Erector Spinae Block vs Morphine in Vertebral Fixation

The study aims to shed light about the potential role of Erector Spinae Block in the management of postoperative pain following vertebral fixation surgery via posterior approach. Patients will be randomized, the block will be performed before inducing general anesthesia, intraoperative management will be uniformed, while postoperative analgesia will compare cases (patients who received the block) versus controls (usual care with endovenous morphine infusion only).