1. Department of Orthopaedic Surgery; Keio University School of Medicine; Tokyo; Japan
2. Department of Surgical Pathology; Sapporo Medical University School of Medicine; Sapporo; Japan
3. Department of Orthopaedic Surgery; Tokyo Dental College Ichikawa General Hospital; Ichikawa; Japan
4. Division of Diagnostic Pathology; Keio University School of Medicine; Tokyo; Japan