Sex estimation in a contemporary Turkish population based on CT scans of the calcaneus

Morphometric Analysis of the Calcaneus in a Southeast Asian Population

Introduction The calcaneus is the most commonly fractured tarsal bone, accounting for up to 60% of tarsal bone fractures and 2% of all fractures in the body. With the calcaneus playing an important role in maintaining a stable and efficient bipedal gait, the sequelae of these injuries have also been associated with potential long-term disability or discomfort, especially if improperly managed. Incorrectly sized implants similarly cause their own set of complications, such as poor fixation, impingement, or implant prominence. This potentially increases the need for revision surgery or implant removal, with increased morbidity for the patient. As such, a thorough understanding of calcaneal morphology is vital to ensure optimal conservative and surgical management of calcaneal pathology. CT imaging has become an indispensable tool in the evaluation of such a complex three-dimensional structure and allows us to accurately map out calcaneal morphology. This study aims to evaluate calcaneal morphology in the Southeast Asian population using CT imaging and to determine if morphological differences exist between male and female patients. Methods Calcaneus measurements were taken from CT scans of 100 patients with intact calcanei, consisting of 34 female and 66 male patients. Patients who have had fractures or previous calcaneus surgery were excluded. IBM SPSS Statistics for Windows, Version 28.0 (Released 2021; IBM Corp., Armonk, NY, USA) was used for statistical calculations. Mean values were calculated, and t-tests were performed to establish any significant differences between measurements taken from male and female patients. Results were deemed to have a significant difference if the p-value was less than 0.05. Results Males had larger calcanei measurements than females in all parameters included. Calcaneal length in females measured on CT axial views was 66.2 mm, compared to 75.2 mm in males (p < 0.001). Calcaneal height, measured at the medial wall, was 28.2 mm in females and 33.9 mm in males (p < 0.001). Calcaneal height measured at the lateral wall was 33.3 mm and 38.1 mm in females and males, respectively (p > 0.001). Calcaneal width was 33.0 mm in females and 36.9 mm in males (p < 0.001). The mean dimensions measured in the total sample were an axial length of 72.1 mm, a medial wall height of 32.0 mm, a lateral wall height of 36.4 mm, and a width of 35.6 mm. Conclusion There is a significant difference in calcaneal morphology on CT imaging between male and female patients in the Southeast Asian population, which is an important consideration for surgical planning and the selection of appropriately sized implants.

Estimation of sex from computed tomography images of skull measurements in an adult Turkish population

BACKGROUND

Nowadays, data on the anthropometric measurements of populations is needed in many areas, especially forensic and legal. Using various methods, researchers obtain various data such as race, sex, and age, and thus provide identification of the material used. Morphological or metric methods are often used for identification.

PURPOSE

To evaluate the usefulness of the results of skull measurements using computed tomography (CT) to determine sex in a Turkish population.

MATERIAL AND METHODS

We analyzed 300 male and 300 female CT images of Turkish individuals with an age range of 21-50 years. Maximum cranial length, maximum cranial breadth, bimastoid diameter, bizygomatic diameter, and bigonial breadth were measured by CT tomography. All data were subjected to discriminant function analyses for estimating sex. Intra-observer and inter-observer variances of the measurements were examined using intraclass correlation coefficient analysis.

RESULTS

Discriminant function analysis indicated that there was a significant difference between male and female with 88% accuracy. Discriminant function for estimation of sex was obtained with satisfactory accuracy rates for the parameters used.

CONCLUSION

This study confirms that skull measurements show sexual dimorphism in the Turkish population, and also suggests that it may be useful to use CT to assess skull anthropometric measurements.

