Ultrasound-guided lateral femoral cutaneous nerve block: comparison of two techniques

The aim of this study was to compare the feasibility and efficacy between two techniques of ultrasound-guided lateral femoral cutaneous nerve with or without locating the nerve. The study enrolled 106 patients undergoing knee surgery who received 5 ml of 1% mepivacaine immediately under the inguinal ligament 1 to 2 cm medial to the anterior superior iliac spine (subinguinal technique) or around the lateral femoral cutaneous nerve located (nerve-targeting technique). The time required to perform the block and the onset time of the block were similar for both techniques. However, a significantly higher percentage of patients obtained loss of pinprick sensation on the lateral thigh within 10 minutes with the subinguinal technique than with the nerve-targeting technique. The findings suggest that ultrasound-guided lateral femoral cutaneous nerve blocks can be easily performed and that injecting local anaesthetic immediately under the inguinal ligament rather than around the nerve itself blocks the nerve more reliably.