Cortical Bone Area Predicts Incident Fractures Independently of Areal Bone Mineral Density in Older Men

Abstract

Context: Areal bone mineral density (aBMD) measured using dual-energy X-ray absorptiometry (DXA) is used clinically to predict fracture but does not discriminate between trabecular and cortical bone assessment. Objective: This study aimed to investigate whether information on cortical and trabecular bone predict fracture risk independently of aBMD and clinical risk factors. Design and Participants: Cortical area, bone mass, porosity, and trabecular bone volume fraction (BVTV) were measured at the tibia using high-resolution peripheral quantitative computed tomography (HR-pQCT) in 456 men (80.2 ± 3.5 years) recruited from the general population in Gothenburg, Sweden. aBMD was measured using DXA. Incident fractures (71 men) were X-ray verified. Associations were evaluated using Cox regression. Results: Cortical area [hazard ratio (HR) per standard deviation (SD) decrease, 2.05; 95% confidence interval (CI), 1.58 to 2.65], cortical bone mass (HR, 2.07; 95% CI, 1.58 to 2.70), and BVTV (HR, 1.62; 95% CI, 1.26 to 2.07), but not cortical porosity, were independently associated with fracture risk. These associations remained after adjustment for femoral neck aBMD and Fracture Risk Assessment risk factors (area: HR 1.96, 95% CI, 1.44 to 2.66; mass: HR 1.99, 95% CI, 1.45 to 2.74; BV/TV: HR 1.46, 95% CI, 1.09 to 1.96). After entering BV/TV and cortical area or bone mass simultaneously in the adjusted models, only the cortical parameters remained important predictors of fracture. Conclusion: HR-pQCT measurement of cortical area and mass might add clinically useful information for the evaluation of fracture risk.