1 Department of Spine Surgery, The Second Xiangya Hospital, Central South University, Changsha, 410011, China.
2 Department of Spine Surgery, The Second Xiangya Hospital, Central South University, Changsha, 410011, China; Musculoskeletal Tumor Center, Peking University People's Hospital, Peking University, Beijing, 100044, China. Electronic address: xcbowen@foxmail.com.