1. Emory University, Atlanta, GA, USA
2. USC Spine Center, Los Angeles, CA, USA
3. Spine Colorado, Durango, CO, USA
4. BG Klinikum Bergmannstrost, Halle, Germany
5. University of Utah, Salt Lake City, UT, USA
6. Uijeongbu St. Mary’s Hospital, Catholic University of Korea, Uijeongbu-si, Korea