Epidural Morphine for Postoperative Analgesia After Total Knee Arthroplasty

2 mg of morphine (0.4 mg/ml morphine in 5 ml normal saline) is administered through the epidural catheter at the end of surgery.

5 ml normal saline is administered through the epidural catheter at the end of surgery.

Single femoral nerve block is performed with 20 ml 0.5% ropivacaine under the guidance of ultrasonography and nerve stimulator after surgery.

Intravenous morphine analgesia is provided with a patient-controlled analgesia pump which is established with 100 ml of 0.5 mg/ml morphine, programmed to deliver a 2 ml bolus with a lockout interval of 8-10 min and a background infusion of 0.5 ml/h.