Comparison of modified thoracolumbar interfascial plane and anterior quadratus lumborum blocks for postoperative analgesia and recovery after lumbar transpedicular fixation surgery: a prospective randomized clinical study

BACKGROUND: Effective postoperative analgesia after lumbar transpedicular fixation (TPF) surgery remains challenging because of extensive tissue trauma and high nociceptive burden. Ultrasound-guided fascial plane blocks have emerged as important components of multimodal analgesia in spinal surgery. This study aimed to compare the analgesic efficacy, opioid consumption, technical performance, and quality of recovery associated with the modified thoracolumbar interfascial plane (mTLIP) block versus the anterior quadratus lumborum block (QLB) in patients undergoing two- or three-level lumbar TPF surgery. METHODS: In this prospective, randomized, single-center trial, 100 patients (ASA I-II) scheduled for two- or three-level lumbar TPF surgery were randomly assigned to receive bilateral ultrasound-guided mTLIP (n = 50) or anterior QLB (n = 50) in addition to standardized general anesthesia and multimodal postoperative analgesia. The primary outcome was cumulative fentanyl consumption during the first 24 postoperative hours. Secondary outcomes included interval opioid consumption, postoperative pain scores, time to first analgesic request, block performance characteristics, opioid-related adverse effects, and quality of recovery assessed using the QoR-15 questionnaire. RESULTS: Baseline demographic and surgical characteristics were comparable between groups. Fentanyl consumption during the first 4 postoperative hours was significantly lower in the mTLIP group compared with the QLB group (75 [50-125] µg vs. 125 [75-175] µg; p = 0.017). Opioid consumption during the 4-8 h and 8-24 h intervals, as well as total 24-hour fentanyl consumption, did not differ significantly between groups. Postoperative pain scores at rest and during movement, time to first analgesic request, additional analgesic requirements, QoR-15 scores, and opioid-related adverse effects were similar. The mTLIP block demonstrated significantly shorter performance time and superior needle visualization compared with QLB (p < 0.001). CONCLUSIONS: In patients undergoing multi-level lumbar TPF surgery, the mTLIP block provided superior opioid-sparing analgesia in the early postoperative period compared with anterior QLB, while overall analgesic efficacy and quality of recovery were comparable thereafter. Improved technical performance and procedural efficiency may favor mTLIP as a practical regional analgesia option in extensive lumbar spinal surgery.