1. Department of Orthopaedic Surgery, Kangwon National University College of Medicine, Chuncheon, Korea.
2. Department of Orthopaedic Surgery, Armed Forces Yangju Hospital, Yangju, Korea.
3. Department of Orthopaedic Surgery, Dankook University College of Medicine, Cheonan, Korea.
4. Department of Orthopaedic Surgery, Sun General Hospital, Daejeon, Korea.
5. Department of Orthopaedic Surgery, Chamjoeun Hospital, Gwangju, Korea.
6. Department of Orthopaedic Surgery, National Police Hospital, Seoul, Korea.
7. Department of Orthopaedic Surgery, Uijung-bu Chuk Hospital, Uijung-bu, Korea.
8. Spine Center and Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Sungnam, Korea.