1. Department of Clinical Medicine, University of Bergen, Norway;
2. Julius Wolff Institute, Charité—Universitätsmedizin Berlin, Germany;
3. The Norwegian Arthroplasty Register, Department of Orthopaedic Surgery, Haukeland University Hospital, Bergen, Norway;
4. Haugesund Hospital, Haugesund, Norway
5. Orthopedic Department, Baerum Hospital, Vestre Viken Hospital Trust, Norway;
6. Department of Mechanical Engineering, Imperial College London, UK;