1. The Danish Hip Arthroplasty Register
2. Department of Orthopaedic Surgery, Vejle Hospital, Vejle, Denmark
3. Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark
4. The Swedish Hip Arthroplasty Register
5. Department of Orthopaedics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
6. Lund University, Skåne University Hospital, Department of Orthopedics, Malmö, Sweden
7. The Norwegian Arthroplasty Register, Department of Orthopedic Surgery, Haukeland University Hospital, Bergen, Norway
8. Department of Clinical Medicine, University of Bergen, Bergen, Norway
9. The Finnish Arthroplasty Register
10. Department of Orthopaedics and Traumatology, Turku University Hospital, Turku, Finland
11. Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), Adelaide, Australia
12. Department of Surgery, Epworth HealthCare, University of Melbourne, Melbourne, Australia
13. The National Joint Registry of England, Wales, Northern Ireland and Isle of Man
14. Centre for Hip Surgery, Wrightington Hospital, Wrightington, Wigan and Leigh NHS Trust, Lancashire, United Kingdom
15. Orthopaedic Research Unit, Department of Clinical Research, University of Southern Denmark, Odense, Denmark
16. Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, Odense, Denmark