Fig. 3

Schematic of imaging measurements. A Disc height index (DHI), DHI = [2(b1 + b2 + b3)] / [(a1 + a2 + a2) + (c1 + c2 + c3)] *100%. B Ratio value of the greyscale (RVG). Midsagittal T2-weighted images were chosen, and RVG was the greyscale of discs a normalized against the greyscale of cerebrospinal fluid at the same level b. C and D Schematic diagram of the range of motion (ROM). C the segmental angle in hyperextension position (14.16°). D the segmental angle in hyperflexion position (6.31°); the range of motion of the segment (ROM = 14.16 − 6.31° = 7.85°)