Fig. 1
Schematic diagram of VD angle measurement of L1. a: Four marginal points (a, b, c and d) of the maximum sagittal plane of the L1 vertebral body were established, and distance between point a and point c (identified Dac), and distance between point b and point d (identified Dbd) were measured. b: The tangent line of the anterior arc at the maximum plane of the axial L1 vertebral body was identified as the anterior edge line, and the parallel line of the anterior edge line and across the posterior margin of the vertebral body was identified as the posterior edge line. Distance between the anterior edge line and the posterior edge line was identified Dap. VD angle = (Dac—Dbd)/ Dap. VD angle: vertebral deformity angle. L1: 1st lumbar vertebral body