Efficacy of Dual Energy X-ray Absorptiometry for Evaluation of Biomechanical Properties: Bone Mineral Density and Actual Bone Strength

INTRODUCTION Bone mineral density (BMD) is an important index in diagnosis of osteoporosis and other metabolic bone diseases, prediction of fractures, and monitoring treatment. This study was to find a more feasible technique for prediction of osteoporotic fracture between dual energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) and to reveal the actual change of bone strength when BMD was changed. METHODS Ten of these 20 specimens were used as the demineralized group and the other 10 as the control. Each specimen was immersed in HCl solution at for a period of at least 10 minutes, up to 100 minutes, at an interval of 10 minutes for different levels of demineralization. BMD was measured using DXA and QCT. Uniaxial compression tests were conducted to measure biomechanical parameters. Pearson correlation analysis was used respectively between BMD and biomechanical parameters and between DXA and QCT. RESULTS Elastic modulus (r=0.87) and yield stress (r=0.84) showed a statistically significant correlation with DXA BMD. Through correlation analysis with QCT BMD and elastic modulus, correlation coefficient showed hemi-vertebra (r=0.80) and trabecular (r=0.68). In yield stress, there was a statistically significant correlation in hemi-vertebra (r=0.87) and trabecular bone (r=0.84). CONCLUSION DXA is a current standard technique not only for diagnosis of osteoporosis but also for prediction of fracture risk compared to QCT. Actual decrease of bone strength was much greater than that of BMD by both DXA and QCT.