Osteonecrosis is a condition that develops when the bones lose their blood supply. This causes them to die and eventually collapse, resulting in pain and arthritis. Osteonecrosis can occur in one or several bones and is most common in the hip or upper leg. As Osteonecrosis is a disease of the bone cells it has been shown that implanting bone marrow containing stem cells into the effected area can have a beneficial impact on the condition. Stem cells are unspecialised cells that have the ability to self-generate into new healthy specialised cells, replacing the ones that have died or are damaged. Also known as Avascular Necrosis Stem Cell Therapy.