Idiopathic scoliosis surgery is a major surgery, causing significant post-operative pain which can have a significant impact, both for the patient and for society. Different analgesic strategies have emerged in recent years, within the framework of multimodal analgesia including systemic analgesics, but also axial or peripheral loco-regional anesthesia (LRA). These techniques are integrated into the recommendations of learned societies, aimed at optimizing the post-operative rehabilitation of patients. If intrathecal morphine injection (ITM) and spinal erector block (ESPB) have already shown their effectiveness in reducing postoperative pain, the combination of these techniques can have a real benefit in major spinal surgery. , and has not yet been studied.