Intrathecal Morphine Versus Epidural Extended Release Morphine for Pediatric Patients Undergoing Spinal Fusion

This study plans to learn more about preventing pain in children who are having posterior spinal fusion surgery using two different kinds of morphine (a pain medicine). Also, this study plans to learn about individual differences in the how the different kinds of morphine work in children. Subjects are being asked to be in this research study because they are having spinal fusion surgery, will have pain some of the time and will be getting morphine during and after surgery to help control their pain.