Fig. 1From: Non-fusion procedure using PEEK rod systems for lumbar degenerative diseases: clinical experience with a 2-year follow-upDHI (disc height index) measurement by ab/bc. Ab represents the disc height and bc represents the vertebrae height. Ac is the line labeling the centers. The center of the vertebral body is marked by the crossing point of two diagonal lines, which are drawn from the corners of vertebral bodyBack to article page