1. Department of Orthopaedics and Trauma Surgery, University of Duisburg-Essen, Mülheim, Germany
2. Department of Neurology, Heinrich-Heine-University, Düsseldorf, Germany
3. Department of Orthopedics and Orthopedic Rheumatology, St. Elisabeth-Hospital Meerbusch-Lank, Meerbusch-Lank, Germany
4. Department of Orthopedics, Trauma and Reconstructive Surgery, University of Duisburg-Essen, Mülheim, Germany