Microarchitectural changes in the juvenile S1 vertebra using Skyscan CT-Analyser

Introduction: The sacrum’s trabecular framework adapts dynamically to changing biomechanical demands from weight transmission in the pelvic region. Recent histomorphometry studies reveal the complexity of cancellous bone development in accommodating growth and mechanical loads. The study aims to analyze the changing trabecular microarchitecture in the developing sacrum. Methods: 26 juvenile human S1 vertebrae were scanned using micro-CT and analyzed via SkyScan CT-Analyser. The ages ranged from infancy to 8 years and were divided into four age groups. 14 VOIs were placed on the right half of the S1 vertebra. Six parameters were selected: Bone volume fraction (BV/TV%), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular number (Tb.N), structural model index (SMI), and degree of anisotropy (DA). Data were analyzed using ANOVA and pairwise multiple comparison method (Sigmaplot 12.0). Results: Results showed BV/TV% ranging from 27.35–34.42%, Tb.Th (0.274–0.402mm), Tb.Sp (0.456–0.763mm), Tb.N (0.729–1.362mm-1), SMI (1.539–2.052), and DA (0.453–0.511). Across the four age groups, significant changes were seen in BV/TV, Tb.Th, Tb.Sp, Tb.N and SMI (p < 0.001). Comparing the 14 VOIs throughout groups showed significantly higher bone density in VOI 10 than all other VOIs (p < 0.05). Conclusion: Throughout the first eight years, the anteromedial part of the sacral ala (VOI 10) significantly exhibits the highest bone volume, thickest and highest number of trabeculae, low spacing, plate-like morphology, and the most anisotropic. It is suggested that future studies should compare these findings with the rest of the sacral vertebrae.