Gout. Gout is a form of arthritis that occurs when excess uric acid, a bodily waste product circulating in the bloodstream, is deposited as needle-shaped monosodium urate crystals in tissues of the body, including the joints. For many people, the first symptom of gout is excruciating pain and swelling in the big toe – often following a trauma, such as an illness or injury. Subsequent attacks may occur off and on in other joints, primarily those of the foot and knee, before becoming chronic.
Read more about gout, including risk factors, medications and diet.
Reactive arthritis. Reactive arthritis is a chronic form of arthritis that often occurs following an infection of the genital, urinary or gastrointestinal system. Features of reactive arthritis include inflammation and swelling of the joints (primarily the knee, sacroiliac joints and joints of the feet), eyes and structures within the gastrointestinal or genitourinary tracts, such as intestines, kidneys or bladder.
Lyme disease. Lyme disease is an infectious disease characterized by a skin, rash, joint swelling and flu-like symptoms. The disease is caused by the bite of a tick infected with a bacterium called B. burgdorferi. The knee is often the first joint affected by Lyme disease.
Learn about the effects of Lyme disease from the Arthritis Foundation Disease Center.
Lupus. Lupus, or systemic lupus erythematosus, is a chronic autoimmune disease, meaning the body's immune system creates antibodies that attack healthy tissues. In addition to causing inflammation in the knee and other joints, lupus can affect many organs, including the skin, heart, lungs, and kidney.
Learn more about lupus from the Arthritis Foundation Disease Center.
Read news headlines about lupus.
Ankylosing spondylitis. Ankylosing spondylitis is a form of arthritis that primarily affects the spine, causing inflammation in the spine that can lead to chronic pain and stiffening of the spine. In some people, particularly younger people, it begins with pain and swelling in the knee rather than the spine.
Learn more about ankylosing spondylitis from the National Library of Medicine.
