Arthritis is a general term for the inflammation of a joint. Osteoarthritis (OA) is one of the most common causes of joint pain. Sometimes called degenerative arthritis or degenerative joint disease, it’s a condition that causes the breakdown of joint cartilage. Cartilage is the rubbery tissue covering the ends of moving bones within a joint, acting as both a shock absorber and lubricant that protects your bones from damage and provides a smooth, pain-free movement. As osteoarthritis wears down this tissue, the bones begin to make painful bone-on-bone contact.