Calculation of likelihood ratios for inference of biological sex from human skeletal remains

It is common in forensic anthropology to draw inferences (e.g., inferences with respect to biological sex of human remains) using statistical models applied to anthropometric data. Commonly used models can output posterior probabilities, but a threshold is usually applied in order to obtain a classification. In the forensic-anthropology literature, there is some unease with this "fall-off-the-cliff" approach. Proposals have been made to exclude results that fall within a "zone of uncertainty", e.g., if the posterior probability for "male" is greater than 0.95 then the remains are classified as male, and if the posterior probability for "male" is less than 0.05 then the remains are classified as female, but if the posterior probability for "male" is between 0.05 and 0.95 the remains are not classified as either male or female. In the present paper, we propose what we believe is a simpler solution that is in line with interpretation of evidence in other branches of forensic science: implementation of the likelihood-ratio framework using relevant data, quantitative measurements, and statistical models. Statistical models that can implement this approach are already widely used in forensic anthropology. All that is required are minor modifications in the way those models are used and a change in the way practitioners and researchers think about the meaning of the output of those models. We explain how to calculate likelihood ratios using osteometric data and linear discriminant analysis, quadratic discriminant analysis, and logistic regression models. We also explain how to empirically validate likelihood-ratio models.

Testing the validity of population-specific sex estimation equations: An evaluation based on talus and patella measurements

Sex estimation is essential for forensic scientists to identify human skeletal remains. However, the most sexually dimorphic elements like pelvis or skull are not always assessable. Osteometric analyses have proven useful in sex estimation, but also to be population specific. The main purpose of this study was to test the validity of contemporary Greek and Spanish discriminant functions for the talus and the patella, respectively, on a Swiss skeletal sample and to quantify the utility of the measurements as a novel approach in osteometric sex assessment. Four talus and three patella measurements on dry bone were obtained from 234 individuals of the modern cemetery SIMON Identified Skeletal Collection. The previously derived discriminant functions were applied, accuracies determined, the utility of the different measurements was assessed and new multivariable equations constructed. Accuracies varied between 67% and 86% for talus and 63% and 84% for patella, similar to those reported by the original studies. Multivariable equations should be preferred over equations based on single measurements and combining the most significant measurements rather than using several variables obtained the best possible accuracy. The new discriminant functions did not provide a substantial improvement to the original ones. The overall utility of talus and patella is limited, allowing sex estimation with sufficient certainty only in a small proportion of individuals. Discriminant functions developed in contemporary Greek or Spanish populations are in principle applicable also to Swiss contemporary populations. We recommend that at present existent studies of this type should be validated and tested rather than developing new formulas.

Gender determination in adults using calcaneal diameters from lateral foot X-ray images in the Iranian population

Background: Using morphologic features of the bones is the basis of gender determination in anthropology and forensic medicine. In this study, we evaluated the calcaneus diameters for gender determination in the Iranian population.

Methods: This cross-sectional study was conducted on Iranians referring to Hazrat-e Rasool Hospital’s radiology ward for plain lateral X-ray of the foot. Lateral foot X-rays from 100 men and 100 women were gathered and evaluated for calcaneal indexes. These patients aged between 18 and 80 years old who did not suffer major trauma to the calcaneus bone were recruited. Using a picture archiving and communication system (PACS), four variables were calculated for each X-ray graph: Maximum anterior-posterior length of the calcaneus (MAXL), Maximum height of the bone (MAXH), Height of the cuboid facet (CFH) and Height the calcaneal body (BH). Cut off points for each index were calculated using the area under curve (AUC) in ROC curves.

Results: Lateral foot X-rays from 100 men and 100 women were gathered and evaluated for calcaneal indexes. The means of the four indexes were compared between the sexes which showed all four means are significantly different p value <0.001. AUC for MAXL in differentiating the genders was 0.824, which showed 86.8 as the cut off with a sensitivity of 80% and specificity of 69.0%. Cut off point for MAXH was set at 59.8 with sensitivity and specificity of 78.0% and 60.0%, respectively. For BH, 49.5 was set as the cut off point with a sensitivity of 79.0% and specificity of 64.0%. The best cut off point for CFH was 27.8 with 76.0% sensitivity and 63.0% specificity.

