Morphometric changes in lumbar vertebral bodies and intervertebral discs in tandem with diminution in bone mineral density

Abstract

Background: Morphometry of vertebral body (VB) and intervertebral disc space (IVD) is a reflection of the osseous strength, which primarily depends on the bone mineral density (BMD) and a host of other factors. As an individual ages, the internal hormonal milieu and the BMD undergoes a change. This is a ubiquitous phenomenon that impacts the quality of life and increases morbidity and mortality. The pathophysiologic process that causes changes in the BMD tends to alter the morphology of VB and the adjacent IVD as well. Aim: To correlate the morphological changes in the lumbar VBs and IVDs using MRI with changes in BMD in the Indian population. Materials and Methods: A total of 100 ambulatory adults in the age group 40–70 years were included in the study. The lumbar BMD was measured using a dual-energy X-ray absorptiometry (DEXA). Morphometry of the VBs and IVDs was performed using 1.5-T MRI, T2-weighted sagittal images and their heights (at various levels) and volumes were measured. Continuous variables were examined by analysis of covariance after correction for height and age. Results: There was no age difference among the subjects of normal BMD, osteopenia, and osteoporosis. Lower BMD was associated with a decrease in anterior, middle, and posterior heights (Ha, Hm, and Hp, respectively) and antero-posterior dimension (AP) of the vertebral body, leading to an increased biconcavity index. With regard to IVD, decrease in BMD was associated with a decline in Ha and Hp and AP dimension and increase in middle height, leading to an increased biconvexity index in both genders. Lower BMD was further associated with an overall decrease in both VB and IVD volume. Conclusion: The change in BMD in subjects with osteopenia and osteoporosis affects the morphology of spinal vertebra and adjacent IVDs and is associated with a decrease in VB and IVD volumes. MRI morphometry correlates well with the BMD measurements.