1. Department of Pediatric Orthopedic Surgery and Traumatology, University Children’s Hospital, Medical University of Bialystok, Waszyngtona 17, 15-274 Bialystok, Poland
2. Paley European Institute, Al. Rzeczypospolitej 1, 02-972 Warsaw, Poland
3. Department of Orthopedics and Traumatology, Helsinki University Hospital, 00260 Helsinki, Finland
4. Department of Neurosurgery, University of North Carolina, Chapel Hill, NC 27516, USA