1. Department of Orthopedic Surgery, Diakonhjemmet Hospital, Oslo, Norway
2. Center for Treatment of Rheumatic and Musculoskeletal Diseases (REMEDY), Diakonhjemmet Hospital, Oslo, Norway
3. The Norwegian Arthroplasty Register, Department of Orthopaedic Surgery, Haukeland University Hospital, Bergen, Norway
4. The Norwegian Medial Association, Bergen, Norway
5. Department of Clinical Medicine, University of Bergen, Norway