Stature estimation from radiographic sternum length in a contemporary Spanish population.

The ability to estimate stature from various parts of the body is essential in medicolegal investigations, particularly in cases in which human remains have been dismembered or mutilated. Therefore, the aim of this study was to generate linear regression models for predicting stature on the basis of sternum length in contemporary Spaniards. Sternal length, or the combined length of the manubrium and mesosternum, was recorded from digital radiographs of the chest plate for 65 males and 52 females. Correlation coefficients for the regression models were r=0.391 and r=0.461 for the male and female formulae, respectively. The standard errors of the estimate were 6.20 cm for the male equation and 5.56 cm for the female equation. Given these relatively large standard error rates, the derived stature estimation models should only be used when other more accurate skeletal elements, such as intact long bones, are unavailable for analysis.

Estimation of sex from sternal dimensions derived from chest plate radiographs in contemporary Spaniards.

A number of previous studies have demonstrated that osteometric analysis of the sternum provides a highly accurate method for discriminating adult sex in diverse population groups. In this study, sternal measurements were recorded from posteroanterior digital radiographs of the chest plate of 116 Spanish individuals (65 males and 51 females). Results demonstrated that all linear dimensions of the manubrium and mesosternum, sternal area, and sternal index were significantly sexually dimorphic in this population group. Discriminant function analyses incorporating several of these variables, individually or in combination, provided sex classification accuracy rates greater than 80.0%, with associated sex biases below 5.0%. A stepwise procedure, which can be used when a complete sternum is present, yielded the highest correct sex classification rate at 89.7%. Only slightly lower allocation accuracy rates were obtained for multivariate equations which incorporated either dimensions of the manubrium or mesosternum (87.1% for both formulae). Thus, the derived discriminant function equations should prove useful in forensic investigations, particularly those in which the pelvis or bones of the extremities are not available for analysis.

Test of a new components method for age-at-death estimation from the medial end of the fourth rib using a modern Spanish sample.

Recently, Verzeletti et al. (Am J Forensic Med Pathol 31:27-33, 2010) developed a new components method for the estimation of age-at-death from the sternal end of the fourth rib. This approach consists of the assignment of numerical scores for several age-related morphological characteristics, which are then inserted into a regression equation for predicting chronological age. The present study tested the accuracy of the new components method on a sample from Spain, consisting of 58 males and 36 females. The results demonstrated that the regression equation devised by the aforementioned authors for an Italian male sample was less accurate when applied to the Spanish population sample. This was true for separate male and female samples, as well as a combined-sex sample. A pair of population-specific regression formulae was then generated from the Spanish sample data in an attempt to improve the accuracy of the age estimate. The new equation which incorporated sex as an independent variable did not yield more accurate age estimates than a non-sex-specific equation. Furthermore, both of these formulae provided only marginally more accurate results for the Spanish sample compared to the original Italian equation. Thus, the standard errors of the estimate associated with these population-specific models (8.1-8.9 years) were still noticeably larger than the 5.2 years observed by Verzeletti and colleagues in their Italian study. Given the high standard errors associated with the age estimates for the Spanish population sample, the new rib components method should be used in conjunction with other adult aging techniques.

Sex discrimination from the glenoid cavity in black South Africans: morphometric analysis of digital photographs.

Given that skeletal material recovered from medicolegal contexts is often incomplete or damaged, forensic anthropologists need to have a variety of techniques at their disposal in order to correctly determine the sex of unidentified human remains. The purpose of the present study, therefore, was to produce practical standards for discriminating the sex of black South Africans using measurements of the glenoid cavity of the scapula. Standardized digital photographs of the left glenoid fossa were taken for 60 males and 60 females drawn from the Pretoria Bone Collection. An image analysis software program was then used to collect height, breadth, area, and perimeter data from each digital photograph. All four dimensions of the glenoid cavity were highly sexually dimorphic in this population group (p < 0.0001). Univariate logistic regression analysis yielded overall sex prediction success rates ranging from 88.3% for area of the glenoid fossa to 85.8% for glenoid fossa breadth. Multivariate procedures did not provide increased accuracy over those using only a single variable. Classification sex biases were below 5.0% for all equations. These results demonstrate that the analysis of glenoid cavity size provides a highly accurate method for discriminating the sex of black South Africans.

