1. Department of Trauma and Orthopeadic Surgery, University Medical Center Hamburg-Eppendorf, Martinistr. 52 20246 Hamburg, Germany
2. Department of Trauma Surgery and Orthopeadics, Pediatric Orthopeadics, Agaplesion Diakonieklinikum Rotenburg, Elise-Averdieck-Str. 17, 27356 Rotenburg (Wümme), Germany
3. Department of Trauma Surgery, Orthopeadics and Sports Traumatology, BG Hospital Hamburg, Bergedorfer Str. 10, 21033 Hamburg, Germany
4. Department of Trauma and Orthopeadic Surgery, Katharinenhospital Klinikum Stuttgart, Kriegsbergstr. 60 70714 Stuttgart, Germany