Lumbar plexus block (anterior approach)

Femoral nerve block alone or combined with other nerve blocks is one of the most commonly used regional blockade techniques for lower extremity surgery. If the goal is to block all branches of the lumbar plexus, the lateral cutaneous and obturator nerves must be blocked as well. Blockade of the three nerves of the lumbar plexus that course to the lower extremity with a single injection is known as the ‘3-in-1’ block and is discussed in this review. If the goal is to completely and unilaterally block the sensitivity of the leg, a combined blockade of femoral, lateral cutaneous, obturator, and sciatic nerves should be performed. The insertion site located directly on the inguinal fold is our preference. This technique is easy to perform. It produces very little discomfort in patients; although most of them, especially young patients, are somewhat uncomfortable about the insertion area and its proximity to the genital area. We prefer the peripheral nerve stimulation (PNS) technique. The search for an MR begins at an intensity of 1 mA, a duration of 0.1 msec and a frequency of 2 Hz. The needle is advanced until obtaining the appropriate muscular response: up and down movements of the patella (rotulian dance) and/or twitch of the entire quadriceps muscle, Grade II, with <0.5 mA, a pulse duration of 0.1 msec and a frequency of 2 Hz. Continuous femoral catheter infusions are frequently performed. With an understanding of the relevant anatomy and the use of the PNS, nerve blockade of the lumbar plexus via anterior or the isolated nerves is safe, effective and well tolerated.

Keywords: Lumbar plexus block, Femoral, Femorocutaneous, Obturator