Correlation of Thoracic Kyphosis and Lumbar Lordosis and Bone Mineral Density in Women

Abstract

Although measures of spinal curvature have been used to predict bone mineral density in postmenopausal women and patients with scoliosis, such relationships have not been examined in healthy premenopausal women. PURPOSE: The purpose of this study was to examine the correlation between spinal measurements of thoracic kyphosis (TC) and lumbar lordosis (LC) and bone mineral density in pre and postmenopausal women. METHODS: The data for this study were obtained from the Texas Woman's University Pioneer Project. Female participants (n = 242; premenopausal n=104, postmenopausal n=138) between the ages of 18 - 60 yrs (mean + SD age, weight, body fat% = 45.9 + 9.0 years, 65.8 + 12.2 kg, and 36.5 + 7.8%) were evaluated on multiple health measures. Thoracic kyphosis and lumbar lordosis were measured with a 24 inch flexicurve. Bone mineral density of the lumbar spine (LS), proximal femur (FN), and total body (TB) were assessed via dual-energy x-ray absorptiometry (Lunar DPX-IQ, version 4.6e). Pearson correlations and multiple regression analysis were used to examine the relationship between the obtained spinal measurements and bone mineral density. Fisher Z transformations were used to compare correlation coefficients between pre and postmenopausal women. Significance was set at p <.05. RESULTS: Significant correlations were observed for the femoral neck and lumbar spine bone mineral density with thoracic and lumbar curve in premenopausal women (FN and LC: r = -.464, FN and TC: r = -.525, LS and LC: r = -.344, LS and TC: r = -.446; p <.001). Similarly, slightly weaker, but significant, correlations were observed for femoral neck and lumbar spine in relation to thoracic and lumbar curve in postmenopausal women (FN and LC: r =.-371, FN and TC: r =.397, LS and LC: r = -.321, LS and TC: -.288, p 1.96; FN and LC: z = 6.29, FN and TC: z = 9.16, LS and TC: z = 10.39). CONCLUSION: The observed negative linear relationship suggests that as either thoracic or lumbar curvature increases, the regional bone mineral density decreases. This relationship appears to be more noticeable in pre-menopausal women as opposed to their postmenopausal counterparts.