1 Orthopaedic Department, University Hospital of Nantes, Hôtel-Dieu, 44093 Nantes Cedex 1, France; UMR 1238, Laboratory of Bone Sarcomas and Remodelling of Calcified Tissues, University of Nantes, Nantes, France; INSERM, Sarcoma Research Unit, University of Sheffield, Sheffield, UK. Electronic address: francois.gouin@chu-nantes.fr.