The sacroiliac (SI) joints are the source pain in approximately 10 – 20 percent of people with chronic low back pain. The spine sits on top of the sacrum, which is part of the pelvis. The sacroiliac joints are located in the pelvis between the sacrum and the iliac bones. There are two sacroiliac joints, one on each side. People often experience pain in the lower back, posterior hip and sometimes pain radiating down their leg, usually to the calf. They often have tenderness in the back...