1. Division of Orthopaedic Surgery, Oslo University Hospital, Oslo, Norway;
2. Institute of Clinical Medicine, University of Oslo, Oslo, Norway;
3. Department of Radiology, Oslo University Hospital-Radiumhospital, Oslo, Norway;
4. Department of Pathology, Oslo University Hospital-Radiumhospital, Oslo, Norway;
5. Cancer Registry of Norway, Oslo, Norway;
6. Department of Pathology, Haukeland University Hospital, Bergen, Norway;
7. Department of Pathology, St Olav’s Hospital, University Hospital of Trondheim, Trondheim, Norway;
8. Department of Oncology, Oslo University Hospital-Radiumhospital, Oslo, Norway