The Effect of Bilateral Femoral Nerve Block Combined with Intravenous Patient-controlled Analgesia after a Bilateral Total Knee Replacement

Background: Postoperative pain after bilateral total knee replacement (TKR) is expected to be more severe than unilateral TKR. Intravenous patient-controlled analgesia (IV PCA) is less effective than other methods of pain management especially immediately after an operation even though it is an easily controlled method for managing pain. This study was designed to evaluate the effect of femoral nerve blocks combined with IV PCA after bilateral TKR for postoperative pain control. Methods: The patients in group I (n = 20) were given only IV PCA with morphine and group II (n = 20) were given bilateral femoral nerve blocks with 12 ml of 0.25% bupivacaine and epinephrine 1: 400,000 before extubation followed by an IV PCA. Main outcome measures included numerical rating pain score, cumulative opioid consumption, hourly dose during each time interval, and side effects. Results: The pain score in group II was significantly lower than that in group I immediately after recovery of awareness and at 3, 6, 12 hours postoperatively. Cumulative opioid consumption was significantly decreased in group II during the first 48 hours postoperatively. The hourly dose in group II was also significantly lower than that in group I until 12 hours postoperatively. There was no difference in side effects between the groups. Conclusions: We concluded that bilateral femoral nerve blocks improve analgesia and decrease morphine use during IV PCA after bilateral TKR.