The parcicipants were randomly assingned to epidural infusion group and femoral sciatic block. In epidural infusion group, a lumbar epidural catheter was placed at the L3-4 level using loss-ofresistance procedure. ropivacaine 0.2% and fentayl 2mcg/ml were infused at a rate of 5ml/hr from the end of operation. In femoral sciatic group, the femoral and sciatic nerve are located using ultrasound and 0.2% ropivacain is injected. A catheter is inserted to femoral nerve. From the end of operation, 0.2% ropivacaine was infused through the femoral catheter at a rate of 5ml/hr. The incidence of side effects is measured.