1. Department of Trauma, University Hospital Zurich, Zurich, Switzerland
2. Department of Hip and Knee Surgery, Schulthess Clinic, Zurich, Switzerland
3. Orthopaedic Research Unit, University of Cape Town, Cape Town, South Africa
4. Institute for Research in Operative Medicine (IFOM), Witten/Herdecke University, Cologne, Germany
5. Faculty of Medicine, University of Zurich, Zurich, Switzerland
6. Department of Trauma, Hirslanden Clinic St. Anna and University of Lucerne, Lucerne, Switzerland