Stem cell therapy has been also assessed in unusual forms of osteonecrosis, such as sickle cell disease. Hernigou et al. administered allogeneic stem cells by the intravenous route in a patient who had osteonecrosis of the humeral head secondary to sickle-cell disease, leading to a favourable outcome and total repair of the osteonecrosis after a follow-up of 4 years (Hernigou et all., 1997)