Intraoperative Methadone vs Morphine for Postoperative Pain Control in Patients Undergoing Surgery of the Tibia

The purpose of this study is to determine whether, for surgery of the tibia, one dose of methadone provides better control of pain afterward as compared to morphine, which is the usual drug given to control pain after surgery. Immediately after the beginning of general anesthesia ("intraoperatively"), subjects will receive one dose of either methadone or morphine, in the amount of 0.2 milligrams per kilogram of body weight, intravenously. The primary hypothesis is that, subjects who receive one dose of methadone intraoperatively will require less pain medicine than subjects who receive one dose of morphine intraoperatively.