Fig. 1From: Transforaminal lumbar interbody fusion (TLIF) versus posterior lumbar interbody fusion (PLIF) in the treatment of single-level lumbar spondylolisthesisDegree of spondylolisthesis (%) = distance (2)/distance (1) × 100%. The spondylolisthesis degree was measured as a percentage of the distance from the posterior border of the caudal vertebra to the posterior border of the rostral vertebra, normalized to the superior end plate diameter of the formerBack to article page