1. Institute for Research in Operative Medicine (IFOM), Faculty of Medicine; University of Witten/Herdecke; Cologne; Germany
2. Pain Research Center, Department of Anesthesiology; University of Utah; Salt Lake City; UT; USA
3. Department of Sociology; Chemnitz University of Technology; Chemnitz; Germany
4. Department of Trauma and Orthopedic Surgery; University of Witten/Herdecke, Cologne-Merheim Medical Center (CMMC); Cologne; Germany
5. Department of Neurosurgery; University of Witten/Herdecke, Cologne-Merheim Medical Center (CMMC); Cologne; Germany
6. Centre for Ambulant Surgery; Cologne; Germany
7. Department of Anesthesiology and Intensive Care Medicine; University Hospital Witten/Herdecke; Cologne; Germany