1. Shizuoka Tokusyukai Hospital, 1-11 Surugaku-Simokawahara-Minami, Shizuoka 421-0117, Japan
2. Department of Orthopedic Surgery, Akita University Graduate School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan
3. South Akita Orthopedic Clinic, Seiwakai, 96-2 Kaidousita, Syowa-Ookubo, Katagami 018-1401, Japan