1. University of Athens Medical School, 21 Fotiou Patriarchou Street, Athens 11471, Greece.
2. First Orthopaedic Department, Attikon University Hospital, 1 Rimini Street, Chaidari, Athens 12462, Greece.
3. Orthopaedic Department, Tripoli Hospital, 31 Kousianofsky Street, N. Psychiko, Athens 11525, Greece.
4. Office of Biostatistics, Harokopio University, 17 Laodikias Street, Athens 11528, Greece.