The subpubic angle in sex determination: anthropometric measurements and analyses on Anatolian Caucasians using...

The investigation of new anatomical criteria and revalidation of existing ones in sex determination for different populations are among main research foci of forensic anthropometry. In that context, the pelvis is the most extensively studied bone. A number of qualitative classifications, dimensional measurements and indices have been proposed for investigative anthropometry and forensic studies. Independent use of these parameters generally provided an accuracy rate of 70-75%. In this study, the accuracy rate of the subpubic angle in sex determination was investigated in living Anatolian Caucasians.

The subpubic angle was identified and measured on three-dimensional computed tomographic images of pelves. Data were obtained using 64-detector computed tomography (MDCT) with an isotrophic resolution of 500 μm. The sample included 66 males (41.6 ± 14.9 years of age) and 43 females (41.1 ± 14.2 years of age). Measurements were taken on a dedicated three-dimensional image analysis workstation. The subpubic angle was electronically measured. The technique and methodology was validated on a standard skeletal model. Intraobserver agreement was analyzed with intraclass correlation coefficient, and intraobserver variability was evaluated with technical error of measurement (inter- and intra-observer TEM), relative technical error of measurement (rTEM) and coefficient of reliability (R) measures. The subpubic angle for the study group and for both sexes was reported as minimum-maximum (mean ± SD). Independent-Samples T Test for equality of means was used to determine the difference between the two sexes regarding the subpubic angle. The correlation between the subpubic angle and the age of subjects were using Pearson Correlation Coefficients in males and in females. Logistic regression model was used to classify subjects according to their sex. Receiver operating characteristic curve analysis was performed to determine a cut-off value for further studies and to test the performance of the binary classification test.

Intraclass correlation for the subpubic angle (0.990), TEM (1082), rTEM (1.492), and R (0.990) represented almost complete reliability and accuracy of the measurement method. The subpubic angle was between 48° and 81° (65.9° ± 7.2°) in males and was between 64° and 100° (82.6° ± 7.7°) in females. Statistically significant difference was found between males and females regarding the subpubic angle (p < 0.0001). The subpubic angle was not significantly correlated with age in males (p = 0.953), or in females (r = 0.975). The accuracy of the subpubic angle in sex determination was 90.8%. With a cut-off value of 74°, sensitivity of subpubic angle to detect female phenotype was 88% and its specificity was 95%.

The subpubic angle is an accurate parameter in sex determination with high sensitivity and specificity.