Effects of Perioperative Magnesium Sulfate Administration on Postoperative Chronic Knee Pain in Patients Undergoing Total Knee Arthroplasty: A Retrospective Evaluation.

We aimed to investigate whether perioperative magnesium sulfate administration was associated with the incidence of chronic persistent postoperative pain (PPP) following total knee arthroplasty (TKA). This retrospective observational study was performed at a single tertiary academic hospital. We reviewed the medical records of adult patients who were admitted between August 2012 and July 2017. Patients who received magnesium sulfate during surgery were the magnesium group. The presence of PPP, one year after TKA, was evaluated using a binary logistic regression analysis. A total of 924 patients were included in the analysis, and 148 patients (16.0%) experienced PPP one year after TKA. In the multivariable model, the magnesium group had a 62% lower rate of PPP one year after TKA compared to the control group (odds ratio (OR): 0.38, 95% confidence interval (CI): 0.16 to 0.90; p = 0.027). This finding was similar in the sensitivity analysis using propensity score adjustment (OR: 0.38, 95% CI: 0.16 to 0.93; p = 0.036). We showed that perioperative magnesium sulfate administration was associated with a lower rate of PPP one year after TKA. Our results suggest that magnesium sulfate administered perioperatively is effective for the alleviation of acute and chronic pain after surgery.