1. Department of Orthopaedic Surgery and Traumatology, Hôpital Fribourgeois HFR Cantonal Hospital, Zurich, Switzerland
2. Department of Hip Surgery, Schulthess Clinic, Zurich, Switzerland
3. Department of Paediatric Orthopaedics, Schulthess Clinic, Zürich, Switzerland
4. Department of Orthopaedic Surgery and Traumatology, Hôpital Fribourgeois HFR Cantonal Hospital, University of Fribourg, Fribourg, Switzerland
5. University of Bern, Bern, Switzerland