Ankylosing spondylitis

Ankylosing spondylitis (AS) is a systemic inflammatory disease that mainly invades the sacroiliac joints and spine and can affect the surrounding joints and visceral system to varying degrees. The early stage of this disease is considered to be a special type of rheumatoid arthritis, called rheumatoid spondylitis, deformed spondylitis, rheumatoid center type, etc., and is now collectively referred to as ankylosing spondylitis. The characteristic pathological changes of AS are lesions of tendons, ligaments, and bone attachment points, and calcification of ligaments and rigidity are the important features. The disease is generally negative for rheumatoid factor, and is associated with psoriatic arthritis, reactive arthritis, inflammatory bowel disease arthritis, undifferentiated spinal arthrosis and other seronegative spinal arthropathy.