1. Center of Orthopaedics and Traumatology, Brandenburg Medical School Theodor Fontane, University Hospital Brandenburg an der Havel, 14770 Brandenburg an der Havel, Germany
2. Department of Surgical Propaedeutics, Faculty of Medicine, Medical University of Pleven, 5800 Pleven, Bulgaria
3. Faculty of Applied Computer Science, Deggendorf Institute of Technology, 94469 Deggendorf, Germany
4. Department of Surgical Diseases, Faculty of Medicine, Medical University of Pleven, 5800 Pleven, Bulgaria