1. Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
2. Department of Clinical Epidemiology and Biostatics, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
3. Department of Preventive Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
4. Department of Orthopedic Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.