A sacroiliac (SI) joint injection is primarily used either to diagnose or treat lower back pain and/or sciatica symptoms associated with sacroiliac joint dysfunction. The sacroiliac joints lie and connect the sacrum of the spine to the pelvis and hip on both sides. Joint inflammation and/or dysfunction in this area can produce pain in the back, buttock, hip, and groin frequently radiates down the leg. Patients with sacroiliac joint dysfunction typically have increased discomfort with prolonged standing and walking activities. This injury is often due to a twisting and turning motion, jarring from the leg up or a fall backwards onto the buttocks. The sacroiliac joint problem can often go undiagnosed for a period of time. The purpose of a sacroiliac joint injection is two-fold: to diagnose the source of a patient’s pain, and to provide therapeutic pain relief. At times, these are separated and a patient will undergo a purely diagnostic or therapeutic injection, although often the two are combined into one injection.