1. Research Department, Spine Centre of Southern Denmark, Hospital Lillebaelt, Middelfart, Denmark
2. Institute of Regional Health Research, University of Southern Denmark, Odense, Denmark
3. King Christian X Hospital for Rheumatic Diseases, Graasten, Denmark
4. Department of Radiology, Aarhus University Hospital, Aarhus, Denmark
5. Copenhagen Centre for Arthritis Research, Centre for Rheumatology and Spine Diseases, Glostrup, Denmark
6. Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
7. Department of Medicine, Hospital Lillebaelt, Vejle, Denmark
8. Department of Rheumatology, Aarhus University Hospital, Aarhus, Denmark