1. Department of Orthopedics and Traumatology, Helsinki University and Helsinki University Hospital, Helsinki, Finland
2. Department of Orthopedics and Traumatology, Oulu University Hospital, Oulu, Finland
3. Department of Pediatric Surgery, Kuopio University Hospital, Kuopio, Finland
4. Department of Orthopaedics and Traumatology, Rovaniemi Central Hospital, Rovaniemi, Finland