1. Department of Orthopaedic Surgery, Murayama Medical Center, National Hospital Organization, 2-37-1 Gakuen Musashimurayama, Tokyo 208-0011, Japan
2. Nursing Department, Murayama Medical Center, National Hospital Organization, 2-37-1 Gakuen Musashimurayama, Tokyo 208-0011, Japan
3. Department of Orthopaedic Surgery, National Defense Medical College, 3-2 Namiki Tokorozawa, Saitama 359-8513, Japan