Total hip replacements are most commonly performed because of the pain and immobility caused by severe arthritis in the hip joint. The most common type of arthritis leading to total hip replacement is degenerative arthritis, or osteoarthritis, of the hip joint. This type of arthritis is generally seen with aging, congenital abnormality of the hip joint or prior trauma to the hip joint. Other causes include rheumatoid arthritis, injury to the hip or childhood hip disease. According to the American Academy of Orthopaedic Surgeons, hip replacement surgery is one of the most successful operations in all of medicine. The Agency for Healthcare Research and Quality reports that more than 285,000 total hip replacements are performed each year in the United States.