1. Musculoskeletal Tumour Section, Department of Orthopaedic Surgery, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark;
2. Paediatric section, Department of Orthopedic Surgery, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark;
3. Department of Orthopaedic Surgery, Clinical Orthopaedic Research Hvidovre, Copenhagen University Hospital Hvidovre, Copenhagen, Denmark;
4. Department of Orthopaedic Surgery, Herlev University Hospital, Herlev, Denmark;
5. Department of Orthopaedic Surgery, Nordsjaellands Hospital, Hillerød, Denmark;
6. Department of Orthopaedic Surgery, Bispebjerg and Frederiksberg University Hospital, Copenhagen, Copenhagen, Denmark