Indication
Surgery of hip, femur and knee
Preferred regional technique for hip or femoral fractures
A femoral catheter can be inserted for analgesia in a patient with a femoral fracture awaiting surgery or for analgesia after major femoral or knee surgery (e.g., patella pulldown, distal femoral osteotomy) and to allow for passive physiotherapy.
A femoral block provides:
A femoral block can be combined with other lower limb blocks depending on the surgical approach:
e.g., obturator block for additional medial thigh coverage, lateral femoral cutaneous nerve block for additional lateral thigh cover or a sciatic block for posterior leg coverage. In combination with a popliteal block, a block of the entire limb below the knee can be achieved.
Considerations
NOT motor sparing (unlike adductor canal block), so no weight-bearing for duration of the block
If early mobilisation is desirable, the motor-sparing adductor canal block is a better choice, or if not possible, consider using a lower concentration, like 0.125% levobupivacaine
Complications
Contraindications
NOTE: when there is a high likelihood of postoperative muscular spasms (e.g., patient with cerebral palsy), consider prescribing diazepam postoperatively
Anatomy
The femoral nerve is the largest branch that arises from the lumbar plexus (rami of L2-4). The lumbar plexus forms within the body of the psoas major muscle, then descends between psoas and iliacus muscles to travel below the inguinal ligament to emerge at the anterior proximal thigh.
At the femoral crease the femoral nerve is found in the femoral triangle, bordered by the inguinal ligament superiorly, the adductor longus muscle medially and the sartorius muscle laterally.
Within the triangle the femoral nerve lies laterally to the femoral artery and below the fascia lata and fascia iliaca. The fascia lata travels on top of the femoral nerve and vessels. The fascia iliaca travels above the nerve but below the vessels. The femoral nerve lies UNDER the fascia iliaca and on top of the iliopsoas muscle.
The femoral nerve bifurcates at the same level that the femoral artery splits into a superficial and a profunda branch. A femoral block aims to target the nerve above the bifurcation.
Sonoanatomy
Ultrasound probe selection: high frequency linear probe
Target depth: 0.1-5cm
Needling
Levobupivacaine 0.25% 0.2-0.3ml/kg (max. 15mls) (+/- clonidine 1mcg/kg to increase duration
and prevent muscle spasms)
NOTE: The nerve can be difficult to distinguish from the overlying fascia iliaca. Careful hydrodissection in the plane just below this fascia can help delineate the nerve (use saline in smaller children so not to waste LA). If the nerve is not distinguishable, injecting a large volume of local anaesthetic just below the fascia iliaca on the lateral side of the femoral artery will ensure a block.
NOTE: when inserting a femoral catheter an out-of-plane approach may be favourable
NOTE: where an operation is expected to cause a lot of muscle spasm post op (e.g., patellar pulldown) a higher concentration of LA should be used, e.g., 0.5% (Respect maximum dosage)