Assessment of sex differences in size and shape of foramen magnum on CT scans of Bulgarian adults

Abstract

The aim of the study is to assess the sex differences in size and shape of the foramen magnum, to develop discrim­inant functions based on the measurements of the foramen magnum and to establish the most reliable variables for sex determination in Bulgarian adults. Computed tomography scans of the heads of 120 Bulgarian adults (52 males and 68 females) were used in the study. The segmentation of the skulls was performed with the software InVesalius. The length, breadth, and cir­cumference of the foramen were measured digitally based on the 3D coordinates of definite landmarks and semi­landmarks. The area of the foramen magnum was calculated using the Radinsky and Teixeria formulae, based on the dimensions of the foramen length and breadth. The shape of foramen magnum was classified as narrow, medium wide or wide on the basis of the breadth/length index values. The significance of the sex differences in the measurements and shape of foramen magnum was assessed by independent sample t-test and chi-square test. Univariate and multivariate discriminate function analyses were conducted. The leave-one-out classification method was used as a cross-validation procedure. The results demonstrated statistically significant sex differences in the size and shape of the foramen magnum. The area of the foramen magnum is the best discriminating parameter. Generally, the results from the univariate and multivariate discriminant function analysis showed that the measurements of the foramen magnum did not provide high predicting rates for sex estimation among the Bulgarian population. Acknowledgements: The study was supported by the Bulgarian National Science Fund, grant DN01/15-20.12.2016.