Sample size calculation
Assuming that a 20% decrease in POST incidence is clinically significant, experimental results from 20 lumbar spine surgery patients were used to estimate the sample size using PASS software. A type I error rate of α = 0.05 and a test power of β = 90% were set, and at least 26 samples were needed in each group. Taking into account potential loss to follow-up during the study (10%), 30 patients were recruited per group.