Analgesic Effect of Ultrasound-Guided Caudal Block Versus Quadratus Lumborum Plane Block in Lumbar Spine Surgery in Adult Patients: A Double-Blinded Prospective Comparative Study

Background Improving surgical results and patient rehabilitation requires effective postoperative pain management. This study compares analgesic efficacy and safety between quadratus lumborum plane (QLP) block and ultrasound-guided caudal block in adult patients following lumbar spine stabilization procedures. Methods At Fayoum University Hospital, a double-blind, randomized, controlled experiment was carried out. Three groups—a caudal block group, a QLP block group, or a Control group— were randomized to adult patients (18–60 years old) undergoing lumbar spine fixation as an elective procedure. The time to initially request a rescue analgesic, postoperative pain scores using the Numerical Pain Rating Scale (NPRS), total opioid consumption, intraoperative and postoperative hemodynamics, and the frequency of complications were used to measure the effectiveness of analgesics. Results 111 patients were included, with 37 in each group. The QLP block group had a significantly longer time to first rescue analgesic dose compared to both the control (1 hour) and caudal block groups (15 hours vs. 1 hour and 5 hours, respectively; p < 0.001). Total opioid consumption was lowest in the QLP group (50 mg) compared to the control (150 mg) and caudal block groups (80 mg) (p < 0.001). Pain scores were lower in both the QLP and caudal block groups compared to the control group at most time points, with significant differences at 30 minutes, 1 hour, 2 hours, 4 hours, 8 hours, and 24 hours postoperatively (p < 0.001). Intraoperative fentanyl usage was significantly reduced in both the QLP and caudal block groups (p < 0.001). There were no significant differences in the rates of nausea and vomiting among the groups. Conclusions Ultrasound-guided caudal block and QLP block both offer advantages over standard care in managing postoperative pain following lumbar spine fixation. The caudal block provided better analgesic efficacy and hemodynamic stability compared to the control, while the QLP block demonstrated the lowest opioid consumption. These findings suggest that regional anaesthesia techniques can be effective alternatives to standard care, with the QLP block being particularly effective for prolonged pain relief. Trial registration: This study was conducted at Fayoum University Hospital with approval from the ethics committee, the local institutional board, and approval number M696 from the ethical committee. This trial is randomized, double-blind, and controlled. Qualified patients signed a thorough informed consent form before recruitment and randomization.