1. Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
2. Department of Orthopaedic Oncology, Tochigi Cancer Center, 4-9-13 Younann, Utsunomiya-shi, Tochigi 320-0834, Japan
3. Department of Orthopaedic Surgery, Kyosai Tachikawa Hospital, 4-2-22 Nishikicho, Tachikawa-shi, Tokyo 190-8531, Japan
4. Department of Orthopaedic Surgery, Tokyo Dental College Ichikawa General Hospital, 5-11-13 Sugano, Ichikawa-shi, Chiba 272-8513, Japan
5. Department of Diagnostic Pathology, Keio University School of Medicine, Tokyo 160-8582, Japan