The Rorschach butterfly, understanding bone biomechanics prior to using nomenclature in bone trauma interpretations.

Blunt traumas are the most common injuries observed and reported in medical examiner settings. Two common methods to describe bending bone fractures in the anthropological literature include the application of morphology nomenclature and describing characteristic fracture morphology. A nomenclature descriptor of blunt trauma, the butterfly fracture, is commonly used to describe broken long bones. In this paper, a case study of a fractured long bone in a pedestrian vehicle accident is used to highlight the complex interplay of factors involved in bone fracture formation. The application of a butterfly fracture pattern in trauma analysis is useful in establishing the bending direction of a bone, in identifying failure modes, and is valuable in teaching. Yet, butterfly fracture characteristics need to be examined in 3-dimensions for diagnosis of modes of failure, tension, shear and compression, and even then, the bending direction of a broken bone may not provide a reliable indicator of the point of impact (POI); this is especially true when a priori knowledge of the injury is unknown. Common fracture nomenclature, such as oblique, transverse and/or comminuted, as well as eponyms, are medical descriptions of an injury which are impractical to use for interpreting a broken bone from fleshed or skeletonized remains, in establishing a POI and in evaluating total bone trauma (TBT). The examination ofcharacteristic features on the surface of a broken bone associated with the modes of failure is the best approach for establishing the bending direction of a long bone.

Characteristics of child abuse by anteroposterior manual compression versus cardiopulmonary resuscitation: case reports.

Lethal and sublethal injuries to infants caused by anteroposterior manual compression can be accompanied by lateral rib fractures, hemorrhage into the viscera, and when severe, rupture of large vessels and solid organs. Abusers may claim that these injuries were sustained in an attempt to perform cardiopulmonary resuscitation (CPR). The difference between injuries caused by CPR and injuries caused by inflicted anteroposterior compression is examined in one sublethal and two lethal cases.

Diameter of cranial gunshot wounds as a function of bullet caliber.

Determination of bullet caliber becomes increasingly important in homicides where the bullet is missing. In cases with entrance wounds to bone that are circular and well defined it may be tempting to measure the defect and offer suggestions about bullet caliber. For this reason, the relationship between wound diameter and bullet caliber was examined using cranial bones from autopsy cases. The minimum diameter of 35 cranial wounds produced by .22, .25, and .38-caliber bullet was measured. The relationship of minimum wound diameter to bullet caliber was examined using a one way analysis of variance. Fisher's least significant difference test revealed no significant difference between .22-caliber and .25-caliber wounds, while the .38-caliber wounds were significantly different (P < .001) from .22-caliber and .25-caliber wounds. Variation in wound size resulting from such factors as bullet shape, surface treatment, strength characteristics, loss of gyroscopic stability, intermediate targets, tangential impacts, and existing fractures are discussed. Also, the large variety of calibers available are noted as complicating the prediction of caliber from wound size. In view of these factors caution is recommended in any attempt to determine precise bullet caliber from the minimum dimensions of the cranial gunshot entrance wound.

Effects of human decomposition on bullet striations.

Five different types of bullets, representing the major materials used in centerfire handgun and rifle ammunition, were inserted into the cranial, chest and abdominal cavities, muscle and adipose tissues of a fresh cadaver. The bullets were retrieved after the body was 90% decomposed. Observation and comparison of before and after photographs let each bullet serve as its own control. Results indicate the reactivity of bullet materials and the body region are significant factors affecting the corrosion process and may obscure rifling striations.

Identification of gunpowder in healed wounds.

A woman received a contact gunshot wound to the abdomen from a .22 caliber revolver. She recovered only to succumb to another gunshot wound six months later. The initial wound was dissected and multiple intact granules of round flake gunpowder were recovered. Cross sections of granules were clearly identifiable in histologic slides. Recovery of intact powder in remote wounds has not been previously described and may help classify the ammunition and weapon used to produce the injury.

Characteristic features of entrance wounds from hollow-point bullets.

Several cases of gunshot wounds produced by hollow-point bullets showed characteristic central tags. These apparently arise from sparing of the skin surface by the hollow point cavity when the bullet strikes the skin tangentially. This unique feature may be helpful in assessing entrances of perforating wound tracks or other cases where the bullet is either not available or unknown.

Atypical gunshot exit defects to the cranial vault.

Cranial exit wounds typically display external beveling, however, variation has been noted in the literature due to keyhole phenomena and pre-existent fractures. Two cases of atypical exit morphology are presented with features mimicking blunt trauma. In both instances radial fractures created by the exiting impact allowed passage without producing exit beveling. A working knowledge of the biomechanics of bone fracture, radiographs and low power microscopy are essential elements for the proper interpretation of such exit wound fractures.

The meaning of an accessory projectile.

A previously expended pistol casing was removed from a gunshot wound after an apparent accidental shooting. Examination of this foreign body indicated it had ridden the bore ahead of the bullet. Further investigation disclosed this as a deliberate but ignorant means to load an already loaded weapon. The assailants then fired at a passerby and killed him. Disclosure of the foreign body by X-ray, recovery and examination at autopsy were used to corroborate the circumstances and allowed charges of criminally negligent homicide to be placed.

Matching bullets to bone impact signatures.

When bone is penetrated or perforated by a bullet, the bullet's impacting surface is often uniquely modeled by the fractured bone. Reconstructing bone with simple super-imposition of the bullet's contour lines allows matching of a particular bullet to its specific bone defect.

Recognition of cemetery remains in the forensic setting.

Cemetery remains exposed through vandalism or natural phenomena are frequently brought to the attention of law enforcement agents or medical examiners. Although it is often difficult to distinguish cemetery remains from those of medicolegal significance, clues to their origin may exist. Characteristics consistent with cemetery remains include physical characteristics associated with the embalming process. Characteristics indicative of cemetery remains include functional or ornamental artifacts associated with the coffin, devices used in embalming the body, and elevated levels of embalming chemicals in the soft tissue.

Maxillary suture obliteration: aging the human skeleton based on intact or fragmentary maxilla.

Obliteration of the four sutures of the bony palate is examined to determine its value as an age indicator. Thirty-six maxillae from a predominately white series representing both sexes and a wide variety of ages are studied. It is concluded that the amount of obliteration of these sutures is useful in estimating general biological age.