Fig. 9

A forest plot diagram showing VAS. Four RCTs reported VAS on the day of surgery. Ten RCTs reported VAS on the first day after surgery. Six RCTs reported VAS on the third day after surgery. Two RCTs reported VAS on the second and fifth day after surgery. Three RCTs reported VAS on the seventh day after surgery. Two RCTs reported VAS at 1 month after surgery. The results of random-effects meta-analysis showed no significant differences between the two groups in the postoperative VAS score at either the day of surgery (MD = 1.56, 95% CI [− 5.0, 3.62], P = 0.20), first day (MD = 0.42, 95% CI [− 0.29, 1.13], P = 0.25), second day (MD = 0.16, 95% CI [− 0.21, 0.54], P = 0.39), third day (MD = 0.20, 95% CI [− 0.12, 0.53], P = 0.21), fifth day (MD = 0.95, 95% CI [− 0.52, 2.42], P = 0.21), seventh day (MD = 0.89, 95% CI [− 0.04, 1.83], P = 0.06)or 1 month after surgery (MD = 0.16, 95% CI [− 0.06, 0.39], P = 0.16)