A metric method for sex determination using the proximal femur and fragmentary hipbone

The pubic bone is considered one of the best sources of information for determining sex using skeletal remains, but can be easily damaged postmortem. This problem has led to the development of nonpelvic methods for cases when the pubic bone is too damaged for analysis. We approached this problem from a different perspective. In this article, we present an approach using new measurements and angles of the proximal femur to recreate the variation in the pubic bone. With a sample from the Terry Collection (n > 300), we use these new variables along with other traditional measurements of the femur and hipbone to develop two logistic regression equations (femur and fragmentary hipbone, and femur only) that are not population specific. Tests on an independent sample (Grant Collection; n = 37-40) with a different pattern of sexual dimorphism resulted in an allocation accuracy of 95-97% with minimal difference by sex.     

Sex determination of Chinese femur by discriminant function

The objective of this study was to provide a method of sex determination for Chinese femur, especially for fragmentary remains. Statistical analysis of 17 measurements based on 141 northeastern Chinese femora shows that all measurements have significant sex differences. Sex determination by the midpoint method of a single measurement can obtain an average accuracy of 76.8%. The results indicate that of all dimensions the maximum head diameter is the best discriminator of sex. It alone can determine the sex of a femur with 85.1% accuracy. The results also show that maximum head diameter, transverse head diameter, epicondylar breadth, upper breadth, and medial condylar length have higher sexual dimorphisms than the dimensions of length. According to the result to stepwise discriminant analysis and the need for sexing fragmentary remains, 22 discriminant functions composed of various combinations of variables were calculated which can determine the sex of the femur correctly 82.3 to 87.2%. The methods of sex determination provided by this paper can be used to sex poorly preserved femora.     

Sexual dimorphism in the tarsal bones: implications for sex determination

An accurate determination of sex is essential in the identification of human remains in a forensic context. Measurements of some of the tarsals have been shown to be sexually dimorphic by previous researchers. The purpose of the present study is to determine which dimensions of the seven tarsals demonstrate the greatest sexual dimorphism and therefore have the most potential for accurate sex determination. Eighteen measurements of length, width, and height were obtained from the tarsals of 160 European-American males and females from the William M. Bass Donated Skeletal Collection. These measurements were made using a mini-osteometric board. Logistic regression analyses were performed to create equations for sex discrimination. All measurements showed significant sexual dimorphism, with the talus, cuboid, and cuneiform I producing allocation accuracies of between 88 and 92%. Combinations of measurements provided better accuracy (88.1-93.6%) than individual measurements (80.0-88.0%).     

Interobserver variation of selected postcranial skeletal measurements

Osteometric data are of great importance for analytical purposes in the field of forensic anthropology, and it is critical that interobserver concordance is high in order for the results of these analyses to be reliable. Significant interobserver variation of skeletal measurements is cause for concern since it may result in conflicting conclusions. The range of interobserver variation of selected postcranial measurements is addressed. Thirteen standard measurements familiar to most forensic anthropologists were examined, as well as nine nonstandard measurements that were unfamiliar to most participants in the study. Sixty-eight individuals participated in the study, the majority of whom considered themselves to be forensic anthropologists with various levels of experience. In general, interobserver variation of the tested standard postcranial measurements was found to be minimal, with the exception of pubis length and subtrochanteric femur measurements. The difficulties that can lead to measurement error are discussed and possible solutions are recommended.     

Quantifying Sexual Dimorphism in the Human Cranium: A Preliminary Analysis of a Novel Method

In forensic anthropology, sexually dimorphic cranial features are traditionally visually assessed and scored using an ordinal scale, which is highly subjective. This study quantifies six cranial features using original three‐dimensional coordinate measurements to provide greater accuracy in sex estimation. Cranial features include supraorbital ridges, glabella, external occipital protuberance, nuchal protuberances, mastoid processes, and frontal bosses. Measurements were taken using coordinate calipers from 158 White and Black male and female crania from the Maxwell Documented Collection at University of New Mexico and Tennessee's Bass Collection. Overall, 72.2% of the crania were correctly classified. Males were correctly classified 69.9% of the time, while females were correctly classified 74.7% of the time. The overall value is similar to the results from traditional methods and suggests this method may be just as reliable as established visual sex estimation techniques.     

