This prospective randomized controlled study aims to compare the effects of ultrasound-guided thoracolumbar interfascial plane (TLIP) block versus retrolaminar block on postoperative quality of recovery in patients undergoing posterior lumbar spine fusion surgery. Despite advances in surgical techniques, lumbar spine fusion is associated with significant postoperative pain, which may delay recovery and increase opioid consumption.

Recent approaches emphasize multimodal analgesia and opioid-sparing strategies, including regional anesthesia techniques. Interfascial plane blocks, such as TLIP and retrolaminar block, have gained attention due to their safety and effectiveness in targeting the dorsal rami of spinal nerves supplying the posterior spinal structures.

The primary outcome of this study is postoperative quality of recovery assessed using the Quality of Recovery-15 (QoR-15) questionnaire at 24 hours. Secondary outcomes include pain scores, opioid consumption, time to ambulation, time to oral intake, and postoperative complications.

This study is a prospective, randomized, controlled, double-blind clinical trial conducted at Assiut University Hospital. A total of 70 adult patients scheduled for elective one- or two-level posterior lumbar instrumented fusion surgery under general anesthesia will be enrolled and randomly allocated into two equal groups.

Patients in Group T will receive ultrasound-guided thoracolumbar interfascial plane (TLIP) block, while patients in Group R will receive ultrasound-guided retrolaminar block. All blocks will be performed after induction of general anesthesia under strict aseptic precautions by an experienced anesthesiologist.

Randomization will be performed using a computer-generated sequence with allocation concealment via sequentially numbered, opaque, sealed envelopes. The study will be conducted in a double-blind manner, where patients and outcome assessors will be blinded to group allocation.

All patients will receive standardized perioperative care based on enhanced recovery principles, including multimodal analgesia and early mobilization. Postoperative pain will be assessed using the Visual Analog Scale (VAS), and rescue analgesia will be administered when needed.

The primary outcome is the QoR-15 score at 24 hours postoperatively. Secondary outcomes include pain scores at predefined intervals, time to first rescue analgesia, total opioid consumption, time to ambulation, time to oral intake, length of hospital stay, and incidence of postoperative complications.

Inclusion Criteria:

• Adult patients aged 18-65 years
• Male and female patients
• Scheduled for elective one- or two-level posterior lumbar instrumented fusion surgery under general anesthesia
• ASA physical status I-III
• BMI < 35 kg/m²
• Willing to participate and provide informed consent

Exclusion Criteria:

• Patient refusal to participate
• Coagulopathy or anticoagulant therapy
• Infection at the site of block injection
• Known allergy to local anesthetics
• Chronic opioid use (>3 months)
• Severe hepatic, renal, or cardiac dysfunction
• Neurological deficits interfering with pain assessment
• Pregnancy or lactation

This is a double-blind study where participants and outcome assessors are blinded to group allocation. The anesthesiologist performing the block is not blinded. Identical dressings are applied to maintain blinding.