1. Department of Orthopaedic Surgery, Nordsjaellands Hospital, University of Copenhagen, Hilleroed, Denmark.
2. Department of Clinical Research, Nordsjaellands Hospital and Section of Biostatistics, Institute of Public Health, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
3. Department of Anaesthesia and Intensive Care, Nordsjaellands Hospital, University of Copenhagen, Hilleroed, Denmark.
4. Department of Orthopaedic Surgery, Zealand University Hospital, Department of Clinical Medicine, University of Copenhagen, Koege, Denmark.