Intra-Articular Magnesium Plus Bupivacaine Is the Most Effective and Safe Postoperative Analgesic Option Following Knee Arthroscopy: A Network Meta-analysis

Purpose: To evaluate the comparative efficacy and safety of single-dose intra-articular injection of commonly used analgesics after knee arthroscopy. Methods: A systematic literature review was done to search for randomized controlled trials (RCTs) published from database inception to October 1, 2020, that compared analgesics (i.e., morphine, bupivacaine, ropivacaine, and magnesium alone or in combination) with placebo or each other after knee arthroscopy. The primary outcomes were postoperative pain intensity at 2 hours and 24 hours. Secondary outcomes included the time to first analgesic request, number of patients requiring supplementary analgesics and side effects. We estimated summary standardized mean differences (SMDs) or odds ratios with 95% credible intervals (95% CrIs) using Bayesian network meta-analysis with random effects. Results: In total, 78 randomized controlled trials comprising 4,425 participants were included. Compared with placebo, magnesium plus bupivacaine was most likely to be effective in relieving pain at both 2hour (SMD = -3.81, 95% CrI -5.28 to -2.35) and 24-hour after surgery (SMD = -2.81, 95% CrI: -4.29 to -1.30). Following was morphine plus bupivacaine (2-hour: SMD = -2.19, 95% CrI -3.05 to -1.31; 24-hour: SMD = -1.44, 95% CrI -2.14 to -0.73) and bupivacaine alone (2-hour: SMD = -1.66, 95% CrI -2.33 to -0.98; 24-hour: SMD = -0.67, 95% CrI -1.22 to -0.07); ropivacaine alone and magnesium alone were not effective on pain relief. The interval time to first analgesic request was significantly extended compared with placebo except for ropivacaine alone and magnesium alone. The number of patients requiring supplementary analgesics was reduced in all groups except ropivacaine alone. No statistically significant difference was found between any studied analgesics or placebo with regard to side effects. Conclusions: Of 6 common postoperative intra-articular analgesics, magnesium plus bupivacaine provides the most effective pain relief without increasing short-term side effects after knee arthroscopy. Level of Evidence: Level II, metaanalysis of Level I and II studies.