1. University of Southern California, Los Angeles, CA, USA
2. University of Utah, Salt Lake City, UT, USA
3. Spine Colorado, Durango, CO, USA
4. AO Foundation, Dubendorf, Switzerland
5. Uijongbu St. Mary’s Hospital, The Catholic University of Korea, Uijongbu, Korea
6. Emory University, Atlanta, GA, USA
7. Bergmannstrost Hospital, Halle, Germany