1. Department of Orthopaedic and Trauma Surgery; Campus Bio-Medico University of Rome; Via Alvaro del Portillo 200 00128 Rome Italy
2. Department of Animal Medicine; Productions and Health; University of Padua; Legnaro Italy
3. Neurosurgery Division, Department of Neuroscience; University of Padua; Padua Italy
4. AO Research Institute Davos; Clavadelerstrasse 8 7270 Davos Switzerland