1. Department of Ankle and Foot Surgery, IRCCS Instituto Ortopedico Galeazzi, Milan, Italy.
2. Department of Orthopedics, University of Milan, Milan, Italy.
3. Department of Statistics, Carlo Besta Neurological Institute, Milan, Italy.
4. Department of Orthopedics, Cuggiono Hospital, Cuggiono, Italy.
5. Department of Orthopedics, IRCCS Galeazzi, Milan, Italy.
6. Department of Pediatric Orthopedics, IRCCS IRCCS Instituto Ortopedico Galeazzi, Milan, Italy