The medical specialty of Rheumatology is responsible for the study of diseases which affect the joints and their surrounding tissue, causing pain, rigidity and limitation of movement. If the joint is inflamed we are talking about arthritis and if it is the tissue surrounding the joint it depends upon the tissue: alterations in the bursas or sacs of the joints (bursitis), the tendons (tendonitis), the ligaments (enthesitis), the muscles (myositis), blood vessels (vasculitis), or the nerves (neuritis).
Osteoarthritis is the most prevalent disease from the point of view that more than 75% of people over 50 years of age have radiological signs of osteoarthritis in one or several places.