58 adolescents with idiopathic scoliosis undergoing posterior spinal fusion were randomized to receive either methadone (n=38) or morphine (n=28). The primary outcome was postoperative opioid consumption over the first 3 days post-surgery. Secondary outcomes included postoperative pain severity, opioid-related side effects, and the ratio of patient-controlled analgesia (PCA) injections to attempts, as a behavioral index of uncontrolled pain. Outcomes were assessed up to 3 postoperative days. Overall, the results revealed that patients in the methadone group consumed significantly less total opioid postoperatively than the morphine group (p=0.026), while pain scores and side effects were similar between the groups. These findings suggest that methadone may be a beneficial alternative for opioid-sparing strategies in adolescents undergoing this procedure.