This may be because the ligaments that hold your sacroiliac joint together get too loose or too tight. Your sacroiliac (pronounced sa-krow-i-lee-ak) joints are some of the biggest joints in your ...

Your SI joint, or sacroiliac joint, connects your sacrum (otherwise known as the tailbone) and your illiac, the bone of the topside of your pelvis. Technically, there's two of these joints—one ...