1. Department of Orthopedic Surgery, School of Medicine, Ajou University, Suwon, Korea.
2. Department of Biostatistics, The Catholic University of Korea, Seoul, Korea.
3. Psychometric and Research Services, Harcourt Assessment Inc., San Antonio, Texas, U.S.A.
4. Department of Orthopedic Surgery, College of Medicine, Ewha Womans University, Seoul, Korea.
5. Department of Orthopedic Surgery, College of Medicine, Yonsei University, Seoul, Korea.
6. Department of Orthopedic Surgery, Wonju College of Medicine, Yonsei University, Wonju, Korea.