1. Department of Orthopaedics, Institute of Clinical Sciences, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden;
2. Department of Orthopaedics, Skaraborgs Hospital, Lidköping, Sweden;
3. Swedish Hip Arthroplasty Register, Gothenburg, Sweden;
4. Research and Development Centre, Skaraborgs Hospital, Skövde, Sweden
5. Department of Orthopedics, Hywel Dda University Healthboard, Prince Philip Hospital, Bryngwynmawr, UK;