1. Department of Molecular Medicine and Surgery, Section of Orthopaedics
2. Capio AB, St Görans Hospital, SE-11281, Stockholm, Sweden.
3. Department of Medicine, Unit of Clinical Epidemiology, Karolinska Institutet, Karolinska University Hospital, Solna, SE-171 76 Stockholm, Sweden.
4. Department of Orthopaedics Lund University Hospital, SE-22185, Lund, Sweden.