1. Unit of Pediatric Orthopedics and Traumatology, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy
2. Department of Industrial Engineering, Alma Mater Studiorum University of Bologna, 40136 Bologna, Italy
3. Unit of Pediatric Orthopedics and Traumatology, Nuovo Ospedale “Santo Stefano”, 59100 Prato, Italy