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The initial description of the 3-in-1 block was published by Winnie et al.1 in 1973 involving a small number of patients. The authors postulated that a block of the entire lumbar plexus can be accomplished by a single perivascular injection slightly distal to the inguinal ligament. Consequently, a single injection should result in anesthesia of the femoral, the lateral femoral cutaneous, and obturator nerves. Winnie et al.2,3 suggested that the underlying mechanism of this regional anesthetic technique should be a cephalad distribution of the local anesthetic along a fascial layer. This hypothesis, however, was never confirmed clinically. Moreover, an MRI study clarified the spread of local anesthetic after an inguinal injection of local anesthetic lateral to the femoral artery4,5 and concluded that the distribution of local anesthetic follows a lateral and slightly medial direction, but never a cephalad direction. Figures 36–1 and 36–2 illustrate that the spread of local anesthetic does not follow a proximal direction.

Fig. 36-1

Relevant anatomy for the 3-in-1 block on sagittal T2-weighted MRI. (A, Anterior; P, posterior; lFV, left femoral vein; UB, urinary bladder.)

Fig. 36-2

MRI image after administration of local anesthetic on sagittal T2-weighted MRI. (A, Anterior; P, posterior; lFV, left femoral vein; LA, local anesthetic; UB, urinary bladder.)

One of the main proposed advantages of the 3-in-1 block was the ability to achieve block of the obturator nerve using this approach. However, most investigators have used clinical or electrophysiologic methods to analyze analgesia levels and involved nerves. In clinical practice, however, the obturator nerve has never been shown to be anesthetized effectively using this approach.6,7 Cauhepe et al.8 investigated the anesthetic route of the 3-in-1 blocks using standard pelvic radiography and computed tomography and reported two unexpected distributions of local anesthetic. The first type consisted of an internal distribution of local anesthetic toward the psoas major muscle. The second type was an external diffusion of local anesthetic in front of the iliac muscle. The main result of this study in human cadavers was that the local anesthetic never reached the obturator nerve. Capdevila et al.9 reported that the local anesthetic used in 3-in-1 blocks spreads under the iliac fascia, but rarely to the lumbar plexus. Both techniques resulted in poor blocks of the obturator nerve.

Indications & Contraindications

The following are indications for using 3-in-1 block:

  • Surgical procedures in the sensory areas of the femoral, lateral femoral cutaneous, and anterior branches of the obturator nerves (eg, skin surgery, muscle biopsy)
  • Patella surgery
  • Perioperative pain therapy of hip fractures (additional block of the sciatic nerve is necessary)
  • Perioperative pain therapy of femoral shaft fractures (additional block of the sciatic nerve is necessary ...

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