Lateral plain radiograph showing measured factors. The mean height of the vertebral body was defined as the average of the three area heights of the vertebral body ([a+b+c] / 3). The vertebral height ratio was calculated using the following equation : the vertebral height ratio (%) = mean height of the index level / [(mean height of the upper adjacent body + mean height of the lower adjacent body) / 2] × 100. Segmental kyphotic angle (X) was determined at the intersection of lines drawn at the superior plateau of vertebral body and the inferior plateau of vertebral body.