Paediatric Acute care Guidelines PMH Emergency Department


A femoral nerve block is a quick, easy, effective and safe method of providing analgesia to the child with a femoral shaft fracture, since the femoral nerve (L2-L4) innervates the shaft and periosteum of the femur.



  • The inguinal ligament extends from the pubic tubercle to the anterior superior iliac spine
  • At its mid point, the femoral vein, artery and nerve pass beneath it
  • The femoral vein lies medial, the artery in the middle and the nerve lateral
  • A useful acronym is: NAVY = Nerve, Artery, Vein, Y fronts (!)

Femoral Nerve Block1

Anatomy: Left Hand Side


  • The femoral nerve lies in its own tissue plane, is quite superficial (usually 1-2 cm deep; never more than 3cm deep, even in older children) and is separated from the femoral vessels by the fascia iliaca
  • Exact identification of the nerve position isn’t necessary
  • Local anaesthetic injected into the correct plane (just deep to the fascia iliaca) will result in effective nerve block by diffusion of anaesthetic, without the vascular compartment being affected

Anatomy: Left Hand Side

Anatomy: Left Hand Side

Note: ultrasound guided femoral nerve blocks can be done if you are appropriately trained.



  • Sterile gloves
  • Dressing pack
  • Skin cleaning antiseptic solution
  • Needle: 23 gauge (blue) short bevel needle or 25 gauge (orange) in an infant
  • Ropivacaine 0.75% or Bupivacaine 0.5% – appropriate dose drawn up in a syringe



  • For either drug, the lowest dose which provides sufficient analgesia should be used
  • Both drugs come in a range of concentrations
  • If a different concentration solution is used, the volume administered needs to be adjusted accordingly


Preferred Drug 


Local anaesthetic Ropivacaine 0.75% Bupivacaine 0.5%
Dose 0 – 12 years: 0.25mL / kg
> 12 years: 10 – 20 mL
0.2 – 0.4mL / kg (Max 30mL)
Onset of block Within 10 minutes Within 10 minutes
Duration of block 6 hours 4-6 hours
Safety Ropivacaine has a better safety profile  


Positioning and technique

  • Clean the skin with antiseptic solution
  • Identify the site of injection again (see above in Anatomy section)
  • Keeping one finger on the femoral artery 0.5-1cm below the inguinal ligament, insert the needle perpendicular to the skin, 0.5-1cm lateral to the artery
  • The plane in which the nerve lies can be found by feeling a ‘pop’ or loss of resistance twice, first when the needle passes through the fascia late, and then as it passes through the fascia iliaca
  • Note that the nerve is fairly superficial (1-2cm) and most failed blocks are due to injecting too deep
  • Aspirate to make sure the needle is not in a blood vessel
  • Inject the local anaesthetic slowly, while frequently aspirating briefly to make sure the needle tip has not migrated into a vessel
  • Some authors describe injecting in a fan shaped pattern around the nerve, however this is not necessary since local anaesthetic injected anywhere under the fascia iliac will diffuse to the nerve and result in a successful nerve block
  • Place an IV dot (sticker) over the injection site




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