1. a Leiden University Medical Center, Leiden, The Netherlands;
2. b Royal Orthopaedic Hospital, Birmingham, United Kingdom;
3. c Istanbul Tip Fak Capa-FATIH, Istanbul, Turkey;
4. d University Medical Centre Groningen, Groningen, The Netherlands;
5. e Clinica Universitaria de Navarra, Pamplona, Spain;
6. f Hôpital Cochin, Paris, France;
7. g Radboud University Medical Centre, Nijmegen, The Netherlands;
8. h Department of Orthopaedic Surgery, Medical University of Graz, Graz, Austria;
9. i Klinik und Poliklinik für Allgemeiner Orthopädie Uniklinik Münster, Münster, Germany;
10. j Inselspital, University of Bern, Bern, Switzerland;
11. k Hotel-Dieu, Nantes, France;
12. l Orthopaedic Oncology Unit, Azienda Ospedaliera Universitaria Careggi, Firenze, Italy;
13. m Institut d'Hématologie et d'Oncologie Pediatrique, Lyon, France