Discriminant function sexing of the mandible of indigenous South Africans

South Africa currently has a high homicide rate. This results in a large number of unidentified bodies being recovered each year, many of which are referred to the forensic examiner. This situation has resulted in considerable growth of forensic anthropological research devoted to devising standards for specific application in South African medico-legal investigations. The standards suitable for Black South Africans now encompass a wide variety of skeletal elements (e.g. cranium, humerus, pelvis, femur, patella, talus, calcaneus), each with differing degrees of accuracy. Apart from a preliminary investigation of the Zulu local population, however, we note that there appears to be no established metric mandible discriminant function standards for sex determination in this population. The purpose of the present study is to undertake a comprehensive analysis of sexual dimorphism in the mandible of Black South Africans, incorporating individuals from a selection of the larger local population groupings; the primary aim is to produce a series of metrical standards for the determination of sex. The sample analyzed comprises 225 non-pathological mandibles of Black South African individuals drawn from the R.A. Dart Collection. Nine linear measurements, obtained from mathematically transformed three-dimensional landmark data, are analyzed using basic univariate statistics and discriminant function analyses. All of the measurements examined are found to be sexually dimorphic; the dimensions of the ramus and corpus lengths are most dimorphic. The sex classification accuracy of the discriminant functions ranged from 70.7 to 77.3% for the univariate method, 81.8% for the stepwise method, and 63.6 to 84% for the direct method. We conclude that the mandible is a very useful element for sex determination in this population.     

Determination of sex with a discriminant analysis of new pelvic bone measurements: Part II

The pelves of 100 white skeletons were measured on both sides for the following: (1) length from the superiormost aspect of the pubic symphysis to the nearest rim of the acetabulum (PS-A), (2) length from the highest point of the pubic tubercle to the nearest rim of the acetabulum (PT-A), (3) acetabular diameter (AD), (4) the vertical distance from the anterior aspect of the ischial tuberosity to the farthest rim of the acetabulum (IT-A), and (5) greatest femur head diameter. From these, three indices were derived: AD/PS-A (acetabulum/pubis index), AD/PT-A (acetabular diameter/pubic tubercle-acetabular rim index), and IT-A/PS-A (ischium-acetabulum height/pubic symphysis-acetabular rim index). The left AD/PS-A ratio and left IT-A height proved statistically to be of greatest discriminating value. Using these two variables, a discriminant function was derived which correctly separated 98% of our sample. The acetabulum/pubis ratio alone correctly assigned 95%. With either the discriminant function analysis of two variables or the acetabulum/pubis index as a single predictor, 97% of our sample of known sex was correctly identified if all specimens that fell within a doubtful or overlapping range of values were sorted by femur head diameter.     

Determination of sex from the metacarpals in a Thai population

Determination of sex using metacarpals was carried out on a sample of 249 skeletons from a Thai population (154 males and 95 females), ranging in age from 19 to 93 years. Six measurements were taken on each metacarpal, namely maximum length, medio-lateral base width, antero-posterior base height, medio-lateral head width, antero-posterior head height and mid-shaft diameter. Binary logistic regression equations were calculated for determining sex from these measurements. All metacarpals from both sides produced at least one equation that correctly allocated the skeletons with 80% or greater accuracy. In a comparative test using only individuals with no missing measurements (n=196), the most accurate equations for each metacarpal on the right side had pooled allocation accuracies ranging from 85.2% to 89.3%, with the best equation based on three measurements from the 5th metacarpal. On the left side, the most accurate equations for each metacarpal ranged from 83.2% to 89.8% correct allocation, with the best equation based on three measurements of the 2nd metacarpal. When the allocation accuracy for each sex is considered in addition to the pooled accuracy, the best equations involve the same three measurements of the 5th metacarpal on the right side, but shift to three measurements of the first metacarpal on the left side, with a pooled accuracy of 88.3%. The results of this study suggest that metacarpals can be used quite reliably for sexing in forensic contexts in Thailand.     

Sexing North American Eskimo and Indian innominate bones with the acetabulum/pubis index

The acetabulum/pubis index was tested on American Eskimo and Indian samples of innominate bones to which sex had been assigned by visual inspection. The index alone sexed 91 and 89% of the Eskimo and Indian samples, respectively. Subsequent sorting of misclassified specimens with femur head diameter resulted in 96 and 99% rates of classification. The index and a measurement of ischial height were used in a discriminant function model which correctly identified the sex of 93% of the Eskimo and 92% of the Indian bones. Using femur head diameter to sort those specimens which were misclassified by their discriminant function score yielded classification rates of 96 and 98%. These results are compared to a range of 92 to 100% obtained with the index in earlier studies of American black and white pelvic bone samples.     

