1. Department of Orthopaedics, Heidelberg University Hospital, Schlierbacher Landstrasse 200a, 69118 Heidelberg, Germany
2. Institute of Medical Biometry and Informatics, University of Heidelberg, Im Neuenheimer Feld 305, 69120 Heidelberg, Germany
3. Diakonie Klinikum Stuttgart, Rosenbergstraße 38, 70176 Stuttgart, Germany