Correlation between bone mineral density and intervertebral disk degeneration in pre- and postmenopausal women

The purpose of this study was to investigate the relationship between intervertebral disk degeneration and bone mass. Magnetic resonance imaging was performed to evaluate lumbar disk degeneration according to Thompson's classification (grades 1 and 2, normal disk; grades 3, 4, and 5, degenerated disk), and bone mineral density (BMD) in the lumbar vertebrae, radius, and calcaneus was measured by dual-energy X-ray absorptiometry for 90 women (22-74 years old). The relationship between the grade of intervertebral disk degeneration and the BMD (Z score) was analyzed in pre- and postmenopausal women. In premenopausal women, BMD was significantly higher at all measured sites in the degenerated disk group judged at the L5-S1 level than in the normal disk group (P < 0.05). In postmenopausal women, BMD was significantly higher at the anteroposterior L2-L4, lateral L3, and calcaneus in the degenerated disk group judged at the L2-L3 level than in the normal disk group (P < 0.05). BMD at the anteroposterior L2-L4 and calcaneus was significantly higher in the degenerated disk group judged at the L3-L4 level than in the normal disk group (P < 0.05). In conclusion, the BMD of not only the lumbar vertebrae but also the calcaneus and radius was mutually related to lumbar intervertebral disk degeneration from an early stage of degeneration.