1. Department of Sports Medicine and Joint Surgery, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan
2. Katsura Veterinary Hospital, Sapporo, Hokkaido, Japan
3. Department of Orthopaedic Surgery, Yokohama City University School of Medicine, Yokohama, Kanagawa, Japan
4. Department of Orthopedic Surgery, Faculty of Medicine, University of the Ryukyus, Nishihara, Okinawa, Japan