**12. Aknowledgements**

We thank the research fund of the Department of Orthopaedic and Trauma Surgery of the Hospital of the University of Heidelberg for the financial support of the study. Furthermore, we would like to thank the motion analysis team of the University of Heidelberg, especially Petra Armbrust and Waltraud Schuster, for the practical support during the study.[Level of Evidence : Level III, Case-Control Study, Treatment Study.
