1. Department of Orthopaedic Surgery, Kikkoman General Hospital, Noda 278-005, Chiba, Japan
2. Department of Diagnostic and Interventional Radiology, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Ibaraki, Japan
3. Department of Orthopaedic Surgery, Tokyo Medical University Ibaraki Medical Center, Ami 300-0395, Ibaraki, Japan