1. Department of Orthopaedic Surgery, Wakamatsu Hospital of University of Occupational and Environmental Health, 1-17-1, Hamamachi, Wakamatsu, Kitakyushu, Fukuoka 808-0024, Japan
2. Premier Hip Arthroscopy, Marina Del Ray, CA, USA
3. University of Occupational and Environmental Health, Kitakyushu, Japan