1. Department of Orthopedics and Trauma Surgery, Faculty of Medicine, Medical Center—University of Freiburg, 79106 Freiburg, Germany
2. Comprehensive Cancer Center Freiburg (CCCF), Faculty of Medicine, Medical Center—University of Freiburg, 79106 Freiburg, Germany
3. Clinical Trials Unit, Faculty of Medicine, Medical Center—University of Freiburg, 79106 Freiburg, Germany
4. Department of Neurosurgery, Faculty of Medicine, Medical Center—University of Freiburg, 79106 Freiburg, Germany