1. Faculty of Medicine, Department of Orthopaedics and Rehabilitation, Jagiellonian University, Zakopane, Poland
2. Faculty of Medicine, Department of Pediatric Neurosurgery, Jagiellonian University, Krakow, Poland
3. Department of Orthopaedics, Division of Pediatric Orthopaedics, Umeå University Hospital, Umeå, Sweden