Changes in Lumbar Disc Angles of Chinese Subjects from Upright to Flexion

Abstract

This study analyzed the sizes and angles of vertebrae and discs in Chinese subjects. Lateral lumbar spine radiograph films were taken of subjects in upright and 60 degrees flexion positions to evaluate disc height and angle changes. This study sought to gather data regarding the contribution of each segment to lumbar lordotic curvature in upright posture, and angle changes of individual segments from upright to flexion positions. Although the dimensions of vertebrae and discs have been measured, little has been done regarding in vivo measurements of lumbar lordotic curvature formation, especially during flexion. In addition, no data are available for the Chinese population. Five men and six women were studied. The lateral lumbar spine radiograph films were taken for upright and 60 degrees flexion positions. The dimensions of vertebral bodies and discs and lumbosacral angle were measured. The disc heights ranged from 0.7 to 1.2 cm in upright posture. Mean disc angle ranged from 9 degrees to 14 degrees in men and 6 degrees to 13 degrees in women. The lowest three segments (L3-L5) contributed 80% to 90% of the lumbosacral angle (L1-S1), which was approximately 47 degrees. Mean sacral horizontal angle was 35 degrees. From upright to 60 degrees flexion positions, all disc angles decreased uniformly from a total of 53 degrees +/- 6 degrees to 11 degrees +/- 12 degrees in men and 46 degrees +/- 11 degrees to 0 degrees +/- 18 degrees in women. The dimensions of lumbar vertebral bodies and discs, in upright and flexion positions, appear to be similar between Chinese and Western populations.