1. Spine Center and Department of Orthopaedic Surgery, Seoul National University College of Medicine and Seoul National University Bundang Hospital, Seongnam, Korea.
2. Department or Orthopaedic Surgery, Spine Center, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.
3. Department of Orthopaedic Surgery, Chamjoeun Hospital, Gwangju, Korea.
4. Department of Orthopaedic Surgery, Korea University Ansan Hospital, Korea University College of Medicine, Ansan, Korea
5. Department of Orthopaedic Surgery, Yeson Hospital, Bucheon, Korea.