The adductor canal block (ACB) is effective for treating
postoperative pain during arthroscopic knee surgery, but its impact on
anesthesia course and the optimal administration timing are unknown. This retrospective study addressed these questions. The aim of this study was to compare the effects of preoperative ACB and postoperative ACB on
anesthesia course and postoperative recovery. We allocated 215 adult patients who underwent arthroscopic knee surgery under
sevoflurane anesthesia between January 2019 and December 2019 to three groups. Group A received
general anesthesia without ACB, Group B received ACB before
general anesthesia induction, and Group C received ACB in the post-
anesthesia recovery unit (PACU). Group B consumed significantly less
sevoflurane (0.19 mL/kg/h) and milligram
morphine equivalents (0.08
MME) intraoperatively than Groups A (0.22 mL/kg/h; 0.10
MME, respectively) and C (0.22 mL/kg/h; 0.09
MME, respectively). Groups B and C had lower visual analogue scale (VAS) scores upon PACU discharge than Group A. Dynamic, but not at-rest VAS scores, were significantly higher in Group A.
Opioid consumption was similar in the ward, but Group A requested more intravenous
parecoxib for
pain relief. Length of
hospital stay was similar. Thus, preoperative ACB reduced the amount of volatile
anesthetic required and maintained stable hemodynamics intraoperatively. Preoperative or postoperative ACB improved
postoperative pain control. Consequently, preoperative ACB is optimal for intraoperative stress suppression and
postoperative pain control.