1. University of California at Los Angeles, Los Angeles, CA, USA
2. University of Southern California, Los Angeles, CA, USA
3. Bergmannstrost Hospital, Halle, Germany
4. University of Utah School of Medicine, Salt Lake City, UT, USA
5. Emory Spine Center, Atlanta, GA, USA
6. Durango Orthopedic Associates, P.C./Spine Colorado, Durango, CO, USA
7. Uijongbu St. Mary’s Hospital, Catholic University of Korea School of Medicine, Uijongbu, Korea