1. Department of Orthopaedic Surgery, Yonsei University College of Medicine, 250 Seongsan-no, Seodaemun-gu, Seoul 120-752, Republic of Korea.
2. Department of Orthopaedic Surgery, Bundang CHA Hospital, CHA University, Bundang-gu, Seongnam-si, Gyeonggi-do, 463-712, Republic of Korea.