This trial is evaluating the safety and effectiveness of using the patient's own mesenchymal stem cells in treatment of osteonecrosis of the femoral head. The trial is being conducted by the University Hospital of Salamanca and Red de Terapia Celular and proposes to enrol 10 participants. All participants will be treated with mesenchymal stem cells that have been obtained from their own bone marrow and expanded in the laboratory. The trial started in July 2012.