Fig. 5From: Risk factors for adjacent segment degeneration after posterior lumbar fusion surgery in treatment for degenerative lumbar disorders: a meta-analysisa The odds ratio (OR) estimate for the history of hypertension. b The odds ratio (OR) estimate for preoperative Pfirrmann’s classification. c The odds ratio (OR) estimate for the length of fusion (short vs long fusion). CI = confidence interval, df = degrees of freedom, M-H = Mantel–HaenszelBack to article page