Adult sex estimation from the minimum supero-inferior femoral neck diameter in a contemporary osteological sample from Buenos Aires,Argentina

Sex estimation of adult skeletons is an important step in forensic analysis. Although the femur has been metrically studied for sex assessment around the world, very limited information is actually available on modern populations of Argentina. In this paper, the estimation of sex based on the metric evaluation of the supero-inferior femoral neck diameter (SID) in a reference osteological collection from the contemporary Chacarita Cemetery of Buenos Aires City (Argentina), is evaluated. Protocols generated using SID in other three reference skeletal samples are also tested on this collection. One hundred and sixty-four individuals of both sexes and between 24 and 96 years old are analyzed. Inter and intra observer errors suggest that the replicability of the procedure is adequate. The sectioning point calculated from the direct measurements is 30.86 mm and results show a high degree of dimorphism. The proportions of correct sex discrimination and the likelihoods of correct allocation obtained with the direct measurements, along with the results of a discriminant function, a binary logistic regression and a Bayesian approach, are all higher than 0.85 (0.85–0.93 for females, 0.88–0.91 for males). When the formulae from other samples are used in the Chacarita Collection, the percentages of correct estimations range between 72.41% and 81.03% for females and between 80.46% and 88.50% for males, while the likelihoods are between 0.73 and 0.81 for females and between 0.79 and 0.82 for males. As the values for the estimations obtained using the statistical procedures generated in the present research are higher than those available for other collections, the method is more adequate to use in the analysis of contemporary skeletal remains from Buenos Aires and surrounding areas. The trends identified highlight the importance of population-specific metric methodologies in forensic contexts and deserve future testing in contemporary samples from neighbouring regions.     

An assessment of the accuracy of discriminant function equations for sex determination of the femur and tibia from a South African population

The purpose of this study is to test the accuracy of seven discriminant function equations that have been derived by Steyn and Is?an for sex determination using measurements of the femur and tibia of South Africans of European descent (SAED). While the validity of some of the discriminant functions has been assessed by the authors who derived them, no previous independent study has been carried out to assess the accuracy of these equations. These equations have not been tested on skeletons located outside of the Gauteng province. A suite of measurements were taken on 272 femora and 256 tibiae obtained from four South African skeletal collections. The validity of each of the previously published equations for the femur was confirmed. However, two functions of the tibia showed low accuracy rates, most likely due to difficulties in recording the distal epiphyseal breadth measurement, and thus were found to be poor assessors of sex.     

Pubis growth study: applicability in sexual and age diagnostic

The growth of five variables of the ischiopubic area was analyzed from bone material from birth to old age. The main purpose was to evaluate its significance and capacity for age and sex determination during and after growth. The material used consisted of 327 specimens from four documented Western European collections. Growth curves were calculated by polynomial regression for two classical variables of the ischiopubic area (pubis length and ischiopubic index) and three new variables of the pubic acetabular area (horizontal and vertical diameter of the pubic acetabular area and the pubic acetabular index). None of the curves showed lineal growth, with the exception of the ischiopubic index and the masculine vertical diameter of the pubis acetabular area. Pubis length has the most complicated growth, expressed by a five-degree polynomial. All the variables are useful for adult sex determination, except the pubic acetabular index. The ischopubic index, vertical diameter of the pubic acetabular area and the pubic acetabular index seem to be good variables for sub-adult sex determination. For age estimation the best variables, in both archaeological and forensic remains, are the absolute measurements (pubic length, vertical and horizontal diameter of the pubis). However, pubis length is the best variable for age estimation because it can be applied until 25 years of age.     

