Fig. 3. (A) Kaplan-Meier survival curve of patients with revision surgery. Kaplan-Meier survivorship analysis revealed a 1-year revision-free rate of 90.0%, a 2-year survival rate of 86.4%, and a 4-year survival rate of 81.1%. (B) Survivorship of the post-laminectomy instability (PLI) group (69.2%) was lower than that of the stable group (88.2%), and the log-rank test revealed that the difference between the groups was statistically significant (p = 0.034).