Intra-Operative Adjunctive Magnesium Sulfate in Pain Management of Total Knee Arthroplasty; a Systematic Review and Meta-analysis.

INTRODUCTION: There has been growing interest in the potential role of adjunctive magnesium sulfate in improving pain management. This systematic review and meta-analysis aimed to assess the effect of intra-operative adjunctive magnesium sulfate on pain management and opioid consumption in total knee arthroplasty (TKA).

METHODS: A comprehensive search was conducted in Medline, Embase, Scopus, Web of Science, and Cochrane Library databases, covering studies up to April 2023. The extracted data included pain management outcomes, opioid consumption, and adverse effects from the selected studies. Standardized mean differences (SMDs) were calculated for continuous outcomes, while risk ratios (RRs) were calculated for dichotomous outcomes. Meta-analysis was conducted employing random-effects models in STATA 17.

RESULTS: In this meta-analysis of 8 randomized controlled trials involving 536 patients, adjunctive magnesium sulfate in TKA was found to significantly reduce opioid consumption during the first 24 hours after operation (SMD: -1.88, 95% confidence interval (CI): [-3.66 to -0.10]; p = 0.038). It also resulted in lower pain scores at rest 24 hours after surgery (SMD: -1.53, 95% CI: [-2.70 to -0.37]; p = 0.010). There were no significant differences in time to first rescue analgesic and adverse effects between the groups. The included studies were assessed to have low to high levels of risk of bias.

CONCLUSION: This study presents evidence at low to moderate levels supporting the use of intra-operative adjunctive magnesium sulfate in TKA for improved pain management and reduced opioid consumption. However, further research is needed to address the heterogeneity and to explore optimal dosing regimens and routes of administration to maximize the benefits of magnesium sulfate in TKA.