IV Methadone vs EXPAREL Erector Spinae Plane Blockade in Pediatric Subjects Undergoing Idiopathic Scoliosis Correction (AIMS)

Inclusion Criteria: Subjects whose parent(s) or guardian(s) has/have signed and dated the informed consent form (ICF) for the subject to participate in the study Patients with a diagnosis of juvenile idiopathic scoliosis (JIS) or adolescent idiopathic scoliosis (AIS) who will have posterior spinal fusion surgery Male or female patients 11 to less than 18 years of age on the day of surgery. American Society of Anesthesiologists (ASA) Class 1-2. Able to adhere to the study visit schedule and complete all study assessments. Exclusion Criteria: Body mass index ≥35 at the time of screening Contraindication to regional anesthesia (e.g., abnormal coagulation, infection at site) Current opioid use at the time of screening Current diagnosis of chronic pain Allergy, hypersensitivity, intolerance, or contraindication to any of the study medications Administration of liposomal bupivacaine (LB, Exparel) Subject/parent/guardian primary language other than English or Spanish Inability of patient to verbally express symptoms such as pain and side effects (as in moderate to severe developmental delay) A prolonged QTc on preoperative EKG (QTc longer than 450 milliseconds) History of Torsades de Pointes Renal or hepatic impairment Diagnosed active seizure disorder Any other condition that causes patient to be ineligible for surgery, i.e. pregnancy.