Analgesic Efficacy of Adductor Canal Block in Total Knee Arthroplasty: A Meta-analysis and Systematic Review

The aim of this meta-analysis and systematic review of randomized controlled trials (RCTs) was to evaluate the efficacy and safety of adductor canal block (ACB) for early postoperative pain management in patients undergoing total knee arthroplasty (TKA). Relevant manuscripts comparing ACB with saline or femoral nerve block (FNB) in TKA patients were searched for in the databases of PubMed, EMBASE, and Cochrane library. The outcomes assessed included cumulative analgesic consumption, pain at rest or during movement, ability to ambulate, quadriceps strength, and complications (nausea, vomiting or sedation). For continuous outcomes, pooled effects were measured using weighted mean difference (WMD) or standard mean difference (SMD), together with 95% confidence intervals (CIs). For outcomes without sufficient data for synthesis, qualitative interpretation of individual studies was summarized. Finally, 11 RCTs involving 675 patients met the inclusion criteria. The pooled results showed that ACB resulted in less postoperative analgesic consumption than saline (WMD, -12.84 mg; 95% CI, -19.40 mg to -6.27 mg; P < 0.001) and less pain at rest or during activity. No conclusions could be drawn regarding ability to ambulate and quadriceps strength, because only one study reported these variables. Most studies comparing ACB and FNB reported similar effects on postoperative analgesic consumption (WMD, -0.56 mg; 95% CI, -8.05 mg to 6.93 mg; P = 0.884) and pain; however, ability to ambulate and quadriceps strength were significantly better with ACB (SMD, 0.99; 95% CI, 0.04-1.94; P = 0.041). Additionally, ACB did not increase the rate of complications. Our results suggest that, compared with saline, ACB decreases analgesic consumption and offers short-term advantages in terms of pain relief. Compared with FNB, ACB was associated with better ability to ambulate and quadriceps strength.