1. Department of Orthopaedics, Changhai Hospital, the Naval Medical University, Shanghai 200433, China
2. Department of Neurosurgery, Yuquan Hospital, Tsinghua University, Beijing 100040, China
3. Department of Anatomy, the Second Military Medical University, Shanghai 200433, China
4. Department of Orthopaedics, Jingmen No. 2 People's Hospital, Jingmen 448000, China
5. Department of Orthopaedics, Qinhuangdao Workers' Hospital, Qinhuangdao 066200, China
6. Department of Orthopaedics, Tangshan No. 2 Hospital, Tangshan 063000, China
7. Department of Orthopaedics, Jiaxing Armed Police Force Hospital, Jiaxing 314000, China
8. Department of Neurosurgery, Yantai Hospital, Binzhou Medical University, Yantai 264100, China
9. Department of Anatomy, Binzhou Medical University, Binzhou 256600, China
10. Department of Neurosurgery, North China University of Science and Technology AffiliatedHospital, Tangshan 063000, China
11. Department of Orthopaedics, Tengzhou Central People's Hospital, Tengzhou 277500, China
12. Department of Orthopaedics, Jiangsu Armed Police General Hospital, Yangzhou 225003, China
13. Department of Orthopaedics, the 180th Hospital of PLA, Quanzhou 362008, China