1. Department of Orthopaedic Surgery, Seoul National University, College of Medicine, 28 Yeonkeon-dong, Chongro-gu, Seoul 110-744, Korea.
2. Department of Orthopaedic Surgery, Dongguk University College of Medicine Ilsan Hospital, 814 Siksadong, Donggu, Ilsan, Goyang, Korea.
3. Department of Orthopaedic Surgery, Eulji University, College of Medicine, 1306 Dunsan-dong, Seo-gu, Daejeon 302-799, Korea.