BLUNT FORCE TRAUMA

BLUNT FORCE TRAUMAGuidelines for Reports by Autopsy Pathologists; Vernard Irvine Adams, MD; Department of Pathology and Cell Biology, University of South Florida, Tampa, Florida, USA. 2008Textbook of Traumatic Brain Injury; Thomas Genrelli MD. American Psychiatic. 2005Clinical ForensicMedicine3rd editionEdited by W.D.S. McLay. 2009Blunt Force Trauma; Pathology Forensic Journal. 2010

Forensic PathologyForensic 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.Analysis of WoundsNot 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.Wound CategoriesBruises (or contusions) Abrasions (or grazes or scratches) Lacerations Incised wounds Puncture (or stab) wounds Gunshot wounds

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

The deaths resulting from blunt force trauma occur in a variety of scenarios:almost all transportation fatalitiesjumping 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.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 autopsiesone should not immediately assume that blunt force trauma is the cause of deathFor 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 Deaththe 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."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).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.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.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.This lecture focuses on the cutaneous manifestations of blunt force injury

Note:The blunt force trauma may cause contusions and lacerations of the internalorgans and soft tissues, as well as fractures and dislocations of bony structures.The major types of cutaneous blunt force injuries are as follows:Contusion (bruise)AbrasionLacerationAvulsionFracture

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.

BruisesBruises 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. Important: Natural BruisesBruises 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.Problems with Skin BruisesDelayed appearance Ageing (relative) Site of Trauma Shape of object Degree of force Post-mortem bruises Post-mortem lividity

Classic Causes of BruisesFinger pad bruises: battered babies, manual strangulation Different ages: repeated assaults Shoulders and arms: forceful restraint Wrists and ankles: dragging Inner thighs: forceful intercourse Chest: resuscitationBruising is uncommon in SuicidesBruisesThe 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.Site of TraumaIn 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.

22For 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.Delayed AppearanceDeep 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 soThe 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.23This 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.

Autopsy and BruisingBruising in Deep Tissue1. Possibly life-threatening2. Sometimes no external injury3. Revealed in autopsyDocumenting Bruising1. Photography2. Notes

Degree of ForceThe 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. Determining Degree of Force in Bruise PatternsLocation: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 fatBruising is less apparent where the skin is strongly supported by fibrous tissue or if the muscle tone is good.Determining Degree of Force in Bruise PatternsAgeInfants 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 DiseaseSkin color Causitive ObjectThe 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

Causitive ObjectA 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 stickBruises can follow rounded contours if they are caused by a flexible object like a lash29If 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.

Causitive ObjectBruises 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 throttlingOn the upper arms in restraint.Such bruises are referred to as patterned.

30A 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 strangulationthe headlight or bumper of a vehicle in hit and runthe muzzle or sight of a gun in contact gunshot wounds.

Aging of BruisesColor changes a bruise goes through can give a rough estimate of time of injuryColors result from breakdown of hemoglobin from tissuesDark blue/purple (1-18 hours)Blue/brown (~1 to 2days)Green (~ 2 to 3 days)Yellow (~3 to 7 days)This rate assumes person is healthy, however. 31Contusions

Bruise due to rupture of small blood vessels (skin or internal organs)

Colors result from breakdown of hemoglobin from tissuesAging BruisesWhile 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 beatingWhere pre-existing injuries need to be distinguished from those produced by a recent assault like a chronic alcoholic who was assaulted.

Post Mortem BruisesBruising is a phenomenon of living tissue- since 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.Post Mortem BruisesIt 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.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.35In 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.

Patterns of InjuryBruises 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.Patterns of InjuryInjuries 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.