Efficacy of a Modified Cocktail for Quadratus Lumborum Block combined With Periarticular Local Infiltration Analgesia in Total Hip Arthroplasty

OBJECTIVES: Quadratus lumborum block(QLB) and periarticular local infiltration analgesia(LIA) are both widely used for postoperative pain control in total hip arthroplasty. The additive benefit of using a modified anesthetic cocktail remains uncertain when both techniques incorporate active adjuvants. METHODS: In this randomized controlled trial, 70 patients undergoing unilateral total hip arthroplasty under general anesthesia were randomized to receive either QLB combined with LIA (QLB+LIA group) or LIA alone. Both groups received an identical modified analgesic cocktail composed of ropivacaine, dexamethasone, magnesium sulfate, and sodium bicarbonate. The primary outcome was total opioid consumption within 24 hours postoperatively. Secondary outcomes included intraoperative remifentanil usage, numerical rating scale pain scores, plasma ropivacaine concentrations, quadriceps muscle strength, daily walking distance, quality of recovery-15 score, inflammatory markers , and adverse events. RESULTS: Compared to the LIA group, the QLB+LIA group showed significantly reduced 24-hour opioid consumption (12.7±4.7 mg vs. 16.2±7.3 mg; P=0.026) and intraoperative remifentanil use (P=0.034). Numerical rating scale pain scores during mobilization at 12 and 24 hours were lower in the QLB+LIA group. No differences were observed in functional recovery or inflammatory responses. Plasma ropivacaine levels remained below toxicity thresholds in both groups. CONCLUSION: Compared with LIA alone, added LIA to QLB with a modified cocktail can reduce the use of opioids and reduce the postoperative pain score during mobilization within 24 hours after the operation.