1. 1Foot and Ankle Unit, Orthopaedic Department, Hospital Universitario de Canarias, Tenerife, Spain
2. 2School of Medicine, Universidad de La Laguna, Tenerife, Spain
3. 3Foot and Ankle Unit, Complejo Hospitalario Universitario de Badajoz, Badajoz, Spain
4. 4Specialty Doctor Trauma and Orthopaedics, George Eliot Hospital NHS Trust, Nuneaton, UK
5. 5Schmerzklinik, Basel, Switzerland
6. 6University of Basel, Basel, Switzerland
7. 7Foot and Ankle Unit, Hospital Universitario Virgen del Rocío, Sevilla, Spain
8. 8School of Medicine, Universidad de Sevilla, Sevilla, Spain