Investigation on the utility of permanent maxillary molar cusp areas for sex estimation.

Digital photogrammetric methods were employed to assess the level of sexual dimorphism present in permanent maxillary molar cusp areas of black South Africans (130 males, 105 females). Odontometric standards were then developed for diagnosing sex, based on the cusp area data derived for these teeth. Results demonstrated that all cusp area measurements of both the first and second maxillary molars were significantly dimorphic (P < 0.0001) in this group. Univariate and multivariate discriminant function analyses yielded overall sex prediction accuracy rates between 59.6 and 74.5%. Comparable allocation results were also obtained for binary logistic regression analyses, but with larger classification sex biases. The highest classification accuracies were observed for different combinations of just two cusp areas for the first molar. Allocation rates of formulae derived for second molar dimensions were on average 4.3% lower than those obtained for the first molar. Analyses incorporating cusp areas of both maxillary molars did not improve classification accuracies achieved when only using first molar measurements. The classification rates are below the suggested minimum accuracy of 75-80% for reliable forensic application of a method; however, the derived formulae may provide a useful statistical indication as to the sex of fragmentary remains in which complete or even partial tooth crowns are the only materials available for examination. Furthermore, the formulae can be applied not only to adults but also to subadults (above the age of 3 years) in which the more accurate sex discriminating features of the pelvis and skull are yet to develop.

Morphological variations of the anterior thoracic skeleton and their forensic significance: radiographic findings in a Spanish autopsy sample.

The anterior thoracic skeleton may exhibit a number of morphological variations or anomalies, including accessory ossicles, atypical fusion or nonfusion of bony segments, and accessory foramina. Awareness of these minor skeletal variants is important in forensic medicine given that they may be mistakenly identified as pathological or traumatic lesions. The identification of subtle morphological anomalies may also aid in the process of individualization by serving as points of similarity if their occurrence was recorded antemortem. This study assessed the prevalence of anatomical variants of the sternum and ribs in a modern population from Spain, since the frequency of these skeletal anomalies differs between population groups. The occurrence of sternal clefts and foramina, bifurcated ribs, fusion of the manubriosternal and sternoxiphoidal junctions, and type of xiphoid process end was evaluated on posterior-anterior digital radiographs. None of the morphological variations were associated with sex or age, with the exception of two traits related to the xiphoid process. The xiphoid process was absent more often in younger individuals, particularly specimens below the age of 30 years, whereas, complete fusion of the sternoxiphoidal junction was more often observed in individuals above 50 years of age. However, these morphological variants are highly variable in the study sample and thus they have limited utility in forensic age estimation in the Spanish population. Nonetheless, the presence of various morphological anomalies such as sternal foramina, bifid ribs, and triple-ended xiphoid processes may provide information useful for establishing a personal identification.

Testing the effectiveness of two cranial base foramina for metric sex assessment of fragmentary remains.

Sex differences in linear and area dimensions of the foramen ovale and external opening of the carotid canal were analyzed in a documented French sample (35 men and 32 women). The results demonstrated that a low level of sexual dimorphism is present in the cranial base foramina of this sample, with only two-thirds of the examined variables exhibiting statistically significant differences (p < 0.05) between the sexes. The cross-validated sex classification accuracy rates obtained for univariate and multivariate discriminant functions ranged from only 54.7 to 72.1%. In addition, measurements of the cranial base foramina were found to be difficult to record with precision, with intra-observer error percentages ranging from 2.35 to 4.23%. Error rates of this magnitude may result in the misallocation of specimens. Therefore, osteometric analysis of the foramen ovale and carotid canal external opening cannot be recommended as a useful method for cranial sex assessment in this population group.

