Total hip replacements are most commonly used to relieve severe arthritic problems that cause the hip joint to wear down. Other disorders that may necessitate hip replacement surgery include Rheumatoid Arthritis, Avascular Necrosis (lack of or inadequate blood supply), traumas, and bone malignancies. Other disorders, such as hip fractures, are treated with the operation. The majority of total hip replacement patients are over 55 years old, however younger patients are occasionally treated as well. Patients who are candidates for total hip replacement surgery usually have the following characteristics: