Sex identification of skeletal remains is an important issue in forensic medicine. 2 The pelvic bones are the most reliable gender differentiation parameter because it is the most dimorphic bone, especially in adult individuals. 2 Each population has its special identification standard.2 Implementing visual or morphological techniques is the quick way to assess the samples. The weakness of this technique is in the sense of a very subjective assessment which requires an experienced observers and the level of accuracy is still not guaranteed. Moreover, sexual dimorphism varies geographically. Therefore, forensic anthropologists are constantly trying to test the existing methods and developing standards that are more efficient and objective in which it can optimize the positive identification of the human skeleton.7–10 The use of advance imaging technology with multislice computed tomography (MSCT) for anthropological purposes is recently developed. It is a suitable tool for determining sexual dimorphic characteristics in various anatomies area.3,4,6,11 This study demonstrates the importance of an objective method utilizing radiological technology in human anthropometric determination in order to assist the analysis of sex identification.
The mean age of sample in this study was 50.23 ± 14.36 years. Moreover, a study conducted by Kolesova et al, pelvic size difference was associated with changes in age. Age-related changes observed in the study were carried out in linear parameters of pelvic cavity and confirmed the anterior tilt of sacral floor as well as more horizontal sacrum location in accordance to aging. This study also showed that there was no change in pelvic proportion to ischial height in female while the distance of transverse pelvic diameter shortens with age.7 As it is stated previously, age-related ankylotic processes decreased sacroiliac joints motility and facilitated these changes.8–10
There were significant differences (p < 0.05) on radiologic components measured between male and female except for transverse diameter of the sacral segment (p = 0.180). These significant differences finding was similar to other studies in different populations which there were significant differences in pelvic measurements between the sexes.9,11 In a study by Patriquin et al., they demonstrated significant sexual dysmorphism in a population study on South Africa. This study reported differences in pelvic size between sexes as well as differences between races.9
Furthermore, this study shows a significant difference in APOD measurement between male and female group. This result is in accordance to a study conducted by Kolesova and Vetra, that there was significant difference in APOD measurements of the two sexes.12 The result obtained from our study provides a lower mean of APOD value than their study, but it is similar in the sense of APOD value for male due to the fact that it has lower mean than female. The measurement of CPID component in this study showed a higher value in female group.
In previous study, male pelvic structure is significantly heavier and thicker than female. The male pelvis is also adjusted to fit in more massive and sturdy body architecture e.g. the male acetabulum has been designed to fit a larger femur. Even though most of pelvic sexual dimorphisms are due to size differences, sex-related shape variations are also very striking and cannot be considered as an allometric differences in body size between both sexes.13 This variation in shape is indicated by a rounder frame of female pelvis. Sciatic indentation is wider in female rather than those in male. They have larger, shallower, lower, bigger pelvis and larger pelvic inlet and outlet (Pubic bone is longer and curvature degree of pectineal line is greater). Therefore, women’s pelvic bones also differ in characteristics related to sacroiliac joints position on the iliac bones.14
The SPA measurement showed a significant difference between male and female group with high correlation strength. This result is in accordance to previous studies which concluded that SPA was the most reliable indicator of pelvic sex.15 This is also in accordance to a study by Igbigbi and Msamati, who stated that the accuracy of SPA dimensions in determining sex was 94.7% for female and 95.5% for male.16 Moreover, a similar result is also portrayed in a study by Mostafa, which showed a significant difference in SPA measurements between both sexes.17 Women’s growth tend to increase during adolescence, especially in ischium and pubic areas, resulting in a larger pelvic outlet, longer pubic and a blunter SPA. This growth difference is related to sexual dimorphism associated to birth process.18,19
The TPO measurement showed a significant difference in both sexes with high strength of correlation between male and female group. These findings are in accordance to previous studies which concluded that a significant difference was observed in transverse diameter of pelvic midplane and outlet. This could be explained by hormonal effects of pregnancy which result in pubic symphysis softening and pubic bone movement as wide as one cm, as a consequence there was an increase on pelvic diameter.12,17
The APOD, CPID, LIH, SPA, and TPO were conducted through multivariate analysis using logistic regression in order to find significant variables and generate a formula that might determine a person’s sex with high accuracy. The CPID, LIH, and SPA components showed significant values in accordance to previous discussion. These three components consistently showed differences in sexual dysmorphism in both sexes, especially SPA served as one of the high scoring factors consistently. This study shows that the estimated values of pelvic measurements using 3D-CT could provide a pelvic model with a formula that has a high accuracy value using CPID, LIH, and SPA values with p = 0.035, p = 0.001 and p = 0.015 respectively. This formula was able to provide a high overall validity (91.05%) with 100% sensitivity for male identification and 81.1% specificity for female identification. Nevertheless, these results need to be compared with previous studies in which they were able to provide higher validity values that could reach 100%.3,17
This study has some limitations that it has few data from patients under 30 years of age, therefore multicentric study with more population under 30 years of age is needed to obtain a greater variety of data and produce more accurate formula for sex determination. In addition, an analytical study of previously published studies may be carried out to compare differences the value of pelvic anthropometry of various races and geographic areas.