1. Department of Orthopaedics and Trauma Surgery, Faculty of Medicine, University Clinics, University of Cologne, Cologne, Germany
2. Department I of Internal Medicine, Faculty of Medicine, University Clinics, University of Cologne, Cologne, Germany
3. Department of Orthopaedics and Trauma Surgery, Helios Klinikum Hildesheim, Hildesheim, Germany
4. Department of Orthopedics, Trauma and Reconstructive Surgery, University Hospital RWTH Aachen, Aachen, Germany