Conclusion: It can be concluded that the calcaneal diameters are reliable criteria for sex determination. Although the cutoff points are different between various races and populations, it is evident that these diameters can be used for sex determination in general.

Evaluation of computed tomography images of calcaneus for estimation of sex

Estimation of sex from bone remnants after medicolegal issues or mass disasters constitute a challenge. Our objective was to investigate if morphometric measurements performed on computed tomography (CT) images of the calcaneus can be useful for sex estimation. The measurements were performed on CT images of calcaneus bones of 489 patients (203 women, 286 men). The parameters under investigation were maximum length (MAXL), load arm length (LAL), minimum breadth (MINB), body height (BH), maximum height (MAXH), dorsal articular facet length (DAFL), dorsal articular facet breadth (DAFB), and cuboidal facet height (CFH). All parameters were remarkably increased in men compared to women (p < 0.001, for all). The highest performances for sex estimation were displayed by DAFL (92.8%) and BH (92.6%). The concomitant use of variables MAXL, BH, CFH, and DAFL revealed accuracy as high as 96% for gender discrimination. We suggest that morphometric measurements performed on CT images of the calcaneus can provide useful data for the estimation of sex.

Sex estimation in a Turkish population using Purkait’s triangle: a virtual approach by 3-dimensional computed tomography (3D-CT)

Sex estimation is considered one of the first steps in the forensic identification process. Morphological and morphometrical differences between males and females have been used as means for morphoscopic and metric methods on both cranial and postcranial skeletal elements. When dry skeletal elements are not available, virtual data can be used as a substitute. The present research explores 3-dimensional (3D) scans from a Turkish population to test a sex estimation method developed by Purkait (2005).

Overall, 296 individuals were used in this study (158 males and 138 females). Purkait’s triangle parameters were measured on computed tomography (CT) scans obtained from both right and left femora of each patient at the Bakirkoy Dr. Sadi Konuk Training Research Hospital (Istanbul, Turkey). Intra- and inter-observer errors were assessed for all variables through technical error of measurements analysis. Bilateral asymmetry and sex differences were evaluated using parametric and non-parametric statistical approaches. Univariate and multivariate discriminant function analyses were then conducted.

Observer errors demonstrated an overall agreement within and between experts, as indicated by technical error of measurement (TEM) results. No bilateral asymmetries were reported, and all parameters demonstrated a statistically significant difference between males and females. Fourteen discriminant models were generated by applying single and combined parameters, producing a total correct sex classification ranging from 78.4% to 92.6%. In addition, over 67% of the total sample was accurately classified, with 95% or greater posterior probabilities.

Our study demonstrates the feasibility of 3D sex estimation using Purkait’s triangle on a Turkish population, with accuracy rates comparable to those reported in other populations. This is the first attempt to apply this method on virtual data and although further validation and standardisation are recommended for its application on dry bone, this research constitutes a significant contribution to the development of population-specific standards when only virtual data are available.

Key points

CT analysis using Purkait’s triangle is a suitable tool for assessment of sex in unidentified individuals.

The best overall estimation rate was achieved with the F11 model, with around 92% of accuracy.

The results suggested 78.4% to 92.6% correct sex identification rates.

More research is needed to expand the sample set and verify the results.

Pitfalls of Computed Tomography 3D Reconstruction Models in Cranial Nonmetric Analysis

