Analgesic effects of Adductor Canal Block after Knee Surgery – A Meta-Analysis of Randomized Controlled Trials

Abstract

Introduction: Providing effective analgesia is important to reduce immobilization and to achieve better functional activity after knee surgery. The adductor canal block (ACB) is a newly developing analgesic method for postoperative pain management of knee surgery. We performed a meta-analysis to extensively investigate the analgesic effects of the ACB after knee surgery as compared with the use of placebo.

Methods: The databases MEDLINE, EMBASE, CENTRAL, CINAHL, Web of science and KoreaMed were systematically searched to retrieve eligible randomized controlled clinical trials. The primary outcome was visual analog scale (VAS) of pain severity at rest within 48 h after surgery. The secondary outcomes were VAS during knee flexion and postoperative morphine consumption. Mean differences (MDs) with 95% confidence intervals (CIs) was calculated for the outcomes. Relevant subgroup analyses were performed to evaluate potential sources of heterogeneity.

Results: Fourteen randomized controlled trials were retrieved and analyzed. The pooled results showed that the ACB significant decreased VAS at rest within 48 h after surgery compared with the use of placebo [MD (95% CI) = -0.64 (-0.84, -0.44)

P < 0.001] and during knee flexion within 24 h after surgery [MD (95% CI) = -1.17 (-1.53, -0.80)

P < 0.001]. Postoperative morphine consumption was significantly lower within 48 h postoperatively in patients receiving the ACB [MD (95% CI) = −1.17 (-1.53, -0.80)

P < 0.001].

Conclusion: This meta-analysis suggests that the ACB has an advantage in pain relief at rest and during knee flexion and in postoperative analgesic requirement after knee surgery. Therefore, the ACB can be effectively used as one of multimodal analgesia after knee surgery.