Tegileridine for Postoperative Pain After Adolescent Scoliosis Surgery

Inclusion Criteria: * Aged 10 years to less than 18 years. * Scheduled to undergo posterior spinal fusion (PSF) surgery for adolescent idiopathic scoliosis under general anesthesia. * American Society of Anesthesiologists (ASA) physical status classification I to III. * The participant and their parent or legal guardian voluntarily provide written informed consent prior to any study-related procedures. Exclusion Criteria: * Baseline room-air oxygen saturation (SpO2) \< 90% at rest, acute or severe bronchial asthma. * History of severe cardiovascular or cerebrovascular disease, such as myocardial infarction, unstable angina, second-degree or higher atrioventricular block, NYHA Class III or higher heart failure, or stroke. * Known or suspected gastrointestinal obstruction, including paralytic ileus. * Known hypersensitivity to opioids or any component of the study drug formulation. * Severe cognitive impairment or uncontrolled psychiatric disorders (e.g., active schizophrenia) that preclude the patient's ability to comprehend the NRS or independently operate the patient-controlled analgesia (PCA) pump. * Diagnosis of neuromuscular scoliosis or presence of any other chronic pain condition that may interfere with postoperative pain assessment. * Chronic use of opioid analgesics, or use of any long-acting analgesics within 48 hours prior to surgery (short-acting non-opioid analgesics are permitted but must be discontinued at least 12 hours preoperatively). * Planned postoperative admission to the intensive care unit (ICU).