Line drawn from GT to PSIS, and the hip flexed to form continuation of this line. At the midpoint, a perpendicular line is drawn to a point 4-5cm to mark the point for needle insertion
From the midpoint of the posterior skin crease, a line is drawn at right angles to the apex of the triangle formed by the medial (semimembranosus, semitendinosis) and lateral (biceps femoris) and the needle inserted 6-7cm proximal and 1cm lateral from the crease
Lateral approach
7cm proximal to the femoral epicondyle, the groove between the vastus laterals and biceps femoris is identified and needle advanced until it hits bone, then redirected at 30 degrees.