1. Department of Pediatric Surgery and Orthopedics University of Turku and Turku University Hospital Turku Finland
2. Department of Orthopedics and Traumatology University of Helsinki and Helsinki University Hospital Helsinki Finland
3. Department of Biostatistics University of Turku and Turku University Hospital Turku Finland
4. Information Services Department Finnish Institute for Health and Welfare Helsinki Finland
5. Department of Neurobiology Care Sciences and Society, Karolinska Institute Stockholm Sweden
6. Department of Pediatric Surgery Kuopio University Hospital Kuopio Finland