1. SportClinic Zurich Hirslanden Clinic, Zurich, Switzerland
2. University of Schleswig-Holstein, Campus Luebeck, Luebeck, Germany
3. Sportklinik Ravensburg, Ravensburg, Germany
4. Universitat Regensburg, Bad Abbach, Germany
5. Motier, Switzerland
6. IRCCS Istituto Ortopedico Galeazzi, Milano, Italy
7. Humanitas Hospital, Rozzano, Milano, Italy
8. University Campagna Luigi Vanvitelli, Roma, Italy
9. Private Practice for Joint Surgery, Berlin, Germany
10. OrthoPraxis, Zofingen, Switzerland
11. Consult AG Statistical Services, Zurich, Switzerland