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