Cartilage is a tough but pliable connective tissue found in your joints. It protects the joints by absorbing the pressure and shock caused by movement and stress. Some types of arthritis are caused by a decrease in the normal amount of this cartilage tissue.
One of the most common types of arthritis is OA, which is caused by normal wear and tear. An infection or joint injury can aggravate the natural breakdown of cartilage tissue. If you have a family history of the disease, your chances of developing it are higher.
An autoimmune disorder, RA, is another common type of arthritis. It happens when your body's immune system attacks its own tissues. These attacks are directed at the synovium, a soft tissue in your joints that produces a fluid that nourishes and lubricates the cartilage.
RA is a synovium disease that invades and destroys joints. It can eventually cause bone and cartilage inside the joint to be destroyed. The precise cause of immune system attacks is unknown. However, scientists have discovered genetic markers that increase your risk of developing RA by a factor of five.