Rheumatism or rheumatic disorders are conditions causing chronic, often intermittent pain affecting the joints or connective tissue. Rheumatism does not designate any specific disorder, but covers at least 200 different conditions, including arthritis and "non-articular rheumatism", also known as "regional pain syndrome" or "soft tissue rheumatism".There is a close overlap between the term soft tissue disorder and rheumatism. Sometimes the term "soft tissue rheumatic disorders" is used to describe these conditions.
Many rheumatic disorders of chronic, intermittent pain (including joint pain, neck pain or back pain) have historically been caused by infectious diseases. Their etiology was unknown until the 20th century and not treatable, like Lyme disease (in the Northern, Northeastern, and Appalachians of the US), coccidiomycosis or valley fever (in the Western US), and chikungunya in India, Africa, and South America. Postinfectious arthritis, also known as reactive arthritis, and rheumatic fever are other examples.