1. Department of Paediatric Orthopaedic Surgery, Turku University Hospital, Turku, Finland
2. Department of Paediatric Orthopaedic Surgery, University of Turku and Turku University Hospital, Turku, Finland
3. Department of Anaesthesia and Critical Care, University of Turku and Turku University Hospital, Turku, Finland
4. Department of Orthopaedic Surgery, Spine Unit, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark