Effects of Combined Intravenous and Topical Magnesium Sulfate Administration on Pain, Stress, and Functional Recovery After Total Knee Arthroplasty: A Prospective, Randomized, Blinded Controlled Trial.

PURPOSE: Evidence suggests that both intravenous and intraoperative topical application of magnesium sulfate can improve pain management after total knee arthroplasty (TKA). However, the optimal method of magnesium sulfate administration remains unclear, and no studies have evaluated the effect of combined intravenous and topical application on post-TKA pain management. This study aimed to assess the effects of combined intravenous and topical magnesium sulfate on pain, stress, and functional recovery following TKA. METHODS: In this randomized controlled trial, 150 patients undergoing TKA were randomly assigned to one of three groups: the Intravenous Group (received intravenous magnesium sulfate intraoperatively), the Topical Group (received magnesium sulfate added to the local infiltration analgesic cocktail), and the Combined Group (received both intravenous and topical magnesium sulfate). The primary outcome was the resting pain score at 24 hours postoperatively. Secondary outcomes included pain scores at other time points, postoperative morphine consumption for rescue analgesia, postoperative knee range of motion, walking ability, hospital length of stay, intraoperative stress levels (intraoperative inhaled anesthetic consumption, incidence of intraoperative hypertension), postoperative stress levels (postoperative serum cortisol/ACTH levels), and complication rates. RESULTS: No significant difference was found in the resting Visual Analogue Scale (VAS) pain scores at 24 hours postoperatively among the three groups. Compared to the Intravenous and Topical groups, the Combined Group showed significantly lower VAS scores at several time points on the day of surgery, although this did not reach the minimal clinically important difference. No significant differences were observed among the three groups for the other secondary outcomes. CONCLUSION: Compared with intravenous or topical magnesium sulfate alone, combined intravenous and topical administration did not demonstrate a clinically significant advantage in postoperative pain management, stress response, or functional recovery. Further studies are warranted to determine the optimal route and regimen for perioperative magnesium sulfate administration in TKA.