1. Department of Orthopaedic Surgery, Cheong-ju St. Mary’s Hospital, 589-5, Jujung-dong, Sangdang-gu, Cheong-ju 360-568, Chungcheongbukdo, South Korea.
2. Department of Orthopaedic Surgery, Korea University Anam Hospital, College of Medicine, Korea University, Anam-dong 5-Ga, Seongbuk-gu, Seoul 136-705, South Korea.
3. Department of Orthopaedic Surgery, Asan Medical Center, College of Medicine, Ulsan University, 388-1, Pungnap-2-dong, Songpa-gu, Seoul 138-736, South Korea.