Morphometric study of the true S1 and S2 of the normal and dysmorphic sacralized sacra

Abstract

Background/aim: This study aimed to generate data for the S1 and S2 alar pedicle and body and the alar orientations for both dysmorphic and normal sacra. Materials and methods: The study comprised two groups: Group N consisted of 53 normal sacra and Group D included 10 dysmorphic sacra. Various features such as alar pedicle circumference; anterior, middle, and posterior axis of the sacral ala; sacral body height and width; and sagittal thickness were measured. Results: In group N, the median anterior axis of the alae was observed to be 30° on the right and 25° on the left, the median midline axis was found to be 20° on the right and 15° on the left, and the median posterior alar axis was -15° on the right and -20° on the left. The true S1 and S2 alar pedicle circumferences were observed to be significantly smaller in group D, which demonstrated a shorter S1 alar pedicle mean circumference, significantly narrower S1 body mean width, and considerably tapered sagittal thickness. Conclusion: Our analysis indicated that dysmorphic sacra have a lower sagittal thickness and width of bodies and smaller alar pedicles, which explains the difficulties in their percutaneous fixation.