Poster Presentation Annual Meetings of the Endocrine Society of Australia and Society for Reproductive Biology and Australia and New Zealand Bone and Mineral Society 2016

Racial differences in bone length overstate differences in cortical porosity in Chinese and Caucasians (#283)

Xiao-Fang Wang 1 , Ali Ghasem-Zadeh 1 , Roger Zebaze 1 , Ego Seeman 1
  1. Departments of Endocrinology and Medicine, Austin Health, University of Melbourne, West Heidelberg, VIC, Australia

Chinese have lower hip and forearm fracture rates, appendicular bones with a smaller total cross-sectional area (CSA) but thicker and less porous cortices. As morphology differs along the length of a bone, and the region of interest (ROI) is more proximal in a shorter bone, positioning errors may influence racial difference in bone microarchitecture.    

Distal radius images acquired using high-resolution peripheral quantitative computed tomography (XTreme CT, Scanco) in 76 healthy Chinese (40 women) and 80 Caucasians (32 women) aged 20 to 55 years. The manufacturer method started at 9.5 mm from the endplate. The corrected ROI started at 4% of the forearm length. StrAx 1.0 algorithm was used to segment the matrix and void volumes of the compact-appearing cortex (CC), the transitional and trabecular regions.

Chinese were shorter and leaner. The forearm length was 1.2 cm and 1.5 cm shorter in Chinese women and men respectively compared to Caucasians (p<0.001). Using the manufacturer method in women, total CSA was smaller (-0.67SD, p=0.001), CSA of CC was greater (0.59 SD, p=0.026) in Chinese with lower porosity of CC (-0.97 SD, p<0.001) and higher matrix mineral density (MMD, 0.59SD, p=0.006) in Chinese than Caucasians. Using the corrected ROI, differences were smaller but significant (total CSA: -0.64SD, p=0.002; CSA of the CC: 0.47 SD, p=0.078; porosity of the CC: -0.76 SD, p=0.002; MMD: 0.52SD, p=0.017). Chinese men had smaller total CSA but similar CSA of CC compared to Caucasians using both the manufacturer and corrected method. The lower porosity of CC and higher MMD in Chinese men were not presented in the corrected ROI.    

The lower cortical porosity in Chinese is exaggerated compared to Caucasians, especially in men. Bone length differences need to be addressed when comparing racial differences in morphology.