Fig. 1From: Hybrid surgery with PEEK rods for lumbar degenerative diseases: a 2-year follow-up studySchematic diagram of the disc height index (DHI). The midpoints of the upper and lower endplates of the upper vertebral body are marked as a and b, respectively, and the midpoint of the upper endplate of the lower vertebral body is marked as c, DHI = bc/abBack to article page