1. Department of Orthopaedic Surgery, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Korea.
2. Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Neurosurgery, Hallym University Sacred Heart Hospital, Hallym University College of Medical, Anyang, Korea.
4. Washington University Orthopedics, BJC Institute of Health at Washington University School of Medicine, Chesterfield, MO, USA.