1. Division of Medical Bioengineering and Sports Medicine, Department of Advanced Surgery, Hokkaido University School of Medicine, Sapporo
2. Department of Orthopaedic Surgery, Hakodate Central General Hospital, Hakodate, Japan
3. Department of Orthopaedics and Rehabilitation, University of Vermont College of Medicine, Burlington, Vermont
4. Section of Sports Medicine, Department of Surgical Science, Karolinska Institute, Stockholm, Sweden