1. Department of Orthopaedics 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. Swedish Neuroscience Institute Swedish Medical Center Seattle Washington USA
4. Seattle Science Foundation Seattle Washington USA
5. Department of Orthopaedics and Trauma Surgery University Hospital Dresden Dresden Germany