1. Department of Psychosomatic Medicine and Psychotherapy, University Hospital of Cologne, Cologne, Germany
2. Martin Luther University of Halle-Wittenberg, Halle, Germany
3. Centre for Ambulant Surgery, Cologne-Merheim Medical Center (CMMC), Cologne, Germany
4. Hospital for Pain and Palliative Medicine, Klinikum St-Marien-Hospital, Amberg, Germany
5. Department of Neurosurgery
6. Institute for Research in Operative Medicine, University of Witten/Herdecke, Witten, Germany
7. Department of Trauma, Hand and Foot Surgery, St. Martinus Hospital, Langenfeld, Germany