Inclusion Criteria:  1. pediatric patients (aged 3-14 years) with scoliosis (cobb angle >10 degree) scheduled for correctional osteotomy of the lower extremity and requesting epidural analgesia for postoperative pain control  Exclusion Criteria:  Contraindications to epidural analgesia (local infection, blood clotting disorder, anatomical abnormality, sepsis, etc.) If all of the parents of the subject are foreigners or illiterate (if the parents of the subject can not read the agreement)