1Department of Orthopaedic Surgery Tsukuba Memorial Hospital 1187‐299 Kaname 300‐2622 Tsukuba Ibaraki Japan
2Department of Orthopaedic Surgery, Faculty of Medicine, University of Tsukuba, 1-1-1Tennodai, Tsukuba, Ibaraki, 305-8575, Japan
3Department of Orthopaedic Surgery, Tsukuba Memorial Hospital, 1187-299 Kaname, Tsukuba, Ibaraki, 300-2622, Japan