Sample size
The sample size was calculated according to the pilot study including 10 patients in each group. Postoperative %20 reduction of tramadol consumption at the 24th hour was accepted clinically meaningful. The mean tramadol consumption was 120 ± 34 in the group OSTAP and 95 ± 47 in the group M-TAPA. Therefore, assuming Type I error = 0.05 and Type II error = 0.2 (%80 power to detect this difference), then 32 patients were needed per each group. Considering dropouts, 38 patients were decided to include in each group.