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 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: * History of difficult airway, severe respiratory depression (SpO₂ \< 90%), 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. * History of psychiatric disorders (e.g., schizophrenia, depression) or cognitive impairment. * 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 analgesic medication within 48 hours prior to surgery. * Planned postoperative admission to the intensive care unit (ICU). * Any other condition deemed by the investigator to be inappropriate for participation in the study.