1. School of Mechanical Engineering and Automation, Beihang University, Beijing, China;
2. Department of Orthopaedic Surgery, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Science, Beijing, China;
3. Orthopaedic Department, Peking University Third Hospital, Beijing, China;
4. Department of Orthopaedic Surgery, The First Affiliated Hospital of Soochow University, Jiangsu, Suzhou, China