1. Department of Trauma and Orthopedic Surgery, Cologne-Merheim Medical Center, WittenHerdecke University, Ostmerheimer Street, 200, 51109 Cologne, Germany
2. Department of Orthopedic Surgery, University of Münster, Albert-Schweitzer-Straße 33, 48149 Muenster, Germany
3. Department of Clinical Radiology, University of Münster, Albert-Schweitzer-Straße 33, 48149 Muenster, Germany