Statistical analysis
The sample size was calculated using an a priori power analysis. Based on previous literature that reported mean VAS difference of 1.7 mm with a standard deviation of 1.8 mm at 16 weeks after IA PN injection (α = 0.05, β = 0.8), it was expected that at least 19 cases were required for each group. Anticipating possible loss, 30 patients were enrolled in each group. Statistical analysis was conducted using SPSS version 25.0 (IBM, Armonk, NY, USA), and 