Joint Replacement and You Each year, 43 million Americans are affected by arthritis. Osteoarthritis and rheumatoid arthritis are the two most common forms, which destroy the lubricating tissue found at the ends of all moving bones. This tissue, called cartilage, helps the joints move freely and painlessly. However, when the cartilage is destroyed, bone painfully rubs against bone. To relieve the pain, surgeons can use implants that resurface or replace the damaged bone and cartilage to restore movement and function. The joints most often replaced are the hips, knees, and shoulders.