1. University Hospital Marburg, Center for Orthopedics and Traumatology, Marburg, Germany;
2. Sydney Orthopaedic Research Institute, Chatswood, Australia;
3. University Hospital St. Etienne, Department of Orthopaedic Surgery, Saint-Priest-en-Jatez, France;
4. Orthomedic Frankfurt Offenbach, Offenbach, Germany