Sacroiliac joint injections can help to alleviate pain to the low back, buttocks, hips, abdomen, groin, or legs. This pain can be caused by arthritis. The sacroiliac joint is a large joint at the low back where the pelvis joins with the spine. An injection to this site includes the injection of local anesthetic and steroid medication to help reduce any inflammation that may exist in the joint. You may require a series of three injections. Depending upon the amount of relief that you receive the doctor may discuss a more permanent procedure to alleviate your pain called a radiofrequency.