1. Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N;
2. Department of Orthopaedic Surgery, Lillebaelt Hospital, Vejle;;
3. Department of Regional Health Research, University of Southern Denmark;
4. Danish Hip Arthroplasty Register;
5. Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, Denmark;
6. Department of Clinical Research, University of Southern Denmark, Denmark