A Prospective, Randomized, Blinded Trial to Compare ContinuousEpidural Block and Femoral Nerve Block for Total Knee Arthroplasty

Objective: We conducted a prospective, randomized, and blinded trial to compare the perioperative quality of anesthesia and analgesia for Total Knee Arthroplasty (TKA) using either Epidural Analgesia (EA) or ultrasoundguided continuous Femoral Nerve Block (FNB). Methods: Forty patients scheduled for TKA were randomized to two groups, EA or FNB. The initial local anesthetic doses for EA and FNB blocks were 5 mL and 20 mL 0.5% ropivacaine, respectively. After epidural or femoral nerve sheath catheterization, patients were anesthetized using propofol infusion and air-mixed 40% oxygen. A ProSealTM laryngeal mask airway was inserted and intravenous fentanyl was used as supplementary analgesia if necessary. After surgery, patients in both groups were administered an infusion of 4 mL/h 0.2% ropivacaine and 12.5 μg/h fentanyl via the epidural or femoral nerve catheter. We recorded the total doses of fentanyl administered during surgery, and the extent of postoperative pain using a visual analog scale (VAS) at rest and on movement until the third postoperative day (POD3). Results: The mean doses of fentanyl administered during surgery in the EA and FNB groups were 106.6 ± 45.8 μg and 232.5 ± 84.7 μg, respectively [mean ± standard deviation; p < 0.0001]. Significantly lower VAS pain scores were reported during movement in the EA group on POD1 [EA vs. FNB=23 (0-77) vs. 47 (0-100), p=0.027] and POD2 [43 (0-70) vs. 63 (15-100), p=0.031]. Conclusions: Continuous epidural analgesia requires less fentanyl for TKA than FNB and is more effective for postoperative pain on movement.