1 Department of Orthopaedic Surgery & Rehabilitation, Yamagata University Faculty of Medicine, 2-2-2 Iida-Nishi, Yamagata, Japan. takakubo-y@med.id.yamagata-u.ac.jp.
2 Department of Orthopaedic Surgery, Yamagata University Faculty of Medicine, Yamagata, Japan.
3 Department of Orthopaedic Surgery, Yamagata Saisei Hospital, Yamagata, Japan.