Intraoperative single-shot "3-in-1" femoral nerve block with ropivacaine 0.25%, ropivacaine 0.5% or bupivacaine 0.25% provides comparable 48-hr analgesia after unilateral total knee replacement

Abstract

Purpose: To compare analgesia after intraoperative single shot "3-in-1" femoral nerve block (FNB) in combination with general anesthesia using ropivacaine 0.25%, ropivacaine 0.5% with bupivacaine 0.25% for total knee replacement (TKR).

Methods: We performed a randomized, double-blind study in 48 patients for elective TKR under general anesthesia. Patients were randomized to one of four groups (C: sham block, R1: "3-in-1" FNB using 30 mL of ropivacaine 0.25%, R2: "3-in-1" FNB using 30 mL of ropivacaine 0.5%, B: "3-in-1" FNB using 30 mL of bupivacaine 0.25%). Verbal pain score (VPS) both at rest and movement were assessed for 48 hr after TKR (0=none; 1=mild; 2=moderate; 3=severe). Total morphine consumption and its associated side effects, duration of hospitalization after operation were also compared.

Results: There were no differences in patients' physical characteristics, intraoperative morphine usage, operation time, tourniquet time or length of hospitalization between the four groups. When compared with group C, the VPS was significantly lower in groups R1, R2 and B at one, four, eight, 24 and 48 hr after TKR (P <0.05). The morphine requirement of groups R1, R2 and B were also significantly lower when comparing with group C up to 48 hr postoperatively (P <0.05). There were no significant differences in VPS and postoperative morphine requirement at any time between groups R1, R2 and B.

Conclusion: "3-in-1" FNB with ropivacaine provided analgesia that was clinically comparable to that of bupivacaine up to 48 hr after TKR. Increasing the concentration of ropivacaine from 0.25% to 0.5% failed to improve the postoperative analgesia of "3-in-1" FNB.