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The use of lumbar or sacral plexus blockade for lower extremity surgeries has
not been commonplace until recently. This is because these techniques were
thought to be difficult to perform and resulted in frequent failure to
accomplish surgical anesthesia.1–3
Dogliotti4 pointed out, “the nerve trunks of the lumbar
plexus which run into the inferior extremity are at a great distance from
each other, so much so that in order to produce anesthesia, multiple
procedures are necessary with separate injections, for each nerve trunk.”
Hence, anesthesiologists preferred the quicker and more effective techniques
of spinal or epidural anesthesia for most patients. Several variations of
the original technique have been proposed, with the main differences
being in the level of blockade and the distance from the
midline for the needle insertion.4–6 However, given
the deep location of the lumbar plexus, various approaches often represent
minuscule technical variations rather than clinically relevant
modifications. For instance, Chayen's approach is thought to result in
too high of an incidence of epidural blockade.7 However, newly
proposed techniques have also resulted in a 15% incidence of epidural
blockade.8 More recently, ultrasound-guided lumbar plexus
block technique has been suggested; unfortunately this requires substantial
ultrasonographic skill, and adequate images are difficult to obtain in many
patients.9 Regardless of which technique is followed,
safety precautions must be used for successful and safe use of
this technique.
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Lumbar plexus block has been used for a number of lower extremity
procedures. It has been shown to be particularly useful for femoral shaft
and neck fractures, knee procedures, and procedures involving the anterior
thigh.1,10–12 Lumbar plexus block alone
cannot provide adequate anesthesia for major surgery of the lower extremity
because of the contributing innervation by the sciatic nerve. Even
when combined lumbar plexus–sciatic blocks are used for anesthesia in
patients undergoing total knee arthroplasty, conversion to general anesthesia may be required in up to 22%
of the time.13
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Regional Anesthesia Anatomy & Management
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The lumbar plexus consists of six nerves on each side, the first of
which emerges between the first and second lumbar vertebrae and the last
between the last lumbar vertebra and the base of the sacrum. As soon as the
L2, L3, and L4 roots of the lumbar plexus depart from their spinal nerves and
emerge from the intervertebral foramina, they become embedded in the psoas
major muscle14 (Figure 33–1). This is because
the psoas is attached to the lateral surfaces and transverse processes of
the lumbar vertebrae. Within the muscle, these roots then split into
anterior and posterior divisions, which reunite to form the individual
branches (nerves) of the plexus.15 The major branches of
the lumbar plexus are the genitofemoral nerve, lateral femoral cutaneous
nerve, femoral, and obturator nerves (Figure 33–2). Within the
psoas major muscle, the lateral femoral cutaneous and femoral nerves ...