Postoperative continuous intravenous analgesia may not provide effective postoperative analgesia following total knee arthroplasty. This study was conducted to determine if combined continuous intravenous analgesia and peri-articular infiltration provided a better quality of analgesia following total knee arthroplasty than epidural analgesia.

A prospective, double-blind study involving 50 patients who had undergone total knee arthroplasty was conducted. Patients were divided into control group and an experimental group. Patients in the control group (n = 25) received peri-articular infiltration with 47 mL normal saline prior to closure of the wound and postoperative epidural analgesia for 48 hours. Patients in the experimental group (n = 25) received a mixture of peri-articular infiltration of 16 mL of 0.75% ropivacaine, 6 mg morphine, 0.2 mg of epinephrine and 25 mL normal saline prior to closure of the wound and postoperative continuous intravenous analgesia for 48 hours. The analgesic efficacy was then evaluated using the verbal numeric rating scale at 1, 2, 6, 12, 24, and 48 hours postoperatively. The side effects and the dosage of rescue analgesics were then recorded.

The experimental group showed a significantly higher pain score than the control group 2 and, 6 hours postoperatively at rest and 2 hours postoperatively following passive knee movement (P < 0.05). In addition, the rescue analgesic requirement was higher for the experimental group during the first 24 hours following surgery than for the control group (P < 0.05).

We found that combined continuous intravenous analgesia and peri-articular infiltration of a mixture of ropivacaine and, morphine injected into the peri-articular tissue provided minimal benefits for pain control during the early postoperative period when compared to epidural analgesia after total knee arthroplasty.