Does Proximal Adductor Canal Block Provide Better Analgesic Efficacy than Distal Adductor Canal Block in Patients Undergoing Knee Arthroplasty: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

To compare the analgesic efficacy and adverse events of proximal versus distal ACB for adults undergoing knee arthroplasty, we searched PubMed, Cochrane, Web of Science, and Embase to identify all eligible randomized controlled trials (RCTs). The study quality of the RCTs was evaluated using the Cochrane risk of bias assessment tool. Heterogeneity among studies was examined by Cochrane Q test. Our primary outcomes were pain intensity at rest/during movement and morphine consumption. Statistical analyses were conducted by RevMan Software. Seven eligible studies involving 400 subjects were included in this meta-analysis with 202 participants in the proximal ACB group and 198 participants in the distal ACB group. The results demonstrated that proximal ACB provided significantly better pain relief at rest at 2 h (SMD -0.27, 95% CI -0.54 to -0.01, four trials, 222 participants, I2 = 0, p = 0.04) and 24 h (SMD -0.28, 95% CI -0.48 to -0.08, seven trials, 400 participants, I2 = 0, p = 0.006) following the surgery. We found no evidence of a difference in postoperative pain intensity at other timepoints. Furthermore, we noted no evidence of a difference in cumulative morphine consumption and occurrence of adverse events. Proximal ACB provides better pain relief and comparable adverse effects profile compared with distal ACB. The analgesic benefit offered by proximal ACB, however, did not appear to extend beyond the first 24 h. The overall evidence level was mostly low or very low, which requires more well-organized multicenter randomized trials in the future. Proximal ACB provides better pain relief compared with distal ACB, which did not appear to extend beyond the first 24 h. image