- Indications: anterior thigh and knee surgery, analgesia following hip and knee procedures
- Transducer position: transverse, close to the femoral crease and lateral to the femoral artery (blue dot)
- Goal: medial-lateral spread of local anesthetic underneath fascia iliaca
- Local anesthetic: 30–40 mL of dilute local anesthetic (e.g., 0.2% ropivacaine)
Needle insertion for the fascia iliaca block. The blue dot indicates the position of the femoral artery.
Fascia iliaca block is a low-tech alternative to a femoral nerve or a lumbar plexus block. The mechanism behind this block is that the femoral and lateral femoral cutaneous nerves lie under the iliacus fascia. Therefore, a sufficient volume of local anesthetic deposited beneath the fascia iliaca, even if placed some distance from the nerves, has the potential to spread underneath the fascia and reach these nerves. Traditionally, it was believed that the local anesthetic could also spread underneath fascia iliaca proximally toward the lumbosacral plexus; however, this has not been demonstrated consistently. The non-ultrasound technique involved placement of the needle at the lateral third of the distance from the anterior superior iliac spine and the pubic tubercle, using a "double-pop" technique as the needle passes through fascia lata and fascia iliaca. However, block success with this "feel" technique is sporadic because false "pops" can occur. The ultrasound-guided technique is essentially the same; however, monitoring of the needle placement and local anesthetic delivery assures deposition of the local anesthetic into the correct plane.
The fascia iliaca is located anterior to the iliacus muscle (on its surface) within the pelvis. It is bound superolaterally by the iliac crest and medially merges with the fascia overlying the psoas muscle. Both the femoral nerve and the lateral cutaneous nerve of the thigh lie under the iliacus fascia in their intrapelvic course. Anatomic orientation begins in the same manner as with the femoral block: with identification of the femoral artery at the level of the inguinal crease. If it is not immediately visible, sliding the transducer medially and laterally will eventually bring the vessel into view. Immediately lateral and deep to the femoral artery and vein is a large hypoechoic structure, the iliopsoas muscle (Figure 36-2). It is covered by a thin layer of connective tissue fascia, which can be seen separating the muscle from the subcutaneous tissue superficial to it. The hyperechoic femoral nerve should be seen wedged between the iliopsoas muscle and the fascia iliaca, lateral to the femoral artery. The fascia lata (superficial in the subcutaneous layer) is more superficial and may have more then one layer. Moving the transducer laterally several centimeters brings into view the sartorius muscle covered by its own fascia as well as the fascia iliaca. Further lateral movement of the transducer reveals the anterior superior iliac spine (Figure 36-2). Additional anatomical detail can be seen in cross sectional anatomy in Section ...