Regional anesthesia and pain medicine
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Reg Anesth Pain Med · May 2010
Revisiting anatomic landmarks: lateral popliteal approach for sciatic nerve block based on magnetic resonance imaging.
When the conventional lateral popliteal sciatic nerve (SN) block is performed, the needle angle required to localize and the level of the SN bifurcation are highly variable. The aim of our magnetic resonance imaging (MRI) study was to determine the most common range of needle-insertion angles and the relationship between skin-to-femur distance and angle. We also evaluated the variability of the SN bifurcation level and the relationship between patient height and nerve bifurcation level. ⋯ Our simulated lateral popliteal SN block on MRIs shows a 15- to 45-degree range of needle-insertion angles. As the skin-to-femur distance was greater than 4.5 cm, the angles were progressively smaller than 30 degrees. Although this was an MRI study, it does provide some evidence that indicates the conventional clinically recommended 25- to 30-degree-angle ranges may need to be reevaluated. Needle insertion of 10 cm or greater proximal to the popliteal crease may increase the chance of placement at or proximal to the SN bifurcation.