What is an incised wound

An incised wound (cut, slash, slice) is a clean cut through the tissues, (usually the skin and subcutaneous tissues, including blood vessels), caused by sharp-edged instrument, which is longer than it is deep. It is produced by the pressure and friction against the tissue, by an object having a sharp cutting edge, such as knife, razor, scalpel, sword, etc.

In this, the force is delivered over a very narrow area, corresponding with the cutting edge of the blade. Some injuries cannot be divided clearly into stab or incised wound, but may exhibit features of both.

Causes

(1) Striking the body with the edge of sharp-cutting weapon,

(2) by drawing the weapon, and

(3) by using the weapon like a saw in which case there may be more than one cut in the skin at the beginning of the incised wound which merge into one at the end.

A curved weapon like a sickle, produces a stab from the pointed end, and the one from the blade, sometimes with an intervening intact skin. When the skin becomes folded under the cutting edge of the weapon, a single movement of a sharp weapon may produce a series of incision, separated one from another by bridges of normal skin.

Characters

Margins

The margins are clean cut, well-defined and usually averted. The margins may be inverted, if a thin layer of muscle fibers is adherent to the skin as in the scrotum. They are free from contusions and abrasions.

A dull irregular-edged or nicked cutting edge may produce a incised wound with irregular, contused, and/or abraded margins, as it is caused more by the pressure applied by the weapon than by the cutting edge. A serrated knife may produce a saw-toothed cut on the body, if the blade passes obliquely or at shallow angle. The depth of it will not show bridging tissue.

Width

The width is greater than the edge of the weapon causing it, due to retraction of the divided tissues. Shaking of the blade tends to make it wider than the weapon.

Length

The length is greater than its width and depth, and has no relation to the cutting end of the weapon, for it may be drawn to any distance. When the skin becomes folded under the cutting edge of the weapon, a single movement of the weapon may produce a series of incised wound separated one from another by bridges of normal skin.

Shape

It is usually spindle-shaped due to greater retraction of it in the center. Gaping is greater if the underlying muscle fibers have been cut transversely or obliquely, and less when cut longitudinally. Incised wound crossing irregular surfaces may be irregular in depth, but will be linear.

It may take zig-zag course if the skin is loosely attached as in axillary fold, because the skin is pushed in front of the blade before it is cut. If the blade is curved, it will be crescentic. If the surface is convex, the straight-bladed weapon may also produce a crescentic one.

Hemorrhage

As the vessels are cut cleanly, the hemorrhage is more. If the artery is completely cut, the bleeding will be more. Spurting of blood occurs if an artery is cut.

Direction

Incised wound is deeper at the beginning, because more pressure is exerted on the knife at this point. This is known as the head of it. Towards the end of the cut it becomes increasingly shallow, till finally as the knife leaves the tissues the skin alone is cut. This is known as the tailing of it, and indicates the direction in which the cut was made.

Beveling cut

If the blade of weapon enters obliquely, the tissues will be visible at one margin, and the other margin will be undermined, and if the blade is nearly horizontal, a flap is caused. Beveling can be produced by sharp weapon only. It is usually homicidal and may indicate the relative position of the assailant and the victim.

Age of incised wound

In an uncomplicated type, healing occurs as follows: Fresh: Haematoma formation. 12 hours: The edges are red, swollen and adherent with blood and lymph; leucocytic infiltration.

24 hours : A continuous layer of endothelial cells covers the surface; overlying this a crust or scab of dried clot is seen.

Histopathology

Few minutes: Dilatation of capillaries and margination and emigration of neutrophils, reactive changes in the tissue histiocytes and swelling of the vascular endothelium. 12 hours: Reactive changes occur in the firlioblasts at the site of injury within few hours; monocytes’ appear in the exudate.

15 hours: Monocytes begin to undergo mitotic division.

24 hours: Epithelium begins to grow at the edges. Vascular buds begin to form.

72 hours: Vascularised granulation tissue is formed.

4 to 5 days: New fibrils are formed.

One week: Scar formation in small incised wound.

The above changes are considerably modified if infection occurs. In healing by second intention, inflammatory reaction is more intense and much larger amounts of granulation tissue are formed resulting in greater mass of scar tissue.

Wounds by Glass

Those produced by glass are lacerated, but can resemble incised and stabs. If a sharp-pointed piece of glass enters by its point, it has a stab-like appearance. Margins of it will almost always show tiny side cuts due to irregularities of the glass. Particles of glass may be found in it. Assault with broken glasses or bottles show multiple irregular incised-type wounds of variable depth and severity.

Medico-legal Importance

(1) They indicate the nature of weapon (sharp-edged).

(2) The age of the injury can be determined.

(3) They give an idea about the direction of the force.