Sexual Dimorphism of Maxillary Sinus Dimensions Using Cone‐Beam Computed Tomography

Sex determination of unknown persons plays an important role in forensic medicine. Cone‐beam computed tomography (CBCT) is an excellent imaging modality for accurate measurement of maxillary sinus dimensions. This study aimed to evaluate whether maxillary sinus measurements on CBCT scans can be applied for sex determination. The width, length, and height of maxillary sinuses in CBCT images of 100 patients (50 males and 50 females) were measured. Student's t‐test and discriminant function analysis were used to compare differences in the measured parameters between males and females. The correct predictive accuracy rate of sex determination was 78% in females and 74% in males with overall accuracy of 76%. Based on discriminant analysis, the most pronounced variable in differentiation of sex groups was maxillary sinus height. This study suggests that maxillary sinus measurements can be valuable for sex determination in forensic investigation, especially for cases in which other traditional methods are not applicable.     

Stature reconstruction using fragmentary femora in South Africans of European descent

It is well documented that the intact femur has the highest correlation with stature and as such has been widely used in the derivation of regression equations for stature estimation. As intact femur is not always present for analyses in forensic cases, it has become necessary to derive regression equations for the estimation of stature from fragments of this bone. Few studies have presented regression equations for stature estimation from fragments of the femur. Because these equations are population specific, it was the aim of this study to derive similar equations for estimation of stature and maximum length of femur from measurements of the femur of South Africans of European descent. A sample of 50 male and 50 female complete skeletons were obtained from the Raymond A. Dart Collection of Human Skeletons. Total skeletal height for each of the skeletons was calculated using the Fully's method. Six variables were measured on each femur which included the vertical neck diameter, upper breadth of femur, epicondylar breadth, bicondylar breadth, lateral condyle length, and medial condyle length. Regression equations for the estimation of stature are presented. The range of standard error of estimate for these equations (3.71-5.31) was slightly higher than those obtained for intact long bones (2.13-3.79). It is therefore suggested that in the absence of intact femur, regression equations derived from the present study can provide a reliable estimate of adult stature.     

中国汉族男女股骨性别差异

经测量235副（男158副，女77副）已知生前确切性别的成年股骨的21项指标，对单一测量项目判定股骨性别的效果进行了检验。结果表明，21项测量指标中有11项单一指标的判别效果达80％以上。采用Fisher两类判别分析法对测量数据进行统计处理，得到根据单侧股骨测量值判别性别的函数方程14个；对南方和北方人群组的测量数据，分别用Fisher两类判别法进行统计，建立了根据单侧股骨测量值判断性别的函数34个，判别率最高达98．23％。与盲测判别准确率相近。该法可用于法医人类学的个体识别。     

Sex determination from the distal part of the femur in a French contemporary population

Until now, determining the sex of a recently deceased individual using the measurement of the bicondylar breadth of the femur (also known as condylar width, epicondylar breadth and distal epiphyseal breadth) raised some concerns as to accuracy because no sample of contemporary French subjects was available. In this study, a sample of 88 female and male femurs taken from recently deceased elderly French people was studied. The bones were collected from subjects who had donated their bodies to the Medical School of Nice. The mean value of the male bicondylar breadth was found to be greater than that of females (84.3mm versus 74.8mm), confirming the sexual dimorphism of this parameter. Furthermore, the results showed a 95.4% accuracy rate for sexing individuals. To date, in the French population, as in some other samples, epicondylar breadth is the single most accurate measurement of sex determination, ahead even of head diameter. A discriminant function is presented to allow sex determination from remains of the distal femur. With regard to the data available in the literature, sexual dimorphism is probably the result of both genetic and environmental factors. The comparison of our results with those of other populations shows that there are inter-population variations of the bicondylar breadth, and also intra-population variations that account for the differences in the accuracy rate of this variable for the purposes of sex determination. These findings underscore the need to re-evaluate bone measurements within various contemporary populations.     

Sex estimation in a modern American osteological sample using a discriminant function analysis from the calcaneus

