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BLUNT FORCE TRAUMA

Berti Nelwan

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Forensic Pathology
Forensic Pathology is the branch of medicine which analyses victims of crime scenes medically. They are the last physician for the deceased and their role is to discover and interpret the evidence left during the autopsy.

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Analysis of Wounds
Not every crime victim is murdered. Physicians can contribute to proof of the severity of a crime or that a crime actually occurred in some cases for a living victim. Wounds provide evidence of the crime.

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Wound Categories
Bruises (or contusions) Abrasions (or grazes or scratches) Lacerations Incised wounds Puncture (or stab) wounds Gunshot wounds

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Definition

Injuries resulting from an impact with a dull, firm surface or object.

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The deaths resulting from blunt force trauma occur in a variety of scenarios:
almost all transportation fatalities jumping or falling from heights, blast injuries, Be struck by a firm object, such as a fist, crowbar, bat, or ball. Bite wounds and chop injuries may be considered variants of blunt force trauma, sharp force trauma, or a class of injuries unto themselves.

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Blunt force trauma is routinely involved in cases classified as accidents, as well as in cases of suicide and homicide.
it is important to document evidence of blunt force trauma in all autopsies one should not immediately assume that blunt force trauma is the cause of death

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For example,
Individuals may die of infections, thromboemboli, or organ failure that occurs as a delayed result of previous blunt force trauma. For purposes of death certification: Proximate Cause of Death the cause of death of an individual who dies of pneumonia after being hospitalized for several days for treatment of blunt force injuries following a motor vehicle collision should be certified as "acute bronchopneumonia complicating blunt force injuries due to a motor vehicle accident." the manner of death should then be certified as "accident."

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The severity of injuries inflicted as a result of blunt force trauma is dependent on the amount of kinetic energy transferred and the tissue to which the energy is transferred.
The kinetic energy associated with a moving object is equal to one half the mass of that object multiplied by the velocity of the object squared (W= 1/2 mv2).

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Important: the characteristics of the blunt object and the surface that is impacted.
Impacts involving a large surface will result in a greater dispersion of energy over a larger area and less injury to the impacted tissues. an impact on a small area of a curved surface, such as the head, will cause greater damage than would be caused were that same impact to occur on a flat surface, such as the back, since there will be a more concentrated point of impact on the head.

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The composition, or plasticity, of the tissues impacted also affects the resultant injuries.
For example, a person who is kicked in the chest may have only minimal injuries to the elastic skin surface, whereas deeper, more solid tissues such as ribs and internal organs may experience fractures and lacerations.

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The another factor affecting the severity of blunt force injuries is the amount of time the body and the impacting object are in contact.
A longer period of contact allows kinetic energy to be dissipated over a prolonged period, resulting in less damage to the tissues than an equally forceful impact with dispersion of energy over a brief period.

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This lecture focuses on the cutaneous manifestations of blunt force injury
Note: The blunt force trauma may cause contusions and lacerations of the internal organs and soft tissues, as well as fractures and dislocations of bony structures.

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The major types of cutaneous blunt force injuries are as follows:
Contusion (bruise) Abrasion Laceration Avulsion Fracture

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Bruises
A bruise is "a hemorrhage into tissues produced by the escape of blood from blood vessels". Bruises may be found in the skin, muscles, and internal organs.

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Bruises
Bruises are typically produced by a blunt force impact, such as a blow or a fall. They may also be produced by squeezing or pinching, where the force is applied gradually and then maintained.

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Important: Natural Bruises

Bruises may occur in a variety of natural diseases in which there is an abnormality of the clotting mechanism of the blood, e.g. scurvy (vitamin C deficiency), leukemia, alcoholic liver disease. This bruising is "spontaneous" because the injury which produces it is so insignificant as to typically pass unnoticed. The presence of such natural disease will exaggerate the bruising effects of any trauma.

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Problems with Skin Bruises

Delayed appearance Ageing (relative) Site of Trauma Shape of object Degree of force Post-mortem bruises Post-mortem lividity

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Classic Causes of Bruises

Finger pad bruises: battered babies, manual strangulation Different ages: repeated assaults Shoulders and arms: forceful restraint Wrists and ankles: dragging Inner thighs: forceful intercourse Chest: resuscitation Bruising is uncommon in Suicides

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Bruises
The extent of bruising is inversely proportional to the sharpness of the impacting object. Bruises may be associated with other blunt force injuries such as abrasions and lacerations. As a general rule bruising is not associated with incised wounds or stab wounds where there is a free flow of blood from the cut blood vessels rather than leaking into the tissues.

