This form of arthritis primarily affects the spine, causing inflammation of the vertebrae. The shoulders, hips, ribs, heels and small joints of the hands and feet can also be affected. The general onset is usually in younger people, between the ages of 17 to 35. Genetics, a family history of AS and a history of frequent gastrointestinal infections are risk factors. Inflammation of the spinal joints leads to severe, chronic pain and discomfort. In advanced cases, inflammation leads to new bone formation in the spine. This causes the spine to fuse in a fixed, immobile position. The resulting forward curvature of the spine is called kyphosis. The distinguishing feature of disease progression is involvement of the sacroiliac joints where the spine meets the pelvis. There is no cure for AS. Current treatment includes the use of NSAIDs, nonsteroidal anti-inflammatory drugs, disease modifying anti-rheumatic drugs and biologics or TNF-Blockers. Lifestyle treatments such as exercise, applying heat to stiff joints and tight muscles, applying cold to reduce swelling, massage and maintaining a healthy body weight are recommended to lessen pain. In severe cases, joint replacement and surgical correction of severe flexion deformities of the spine are necessary.