1. Department of Neurosurgery, Yongin Severance Hospital, Yonsei University School of Medicine, Yongin;
2. Department of Neurosurgery, Spine and Spinal Cord Institute, Severance Hospital, Yonsei University College of Medicine, Seoul;
3. Department of Neurosurgery, Bundang Jesaeng Hospital, Seoul;
4. Department of Neurosurgery, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea;
5. Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan;
6. Department of Spine Surgery, Beijing Jishuitan Hospital, the 4th Teaching Hospital of Peking University, Beijing;
7. Department of Orthopaedics and Traumatology, LKS Faculty of Medicine, The University of Hong Kong, China;
8. Department of Orthopedic Surgery, Columbia University College of Physicians and Surgeons, New York;
9. Department of Neurological Surgery, Weill Cornell Medical College, Cornell University, New York, New York;
10. Department of Neurosurgery, University of Florida, Gainesville, Florida; and
11. POSTECH Biotech Center, Pohang University of Science and Technology, Pohang, Gyeongbuk, Korea