The sacroiliac (SI) joint and low back pain
Like any other joint in the body, the sacroiliac (SI) joint can become arthritic or its support ligaments can become loose or injured. When this happens, people can feel pain in their buttock and sometimes even well above their buttock and higher on the skeleton. This is especially true with lifting, running, walking or even sleeping on the involved side.
It is important to note that on occasion, patients who have not had symptomatic relief from lumbar spine surgery may actually have had other issues to begin with. This could include the SI joint, the hip, the spine separately or any combination of these three pain generators.
Possible causes of SI joint pain or SI joint dysfunction: