Anatomy and Function of the Sacroiliac Joint Fusion The sacroiliac joint, also known as the SI joint, is located in the pelvis where the sacrum meets the ilium of the pelvis. This joint is comprised of irregular bone surfaces that are connected by strong ligaments providing stability to the pelvis. The SI joint acts to both absorb stress from the upper body as well as allow for mo... https://heyjinni.com/read-blog/108044