Assessing changes in internal bone architecture of the immature human pars basilaris and pars lateralis during the prenatal and postnatal stages of growth

Abstract

The internal architectural arrangement of bone serves as a reflection of bone adapting to the surrounding biomechanical environment, as well as the functional demands imposed on the bone. The pars basilaris and pars lateralis contribute significantly to the borders of the foramen magnum within the posterior cranial base, and as such, understanding the impact of the growth of the surrounding brain, neurovasculature, and muscles on these bones is important. Thus, the aim of the study was to investigate the internal structure of 84 pars basilari and 96 pars laterali during the prenatal and postnatal stages of growth. Skeletal elements were sourced from early prenatal (20-30 gestational weeks, n=34), late prenatal (30- 40 gestational weeks, n=42) and postnatal (birth-7.5 months, n=30) individuals housed by the Johannesburg Forensic Paediatric Collection. Micro-computed tomography was used to assess bone volume fraction (BV/TV), bone surface area fraction (BS/BV), trabecular thickness (TbTh), trabecular number (TbN), trabecular separation (TbSp), degree of anisotropy (DA) and mean grey value (MGV) in 14 regions across both skeletal elements using multivariate analysis of variance within and between the age groups. Findings revealed that the late prenatal group generally had a higher BV/TV and TbTh but lower TbN compared to the early prenatal group, indicating that modelling is the primary mechanism of development. Limited differences between the late prenatal and postnatal groups indicate that the trabecular architecture of the posterior cranial fossa achieves stability postnatally. Variations between the regions within the age groups show that internal architecture is not uniform throughout the bones, reflecting functional regions within the bones.