1. Department of Orthopaedics, School of Medicine, University of Phayao, Phayao, Thailand
2. Department of Orthopaedic Surgery, Uijeongbu St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Uijeongbu, Korea
3. Department of Mathematics, School of Science, University of Phayao, Phayao, Thailand
4. Department of Orthopaedics, Phramongkutklao Hospital and College of Medicine, Bangkok, Thailand
5. Department of Neurological Surgery, Weill-Cornell Medicine and Department of Orthopedic Surgery, the Och Spine Hospital at New York Presbyterian Hospital, Columbia University, New York, NY, USA