Local anesthetic block of the sacroiliac joint

Local anesthetic block of the sacroiliac joint is used to confirm the sacroiliac joint is the source of posterior hip pain. The patient is positioned lying prone, completely flat. A 1.5 inch (3.8 cm), 22-gauge needle is inserted perpendicular to the skin, 2.5 to 3.8 cm (1 to 1.5 in) lateral to the midline, to a depth of 2.5 to 3.8 cm (1 to 1.5 in). 1 mL of local anesthetic is placed at the interface of the subcutaneous fat and the outer muscle fascia. The needle is withdrawn a 0.7 cm (0.25 in) and redirected laterally at an angle of 10-15 degrees (this point of entry and angulation allows safe passage under the wing of the posterior iliac crest). The needle is advanced through the fascia gently until the firm resistance of bone is reached. 1 to 2 mL of anesthetic is injected adjacent to the posterior aspect of the sacroiliac joint.