What is arthritis primarily defined as?

Arthritis is primarily defined as inflammation of a joint. It encompasses over 100 different types of conditions that can affect the joints, including osteoarthritis and rheumatoid arthritis. The inflammation in arthritis can lead to pain, swelling, and reduced mobility in the affected joint, making it a significant concern in the realm of musculoskeletal disorders. This definition captures the essential characteristic of arthritis, which is the inflammation, rather than other considerations such as infection, tissue death, or tendon injuries, which are distinct medical issues.