Sacroiliac joint dysfunction is often described as pain that is focused in the lower portion of the back and hip, although it may also radiate out to the buttocks and lower back. In some cases the pain may travel down the legs or around to the front, into the groin area. SI joint dysfunction may be caused by displacement of the SI joint or inflammation in the joint from trauma, chronic overuse, illness or infection.

The sacroiliac joint connects the sacrum (the lower part of the spine) and the pelvis (at the ilium). The bones are held together by strong ligaments that stabilize the joint allowing for little movement. The motion that does occur is a combination of sliding, tilting and rotation. The most the joint moves in sliding is only about a couple of millimeters, and may tilt and rotate two or three degrees.

SI joint dysfunction may result from injuries or disease processes. Traumatic injuries can result from car accidents, falls, or collisions during contact sports that lead to sprains or strains of the SI joint. Repetitive stress injuries can result from improper biomechanics that lead to abnormal alignment of the SI joint (such as when one leg is shorter than the other), or when engaging in activities that require repeated bending or twisting.