1. Surgical Institute of Tucson, United States; Fundación Universitaria Sanitas Bogotá, Colombia; Universidade Federal do Estado do Rio de Janeiro, Brazil
2. Universitaetsmedizine Berlin,, Germany
3. University of Tbilisi
4. Universitaetsmedizine Berlin,, Germany; University of Tbilisi
5. Wirbelsäulenzentrum / Spine Center