Frozen human bone: a microscopic investigation

The taphonomic effects of prolonged extreme cold and freezing on human bone have received little research attention. Questions of specific interest include whether previously frozen bone can be identified and whether freezing alters the structural integrity enough to prevent histological aging. There is no evidence from previous studies that freezing damages the structural integrity, and to date no research investigating the freezing process on bone microstructure has been undertaken. This research attempts to distinguish histologically previously frozen bone from nonfrozen bone by identifying patterned defects. To determine the effects of freezing in bone microstructure using light and scanning electron microscopy (SEM), several human bone sections were subjected to prolonged freezing and allowed to thaw before thin sectioning. Light microscopy failed to demonstrate statistically significant differences between frozen and nonfrozen specimens. SEM analysis revealed fractures, although these lacked pattern and did not occur systematically throughout the section. Evidence of microstructural changes caused by liquid expansion, however, was remarkable but did not alter the structural integrity of the microstructure. The results of this study suggest that freezing does not alter the process of histomorphological analysis.     

A Comparison of Histomorphometric Data Collection Methods*

Abstract: Although many variables that skeletal biologists examine have been standardized, the actual techniques used to collect these data from bone thin sections vary. This project compares different methods of obtaining data (relative cortical area values) for histomorphometric research. One visual and three digital methods of histomorphometric data collection are compared: (i) Merz microscopic eyepiece counting reticule, (ii) flatbed scanner, (iii) overlaying multiple images of a thin section, and (iv) digital SLR camera with macro settings. The discussion includes a comparison of usability factors such as cost, time, user‐experience, and ease‐of‐use, which vary for each method. Values from the different methods are compared using ANOVA tests to evaluate inter‐method, inter‐observer, and intra‐observer variability. Intra‐observer error was greater for the microscopic method, although the error values are concomitant with experience. We found no statistically significant differences between the four methods examined, but certain caveats must be addressed when these methods are used.     

东莞市15～22岁男性青少年牙齿钙化及其法医学意义

目的调查东莞市15～22岁男性青少年牙齿钙化情况,为法医年龄推断提供新的基础数据。方法拍摄310名东莞市15～22岁男性青少年全口曲面断层片,参照田雪梅牙齿钙化分级评分标准,分别对下颌第1-7恒牙及上下颌第三磨牙钙化程度进行评分。利用SPSS 17.0进行配对样本T检验、与年龄的相关性分析及Fisher's两类判别分析。结果下颌第1-7恒牙在16.5岁均已发育完全,第三磨牙从16岁开始出现8级钙化,上、下颌第三磨牙分别从17.5岁及18岁开始出现9级钙化;上颌第三磨牙间钙化程度存在差异(P0.01),下颌左右侧同名牙齿钙化无差异(P0.05);第三磨牙与年龄的Spearman相关系数为0.5～0.64,根据第二、三磨牙发育建立的16、17、18岁Fisher's线性两类判别综合判别率分别为84.8%、75.2%、73.1%。结论第1-7恒牙对17岁以上青少年的年龄推断有局限性,第三磨牙与年龄之间呈中度相关,需综合机体其他年龄特征进行年龄判别。     

Recognition of Skeletal Fractures in Infants: An Autopsy Technique

Abstract:  Complete recognition and documentation of injury pattern is crucial in the diagnosis of child abuse. Skeletal fractures regarded as highly specific to nonaccidental injury in infants include posterior rib, scapular, metaphyseal, and spinous process fractures. These injuries are often occult, especially when acute, to standard radiologic and autopsy procedures. The presented autopsy technique requires incising and reflecting skeletal muscles to expose the bones and costal osseous joints in situ , increasing the opportunity to recognize skeletal injury. Fractured or atypical appearing bones are removed and processed for complete evaluation. The bones are processed by macerating the soft tissue in a water soap bath at an elevated temperature. To aid in reconstruction of the decedent, long bones are replaced with wooden dowels and the chest cavity is packed with the organ bag. The technique is invasive and recommended for cases in which the pathologist has reasonable suspicion of acute or remote trauma.     

Santeria and Palo Mayombe: Skulls, Mercury, and Artifacts

Abstract:  Santeria and Palo Mayombe are syncretic religions created in the New World based upon African religious beliefs combined with Christianity. The main worship of Palo Mayombe involves religious receptacles that may contain earth, sticks, varied artifacts, and animal and human remains. Due to the use of human and nonhuman remains, discovery of these items often leads to involvement by the police due to a concern of homicide. We review in detail the medical examiner records of two of these ritualistic cases including the autopsy, anthropology, police, and investigators' reports. For the human remains, careful consideration of the context in which the remains were recovered, their state of preservation, and the associated artifacts (e.g., beads and mercury) are important in determining the appropriate level of forensic significance. Anthropological examination with particular attention to taphonomic characteristics also may help determine the origin and forensic significance.     

