A sacroiliac joint injection is a very simple injection of local anesthetic and steroid deposited into the sacroiliac joint. The sacroiliac is the joint between the lowest part of the spine (sacrum) and the pelvis (iliac bone). Pain from the SI joint can be felt in the back, buttock, hip and leg. The goal of a sacroiliac (SI) joint injection is to provide pain relief by reducing inflammation due to arthritis or repetitive traumas of the sacroiliac joint. A sacroiliac (SI) joint injection may not cure the preexisting medical problem (i.e. arthritis, abnormal alignment, etc.) but can improve the level of pain. It is not unusual for someone to need more than one injection to get long term benefit. If the pain is significantly improved no further injection may be needed unless the pain returns.