1. Orthopedic Section, National Hospital of SS. Antonio and Biagio and C. Arrigo, 15121 Alessandria, Italy
2. Department of Radiology, IRCCS-Ospedale Policlinico San Martino, 16132 Genova, Italy
3. Radiology Section, Department of Health Sciences (DISSAL), University of Genova, 16126 Genova, Italy
4. Biostatistics Section, Department of Health Sciences (DISSAL), University of Genova, 16126 Genova, Italy