Department of Orthopedic Surgery, Stem Cell and Regenerative Medicine Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81, Irwon-ro, Gangnam-gu, Seoul, South Korea. Department of Orthopedic Surgery, Chung-Ang University Hospital, Chung-Ang University College of Medicine, 102, Heukseok-ro, Dongjak-gu, Seoul, South Korea. Department of Orthopedic Surgery, Gangnam Severance Hospital, Yonsei University College of Medicine, 211, Eonju-ro, Gangnam-gu, Seoul, South Korea. Department of Orthopedic Surgery, School of Medicine, Kyungpook National University, 130, Dongdeok-ro, Jung-gu, Daegu, South Korea. Department of Orthopedic Surgery, Chonbuk National University Hospital, Research Institute of Clinical Medicine, Chonbuk National University Medical School, 20, Geonji-ro, Deokjin-gu, Jeonju-si, Jeollabuk-do, South Korea. Department of Orthopedic Surgery, Ewha Womans University Mockdong Hospital, 1071, Anyangcheon-ro, Yangcheon-gu, Seoul, South Korea. Department of Orthopedic Surgery, National Health Insurance Corporation Ilsan Hospital, 100, Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do, South Korea. Department of Orthopedic Surgery, Hanyang University College of Medicine, 222-1, Wangsimni-ro, Seongdong-gu, Seoul, South Korea. Department of Orthopedic Surgery, Busan Paik Hospital, College of Medicine, Inje University, 75, Bokji-ro, Busanjin-gu, Busan, South Korea. Department of Orthopedic Surgery Bundang CHA Hospital, College of Medicine, CHA University, 59, Yatap-ro, Bundang-gu, Seongnam-si, Gyeonggi-do, South Korea. Department of Orthopedic Surgery, KonKuk University Medical Center, KonKuk University School of Medicine, 120-1, Neungdong-ro, Gwangjin-gu, Seoul, South Korea. Department of Orthopedic Surgery, University of Ulsan, College of Medicine, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, South Korea. Department of Orthopaedic Surgery, Seoul National University College of Medicine, 101 Daehak-ro, Jongnogu, Seoul, 110-744, Republic of Korea. leemc@snu.ac.kr.