1. Department of Orthopaedic Surgery, Spine Service, Columbia University College of Physicians and Surgeons, New York, NY, USA.
2. Department of Neurosurgery, Spine Center, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
3. Departments of Orthopedic Surgery, Wooridul Spine Hospital, Seoul, Korea.
4. Department of Orthopaedic Surgery, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
5. Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.