Medically Reviewed by Dr Wang Lushun What's Avascular Necrosis (AVN)? Avascular necrosis, often called osteonecrosis, happens once the blood provide to bone cells is disrupted, leading to the death of bone tissue. It typically targets the hip joint, especially the femoral head–the upper “ball” portion of the femur (thigh bone) https://www.theorthopaedicandpainpractice.com/what-is-avascular-necrosis-of-the-hip/?_gl=1*xbbxlb*_up*MQ..&gclid=Cj0KCQjwkt6aBhDKARIsAAyeLJ2krYJSOuy5mZksrNqH-VDjQwW1ScD49yD8BUWysDG6u6bJPCSbXVUaAuCPEALw_wcB