Rheumatology is that branch of medicine that concerns itself with the arthritic complaints, mainly rheumatoid and osteo-arthritis. From the Greek word rheum, meaning a kind of watery buildup, rheumatoid arthritis, once commonly called rheumatism, was once believed to be caused by a build up of fluid in the joints, the so-called 'water on the joints'. This was probably due to the fact that inflamed joints swell, and the ancients attributed that to fluid buildup. Now any discipline that studies joint and cartilage disease and dysfunction falls under the general category of rheumatology.