title: Better skeletal microstructure confers greater mechanical advantages in Chinese-American women versus white women.
abstract: Despite lower areal bone mineral density (aBMD), Chinese-American women have fewer fractures than white women. We hypothesized that better skeletal microstructure in Chinese-American women in part could account for this paradox. Individual trabecula segmentation (ITS), a novel image-analysis technique, and micro-finite-element analysis (µFEA) were applied to high-resolution peripheral quantitative computed tomography (HR-pQCT) images to determine bone microarchitecture and strength in premenopausal Chinese-American and white women. Chinese-American women had 95% and 80% higher plate bone volume fraction at the distal radius and tibia, respectively, as well as 20% and 18% higher plate number density compared with white women (p < .001). With similar rodlike characteristics, the plate-to-rod ratio was twice as high in the Chinese-American than in white trabecular bone (p < .001). Plate-rod junction density, a parameter indicating trabecular network connections, was 37% and 29% greater at the distal radius and tibia, respectively, in Chinese-American women (p < .002). Moreover, the orientation of the trabecular bone network was more axially aligned in Chinese-American women because axial bone volume fraction was 51% and 32% higher at the distal radius and tibia, respectively, than in white women (p < .001). These striking differences in trabecular bone microstructure translated into 55% to 68% (distal radius, p < .001) and 29% to 43% (distal tibia, p < .01) greater trabecular bone strength, as assessed by Young's moduli, in the Chinese-American versus the white group. The observation that Chinese-American women have a major microstructural advantage over white women may help to explain why their risk of fracture is lower despite their lower BMD.
authors.affiliation: Department of Medicine, Division of Endocrinology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
authors.forename: X Sherry
authors.initials: XS
authors.lastname: Liu
authors.forename: Marcella D
authors.initials: MD
authors.lastname: Walker
authors.forename: Donald J
authors.initials: DJ
authors.lastname: McMahon
authors.forename: Julia
authors.initials: J
authors.lastname: Udesky
authors.forename: George
authors.initials: G
authors.lastname: Liu
authors.forename: John P
authors.initials: JP
authors.lastname: Bilezikian
authors.forename: X Edward
authors.initials: XE
authors.lastname: Guo
mesh_terms: D000328:Adult; D001213:Asian / Q000208:ethnology*; D001696:Biomechanical Phenomena / Q000502:physiology; D005260:Female; D006801:Humans; D008019:Life Style; D009929:Organ Size; D011884:Radius / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D013977:Tibia / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D014057:Tomography, X-Ray Computed; D044465:White People / Q000208:ethnology*