1. Department of Orthopedic Surgery, Saitama City Hospital, Saitama 2460, Mimuro Midori-ku, Saitama-shi, Saitama, Japan
2. Department of Orthopedic Surgery, Saiseikai Yokohamashi Tobu Hospital, 3-6-1, Shimosueyoshi, Tsurumi-ku, Yokohama-shi, Kanagawa, Japan
3. Department of Orthopedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, Tokyo, Japan