1. Department of Orthopedics and Trauma Surgery, University Hospital of Cologne, Cologne, Germany
2. Department of Orthopedics, St. Franziskus Hospital, Cologne, Germany
3. Department of Radiology, University Hospital of Cologne, Cologne, Germany
4. Department of Neurophysiology, Center of Biomedicine and Medical Technology Mannheim, Ruprecht-Karls-University Heidelberg, Mannheim, Germany