Correlates of Bone Mineral Density and Sagittal Spinal Balance in the Aged

OBJECTIVE: To investigate the relationship between bone mineral density (BMD) and sagittal spinal balance in the Korean elderly population. METHODS: The retrospective study included subjects aged 60 years and above, who had whole-spine lateral radiography and dual-energy X-ray absorptiometry (DEXA) within a year's gap between each other. Sagittal vertical axis (SVA) for evaluation of sagittal spinal balance and five spinopelvic parameters were measured through radiography. The presence of compression fracture was identified. Correlations of BMD T-scores with SVA and with the spinopelvic parameters were assessed using Pearson correlation coefficient (PCC). Linear regression analyses were performed between SVA and the clinical and radiologic variables. RESULTS: One hundred twenty-two subjects (42 males and 80 females; mean age, 69.93±5.5 years) were included in the study. BMD, femur or spine, was not correlated with SVA or any spinopelvic parameters in both genders (PCC<±0.2), except that spine BMD in men was associated with sacral slope. Univariate regression analysis revealed association between SVA and lumbar lordosis, pelvic tilt, and compression fractures in both genders; it was also associated with age and pelvic incidence in females and with sacral slope in males. Multivariate linear regression model showed lumbar lordosis and compression fracture as variables affecting SVA in both sexes; pelvic incidence was another factor affecting SVA in women only. CONCLUSION: BMD was not associated with sagittal spinal balance in the aged. Sagittal spinal balance was explained partly by lumbar lordosis and compression fracture. Further study is warranted to understand progression of sagittal imbalance with age.