1 Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, 160-8582, Japan.
2 Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, 160-8582, Japan. Electronic address: nasano@keio.jp.
3 Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, 160-8582, Japan; Department of Musculoskeletal Oncology and Orthopaedic Surgery, Tochigi Cancer Center, Tochigi, 320-0834, Japan.
4 Department of Pathology, Keio University School of Medicine, Tokyo, 160-8582, Japan.