Intervertebral disc degeneration and bone density in degenerative lumbar scoliosis: a comparative study between patients with degenerative lumbar scoliosis and patients with lumbar stenosis

Background Degenerative lumbar scoliosis is common in older patients. Decreased bone density and the degeneration of intervertebral discs are considered to be correlated with degenerative lumbar scoliosis. A means of quantifying the relative signal intensity for degenerative disc disease has not been previously discussed. The purpose of this study was to compare bone mineral density and intervertebral disc degeneration between degenerative lumbar scoliosis and lumbar spinal stenosis patients in a nine-year retrospective study. Methods From January 2001 to August 2010, 96 patients with degenerative lumbar scoliosis were retrospectively enrolled and 96 patients with lumbar spinal stenosis were selected as controls. Cobb angle, height of the apical disc and the contiguous disc superiorly and inferiorly on convex and concave sides, the height of the convex and concave side of the apical and the contiguous vertebral body superiorly and inferiorly were measured in the scoliosis group. The height of L2/L3, L3/L4, L4/L5 discs and the height of L2/L4 vertebral body was measured in the control group. The grade of intervertebral disc degeneration was evaluated using T2WI sagittal images in both groups. The bone density of lumbar vertebrae was measured with dual-energy X-ray. Results In scoliosis group, the intervertebral disc height on the convex side was greater than the height on the concave side (P <0.001). The vertebral body height on the convex side was greater than the height on the concave side (P=0.016). There was a significant difference between the scoliosis group and the control group (P=0.003), and between T-value and the rate of osteoporosis between the two groups (both P <0.001). Results were verified using multiple linear regression analysis. Conclusions Degenerative lumbar scoliosis is accompanied by height asymmetry between the intervertebral disc and vertebral body regarding the convex and concave surfaces. There is a positive correlation between the angle of scoliosis and the disc index, the degree of degeneration of the intervertebral disc, and a negative correlation between the angle of scoliosis and bone density. Chin Med J 2011;124(23)3875-3878