1. Department of Orthopaedic Surgery, School of Medicine, Jichi Medical University, Shimotsuke, Japan.
2. Division of Public Health, Center for Community Medicine, Jichi Medical University, Shimotsuke, Japan.
3. Department of Infection Control, School of Medicine, Jichi Medical University, Shimotsuke, Japan.
4. Division of Infectious Diseases, Tokyo Metropolitan Children's Medical Center, Tokyo, Japan.
5. Gunma Sports Medicine Research Center, Zenshukai Hospital, Maebashi, Japan.