Long Shao1, Xiang-Dong Wu2, Wei Huang3. 1. Department of Orthopaedic Surgery, Ningbo No. 6 Hospital, Ningbo, Zhejiang, China. 2. Department of Orthopaedic Surgery, Peking Union Medical College Hospital, Beijing, China. 3. Department of Orthopaedic Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China.