Osteometric sex discrimination from the sternal extremity of the fourth rib in a recent forensic sample from Southwestern Spain.

The discrimination of sex is central to the process of establishing a personal identification from human skeletal remains. Previous study has demonstrated that osteometric analysis of the sternal extremity of the fourth rib provides a reasonably accurate method for assessing this biological attribute in diverse human groups. As metric standards are generally population-specific, the purpose of the current research was to evaluate the degree of sexual dimorphism present in the fourth rib among contemporary Spaniards, a group thus far not investigated, and generate discriminant function equations which can be used to estimate the sex of unidentified remains in this population. Superior-inferior height and anterior-posterior breadth dimensions of the fourth rib were collected for a sample consisting of 60 males and 57 females derived from postmortem examinations performed at the Institute of Legal Medicine, Seville, Spain. The results demonstrated that both rib dimensions were highly sexually dimorphic (p<0.0001) in this Spanish sample. Univariate discriminant function analyses yielded correct sex classification rates of 76.9% and 83.8% for breadth and height dimensions, respectively. Multivariate analysis incorporating both rib measurements improved the allocation accuracy to 86.3%, with an associated sex bias of only 0.7%. Therefore, the derived discriminant function equations, particularly those that incorporate rib height, can be effectively used in cases involving fragmentary remains in which more dimorphic elements such as the pelvis are not preserved, as well as complete skeletons to complement other metric and morphological sex assessment methods.

The efficacy of sternal measurements for sex estimation in South African blacks.

The correct assessment of sex from the human skeleton is of fundamental importance in forensic medicine and bioarchaeology. In South Africa, unidentified remains are often fragmentary, making it necessary to estimate sex from a variety of skeletal elements. The purpose of the present study was to evaluate the sex discriminating potential of the sternum in black South Africans using standard osteometric techniques. A sample of 123 males and 83 females drawn from the Raymond A. Dart Collection of Human Skeletons and the Pretoria Bone Collection was used. The results demonstrated that all eight sternal variables, including both dimensions and indices, were highly sexually dimorphic in this population. A stepwise discriminant function procedure, which selected corpus sterni length and manubrium width, correctly identified 86.4% of the individuals in the study sample. Additional multivariate discriminant equations incorporating dimensions for either the manubrium or corpus sterni yielded sex prediction rates of 80.6% and 84.5%, respectively. Sternal area, when used in isolation, produced the highest sex classification accuracy with 86.9% of specimens correctly assigned. The remaining single variable functions, which can be applied when well-preserved or complete sterna are not available for analysis, provided classification accuracies ranging from 68.4% to 83.5%. These classification results are comparable to those reported in previous investigations concerning sex estimation of black South Africans for other postcranial elements.

Sex determination from the acetabulum: test of a possible non-population-specific discriminant function equation.

In a recent study of pelvic dimorphism, Steyn and Patriquin demonstrated that sex classification accuracies for a combined sample of South African blacks, South African whites, and Greeks living on Crete, differed very little from those obtained separately for the three groups. These results suggest that population-specific formulae may be unnecessary when using pelvic dimensions to discriminate sex, and according to the authors, the formulae derived in their study from a large and ethnically diverse sample should provide reliable standards for determining sex in a variety of populations. The purpose of the present study was to assess the accuracy of the discriminant function equation for acetabular diameter published by the aforementioned authors on a documented skeletal sample from France. The overall allocation accuracy obtained utilizing the pooled-group equation (84.1%) did not differ appreciably from that achieved using a sample-specific formula developed from the French dataset employed in this study (85.4%). This result is of practical importance to forensic anthropologists working in France, and elsewhere, particularly in situations where there is some question as to the population affinity of the skeletal remains. Future studies should continue to combine pelvic and non-pelvic data from disparate populations, to develop additional osteometric standards for discriminating sex with high accuracy across human groups.