Intervertebral disc height correlates with vertebral body T-scores in premenopausal and postmenopausal women

To assess the correlation between vertebral body T-score and intervertebral disc height in premenopausal and postmenopausal women.

A total of 203 women were recruited from a large bone densitometer directory. The disc heights measured were those between the 12th thoracic and third lumbar vertebra. The discs were assigned the symbols D, whereby D1 applies for the disc between the 12th thoracic and first lumbar vertebra. The disc height of the group of women (n=38) with osteoporotic vertebral fractures was compared with the disc heights of hormone-treated women (n=47), untreated postmenopausal women (n=77) and another group of premenopausal women (n=41). Bone density measurements were taken by a Norland Bone Densitometer (DEXA 586).

The lowest disc heights were found in the fracture group. The total disc height in the fracture group was 1.42+/-0.25 cm, significantly lower (P<0.0001) than the untreated group (1.82+/-0.3 cm), which in turn was significantly (P<0.0001) lower than the hormone-treated group (2.2+/-0.26 cm) and the premenopausal group (2.11+/-0.21 cm). The lowest T-scores were also noted in the vertebral fracture group (T-score=-3.1+/-0.3) (P<0.0001). The highest T-score recorded for the premenopausal group was -0.38+/-45, higher than that of the untreated menopausal -1.4+/-0.32 and hormone treated women -0.65+/-0.3, all three significantly higher than the fracture group (P<0.0001). The lowest T-scores were also noted in the vertebral fracture group (T-score=-3.1+/-0.3) (P<0.0001). The highest T-score recorded for the premenopausal group was -0.38+/-45, higher than that of the untreated menopausal -1.4+/-0.32 and hormone treated women -0.65+/-0.3, all three significantly higher than the fracture group (P<0.0001). Bone density across all groups revealed a correlation with disc height (R=0.29) (P<0.05). The group with vertebral osteoporotic fractures was the only group to show a negative correlation (-0.21) between disc height and vertebral bone density. Conversely, a significant correlation (R=0.47) (P<0.001) between the T-score and the total lumbar intervertebral disc height was noted in the premenopausal group of women. The menopausal group of untreated women also showed a significant correlation between the T-score and disc height (R=0.25 P<0.05); however, an insignificant positive correlation was found in the hormone-treated group.

The fracture group was noted to have the lowest intervertebral disc height and lowest T-scores compared with the other three groups. The hormone-treated and the premenopausal women had the highest disc heights and T-scores recorded. Positive correlations between T-score and disc height were noted for all the groups except for the fracture group. These results suggest a coupling between the vertebral body and intervertebral disc, which if disrupted may lead to increased risk for fracture. The combination of both T-score and disc height may improve the screening sensitivity for vertebral body fracture risk.