1. Department of Orthopedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Hokkaido, Japan
2. Division of Radiology and Nuclear Medicine, Sapporo Medical University Hospital, Sapporo, Hokkaido, Japan
3. Department of Public Health, Sapporo Medical University Hospital, Sapporo, Hokkaido, Japan
4. Department of Orthopedic Surgery, Hokkaido Saiseikai Otaru Hospital, Otaru, Hokkaido, Japan
5. Department of Diagnostic Pathology, Sapporo Medical University School of Medicine, Sapporo, Hokkaido, Japan