Comparison of Spinal Anesthesia With Intrathecal Morphine Versus PENG Block With or Without Dexamethasone in Hip Arthroplasty

Postoperative pain after total hip arthroplasty is associated with increased opioid use, delayed mobilization, and a higher risk of adverse events, particularly in older adults. Spinal anesthesia with intrathecal morphine is widely used to improve postoperative analgesia; however, it may be associated with opioid-related side effects such as nausea, pruritus, urinary retention, and respiratory depression. Ultrasound-guided regional nerve blocks, including the pericapsular nerve group (PENG) block, have emerged as opioid-sparing alternatives that may provide effective analgesia while preserving motor function. This prospective, randomized, multicenter clinical trial is designed to compare the efficacy and safety of three regional anesthesia strategies in patients undergoing elective total hip arthroplasty. Participants aged 60 years and older will be randomly assigned in a 1:1:1 ratio to one of three study groups: spinal anesthesia with intrathecal morphine; spinal anesthesia combined with a PENG block; or spinal anesthesia combined with a PENG block using perineural dexamethasone as an adjuvant. All participants will receive standardized spinal anesthesia with ropivacaine. In the control group, intrathecal morphine will be administered as part of routine spinal anesthesia. In the intervention groups, the PENG block will be performed under ultrasound guidance using ropivacaine, with or without the addition of dexamethasone. Perioperative care, postoperative analgesic protocols, and rehabilitation pathways will be standardized across all study centers to minimize variability. Pain intensity at rest and during movement will be assessed using a visual analog scale at predefined time points within the first 48 hours after surgery. Secondary outcomes include total opioid consumption, time to first rescue analgesia, early mobilization, length of hospital stay, incidence of opioid-related and block-related adverse events, and changes in inflammatory markers measured in peripheral blood. The results of this study will provide comparative evidence on opioid-based versus opioid-sparing regional anesthesia strategies for hip arthroplasty and may help inform clinical decision-making aimed at improving postoperative pain control, functional recovery, and safety in older surgical patients.