1. Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden
2. Department of Orthopaedics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sweden
3. Swedish Hip Arthroplasty Register, Gothenburg, Sweden
4. Department of Orthopaedics, Prince Philip Hospital, HDUHB, Wales
5. Coxa Hospital for Joint Replacement, Tampere, Finland
6. Finnish Arthroplasty Register, Helsinki, Finland