Fascia is a network of connective tissues that supports and organizes structures throughout the body. The fascia iliaca is a distinct sheet of this tissue located deep within the hip and upper thigh.
Anatomical Location and Function
The fascia iliaca is a strong, fibrous layer originating from the lower thoracic vertebrae. It extends into the anterior thigh, blending with the fascia lata, and covers the iliacus and psoas major muscles, which form the iliopsoas. This layer lines the posterior abdomen and pelvis, creating a defined space.
This arrangement forms the fascia iliaca compartment, a potential space bounded by the fascia iliaca and the iliacus muscle. This compartment encases the iliopsoas muscle group and several major nerves from the lumbar spine. This compartmentalization is relevant in medical procedures, allowing targeted access to these nerves.
The Fascia Iliaca Compartment Block
A nerve block uses local anesthetic to temporarily numb an area, reducing pain. The fascia iliaca compartment block is a regional anesthesia technique where anesthetic is introduced into the space beneath the fascia iliaca. This spreads the anesthetic to nerves within the compartment.
The procedure involves guiding a needle into this compartment, often assisted by ultrasound for precise placement. Without ultrasound, a “double-pop” sensation may indicate the needle passing through the fascia lata and then the fascia iliaca, confirming entry. Once in the compartment, 20 to 40 milliliters of local anesthetic are slowly injected. The anesthetic then diffuses, affecting the nerves within this space.
Common Clinical Applications
The fascia iliaca compartment block is used for pain management, particularly for hip fractures. It provides early, effective pain relief, often in emergency settings, before surgery. This technique can reduce the need for systemic opioid medications, which may cause side effects like respiratory depression or altered mental status, especially in older adults.
Studies show fascia iliaca blocks for hip fracture pain significantly lower pain scores, with reductions from 8.5 to 2.3 on a 10-point scale within two hours. Beyond hip fractures, this block controls pain after hip and femur orthopedic procedures, including hip arthroplasty and femoral shaft fractures. It may also be used with other blocks for knee and lower leg procedures.
Nerves Affected and Sensation Changes
The local anesthetic targets nerves traversing the fascia iliaca compartment. The femoral nerve and lateral femoral cutaneous nerve are reliably affected. The femoral nerve, from the lumbar plexus, supplies sensation to the front and inner (medial) thigh, extending to the inner lower leg and foot via its saphenous branch. It also provides motor function for knee extension.
The lateral femoral cutaneous nerve, from lumbar spinal roots L2 and L3, provides sensation to the outer (lateral) thigh. The obturator nerve also passes through this area, but its blockade is less consistent due to its more medial and deeper course. Patients receiving this block experience numbness and reduced pain over the front and outer thigh, with variable effects on the inner thigh.