1. Department of Traumatology and Orthopedic Surgery, Río Hortega University Hospital, 47012 Valladolid, Spain
2. Institute of Orthopedic Surgery and Traumatology (ICOTVA), Hospital Sagrado Corazón, 47002 Valladolid, Spain
3. Department of Traumatology and Orthopedic Surgery, Clínico University Hospital, 47003 Valladolid, Spain
4. Department of Neurosurgery, Clínico University Hospital, 47003 Valladolid, Spain