The body of ilium forms the sacroiliac joint with the sacrum. Certain skeletal joints such as the pubic symphysis and sacroiliac widen or have increased laxity. The dorsal sacroiliac ligaments include both long and short ligaments. The anterior ligament is thin and not as well defined as the posterior sacroiliac ligaments. This capsule is strengthened by the ventral, interosseous, and dorsal sacroiliac ligaments. Biceps femoris could therefore act to stabilise the sacroiliac joint via the sacrotuberous ligament. Unlike psoriatic arthritis, osteoarthritis does not typically involve inflammation of the sacroiliac joint. Psoriatic arthritis can also affect the hips, knees, spine (spondylitis), and sacroiliac joint (sacroiliitis). The facet and sacroiliac joints tend to be uninvolved. The disc spaces, facet and sacroiliac joints remain unaffected. Spine, sternoclavicular and sacroiliac joints can also be involved. MRI can show inflammation of the sacroiliac joint. People with severe and disabling sacroiliac joint dysfunction can suffer from insomnia and depression. There is a lack of evidence that these sacroiliac joint mobility maneuvers detect motion abnormalities. The Tile classification system is based on the integrity of the posterior sacroiliac complex.