Efficacy of a Modified Cocktail for Periarticular Local Infiltration Analgesia in Unicompartmental Knee Arthroplasty: A prospective, double-blind, randomized controlled trial

Background: Periarticular local infiltration analgesia (LIA) has become a widely used method for postoperative pain management after unicompartmental knee arthroplasty (UKA). The present study aimed to evaluate the efficacy of a modified LIA cocktail. Methods: 61 patients who underwent UKA were enrolled and randomly assigned to receive periarticular infiltration of a modified cocktail (comprising ropivacaine, epinephrine, dexamethasone, magnesium sulfate, and sodium bicarbonate ) or a conventional cocktail(comprising ropivacaine, epinephrine, dexamethasone, ketorolac, and morphine). The outcomes included the consumption of patient-controlled intravenous analgesia (PCIA) medication used for postoperative analgesia, pain score, early joint functional recovery, discharge time, and complication rates. Results: In the initial 12 hours after surgery, the conventional cocktail showed no superiority over the modified cocktail in visual analog scale (VAS) scores. However, from the second postoperative day, the analgesic effect was significantly prolonged in the modified group, leading to lower VAS scores and better knee functional recovery. Additionally, patients in the modified group required less pain medication via PCIA, both within the first 24 hours and cumulatively up to 48 hours after surgery. Both groups had similar rates of complications. Conclusions: The present modification of a conventional cocktail significantly prolonged the analgesic effect and reduced pain medication consumption after UKA surgeries, which was associated with better functional recovery on early postoperative days. Trial registration : Chinese Clinical Trial Registry, ChiCTR2200060500. 21 March 2023