1. Centre for Anaesthesiological Research, Department of Anesthesiology Zealand University Hospital Køge Denmark
2. Department of Anaesthesia and Intensive Care Copenhagen University Hospital Bispebjerg and Frederiksberg Denmark
3. Department of Clinical Medicine University of Copenhagen Copenhagen Denmark
4. Research Centre of Anaesthesiology and Intensive Care Medicine, Department of Anesthesiology Næstved, Slagelse, and Ringsted Hospitals Næstved Denmark
5. Department of Orthopedic Surgery Zealand University Hospital Køge Denmark
6. Department of Orthopedic Surgery and Traumatology Odense University Hospital Odense Denmark
7. Department of Orthopedic Surgery and Traumatology Copenhagen University Hospital Bispebjerg Copenhagen Denmark
8. Copenhagen Trial Unit, Centre for Clinical Intervention Research Copenhagen University Hospital, Rigshospitalet Copenhagen Denmark
9. Department of Regional Health Research, The Faculty of Health Sciences University of Southern Denmark Denmark