1. Children’s Hospital, University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland
2. Research Institute Orton, Orton, Helsinki, Finland
3. Department of Medicine, Division of Rheumatology, Helsinki University Central Hospital and University of Helsinki, Helsinki, Finland
4. Orton Orthopaedic Hospital, Orton, Helsinki, Finland
5. Department of General Practice and Primary Health Care, University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland