US-Guided Quadro-Iliac Plane Block for Postoperative Analgesia After Lumbar Instrumentation

Inclusion Criteria: * Classified as American Society of Anesthesiologists (ASA) physical status I-III * Scheduled for elective lumbar instrumentation surgery * Surgery performed under general anesthesia * Provision of written informed consent Exclusion Criteria: * Use of anticoagulant or antiplatelet medications * Presence of bleeding diathesis or coagulation disorders * Known allergy or hypersensitivity to local anesthetics or opioid medications * Infection at the planned block site * Alcohol or drug dependence * Cognitive impairment preventing reliable pain assessment using the NRS * Pregnancy or lactation * History of previous lumbar spine surgery * Diabetes mellitus * Renal or hepatic impairment