Inflammatory changes of sacroiliac joints, consider rheumatologic and immunologic diseases, osteoarthritis, infections, and endocrine system diseases. 1. Rheumatologic and immunologic diseases: for example, ankylosing spondylitis can be secondary to sacroiliac joint inflammatory lesions, manifested as lumbosacral pain. Psoriasis can also involve sacroiliac joint inflammatory lesions. 2. Osteoarthritis: sacroiliac joint hyperplasia, degeneration, narrowing of joint space, lumbosacral pain, and limitation of activities. 3. Infection: bacterial purulent infection or tuberculosis infection can invade sacroiliac joint. 4. Endocrine system diseases: hyperthyroidism, hypothyroidism, diabetes mellitus, cortisolism can also violate the sacroiliac joint. Inflammatory changes in sacroiliac joints are imaging descriptions, which need to be combined with history, symptoms and physical examination by clinicians to further clarify the diagnosis.