1. Oslo Sports Trauma Research Center, Norwegian School of Sport Sciences, Oslo, Norway
2. National Knee Ligament Registry, Bergen, Norway
3. Norwegian Arthroplasty Register, Department of Orthopaedic Surgery, Haukeland University Hospital, Bergen, Norway
4. University Research Bergen, Department of Health, Bergen, Norway
5. Orthopaedic Center, Ullevaal University Hospital and Faculty of Medicine, University of Oslo, Oslo, Norway