a plain edge or serrated edge with rounded or pointed extremity and a single or double edge
      • Atypical sharp and pointed objects that can be used to produce sharp force injuries include but are not limited to scissors, screwdrivers, fragments of glass (e.g. broken bottleneck or glasses), forks, ice picks, etc. (Forensic Sci Int 2001;123:135)
• Sharp force wounds typically show cleanly divided edges and may involve different types of tissue with the same contact
• Depth of the wound track relative to the length of the cutaneous wound distinguishes a stab from an incision
• Sharp force injuries can be subcategorized as follows:
  • Incised wounds
  • Stab wounds
  • Chop wounds
  • Atypical wounds (atypical weapons, combined incised and stab wounds)

• Also called cuts or slashes
• Surgical incision is a typical example of an incised wound
• Wounds caused by sharp objects that contain a blade with at least 1 sharp edge (knives, razors, swords, etc.)
  • Produced by a tangential movement of the blade to the skin
  • Typically, wounds are superficial and longer than they are deep
    • In most cases, incised wounds tend to be deeper at the point of the first contact with the skin (entrance) and become progressively more superficial as the wound approaches the distal end (exit)
  • Wounds show clear separation of the injured and uninjured tissues
  • Tissue bridges absent in the center of the wound (BMC Med Imaging 2012;12:32)
    • Tissue bridging is caused by incomplete separation of stronger tissue elements, such as blood vessels and nerves
    • Critical feature to differentiate incised wounds from laceration (tear in tissue caused by blunt trauma, e.g. tearing or crushing)
  • Based on the depth of penetration and the energy applied to the blade, there may be different wounds:
    • Abrasions: though typically produced by blunt objects, when the blade affects the superficial layer of the skin involving just the epidermis, it may leave superficial linear scratches (abrasions)
    • Cuts: the blade penetrates deeper, resulting in skin and soft tissue splitting
    • Mutilations: the blade is used vigorously on protruding body areas, resulting in their complete detachment
  • Wound tails: tails are superficial, linear scratches localized at the level of the wound's extremities that are due to the blade movement on the skin; as a general rule, the tail is shorter and deeper at the entrance point (entrance tail) where there is higher pressure applied to the blade; it is longer and more superficial at the exit point (exit tail) as the blade progressively rises from the skin, decreasing the pressure toward the end
    • Tails may give information about the direction in which an incised wound was inflicted; associated skin and soft tissue injuries or clothing defects need to be considered to evaluate the direction
    • Tails can be absent
    • Entrance tail can be absent if the applied pressure is too vigorous, causing skin separation without scratching
    • Exit tail may be absent or shorter than the entrance tail when the affected body area is convex: the involved surface escapes the sliding action of the cutting edge
• If the skin surface is not flat but folded (hands, knuckles, breast, etc.), a single cut can determine more than 1 wound (wrinkle wounds); the sharp edge of the object moves from crest to crest, leaving intact skin between the incised wounds
• Incised wounds are rarely fatal but can be life threatening if they affect body areas with superficial major blood vessels, such as the neck and the wrist

Contributed by Lorenzo Gitto, M.D., Ponni Arunkumar, M.D., Luigi Bonaccorso, M.D. and the Cook County Medical Examiner's Office

Contributed by Lorenzo Gitto, M.D., Ponni Arunkumar, M.D., Luigi Bonaccorso, M.D. and the Cook County Medical Examiner's Office

Contributed by Lorenzo Gitto, M.D., Ponni Arunkumar, M.D., Luigi Bonaccorso, M.D. and the Cook County Medical Examiner's Office

What is the injury shown in the picture?

1. Chop wound
2. Incised wound
3. Laceration
4. Scissor wound
5. Stab wound

B. Incised wound. The wound shown in the picture is a typical example of an incised wound. The white arrow indicates the wound tail that is commonly observed in incised wounds. These wounds are superficial and longer than they are deep. It is mandatory to distinguish them from lacerations (answer C) that are produced by blunt objects. The presence of tissue bridges in the center of the wound is the hallmark of lacerations. A stab wound (answer E) is typically deeper than its cutaneous length. A wound track can be frequently observed in the center of the lesion. Chop wounds (answer A) are produced by objects that are generally heavy, relatively blunt and with at least 1 sharp edge. The center of the wound is usually cleaner and deeper than incised wounds. Scissors (answer D) produce different stab wounds based on their action (open or closed).

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Reference: Sharp force injuries

Based on the findings shown in the picture, what is the most probable manner of death?

1. Accident
2. Homicide
3. Natural
4. Suicide
5. Undetermined

B. Homicide. The picture shows a typical example of an active defense wound. These wounds are generally produced by the attempt of the victims to grab the blade. Suicidal sharp force injuries (answer D) are generally multiple and located to the wrist, neck or chest. Accidental sharp force injuries (answer A) are rarely described in the literature and they generally involve random body areas. A natural death (answer C) can be excluded by the evidence of a sharp force injury. An undetermined manner of death (answer E) could be an option if there is no clear evidence of an assault. In this case, this typical active defense wound is most consistent with homicide.

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Reference: Sharp force injuries