Posterior approach to the sacroiliac joint. A, Incision for the posterior approach to the sacroiliac joint is vertical from just above the posterior superior iliac spine distally about 1.0 cm. B, Deeper dissection involves incising the gluteus maximus fascia and subperiosteally elevating the maximus off of the ilium just lateral to the posterior superior iliac spine. SEE TECHNIQUE 1.87.