Gender differentiation in the adult human sacrum and the subpubic angle among indigenes of cross river and Akwa Ibom states of Nigeria using radiographic films

A research study for sexing the sacra and sub-pubic angle of indigenes of Cross River and Akwa Ibom States was carried out using radiographic films of adults aged 18 -80 years. The aim of the study was to determine whether there is any difference in the measurements of the sacrum and pubic angle of males and females of Cross River and Akwa Ibom states origin; and to compare the findings with those obtained in other African population groups. The parameters that were assessed and measured included the length and width of the sacrum, the sacral index, and the sub-pubic angle. The measuring instruments used were a protractor for the sub-pubic angle and a ruler for the sacrum. The sex differences of the sacral length marked a greater mean in males but were not statistically significant (P>0.05) as it ranged from 92-126mm in males and 80-119mm in females. The sacral breadth marked a mean slightly higher in females than in males with insignificant statistical differences (P>0.05). It ranged from 99-134mm in males and 92- 138mm in females. The sacral Index which was calculated as Width (maximum breadth) x 100 divided by maximum length was higher in females than in males with a significant statistical difference (P<0.05) ranging from 94.9 to 118.2mm and 97.6-124.4mm in male and female respectively. The sex difference of the sub-pubic angle was found to be statistically significant in females when male and female x-ray films were compared (P<0.05) with a range of 80-144o in males and 96-142o in females. The sacral index and sub-pubic angle are therefore useful parameters in sexing of the pelvic bone since they were found to be significant by statistical analysis. Keywords : Gender, sacrum, pubic angle, radiograph, dimorphism