When the synovium of a joint becomes inflamed, this is referred to as synovitis (or synovial inflammation). The synovium is a connective tissue that lines the interior of the joint capsule. It is also known as the stratum synoviale or synovial stratum. The term "synovitis" specifically refers to the lining of a joint. The two main types of arthritis are osteoarthritis and rheumatoid arthritis. They are very different conditions that can be difficult to diagnose because they do not cause pain, swelling, or redness of the joint. Instead, they lead to loss of joint function over time. Joints are where bones meet; therefore, they can become damaged if the surrounding tissues - such as cartilage or ligaments - become diseased or injured. This can happen due to age, genetics, obesity, or any other chronic condition. When this occurs, muscles, joints, and organs around the area may suffer from trauma caused by abnormal movement, instability, or degeneration of the bone structure. Arthritis is the name given to inflammation of the joints. There are two main types of arthritis: osteoarthritis and rheumatoid arthritis.