Home > Arthritis > What is osteoarthritis? Get the Flash Player to see this player. Rate: (Click the stars to rate) Published on Jun 23, 2008 by TSculco, Views: 3926 What is osteoarthritis? Osteoarthritis is a disease where the cartilage is destroyed, which protects the bone. Then bone rubs against bone, causing worsening pain in the joints as well as decreased mobility or motion of the joint.