1. Department of Anaesthesiology Centre for Anaesthesiological Research Zealand University Hospital Zealand Region of Denmark Koege Denmark
2. Copenhagen Spine Research Unit (CSRU) Section of Spine Surgery Center of Rheumatology and Spine Diseases Rigshospitalet Denmark
3. Department of Orthopedic Surgery Zealand University Hospital Zealand Region of Denmark Koege Denmark
4. Department of Health Sciences Faculty of Medicine Lund University Lund Sweden
5. Department of Anaesthesiology at the Juliane Marie Centre Copenhagen Denmark