Tetsuya Nemoto1, Yasuhito Tajiri2, Junichi Iijima2. 1. Department of Orthopedic Surgery, Tokyo Metropolitan Hiroo Hospital, 2-34-10 Ebisu, Shibuya, 150-0013, Tokyo, Japan. Electronic address: t-nemoto@grad.showa-u.ac.jp. 2. Department of Orthopedic Surgery, Tokyo Metropolitan Hiroo Hospital, 2-34-10 Ebisu, Shibuya, 150-0013, Tokyo, Japan.