1. Hospital St Agustín and School of Medicine, 33400 Oviedo, Spain
2. Orthopaedic Surgery and Traumatology Institute, 08009 Barcelona, Spain
3. Hospital of Cartagena, 30203 Murcia, Spain
4. Hospital of Cabueñes and School of Medicine, 33394 Oviedo, Spain
5. Hospital Costa del Sol, 29603 Marbella, Spain
6. Hospital Sabogal, Colina 1081, Bellavista-Callao, Peru