Avascular necrosis or osteonecrosis is the death of a segment of bone due to loss of blood supply. Both bone cells are the bone marrow are affected. AVN is a common cause of hip pain in young and middle aged patients between 35-50 years of age. It occurs more in males. AVN leads to severe degenerative arthritis of the hip joint and accounts for 10% of total hip replacement cases in the United States.