Skull fractures in abusive head trauma: a single centre experience and review of the literature.

PURPOSE: The authors provide a comprehensive framework with which to approach paediatric calvarial injury sustained as a result of suspected abusive head trauma (AHT). This is achieved through the presentation of a case series set in the context of the unique morphology of the infant skull and the possible diagnostic pitfalls which may arise due to the presence of variant anatomy or other mimicking conditions. METHODS: A retrospective analysis of sixty-three patients referred to our institution with suspected AHT was carried out. Seventeen patients with skull fractures were identified and their fractures were described in terms of anatomical location, type and course. Our data was then interpreted in the light of known anatomical fracture mimics and the available literature on the subject. RESULTS: Forty-two skull fractures were identified and described in our cohort, most of which were simple linear fractures of the parietal bones (33%). There were also a substantial number of complex stellate fractures, namely of the parietal (29%) and occipital (10%) bones. Eleven fracture mimics including accessory sutures and wormian bones were also identified in this cohort. CONCLUSIONS: Our study supports and builds on the existing literature, thereby offering a more complete view of the spectrum of calvarial damage sustained as a result of AHT in the context of its diagnostic pitfalls.

Assessment of maceration techniques used to remove soft tissue from bone in cut mark analysis.

Maceration techniques employed in forensics must be effective without compromising the bone's integrity and morphology, and prevent destruction of evidence. Techniques must also be fast, safe, easily obtainable and inexpensive; not all techniques currently employed are appropriate for forensic use. To evaluate the most suitable approach, seven techniques including current and new methodologies were applied to fresh, fleshed porcine ribs exhibiting cut marks. A sample size of 30 specimens per technique was examined under scanning electron microscopy at the cut mark and the surrounding uncompromised regions; a scoring system of effectiveness was applied. The previously unpublished microwave method fared best for bone and cut mark preservation. Sodium hypochlorite destroyed cut marks, and was deemed unsuitable for forensic analysis. No single technique fulfilled all criteria; however, this study provides a benchmark for forensic anthropologists to select the most appropriate method for their situation, while maintaining the high standards required by forensic science.

Tattoos and human identification: investigation into the use of X-ray and infrared radiation in the visualization of tattoos.

Any person with a tattoo known to their family or friends could potentially be identified from the presence of such personal identifying markers. Problems in identification utilizing tattoos may arise when these markers are removed or defaced in some way. This paper uses infrared wavelengths at 760, 850, and 950 nm to improve the visualization of laser-removed or covered up tattoos and also to establish whether the ink pigments used can be observed on radiographs from any metal that may be present. The results obtained indicate that some older inks have a high enough metallic content to allow them to be viewed on a radiograph, while infrared light can demonstrate latent ink still present in the skin after laser removal and can also be utilized to distinguish an original tattoo through a secondary "cover-up" tattoo. Infrared photography and radiography have been shown to improve tattoo visualization in a forensic context.

Investigation into the merits of infrared imaging in the investigation of tattoos postmortem.

Infrared imaging has a history of use in the forensic examination of artwork and documents and is investigated here for its wider use in the detection of tattoos on the human body postmortem. Infrared photographic and reflectographic techniques were tested on 18 living individuals, displaying a total of 30 tattoos. It was observed that neither age, sex, age of the tattoo, nor, most significantly, skin color affected the ability to image the tattoos using infrared imaging techniques. Second, a piglet carcass was tattooed and the impact of the decomposition process on the visibility of the tattoos assessed. Changes were recorded for 17 days and decomposition included partial mummification and skin discoloration. Crucially, the discoloration was recorded as greatly affecting the image quality using conventional photography, but was insignificant to the infrared recording of these tattoos. It was concluded that infrared reflectography was beneficial in the investigation into tattoos postmortem.

Rates of enamel formation in human deciduous teeth.

The aim of this study was to document rates of enamel formation in deciduous teeth. Little is known about rates of deciduous enamel formation compared to permanent enamel. In permanent teeth, rates vary between 2.5 microm per day at the EDJ to 6.5 microm per day at the enamel surface. Longitudinal ground sections of twenty mandibular deciduous teeth (4 of each tooth type) made through the crown in the buccolingual plane were selected that showed clearly visible daily enamel cross striations using transmitted polarised light microscopy. Ten average measurements, each one made across five daily increments, were recorded within 100-microm thick zones defined between the EDJ and the enamel surface on each tooth section. This procedure was repeated in occlusal, lateral and cervical regions of each tooth. Overall, daily rates varied less than in permanent teeth and did not show the very low rates at the EDJ or the very high rates often found in the outer enamel of permanent teeth. In deciduous enamel, rates varied between 2.5 and 4.5 microm throughout, but often showed a marked reduction in the zone immediately following the neonatal line or other accentuated markings usually associated with stressful events. A catch-up phase usually followed these events during which rates recovered. These data provide clear evidence of enamel hypoplasia associated with both the birth process and other events that cause stress in perinatal life.

Analysis of experimental cranial skin wounding from screwdriver trauma.

As part of a more extensive investigation of skin wounding mechanisms, we studied wounds created by five common screwdrivers (straight, star, square or Robertson, Posidriv and Phillips) on the shaven foreheads of 12 freshly slaughtered pigs. We fixed the different screwdriver heads to a 5-kg metal cylinder which was directed vertically onto each pig head by a droptube of 700 mm length. We examined skin lesions by photography and also by scanning electron microscopy (SEM). Our evaluation of differences in wound shape and size was based on geometric morphometric methods. Our results show that there are obvious morphological differences between the straight head and the other types. The straight-headed screwdriver penetrates the skin by a mode II crack which results in a compressed skin plug with bundles of collagen fibres forming skin tabs within the actual wound. The sharper-tipped screwdrivers wedge open the skin (mode I), with a clearly defined edge with no skin plugs. Geometric morphometric analysis indicates that shapes of skin wounds created by the five screwdriver types could be classified into three different groups. The straight head results in the most differentiated wound profile, with the Robertson or square and some specimens of star, and also the Posidriv and Phillips giving similar wound outlines. SEM evaluation of wounds created by a new and worn straight-head screwdrivers shows that the outline of the worn screwdriver head is reflected in the shape of the wound it created.

How Neanderthal molar teeth grew.

Growth and development are both fundamental components of demographic structure and life history strategy. Together with information about developmental timing they ultimately contribute to a better understanding of Neanderthal extinction. Primate molar tooth development tracks the pace of life history evolution most closely, and tooth histology reveals a record of birth as well as the timing of crown and root growth. High-resolution micro-computed tomography now allows us to image complex structures and uncover subtle differences in adult tooth morphology that are determined early in embryonic development. Here we show that the timing of molar crown and root completion in Neanderthals matches those known for modern humans but that a more complex enamel-dentine junction morphology and a late peak in root extension rate sets them apart. Previous predictions about Neanderthal growth, based only on anterior tooth surfaces, were necessarily speculative. These data are the first on internal molar microstructure; they firmly place key Neanderthal life history variables within those known for modern humans.