Medicolegal Investigation of Wounds Caused by Sharp Force

Injuries caused using a sharp object are known as sharp force wounds. Injuries caused by such sharp-edged instruments/weapons result in either cutting or stabbing. This depends upon whether the instrument has been used in a swiping manner or a thrusting manner. Careful examination of a cut or stab can help reconstruct the events.

It is necessary to identify the type of wound to estimate the probable type of weapon used. Injuries caused due to a sharp force are different from those caused by a blunt force. Wounds using a sharp object can be a result of accident, suicide, or homicide. The healing of these injuries is a sign that the wounds resulted before death.  

Wounds caused after death and before death are distinguishable because of the signs of healing. The space between the wound gets filled with blood immediately after the injury and the blood gets clotted and seals the wound.

The gross examination shows dry margins after 24 hours. By the 3^rd day, fibroblast will be present at the wound site and then within 48 hours, the wound gets covered by a layer of epithelium. And slowly in 4 weeks, the scar tissue with the epithelialized surface is formed.

Types of Sharp Force Wounds

Sharp Force Wounds are caused by weapons with sharp edges such as knives, razors, swords, etc.

1. Incision

These are also known as cuts or slash. It is a form of mechanical injury characterized by an orderly solution of skin and tissues by a sharp cutting weapon or force. It might be produced by objects like a knife, razor, scalpel, etc. The force is applied over a narrow area corresponding with the cutting edge of the blade of a weapon.

The incision is caused by striking a body with a sharp object, or drawing or swiping action of the weapon, or by sawing. Swiping action will produce tailing at one end and sawing action will produce multiple incision wounds on the skin at the beginning of the wound, which merges into one single wound at the end. Glassing injuries and hesitation cuts are also classified under this.

Features of Incision Wounds

• The length of the wound is greater than the breadth or depth of the wound. The length has no relation with the length of the cutting edge of the weapon.
• It is broader than the edge of the weapon because of the retraction of the dividing tissues. It is sometimes spindle or zig-zag shaped depending on the skin. It appears zig-zag if the skin is lax like the skin of the scrotum or axilla.
• These wounds have clean-cut, well-defined margins. They might appear to be irregular if the wound is inflicted on loose skin. They might be everted. But if the thin layers of muscle fibres are closely attached to the skin as in the scrotum, then the wound might be inverted.
• Because of these clean-cuts hemorrhages are more when compared to lacerated wounds.
• If the weapon is struck obliquely on the body part, it will cause the beveling of one edge and undermining of other edges. These undermined edges indicated the direction from which the slashing stroke was made.

2. Chopping Wounds

These wounds are caused by hacking or chopping motion with a fairly sharp and relatively heavy weapon like an ax, chopper, sword, etc.

Features of Chopping Wounds

• Margins might show bruising or abrasion.
• The edges are not sharp and clean-cut.
• It is wider and deeper than incised wounds.
• If the wound is inflicted obliquely, then the margins will be beveled.
• The heel end of the wound which is the part near to the assailant will be deeper than the distal part from the assailant known as the toe end. This will help in understanding the relative position of the assailant and the victim.
• The weight of the weapon is important for the penetration of weapon into the tissues considerably.

3. Stab Wounds

These are also known as puncture wounds. It is a piercing wound produced by the application of mechanical force along the long axis of a narrow or pointed object. They are mainly classified into penetrating or perforating wounds. The thrusting or stabbing motion produces a wound that is greater in the depth than the dimension of the surface wound.

Features of Stab Wounds

• The length of the surface wounds will be slightly smaller than the width of the weapon.
• Repetition of stabbing without complete withdrawal may double the entry wound or will produce erratic surface wounds.
• Margins are found to be inverted, clean-cut, without bruising. If abrasion or bruising is found, then it indicates that the blade had been inserted completely.
• The breadth of the wound is not related to the thickness of the weapon due to the gaping of the wound margins.
• The depth is related to the length of the blade but it cannot be said for sure.  
• The most common shape of stab wounds is the ellipse. Visceral wounds may produce shapes similar to ‘A’, ‘V’, or square or diamond, cruciate, stellate, etc.

Conclusion

Understanding the wounds and their features are important to estimate the cause of injury, nature of injury, age of injury. It helps to distinguish between fabricated wounds, defense injuries, and self-inflicted injuries.

Some types of sharp force wounds can indicate the dimension of the weapon, direction of thrust, and amount of force applied. Most importantly the manner of infliction, whether it is suicidal, homicidal, or accidental can be understood by observing the type and features of the wounds.