Posterior Lumbar Plexus Block

Abstract

The lumbar plexus block provides anesthesia/analgesia of the hip, anterolateral and medial thigh, the anterior knee, and the cutaneous distribution of the saphenous nerve below the knee (i.e., femoral nerve, obturator nerve, and the lateral cutaneous nerve of the thigh). The ilioinguinal/iliohypogastric nerves are considered part of the lumbar plexus but are less reliably anesthetized with this block. Despite the recent popularity of lumbar plexus blockade, the value of ultrasound guidance for this block is limited in older children and teenagers due to imaging difficulties, although this approach is promising for small children and infants. This is a complex block, with potential complications, including retroperitoneal hematoma (even with correct injection), injury to retroperitoneal structures, systemic toxicity from injection into deep muscle tissue, and unintentional epidural or intrathecal local anesthetic spread.