1. Arcus Sportklinik, Pforzheim, Germany.
2. University Witten/Herdecke, Witten, Germany.
3. Orthopädische Klinik Markgröningen, Abteilung Sportorthopädie, Markgröningen, Germany.
4. Department of Trauma and Orthopaedic Surgery, Division of Orthopaedics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
5. University of Cologne, Cologne, Germany.