All patients receive the same postoperative pain managements, including (1) parecoxib 40 mg administrated as intravenous bolus every 12 hours for 2 days, then diclofenac 25 mg orally every 8 hours until discharge, (2) acetaminophen 300 mg with codeine 15 mg orally every 8 hours until discharge, (3) morphine 2 mg intravenously pro re nata (prn) for pain every 2 hours as a rescue drug.