Korean J Anesthesiol Kim, et al. Fig. 1. Rate of satisfaction with surgical anesthesia and postoperative analgesia. Data are expressed as the mean ± SEM. CSE: combined spinal epidural anesthesia, FSNB: femoral/sciatic nerve block with lateral femoral cutaneous nerve block. Fig. 2. Numbers of patients who are willing to recommend the same surgical anesthesia and postoperative analgesia. CSE: combined spinal epidural anesthesia, FSNB: femoral/sciatic nerve block with lateral femoral cutaneous nerve block. the rate of satisfaction with the surgical anesthesia and the postoperative analgesia, and the willingness to recommend the same surgical anesthesia and postoperative analgesia to others (Fig. 1 and 2). There were no significant changes in VAS scores during the postoperative period in each group (P > 0.05). There was also no statistical difference of pain scores between the two groups (P > 0.05) (Fig. 3). Discussion In the past, lower extremity peripheral nerve blocks were seldom the anesthetic procedure of choice for patients undergoing total joint replacement, primarily because of anesthesiologists’ lack of experience in performing these procedures. These blocks are an excellent anesthetic option www.ekja.org Fig. 3. Visual analog scale score plotted against postoperative hours in the CSE and FSNB groups. Data are expressed as the mean ± SEM. There are no significant changes in VAS scores during postoperative period in each group, and no significant difference of VAS scores between the two groups. CSE: combined spinal epidural anesthesia, FSNB: femoral/sciatic nerve block with lateral femoral cutaneous nerve block. for patients who are not candidates for spinal or epidural anesthesia, because septic or anticoagulated patients may safely receive peripheral blocks. Additionally, patients with disease processes that make the hemodynamically significant sympathectomy seen with neuraxial anesthesia unsafe can undergo a lower extremity nerve block without significant risk of hemodynamic instability. Further, severe neurological complications (spinal hematoma, cauda equina syndrome) after central neural blockade are rare events [4] but should be considered when choosing a safe method for surgical anesthesia or postoperative analgesia. Peripheral nerve damage can occur after peripheral nerve block, but the consequences are not as grave [5]. These benefits of lower extremity peripheral nerve block justify its use as an alternative anesthesia in patients undergoing TKRA. The afferent information of the knee is carried by the lumbar plexus innervating the anterior thigh and medial malleolus, and the sacral plexus innervating the posterior regions of the thigh and knee and some parts of the leg and foot [6]. The lumbar plexus includes the femoral nerve (L2-L4), the obturator nerve (L2-L4), and the lateral femoral cutaneous nerve (L2-L3). And the sacral plexus includes the sciatic nerve [6,7]. Femoral nerve blocks do not reliably cover the obturator nerve [8-10] and addition of obturator nerve blocks improves postoperative analgesia after TKRA [11,12]. Although Eifert et al. [13] showed that 700 mg of mepivacaine without epinephrine in the combined “3-in-1”/sciatic nerve blocks made 3.91 ± 0.95 μg/ml, which is below the threshold for toxic symptoms (5-6 μg/ml), we were reluctant to perform the obturator nerve block in our study where approximately 700 mg of mepivacaine were used 451