Many studies in the literature have highlighted the utility of virtual 3D databanks as a substitute for real skeletal collections and the important application of radiological records in personal identification. However, none have investigated the accuracy of virtual material compared to skeletal remains in nonmetric variant analysis using 3D models. The present study investigates the accuracy of 20 computed tomography (CT) 3D reconstruction models compared to the real crania, focusing on the quality of the reproduction of the real crania and the possibility to detect 29 dental/cranial morphological variations in 3D images. An interobserver analysis was performed to evaluate trait identification, number, position, and shape. Results demonstrate a false bone loss in 3D models in some cranial regions, specifically the maxillary and occipital bones in 85% and 20% of the samples. Additional analyses revealed several difficulties in the detection of cranial nonmetric traits in 3D models, resulting in incorrect identification in circa 70% of the traits. In particular, pitfalls included the detection of erroneous position, error in presence/absence rates, in number, and in shape. The lowest percentages of correct evaluations were found in traits localized in the lateral side of the cranium and for the infraorbital suture, mastoid foramen, and crenulation. The present study highlights important pitfalls in CT scan when compared with the real crania for nonmetric analysis. This may have crucial consequences in cases where 3D databanks are used as a source of reference population data for nonmetric traits and pathologies and during bone-CT comparisons for identification purposes.

Three-Dimensional Morphological Variations of the Human Calcaneus Investigated Using Geometric Morphometrics

The shape of the calcaneus determines the mechanical interaction of the foot with the ground during the heel-strike in human walking. Detailed knowledge of the pattern of sexual dimorphism of the human calcaneus could help to clarify the pathogenetic mechanism of foot and knee disorders, which are more prevalent in females. Therefore, the aim of this study was to characterize and visualize the three-dimensional shape variations of the calcaneus in relation to sex and age using geometric morphometrics. Computed tomography images of 56 feet without subtalar injuries or disorders were used in this study. Thirty-seven anatomical landmarks were identified on the bone model of the calcaneus to calculate principal components (PCs) of shape variations among specimens. The PC scores were compared between males and females, and their correlations with age were also analyzed. The female calcaneus was longer in length and shorter in height than that of males. The medial process of the calcaneal tuberosity in females was more inferiorly projected and the tuberosity was shifted more laterally. Also, the calcaneus was wider and the sustentaculum tali thickened with aging. Female structural features of the calcaneus alter the kinematics of the foot during walking and could be a structural factor in foot and knee disorders. This study contributes to a comprehensive understanding of shape variations in the human calcaneus. Clin. Anat., 33:751-758, 2020. © 2019 Wiley Periodicals, Inc.

Sex determination of Han adults in Northeast China using cone beam computer tomography

The purpose of this study was to obtain the morphological data of the maxillofacial region of Han nationality adults in Northeast China, and to explore the methods and appropriate variables of three-dimensional reconstruction technology for sex determination using Cone beam computer tomography (CBCT). The CBCT images of 420 adults (210 males, 210 females) aged 18-70years were reconstructed by MIMICS 17.0 software and sixteen observation indexes were measured and analyzed statistically. The results demonstrated that twelve of sixteen variables expressed significant sexual difference (p<0.01) which were as follows: mandibular angle (X₁),area of mandibular foramen (X₂), bi-gonial breadth (X₃), koronoidbreite (X₄), Height of symphysis (X₅), Min-height of mandibular notch (X₆), Min-breadth of mandibular ramus (X₇), Buccal side bone thickness of MF (X₈), Horizontal diameter of MF (X₁₁), Vertical from prosthion to palatal breadth (X₁₂), palatal breadth (X₁₃), The ratio of HD-MF and VD-MF (X₁₅). Then the sexual discriminant equation which was suitable for people at the age of 18-70 was established using stepwise method: Y=-0.059X₁+0.313X₂+0.1X₃+0.061X₄+0.044X₅+0.041X₆+0.076X₁₃-17.215. It was found that the cross-validated grouped overall predictive accuracy was 87.4%. It could correctly identify males in 85.7% and females in 89% of the cases. This study has accumulated morphological data of maxillofacial skeleton from adults of Han nationality in Northeast China, which provided guiding significance for sex determination and clinical application in forensic science, archaeology, criminal investigation, iconography and clinical three-dimensional (3D) print. Evaluation variables and related discriminant functions of sex determination using CBCT for three-dimensional reconstruction technology provided a new theoretical basis and practical means for sex determination.