1. Department of Orthopaedic Surgery, Yamagata University School of Medicine, Iida-Nish 2, Yamagata City, 990-9585, Japan.
2. Department of Orthopaedic Surgery, Teine-Keijinkai Hospital, Meada 1-12, Teine-Ku, Sapporo City, 006-8555, Japan.
3. Department of Orthopaedic Surgery, Obihiro-Kousei Hospital, Nishi-6, Minami-8, Obihiro City, 080-0016, Japan.
4. Department of Orthopaedic Surgery, Hokkaido University School of Medicine, Kita-15, Nishi-7, Kitaka, Sapporo City, 060-8638, Japan.