Table 1.

Most common traditional landmark approaches to SNB, including the name of the approach, position of the patient, and the landmarks used

Approach	Position of patient	Landmarks
Labat (1923)	Lateral decubitus position Operative side up, knee flexed	A line is drawn between the GT and PSIS. At the midpoint of this line, a second perpendicular line is drawn caudad for 3 cm marking the point of needle insertion.
Winnie (1975) (modification of Labat's approach)	Lateral decubitus position Operative side up, knee flexed	A line is drawn between the GT and PSIS. A second line is drawn from the GT to the sacral hiatus. The point of needle insertion is defined by drawing a line perpendicular from the midpoint of the first line to its intersection with the second line. This is usually 3–5 cm from the midpoint of the line drawn from the GT to the PSIS.
Raj (1975)	Lithotomy position (only the limb to be blocked) Hip and knee flexed maximally to 90–120 degrees	A line is drawn between the GT and IT. The midpoint marks the point of needle insertion.
Beck (1963) (anterior approach)	Supine position	First line is drawn from the anterior superior iliac spine to the pubic tuberosity. A second line is then drawn from the GT parallel to the first line towards the inside thigh. A third perpendicular line is drawn from the midpoint of the first line to meet the second line. This intersection is the point of needle insertion.
Mansour (1993) (sacral plexus block)	Lateral decubitus position Operative side up	A line is drawn between the midpoints of the PSIS and IT. The point of needle insertion is 6 cm along this line from the PSIS. The needle is slowly advanced in a sagittal plane using nerve stimulation.