1. Department of Orthopedic Surgery, National University College of Medicine, Seoul, Korea.
2. Department of Orthopedic Surgery, Chung-Ang University College of Medicine, Seoul, Korea.
3. Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea.
4. Department of Orthopedic Surgery, Gyeongsang National University School of Medicine, Jinju, Korea.