Evidence for Enhanced Characterization of Cortical Bone Using Novel pQCT Shape Software

Abstract 

Bone shape, mass, structural geometry, and material properties determine bone strength. This study describes novel software that uses peripheral quantitative computed tomography (pQCT) images to quantify cortical bone shape and investigates whether the combination of shape-sensitive and manufacturer's software enhances the characterization of tibiae from contrasting populations. Existing tibial pQCT scans (4% and 50% sites) from Gambian (n=38) and British (n=38) women were used. Bone mass, cross-sectional area (CSA), and geometry were determined using manufacturer's software; cross-sectional shape was quantified using shape-sensitive software. At 4% site, Gambian women had lower total bone mineral content (BMC: −15.4%), CSA (−13.4%), and trabecular bone mineral density (BMD: −19%), but higher cortical subcortical BMD (6.1%). At 50% site, Gambian women had lower cortical BMC (−7.6%), cortical CSA (−12.6%), and mean cortical thickness (−15.0%), but higher cortical BMD (4.9%) and endosteal circumference (8.0%). Shape-sensitive software supported the finding that Gambian women had larger tibial endosteal circumference (9.8%), thinner mean cortical thickness (−26.5%) but smaller periosteal circumference (−5.6%). Shape-sensitive software revealed that Gambian women had tibiae with shorter maximum width (−7.6%) and thinner cortices (−22% to −41.2%) and more closely resembled a circle or ellipse. Significant differences remained after adjusting for age, height, and weight. In conclusion, shape-sensitive software enhanced the characterization of tibiae in 2 contrasting groups of women.

Key Words: pQCT, tibia, bone shape, Gambia, young women