Reliable methods for sex estimation during the development of a biological profile are important to the forensic community in instances when the common skeletal elements used to assess sex are absent or damaged. Sex estimation from the calcaneus has potentially significant importance for the forensic community. Specifically, measurements of the calcaneus provide an additional reliable method for sex estimation via discriminant function analysis based on a North American forensic population. Research on a modern American sample was chosen in order to develop up-to-date population specific discriminant functions for sex estimation. The current study addresses this matter, building upon previous research and introduces a new measurement, posterior circumference that promises to advance the accuracy of use of this single, highly resistant bone in future instances of sex determination from partial skeletal remains. Data were collected from The William Bass Skeletal Collection, housed at The University of Tennessee. Sample size includes 320 adult individuals born between the years 1900 and 1985. The sample was comprised of 136 females and 184 males. Skeletons used for measurements were confined to those with fused diaphyses showing no signs of pathology or damage that may have altered measurements, and that also had accompanying records that included information on ancestry, age, and sex. Measurements collected and analyzed include maximum length, load-arm length, load-arm width, and posterior circumference. The sample was used to compute a discriminant function, based on all four variables, and was performed in SAS 9.1.3. The discriminant function obtained an overall cross-validated classification rate of 86.69%. Females were classified correctly in 88.64% of the cases and males were correctly classified in 84.75% of the cases. Due to the increasing heterogeneity of current populations further discussion on this topic will include the importance that the re-evaluation of past studies has on modern forensic populations. Due to secular and micro evolutionary changes among populations, the near future must include additional methods being updated, and new methods being examined, both which should cover a wide population spectrum.     

Discriminant function sexing of the calcaneus of the South African whites

The skull and some postcranial elements, such as the humerus, femur, and tibia, have been used in their intact states for sex determination in forensic and archaeological cases. But, in practice, these bones are often recovered in fragmented states, which render them unsuitable for use in sex determination. The calcaneus is a compact bone that is able to withstand high tensile forces. Some of its parameters have been used for sex determination in American whites and blacks (1) and Italians (2). This bone has not been used for sex determination in the South African white population. Therefore, the aim of this study was to assess the degree of sexual dimorphism of the calcaneus of the South African white population sample, derive discriminant function score equations for use in sex determination, and determine the level of accuracy of its sex-determining ability. Nine parameters were measured on each pair of 53 male and 60 female calcanei of known South African white skeletons, obtained by a random sampling technique from the Raymond A. Dart Collection of Human Skeletons, School of Anatomical Sciences, University of the Witwatersrand, Johannesburg. Basic statistic and discriminant function analysis was performed on the acquired data. The basic statistics showed that all measured parameters were sexually dimorphic. Discriminant function score equations were generated for use in sex determination. The average accuracy of sex classification ranged from 73 to 86% for the univariate method, 81 to 91% for the stepwise method, and 82 to 92% for the direct method. It is concluded that the calcaneus is useful for sex determination in the South African white population.     

Sex determination with the head of the radius

Analysis of a sample of 1108 radii corresponding to 567 black and white North Americans in the Terry Collection at the Smithsonian Institution demonstrates that the diameter of the radial head is an accurate sex discriminator for human remains. A simple "radial-head method" of sex determination consists of measuring the maximum and minimum diameters of the head and comparing such measurements with the test cutoff points. The subject is female when the maximum radial head diameter (either left or right) is less than or equal to 21 mm, and male when the maximum diameter (either left or right) is greater than or equal to 24 mm. The same decisions apply to the minimum diameters of 20 mm or less and 23 mm or more, respectively. When the maximum diameter is 23 mm or the minimum is 22 mm, the subject is more likely male; when the maximum diameter is 22 mm or the minimum is 21 mm, the subject is more likely female. The sample frequency of any one of these latter diameters is never more than 16%. Cross-validation of the method with a sample of 50 pairs of radii of the Terry Collection, different from the original specimens, resulted in 92% sexing accuracy when using the left radius singly, 94% accuracy when using the right radius singly, and 96% accuracy when using both radii jointly.     

An Analysis of Hounsfield Unit Values and Volumetrics from Computerized Tomography of the Proximal Femur for Sex and Age Estimation

Sex and age are two elements in the establishment of a biological profile for forensic identification. While the pelvic bones are the most ideal structures for sex estimation, the condition of a body is not always ideal due to the nature of death, such as in mass disasters, or postmortem processes. This study utilized CT scans and resultant 3D models of 100 male and 100 female adults of known ages ranging from 18 to 98 years old to collect volumetric and Hounsfield unit measurements of the proximal femur. Equations were created to establish logistic regression models for sex estimation and linear regression models for age estimation. The resultant sex estimation method had an accuracy of 93.5% and utilized the volume of the proximal femur. This study provides three linear regression models for age with an accuracy range of 86%–92% ±12 years. As imaging technologies are increasingly adopted for forensic purposes, the power of 3D data will provide the opportunity for more quantitative and reproducible analyses. The proposed method for sex and age estimation provides a reliable tool that can be utilized in both day-to-day casework and disaster victim identification.