1Department of Orthopedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
2Department of Orthopedics, Tokyo Dental College Ichikawa General Hospital, 5-11-13 Sugano, Ichikawa City, Chiba 272-8513, Japan
3Department of Diagnostic Pathology, Saiseikai Yokohama Tobu Hospital, 3-6-1 Shimosueyoshi, Tsurumi Ward, Yokohama, Kanagawa 230-8765, Japan
4Department of Pathology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
5Department of Orthopaedic Surgery, Gifu University School of Medicine, 1-1 Yanagido, Gifu, Gifu 501-1194, Japan
6Department of Orthopedic Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan