1. Department of Orthopaedic Surgery, Ajou University School of Medicine, Suwon 16499, Republic of Korea
2. Department of Orthopaedic Surgery, Soonchunhyang University Bucheon Hospital, Bucheon 14584, Republic of Korea
3. Department of Orthopedic Surgery, Spine Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Republic of Korea
4. Department of Statistics and Actuarial Science, Soongsil University, Seoul 06978, Republic of Korea
5. Department of Orthopedics, Korea University Hospital, Ansan 15355, Republic of Korea