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Site of Trauma
In contrast with abrasions, the location of a bruise does not necessarily reflect the precise point of injury. Leaking blood will follow the path of least resistance and gravity.

For example, in the elderly, intense and widespread bruising of the lower thigh may follow a fracture of the hip; a bruise of the temple may move down to the cheek; a fractured jaw may result in bruising appearing on the neck.

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Delayed Appearance
Deep bruises may have delayed appearance at the skin surface. Deep bruises may require as long as 12 or 24 hours to become apparent, and some may never do so The more superficial the source of bleeding, the sooner the discoloration will be seen on the skin surface. In a living victim, a second examination in one or two days may show bruising. In the dead, a further examination one or two days after the original autopsy may show bruises which were not previously seen and reveal previously faint bruises.

This may be particularly the case with "fingerpad bruises" produced by hands. Ultraviolet (UV) light may disclose bruises which are not otherwise identifiable at the time of examination.

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Autopsy and Bruising

Bruising in Deep Tissue
1. Possibly life-threatening 2. Sometimes no external injury 3. Revealed in autopsy

Documenting Bruising
1. Photography 2. Notes

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Degree of Force
The size of a bruise is an unreliable indicator of the degree of force causing it. However, a heavy impact is likely to produce a large bruise and a light impact to produce a small bruise. If bruising is slight, it is reasonable to assume that the degree of violence was slight.

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Determining Degree of Force in Bruise Patterns

Location: Some areas of the body bruise more easily than others. The face bruises more readily than the hands. Bruising occurs more readily in loose tissues and where there is a large amount of subcutaneous fat Bruising is less apparent where the skin is strongly supported by fibrous tissue or if the muscle tone is good.

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Determining Degree of Force in Bruise Patterns

Age
Infants and the elderly tend to bruise more easily than young and middle aged adults. Infants have loose and delicate skin, and the abundant subcutaneous fat. Elderly have degenerative changes in the tissues which support the small blood vessels of the skin and subcutaneous tissues.

Gender:
Women bruise more easily than men because they have more subcutaneous fat and this is particularly true of obese women.

Natural Disease Skin color

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Causitive Object
The shape of the bruise is most likely to reflect the shape of the causative object when the object is small and hard and death occurs soon after injury

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Causitive Object
A doughnut bruise is produced by an object with a rounded contour (e.g. baseball). Two parallel linear bruises result from a blow with a rod or stick Bruises can follow rounded contours if they are caused by a flexible object like a lash

If the blow with the rod is struck against the buttocks, - a particularly pliable, curved, soft surface - the tissues are compressed and flattened under the impact; the resulting bruise will follow the curved contour of the buttocks. A pliable weapon such as a strap or electric flex may produce a similar appearance as it wraps around the body on impact.

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Causitive Object
Bruises produced by fingerpads as a result of gripping are usually larger than the fingerpads themselves. The pattern and location suggests the mechanism of causation:
On the neck in throttling On the upper arms in restraint.

Such bruises are referred to as patterned.

A bruise which bears the imprint of the shape or contour of the impacting object is said to be patterned. A tracing of the pattern may be made to match to the causative object, or photographs of the injury and object may be superimposed. Patterned bruises of this type may be associated with patterned (imprint) abrasions. ligatures around the neck in strangulation the headlight or bumper of a vehicle in hit and run the muzzle or sight of a gun in contact gunshot wounds.

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Aging of Bruises
Color changes a bruise goes through can give a rough estimate of time of injury Colors result from breakdown of hemoglobin from tissues
Dark blue/purple (1-18 hours) Blue/brown (~1 to 2days)

Contusions Bruise due to rupture of small blood vessels (skin or internal organs) Colors result from breakdown of hemoglobin from tissues

Green (~ 2 to 3 days) Yellow (~3 to 7 days)

This rate assumes person is healthy, however.

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Camps:
red immediate

dusky purple / black

green

soon after
days 4 -5

Yellow
resolution Glaister: violet blue green yellow

days 7 - 10
days 14 - 15

immediate day 3 days 5 - 7 days 8 - 10

resolution

days 13 - 18

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Polson and Gee: red dark / red black greenish tinge yellow resolution < 24 h around day 7 around day 14 up to 30 days

Smith and Fiddes: red

purple black

immediate
soon after

green
yellow

days 4 -5
days 7 - 10

resolution

days 14 - 15

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Aging Bruises
While accurate estimation of the age of a single bruise is not possible, a fresh bruise can be distinguished easily from one which is several days old. Establishing that bruises are of different ages may be of medical importance where there is an allegation of repeated assaults:
Child abuse Wife beating Where pre-existing injuries need to be distinguished from those produced by a recent assault like a chronic alcoholic who was assaulted.

