Continuous vs. single-shot adductor canal block for pain management following primary total knee arthroplasty: A systematic review and meta-analysis of randomized controlled trials.

Background: Adductor canal block (ACB) provides effective analgesia following total knee arthroplasty (TKA). This systematic review aimed to compare continuous and single-shot ACB for pain management and functional recovery following TKA.

Methods: MEDLINE, Embase, Web of Science and CENTRAL were searched up to January 5th, 2021. Included studies were randomized controlled trials comparing continuous to single-shot ACB for postoperative pain management after primary TKA. Primary outcome was opioid consumption and secondary outcomes were pain intensity, quadriceps strength, mobility, complications, and length of hospital stay. Meta-analyses were performed using random-effects method.

Results: Eleven studies (910 patients) were included in this systematic review. Continuous ACB did not significantly decrease opioid consumption (8 studies; 642 patients; MD=-5.67; 95% CI: -13.87 to 2.54; I=13%) but significantly decreased 48hours pain scores (10 studies; 852 patients; MD=-0,73; 95% CI: -0.93 to -0.54; I=54%). Continuous ACB improved quadriceps strength (4 studies; 250 patients; SMD=0.59; 95% CI: 0.16 to 1.03; I=63%) but not Timed Up and Go test performance (5 studies; 524 patients; MD=3.99; 95% CI: -8.98 to 1.01; I=89%). Type of ACB did not affect nausea and vomiting (5 studies; 357 patients; RR=1.23; 95% CI: 0.65 to 2.34; I=0%) nor length of hospital stay (8 studies; 655 patients; MD=-0.13; 95% CI: -0.28 to 0.01; I=36%).

Conclusion: Continuous ACB did not reduce opioid consumption following TKA. Larger trials are required.