Bone mineral density of human female cervical and lumbar spines from quantitative computed tomography.

STUDY

DESIGN

This study determined bone mineral density (BMD) of cervical, thoracic, and lumbar vertebrae in healthy asymptomatic human subjects.

OBJECTIVES

To test the hypothesis that BMD of neck vertebrae (C2-C7) is equivalent to BMD of lumbar vertebrae (L2-L4).

SUMMARY OF BACKGROUND DATA: BMD of lumbar vertebrae is correlated to their strength. Although numerous studies exist quantifying BMD of the human lumbar spine, such information for the cervical spine is extremely limited. In addition, BMD correlations are not established between the two regions of the spinal column.

METHODS

Adult healthy human female volunteers with ages ranging from 18 to 40 years underwent quantitative computed tomography (CT) scanning of the neck and back. All BMD data were statistically analyzed using paired nonrepeating measures ANOVA techniques. Significance was assigned at a P < 0.05. Linear regression analyses were used to compare BMD as a function of level and region; +/-95% confidence intervals were determined.

RESULTS

When data were grouped by cervical (C2-C7), thoracic (T1), and lumbar (L2-L4) spines, mean BMD was 260.8 +/- 42.5, 206.9 +/- 33.5, and 179.7 +/- 23.4 mg/mL. Average BMD of cervical vertebrae was higher than (P < 0.0001) thoracic and lumbar spines. Correlations between BMD and level indicated the lowest r value for T1 (0.42); in general, the association was the strongest in the lumbar spine (r = 0.89-0.95). The cervical spine also responded with good correlations among cervical vertebrae (r ranging from 0.66 to 0.87).

CONCLUSIONS

The present study failed to support the hypothesis that BMD of lumbar spine vertebrae is equivalent to its cranial counterparts. The lack of differences in BMD among the three lumbar vertebral bodies confirms the appropriateness of using L2, L3, or L4 in clinical or biomechanical situations. However, significant differences were found among different regions of the vertebral column, with the cervical spine demonstrating higher trabecular densities than the thoracic and lumbar spines. In addition, the present study found statistically significant variations in densities even among neck vertebrae.