1. Department of Anaesthesiology; Aarhus University Hospital; Aarhus Denmark
2. Division of Clinical and Functional Anatomy; Department of Anatomy, Histology and Embryology; Medical University of Innsbruck; Innsbruck Austria
3. Department of Orthopaedic Surgery; Aarhus University Hospital; Aarhus Denmark
4. Department of Anaesthesiology; Zealand University Hospital; University of Copenhagen; Roskilde Denmark