The effects of corrosive substances on human bone, teeth, hair, nails, and soft tissue

Abstract: This research investigates the effects of household chemicals on human tissues. Five different human tissues (bone, tooth, hair, fingernails, and skin/muscle/fat) were immersed into six different corrosive agents. These agents consisted of hydrochloric acid, sulfuric acid, lye, bleach, organic septic cleaner, and Coca‐Cola^® soda. Tap water was used as a control. Tissue samples were cut to consistent sizes and submerged in the corrosive liquids. Over time, the appearance, consistency, and weight were documented. Hydrochloric acid was the most destructive agent in this study, consuming most tissues within 24 h. Sulfuric acid was the second most destructive agent in this study. Bleach, lye, and cola had no structural effects on the hard tissues of the body, but did alter the appearance or integrity of the hair, nails, or flesh in some way. The organic septic cleaner and tap water had no effect on any of the human tissue tested during the timeframe of the study.     

A method for studying knife tool marks on bone

The characteristics of knife tool marks retained on hard tissues can be used to outline the shape and angle of a knife. The purpose of this study was to describe such marks on bone tissues that had been chopped with knives. A chopping stage with a gravity accelerator and a fixed bone platform was designed to reconstruct the chopping action. A digital microscope was also used to measure the knife angle (θ) and retained V-shape tool mark angle (ψ) in a pig skull. The κ value (elasticity coefficient; θ/ψ) was derived and recorded after the knife angle (θ) and the accompanied velocity were compared with the proportional impulsive force of the knife and ψ on the bone. The constant impulsive force revealed a correlation between the V-shape tool mark angle (ψ) and the elasticity coefficient (κ). These results describe the tool marks--crucial in the medicolegal investigation--of a knife on hard tissues.     

Planned and unplanned complex suicides: a 5-year retrospective study

The notion of planned and unplanned complex suicides first appeared in 1974 by Marcinkowski and, since then, no systematic study of complex suicides has been published in the English forensic literature. Here, the authors present a 5-year retrospective study of complex suicides. Nineteen complex suicides were reviewed: five unplanned and 14 planned, including the first case of an unplanned complex suicide in a woman. All cases were analyzed in terms of gender, age, methods of suicide, the presence of a suicide note, and past suicide attempts, and statistically compared with a 50-case sample of simple suicides. A further comparison was established with compiled data from the literature. Similarities were revealed regarding incidence of complex suicides, male gender predominance, and types of methods used. In contrast, results showed a higher average age for planned complex suicide victims. Finally, the authors discuss the application of the complex suicide definition.     

Rodents as taphonomic agents: bone gnawing by brown rats and gray squirrels

Passive infrared technology was used to film diurnal and nocturnal scavenging behavior of brown rats and gray squirrels at the University of Tennessee's Anthropological Research Facility. This direct documentation demonstrated that brown rats modified fat-laden cancellous bone while gray squirrels generally gnawed the thicker bone cortices only after fats had leached away. A case study placed in a shaded portion of the Facility indicated the postmortem interval for initial gnawing by gray squirrels was slightly over 30 months. An examination of 53 human skeletons in the William M. Bass Forensic Skeletal Collection revealed that 10 cases had gnaw marks consistent with those made by gray squirrels. One of the 10 cases had been gnawed within 16 months of time-since-death, while the remaining nine had postmortem intervals >30 months. Additional observed modifications made to nonhuman bone by gray squirrels indicate that squirrel gnaw marks on bone can serve as a minimal estimate of time-since-death in a temperate environment similar to that of East Tennessee.     

Structural analysis of human rib fracture and implications for forensic interpretation

Patterns of rib fractures are of significant clinical and forensic interest. Linking patterns of rib fracture with specific physical events provides a foundation for understanding the nature of traumatic events that are associated with rib fracture in forensic contexts. In this study, isolated human ribs (n = 8) were end-loaded to failure to investigate: (i) local deformations (bone strain) prior to and during structural failure, (ii) location of ultimate failure, and (iii) fracture mode. Structural properties of ribs were used to calculate theoretical stresses to determine whether such calculations could be used to predict site of fracture. Ribs fractured on the sternal side of midshaft in all experiments, but mode of failure varied with transverse, buckle, spiral, and "butterfly" fractures observed. Comparison of calculated stress with observed strain values suggest that experimental, rather than theoretical, approaches will be most productive in furthering understanding rib fracture in forensic contexts.     

A Preliminary Assessment of the Identification of Saw Marks on Burned Bone*

Abstract: This study assesses the degree of modification to the saw mark characteristics of dismembered skeletal remains when exposed to a controlled outdoor fire of limited duration. The sample consists of 36 adult pig hind limbs which were dismembered fleshed. Six handsaws and six power saws were used, with three limbs dismembered and burned for each of the saw types. Results indicate that fire exposure affects the visibility and identifiability of saw mark striae. With the handsaws, the bow saw, hacksaw, and keyhole saw were consistently recognizable. In the power saw group, the saw marks of the jigsaw, reciprocating saw, and chainsaw remained identifiable. Although the bone ends exhibited thermal alterations, the false starts were well preserved with minimal damage. Given the parameters of this study, it is possible to identify the class of saw based on the diagnostic characteristics present on the cremated bones.     

