[1] University Hospital of Cologne,Department of Orthopedic and Trauma Surgery
[2] Medical Center City Aachen GmBH,Department of Orthopedics
[3] University Hospital of Cologne,Department of Radiology
[4] University Hospital of Cologne,Institute of Medical Statistics, Informatics and Epidemiology
[5] Vinzenz-Pallotti Hospital,Department of Trauma, Orthopedic and Hand Surgery
[6] KLINIK am RING,Department of Spine Surgery