1. Department of Orthopaedic Surgery, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany
2. Biomechanics Laboratory Department of Sport and Movement Sciences, University of Duisburg-Essen, Essen, Germany
3. Department of Orthopaedic Surgery, Physical Medicine and Rehabilitation, University Hospital of Munich, München, Germany
4. Department of Pathology, Ruhr-University Bochum, Bochum, Germany