1. Department of Rehabilitation Medicine, University of Tsukuba Hospital, Tsukuba, Ibaraki, Japan
2. Department of Orthopaedic Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
3. Department of Orthopaedic Surgery, Tsukuba Gakuen Hospital, Kamiyokoba, Tsukuba-shi, Ibaraki, Japan
4. Department of Cardiovascular Surgery, University of Tsukuba Hospital, Tsukuba, Ibaraki, Japan
5. Department of Orthopaedic Surgery, Ibaraki Prefectural University of Health Sciences, Ami-city, Inashiki-gun, Ibaraki, Japan
6. Department of Orthopaedic Surgery, Kikkoman General Hospital, Noda, Chiba, Japan