1. Scripps Clinic, La Jolla, CA, USA
2. San Diego Spine Foundation, San Diego, CA, USA
3. University of California, San Francisco, CA, USA
4. University of Pittsburgh Medical Center, Pittsburgh, PA, USA
5. Cedars-Sinai, Los Angeles, CA, USA
6. University of Michigan, Ann Arbor, MI, USA
7. Louisiana Spine Institute, Shreveport, LA, USA
8. University of South Florida, Tampa, FL