1. Department of Orthopaedic Surgery; Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku; Tokyo 162-8666 Japan
2. Department of Orthopaedic Surgery, Surgical Science; Tokai University School of Medicine, 143 Shimokasuya; Isehara Kanagawa 259-1193 Japan
3. Transgenic Animal Research Center; National Institute of Agrobiological Sciences, 2 Ikenodai; Tsukuba Ibaraki 305-0901 Japan
4. Department of Pathology and Microbiology Faculty of Medicine; Saga University, 5-1-1 Nabeshima; Saga 849-8501 Japan