1. Valdoltra Orthopaedic Hospital Department of Spine Surgery, , Jadranska cesta 31, 6280 Ankaran , Slovenia
2. University of Ljubljana Faculty of Medicine, , Vrazov trg 2, 1000 Ljubljana , Slovenia
3. University of Maribor Faculty of Medicine, , Taborska ulica 8, 2000 Maribor , Slovenia
4. University of Ljubljana Faculty of Medicine, , Vrazov trg 2, 1000 Ljubljana, Slovenia