Comparative Efficacy of Adductor Canal Block in Total Knee Arthroplasty: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

BACKGROUND

Peripheral nerve blocks are an integral part of the multimodal analgesia for total knee arthroplasty (TKA). The adductor canal block (ACB) gained popularity for its motor-sparing effect. This study evaluated ACB alone or combined with local infiltration analgesia (LIA), in comparison to LIA alone in TKA patients.

METHODS

A systematic review and meta-analysis of randomized controlled trials (RCTs) was performed. The MEDLINE and PMC using PubMed, Cochrane Library, and Scopus databases were searched for RCTs evaluating ACB alone or with LIA compared to LIA alone after TKA published up to December 18, 2024. The random-effect model was used for both the standardized mean difference (SMD) of continuous parameters, as well as for the odds ratio of binary parameters. Postoperative pain scores assessed by a visual analog scale or a numerical rating scale at 24 and 48 hours constituted the primary outcome. Secondary outcomes were opioid consumption, knee range of motion (ROM), length of hospital stay, and postoperative nausea and vomiting (PONV). The risk of bias was assessed with the risk of bias tool 2 (RoB-2).

RESULTS

In total, 26 studies (2,400 patients) were included. Static and dynamic pain scores at 24 and 48 hours in the ACB+LIA group compared to LIA alone were lower (SMD24rest = -0.54, 95% confidence interval [CI], -0.80 to -0.28, P < .00001; SMD24activity = -0.85, 95% CI, -1.37 to -0.32, P = .001; SMD48rest= -0.26, 95% CI, -0.49 to -0.03, P = .02; SMD48activity = -0.66, 95% CI, -0.96 to -0.36, P ≤ .0001). ACB alone reduced pain during activity but not at rest compared to LIA (SMD24activity = -0.93, 95% CI, -1.88 to 0.02, P = .05; SMD48activity = -1.10, 95% CI, -2.03 to -0.17 P = .02). Reduced opioid consumption (P = .005) and greater ROM at 24 hours (P = .02) were observed with ACB+LIA. Regarding the remaining outcomes, no differences were observed in opioid consumption, ROM, and hospital stay. ACB patients experienced lower PONV rates (P = .05). The GRADE framework rated evidence certainty from moderate to very low with a moderate to high bias according to the RoB-2.

CONCLUSION

Adding ACB to LIA improves pain scores at 24 and 48 hours compared to LIA alone.