1. Department of Plastic and Reconstructive Surgery, University of Essen, 445122 Essen, Germany
2. Department of Plastic Surgery, University of Witten Herdecke, Campus Cologne, 51067 Cologne, Germany
3. Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California 90033
4. Department of Plastic and Reconstructive Surgery, Medical School Hannover, 30625 Hannover, Germany