Geometric morphometric study of the early shape of the hip bone (os coxae): variations with age and sex.

Data regarding sexual dimorphism in children are sparse with contradictory results. Recently, geometric morphometric analysis has shown that the pubis and ilium have both sexual shape dimorphism and shape differences that increase during ontogeny, but little is known about the entire pelvic (os coxae) bone shape in very young children. The goal of this study was to show pelvic bone age-related and sex-related shape changes using 3D geometric morphometric analysis in very young children. Geometric morphometric analysis was carried out on CT scans of the pelvic bone of 96 children aged from 3 to 24 months. Eleven landmarks were defined on the left pelvic bone. Geometric morphometric analyses were carried out to identify trends in bone shape in sex-based and age-based subgroups. Age-related differences in shape were statistically significant (Goodall's F = 3.68; p < 0.001) but there were no sex-related differences in shape (Goodall's F = 1.95; p = 0.065). Overall, the superior part of the pelvic bone becomes narrower with age. This study has shown that geometric morphometric analysis of the pelvic bone is feasible in very young children and revealed changes in shape with age but not differences with sex.