1. Department of Orthopaedic Surgery Center of Osteonecrosis and Joint Preserving & Reconstruction, China-Japan Friendship Hospital, 2 Yinghua East Road, Chaoyang District, Beijing, People’s Republic of China 100029.
2. University Paris XII, 51 avenue du Marechal de Lattre de Tassigny, 94010 Creteil, France.