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Post Mortem Bruises

Bruising is a phenomenon of living tissuesince it usually requires circulating blood to push the blood from the veins. It isnt possible to tell bruises that occurred causing death from those that occurred minutes earlier. You can only say they occurred at or about time of death.

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Post Mortem Bruises

It requires considerable violence to produce a bruise post mortem or after death. These bruises are smaller relative to the degree of force used. Post mortem bruises are most readily produced in areas of hypostasis (post mortem lividity, livor mortis) or where tissues can be forcibly compressed against bone. A bruise can develop on the head after the body is left lying on the back.

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Post Mortem Lividity (hypostasis, livor mortis)

The settling, after death, of blood within the blood vessels under the influence of gravity. This results in a purplish discoloration of parts of the body that are lower while sparing areas of pressure contact - contact pallor. The pattern and distribution of lividity distinguishes it from bruising. A body found on its back has livor mortis on the dorsal (back) side with pale areas where the bone contacted the floor.

In doubtful cases, an incision of the skin will cause blood to ooze from the cut ends of vessels in instances of lividity. In contrast, the blood within the tissues in bruises will not ooze. Washing the cut surface with running water will remove the blood from livid tissues but not the blood infiltrating the tissues in bruises. Confirmation of the distinction may be made by microscopic examination.

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Postmortem changes on the chest caused by insect activity.

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Patterns of Injury
Bruises to the knuckles of the hands, together with bruises of the eyelids, bridge of the nose, cheeks and lips, suggest a fist fight. Bruising around the eyes (spectacle bruises) may be produced by direct blows, but also commonly result from a fracture of the base of the skull, e.g. in vehicle collisions or gunshot wounds to the head They may also follow blunt impact to the forehead producing jolting of the eyeballs in their sockets with tearing of small orbital blood vessels.

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Patterns of Injury
Injuries in motor vehicle collisions almost invariably include abrasions and lacerations as well as bruises. Patterns of injury may allow reconstruction of incidents involving pedestrians or allow distinction between driver and front seat passenger.

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Patterned abrasion on the head due to impact by a motor vehicle.

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Two contusions on the skin of the chest

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A contusion on the arm.

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Abrasions
A scraping injury to the superficial layers of the skin (epidermis and dermis) that results from friction against a rough surface

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Abrasions
Side impact produces a moving abrasion:
Indicates direction. Trace material (e.g. grit).

Direct impact produces an imprint abrasion:

Pattern of causative object.

All abrasions reflect site of impact (in contrast with bruises). Assessment of age of abrasions is difficult. Post-mortem abrasions - Brown, leathery

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Abrasion on the elbow.

Abrasion on the knee.

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BRUSH-BURN ABRASION
One common type of blunt force injury is the socalled brush-burn abrasion. Brush-burn abrasions are broad, dried abrasions that often have a yellow-orange or orange-red coloration. These abrasions are caused by dragging or scraping the surface of the skin against a rugged surface; they are most often encountered when a body slides on pavement. These abrasions are sometimes called "road rash."

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Brush-burn type abrasion on the left flank.

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Laceration:
A bursting of the skin or other tissues resulting from compression or stretching associated with impact by a blunt object or surface

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Lacerations (Tears, Splits)

Splitting of the skin by the direct crushing of blunt trauma. Typically over bone, e.g. scalp, eyebrow, cheekbone.

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Lacerations
Distinguished from incised wounds by:
Adjacent abrasion/bruise
Ragged edge Tissue bridges in depth

Forensic Importance
Not related to object shape Trace evidence Relatively little blood loss (except scalp) Rarely suicidal

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Two abraded lacerations on the forehead.

A laceration near the vertex of the scalp.

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Several chop injuries inflicted by a boat propeller.

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Avulsion:
A more severe form of laceration in which the soft tissues, musculature, and/or bone are torn away from the normal points of attachment

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Avulsion of the right leg.

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Fracture:
A break, rupture, or separation of tissue (most often bone) resulting from an impact

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Thank You