(4) Position and character may indicate mode of production, i.e., suicide, accident, homicide.

Circumstances of Incised Injuries

Suicide

The important features of self-inflicted wounds are:

(1) They are multiple and parallel or nearly so, in any one area.

(2) They are uniform in depth and direction.

(3) They are relatively minor.

(4) The fatal ones are present on several limited accessible areas of the body, such as front of the neck, wrists, groin, and occasionally on the back of legs or on chest.

(5) Hesitation marks or tentative cuts or trial wounds – They are cuts which are multiple, small and superficial often involving only the skin and are seen at the beginning of the incised wound.

The sites of election of suicidal incised wound are: throat, wrist and front of chest When preliminary incisions are inflicted with some violence they may be few, but commonly they are superficial and multiple.

The fatal incisions are usually made with great violence, and the large gaping produced by suicide should not be mistaken for homicidal ones. When a safety razor blade is used, unintentional cuts are found on the fingers, where the blade has been gripped.

SUICIDAL incised wound of extremities

They are usually found on the flexor surface of the wrists, outer side of the left arm, and forearm, the front and outer side of the thighs, and the front of the abdomen and chest. Fatal incised wounds of the arms are almost always suicidal. Suicidal ones of chest are usually on the left side and directed downwards and inwards.

The one caused by running on knife tends to be more horizontal in direction. A person who commits suicide usually exposes the portion of the body to be incised, e.g. he may open his collar before cutting his throat, or pull up his shirt before cutting his chest or abdomen. Suicides usually do not injure the face.

HOMICIDAL WOUNDS

They are usually multiple and can occur in any region of the body. Wounds of the chest are usually present over a wider area and are more horizontal. They may be directed from below upwards which is rarely seen in suicidal ones. It is situated on the back, or in such a position as cannot be easily reached by a suicide, are homicidal.

Incised wound on nose, ears and genitals are usually homicidal, and are inflicted on account of jealousy or revenge in cases of adultery, causing dis-figuration. Cut-throats cause immediate death from hemorrhage, air embolism, or inhalation of effused blood into the respiratory tract.

ACCIDENTAL incised wound

They are common usually in the home or workshop, and are of a minor nature. They may be caused by falling upon a sharp cutting weapon held in the hand, or upon a sharp pointed object or by a sharp piece of broken glass. They may be situated anywhere on the body, but are commonly seen about the hands.

Some mentally disordered persons may inflict hundreds of small ones upon themselves. A knife, razor or broken glass may be used and a large number of cuts produced on the arms which may cross each other in groups.

Small stabs may be produced on the chest or temples. Paranoid schizophrenics with a strong religious flavor to their delusions may remove penis, scrotum, and testes. Ears and nose may be mutilated.

In a decomposed body, it is difficult to differentiate a laceration from it. When a body with incised wound, stab, or lacerations is immersed in water soon after infliction of injuries, the blood in it is lysed by water and passes into the water, and whether the injuries are antemortem or postmortem cannot be made out.

CHOP incised wound (Slash)

They are deep gaping ones caused by a blow with the sharp-cutting edge of a fairly heavy weapon, like a hatchet, an axe, sword, broad heavy knife, or meat cleaver. The dimensions of it correspond to cross section of penetrating blade. The margins are sharp and may show slight abrasion and bruising with marked destruction of underlying organs.

If the edge is blunt, the margins are ragged and bruised. Undermining occurs in the direction towards which the chop is made. When the whole blade strikes the body at the same time, the depth may be same throughout it.

Usually the lower end (heel) of the axe strikes the surface first, which produces a deeper incised wound than the upper (toe) end. The deeper end indicates the position of the assailant. In the skull, the undermined edge of the fracture defect is the direction in which the force is exerted, and the slanted one is the side from which the force was directed. In case of long bones, the bone fragments get loosened on the opposite side of the force.

A twisting force, after the chopping weapon has been embedded in bone, and as it is being removed can cause splintering of the bone, particularly near the ends of the chop incised wound. If the extremities are attacked, there may be complete or incomplete amputation of the fingers or other bones, and the joints may be separated or dis-articulated.

Incised wound on the head and trunk are usually associated with injuries to important structures and are fatal. The cranium may be depressed, but if the weapon strikes obliquely, a piece of the skull may be removed. If the chopping blow is tangential, a disk- shaped portion of bone or skin or soft tissue may be cut away. The neck may be almost completely separated.

Most of these injuries are homicidal and usually inflicted on the exposed portions of the body like the head, face, neck, shoulders and extremities.

Accidental injuries are caused by power fans, band saws or ship or airplane propellers, which may lacerate the soft tissues extensively or amputate parts of the body. Suicidal chop injuries are very rare.