1. Department of Orthopaedics Shanghai Key Laboratory for Prevention and Treatment of Bone and Joint Diseases Shanghai Institute of Traumatology and Orthopaedics Ruijin Hospital Shanghai Jiao Tong University School of Medicine Shanghai 200025 P. R. China
2. Department of Orthopaedics Shanghai Jiao Tong University Affiliated Sixth People's Hospital Shanghai Jiao Tong University Shanghai 200233 P. R. China
3. Departments of Radiology and Medical Physics University of Wisconsin Madison WI 53705 USA
4. Department of Interventional Radiology Ruijin Hospital Shanghai Jiao Tong University School of Medicine Shanghai 200025 P. R. China