1. Department of General and Trauma Surgery, BG University Hospital Bergmannsheil, Ruhr-University Bochum, Bochum, Germany
2. Hansjörg Wyss Hip and Pelvic Center, Swedish Hospital, Seattle, Washington, USA
3. Seattle Science Foundation, Seattle, Washington, USA
4. Swedish Neuroscience Institute, Swedish Medical Center, Seattle, Washington, USA
5. Clinic for Special Orthopaedic and Trauma Surgery, Vivantes Auguste Viktoria Hospitals, Berlin, Germany