Jae Hoon Ahn1, Won-Sik Choy, Ha-Yong Kim, Han-Soo Kim. 1. Department of Orthopaedic Surgery, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Seocho-gu, Seoul, 137-040, South Korea. jahn@catholic.ac.kr