Chapter 35. Femoral Nerve Block

The femoral nerve block is considered one of the basic nerve block techniques because it is relatively simple to perform, carries a low risk of complications, and results in a high success rate. When used alone, femoral nerve block is well suited for surgery on the anterior aspect of the thigh and for postoperative pain management after femur and knee surgery. However, when combined with a sciatic block, anesthesia of almost the entire lower limb from the mid-thigh level can be achieved.

Indications

Single-Dose Technique

When used alone, a femoral nerve block is well suited for surgery on the anterior aspect of the thigh and for superficial surgery on the medial aspect of the leg below the knee. Some examples include repair of the quadriceps tendon or quadriceps muscle biopsy, long saphenous vein stripping, and postoperative pain management after femur and knee surgery. Femoral nerve block significantly improves postoperative analgesia after knee surgery during the first 8–12 hours postoperatively.1–5 However, when combined with a sciatic or popliteal block, femoral block provides anesthesia for entire lower leg or ankle surgery.

Continuous Technique

The primary indication of continuous femoral nerve block is pain management after major femur or knee surgery.6–22 In addition, when compared with a single dose technique or placebo, continuous femoral nerve block significantly reduces postoperative morphine consumption in patients after total hip replacement.23,24 For this application, the technique is as efficient as IV patient-controlled analgesia (PCA) with morphine or patient-controlled epidural analgesia, and it results in fewer technical problems and side effects.13

Continuous femoral nerve block provides excellent analgesia in patients with femoral shaft or femoral neck fractures.14,15,21,25 Its relative simplicity makes it uniquely suitable for analgesia in the emergency room and facilitate physical and radiologic examinations as well as manipulations of the fractured femur or hip.

After major knee surgery, continuous femoral nerve block provides better pain relief than parenteral administration of opioids (IV PCA, intramuscular)7,12,16,17,20 or intraarticular analgesia.18,26 For knee surgery, continuous femoral block is as effective as continuous lumbar plexus block27 or continuous epidural analgesia,12,20 with fewer risks of complications. Because this technique results in faster postoperative knee rehabilitation than IV PCA with morphine and fewer side effects than epidural analgesia, continuous femoral nerve block is probably the analgesic technique of choice in patients after total knee arthroplasty.7,12,20,28

Contraindications

Relative contraindications for femoral nerve block may include previous ilioinguinal surgery (femoral vascular graft, kidney transplantation), large inguinal lymph nodes or tumor, local infection, peritoneal infection, and preexisting femoral neuropathy.

Anatomy

The femoral nerve is ...