Chronic infectious arthritis is a condition where joint inflammation is caused by an infective agent or an autoimmune response. There are several synonyms for this condition depending on the underlying cause and clinical features. Reactive arthritis is a term used when the condition results from an infection in another part of the body, such as chlamydia or salmonella. Septic arthritis is a term that is used in cases where bacterial infection invades the joint. Rheumatoid arthritis is a chronic autoimmune condition that affects the joints and can cause chronic inflammation and pain. Lyme arthritis occurs after a tick bite that results in Lyme disease and primarily causes swelling in the knee joint. Different terms are used to describe this condition depending on the underlying cause.