1Department of Orthopedic Surgery, Kikkoman General Hospital, Noda, Chiba Prefecture, Japan
2Department of Orthopedic Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki Prefecture, Japan
3Department of Orthopedic Surgery, Tokyo Medical University Ibaraki Medical Center, Inashiki, Ibaraki Prefecture, Japan
4Department of Orthopedic Surgery, Moriya Daiichi General Hospital, Moriya, Ibaraki Prefecture, Japan