Peripheral nerve block for anesthesia in patients having knee arthroplasty

Total knee arthroplasty is an effective surgical modality for osteoarthritis of the knee. Because the population is aging, the number of TKA procedures is increasing every year [1]. Both general and diverse types of regional anesthesia have been used successfully for this surgery. Femoral nerve block (FNB) was first described in 1973 and used either as a single nerve or 3-in-1 block (including the femoral nerve, the lateral cutaneous nerve, and the obturator nerve), both as an independent anesthetic modality and as an analgesic adjunct to other anesthetic techniques. In this issue of Korean Journal of Anesthesiology, Kim et al. [2] reported a study of peripheral nerve block for total knee arthroplasty. The authors conclude that femoral/sciatic nerve block with lateral femoral cutaneous nerve block can be an alternative to spinal epidural anesthesia in patients having total knee arthroplasty. They did not recommend peripheral nerve blockade as a first choice, because it is associated with a higher use of antihypertensives, analgesics, and sedatives. Nonetheless, peripheral nerve blockade showed comparable patient satisfaction and postoperative analgesia to spinal epidural anesthesia. This report is likely to create controversy because a higher use of antihypertensives, analgesics, and sedatives are associated with incomplete anesthesia. FNB does not consistently produce anesthesia of the obturator nerve [3]. The obturator nerve or sciatic nerve supplies the knee joint. Consequently, the sensation in the back of the knee can be intact after FNB. Sciatic innervations in the back of the knee is a relatively minor contribution to postoperative pain after TKA [4]. The authors argued that sparing the obturator nerve is the main cause of insufficient anesthesia. In the previous report, the addition of the obturator nerve block to FNB improves postoperative analgesia after TKA [5]. In contrast, Bouaziz et al.[6] showed that efficacy of the obturator nerve block is not sufficient as the cutaneous contribution of the obturator nerve is absent in 57% of patients. Further investigations are required to confirm the anesthetic effect of obturator nerve block for TKA. Recently, peripheral nerve blocks are widely used for low extremity surgery, but they are still less common spinal anesthesia, mainly because of the increased time and expertise required as well as the delayed recovery associated with their use. The increased time required to perform peripheral nerve block can be reduced by placing peripheral nerve blocks preoperatively in the block room. Compared with neuroaxial (spinal/epidural) anesthesia, FNB minimizes hypotension, urinary retention, pruritis, and elimi nates the risk of spinal hematoma and infection. Moreover, patients with hemodynamical instability, antiplatelet, or anticoagulant therapy can undergo a lower extremity nerve block without significant risk. The anatomical deformity caused by a degenerative change in elderly patients occasionally makes neuroaxial block inappropriate to surgical anesthesia for low extremity surgery. These benefits of lower extremity peripheral nerve block satisfy its use as an alternative anesthesia in patients undergoing lower extremity surgery. Despite these benefits, complications of peripheral nerve block limit its use for surgery. The common complications of FNB include