Wikipedia
Sacroiliitis
In medicine, sacroiliitis is an inflammation of the sacroiliac joint. Sacroiliitis is a feature of spondylarthropathies, such as ankylosing spondylitis, psoriatic arthritis, reactive arthritis or arthritis related to inflammatory bowel diseases, including ulcerative colitis or Crohn's disease. It is also the most common presentation of arthritis from Brucellosis.