1. University Multiprofile Hospital for Active Treatment, Trakia University, 6003 Stara Zagora, Bulgaria
2. AO Research Institute Davos, 7270 Davos, Switzerland
3. Department of Orthopaedics, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
4. Department for Health, University of Bath, Bath BA2 7AY, UK
5. Bulgarian Academy of Sciences, Institute of Metal Science ‘Acad. A. Balevski’, 1574 Sofia, Bulgaria
6. University Hospital Zurich, 8091 Zurich, Switzerland
7. Department of Orthopaedics and Traumatology, Faculty of Medicine, Medical University Varna, 9002 Varna, Bulgaria