1. Department of Orthopaedics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, SE-41345 Gothenburg, Sweden.
2. Joint and Soft Tissue Unit, Department of Clinical Sciences, Department of Orthopaedics, Lund University, Sk̊ne University Hospital, SE-20502 Malmö, Sweden.
3. Swedish Hip Arthroplasty Register, Registercentrum VGR, SE-41345 Gothenburg, Sweden.