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Regional Anesthesia Hip
October 2024
Final Reviewer: Justine Ko, MD, CAQ-SM
Image 1: Author’s own image.
Image 2: Demonstration of the ultrasound technique for this case. Author’s own image.
An 83-year-old female from a nursing home had a witnessed fall. She is brought in with severe R hip pain, and her leg is shortened and externally rotated. She is found to have a right femoral neck fracture. You decide to perform a fascia iliaca block for pain control.
What are the essential structures to identify on ultrasound to perform a fascia iliaca block?
The “fascia iliaca” block derives its name from the fascia layer superficial to the iliacus muscle. The iliacus muscle is part of the iliopsoas group, which also includes the psoas major and psoas minor muscles. The iliacus is typically located lateral to the psoas muscles.
To easily identify the fascia iliaca, start by positioning the ultrasound probe laterally on the anterior hip. In cross-section, the first muscle seen is usually the sartorius. As you slide the probe medially, the sartorius tapers into a fan or triangle shape. The iliacus muscle lies deep to the sartorius, with the fascia iliaca positioned between them. This fascia is the key structure targeted during the block.
As you continue sliding the probe medially, the femoral vasculature and femoral nerve come into view, with the femoral nerve appearing lateral to the vessels. The femoral nerve is lateral to the femoral vessels—remember the mnemonic ‘NAVEL’ (Nerve-Artery-Vein-Empty space-Lymphatics) from lateral to medial. On ultrasound, the femoral nerve appears as a hypoechoic bundle beneath the fascia iliaca.
Image 4. Ultrasound video of target fascia iliaca structures, author’s image
What is the distribution of anesthesia for a fascia iliaca block?
The fascia iliaca block is effective for pain control in most hip fractures, femur fractures, and thigh lacerations. The block provides analgesia for the hip joint, including the femoral head, femoral neck, and synovial capsule. However, it does not typically provide adequate coverage for the greater trochanter.
Distally, the block provides analgesia to the midshaft and distal femur. In the lower leg, the block can provide anesthesia to the medial malleolus through its effect on the saphenous nerve, a branch of the femoral nerve. Cutaneously, the block primarily anesthetizes the anterior thigh through the femoral and lateral femoral cutaneous nerve distributions.
Image 5. Regional anesthesia distribution of the fascia iliaca block, author’s image.
What is the target for your needle for the block?
Insert and advance your needle through the sartorius muscle and to the fascia iliaca layer. The goal of the anesthetic is to “zipper” open the fascia layer. As long as the anesthetic is in that layer, it will diffuse to the femoral nerve. This allows novice operators to keep the needle several centimeters away from the femoral nerve and femoral vessels while providing adequate analgesia.
Image 6. Fascia Iliaca Injection Video, author’s own video
Image 7. Fascia iliaca Injection, author’s own image. The fascia layer should "zipper open" with injectate.