Human coxal bone sexual dimorphism and multislice computed tomography: geometric morphometric analysis of 65 adults

The authors studied sexually dimorphic differences in coxal shape using geometric morphometric analysis of 15 osteometric landmarks recorded by multislice computed tomography (MSCT), based on three-dimensional reconstructions of 65 Caucasian adults. Geometric morphometric analysis, principal component analysis, canonical variates analysis, and other discriminant analysis (Goodall's F-test and Mahalanobis distance) were performed for the three separate bones of the left innominate (pubis, ilium, and ischium), the modified pubis (pubis and ischiopubic ramus), the modified ilium (ilium and ischial spine), three bone complexes (ischiopubic, iliopubic, and ilio-ischial), and the complete innominate. A cross-validation test was also performed. All areas studied were dimorphic, but results for sexual dimorphism in decreasing order were as follows: the modified pubis, followed by the ischiopubic complex, the iliopubic complex and the complete innominate, the pubis, the modified ilium, the ilio-ischial complex, the ilium, and finally the ischium. These results show the potential of this approach for future anthropological research.     

A re-examination of cremains weight: sex and age variation in a Northern California sample

The reduction of modern commercially cremated remains into a fine powder negates the use of traditional methods of skeletal analysis. The literature on the use of cremains weight for estimating aspects of the biologic profile is limited, often with conflicting results. This study re-evaluates the value of weight in the assessment of biologic parameters from modern cremated remains. A sample of adults was collected in northern California (n = 756), with a cremains weight averaging 2737.1 g. Males were significantly heavier than females (mean = 3233.2 g versus mean = 2238.3 g, respectively; p<0.001). Comparison of this sample with other previously reported samples from southern California, Florida, and Tennessee indicates a consistent sex difference, with the most similar mean values to the Tennessee study. Although cremains weight decreases with age as expected, the relationship is weak; thus, cremains weight cannot accurately predict age-at-death. While sex estimation shows considerable accuracy (86.3% for males and 80.9% for females), sectioning points may be population specific.     

The effect of weight on the femur: a cross-sectional analysis

This study assessed whether obesity significantly affects femoral shape. Femora of 121 white men were divided into two weight classes based on body mass index (BMI) of the deceased. Five external anteroposterior (AP) and mediolateral (ML) measurements were taken at consistent percentages of diaphyseal length. These were then subject to statistical tests. After controlling for age, multivariate statistics show a significant (p<0.05) effect of BMI on the femur, with the greatest significance in ML measurements. T-tests confirm these dimensions are significantly larger in the overweight (p<0.05). The effect of BMI on size-transformed and shape-transformed variables was also evaluated, with ANOVA results showing a significant BMI effect on ML size (p<0.05), but not shape. Significant size-transformed ML variables were then subject to discriminate function analyses with a cross-validation correction. Results show a correct classification rate of 88% in normal weight and 77% in overweight individuals.     

Fingering a Murderer: A Successful Anthropological and Radiological Collaboration*

Abstract: We illustrate an interdisciplinary approach to identify a victim in a case with complex taphonomic and procedural issues. Burning, fragmentation, species commingling, and examination by multiple experts required anthropological preparation and analysis combined with radiographic adaptations to image and match trabecular patterns in unusually small, burned specimens. A missing person was last seen in the company of a reclusive female on a remote rural property. A warranted search found several burn sites containing human and animal bones. Fragment preparation, analysis, and development of a biological profile by anthropologists enabled examination by the odontologist, molecular biologist, and radiologist, and justified use of antemortem radiographs from one potential victim. Visual and radiological comparison resulted in a positive (later confirmed) identification of the victim by radiological matches of three carpal phalanges. Although some dimensional changes are expected with burning, morphological details were preserved, aided by selection of relatively intact, small bones for comparison.     

Tibia and Fibula Stature Formulae for Modern Female Populations Based on Digital Radiographic Measurements

Abstract: This study demonstrates the feasibility of creating bone lengths and stature databases of significant size for modern living human populations from digital radiographic archives and medical records. Tibia and fibula lengths were taken from digital radiographic images of 250 women. The images, drawn from the University of California, Los Angeles Medical Center’s Radiology Department’s General Electric Picture Archiving and Communication System, were taken between 2003 and 2007. Stature measurements were obtained from medical records on 83 individuals, 50 of which were used to regress stature equations for the tibia and fibula. Bone lengths obtained from radiographic images are almost 3 cm longer than those obtained from skeletalized collections. The formulae produce ranges up to 10 cm lower than current formulae. Accuracy could be improved as methods are developed to correct for the small magnification produced by digital images.