The postoperative analgesic effect of the continuous 3-in-1 femoral nerve block (FNB) with ropivacaine/fentanyl or with ropivacaine were compared in total knee arthroplasty.

Forty patients of American Society of Anesthesiologist physical status Ⅰor Ⅱ undergoing total knee arthroplasty under spinal anesthesia would be enrolled and randomly divided into two groups (R, "3-in-1" using a 30 ml of ropivacaine 0.375% and a continuous 3-in-1 with a ropivacaine 0.2%(8mL/h) for 48 h after operation, RF: Fifty ug of fentanyl will be added to a bolus(30ml ropivacaine 0.375%) and 1ug/ml of fentanyl will be mixed to a continuous infusion(8mg/h, ropivacaine 0.2%). Spinal anesthesia will be done after the insertion of femoral catheter. IV PCA with hydromorphone(0.15mg/ml, 0-1-10), will be used for rescue analgesics. Visual analgesia scale, hydromorphone consumption, side effects until 48h after operation and satisfaction will be compared.

Inclusion Criteria:

• ASA PS 1 to 3 undergoing total knee arthroplasty under spinal anesthesia

Exclusion Criteria:

• Patients were excluded from this study if they had contraindications to a regional anesthetic technique (e. g., local infection, sepsis, coagulation abnormality), allergy to local anesthetic or fentanyl, preexisting neurologic deficit in the lower extremities, and inability to comprehend the pain scales or use IV patient-controlled analgesia (PCA) device.