1. Presbyterian-University Hospital, Pittsburgh, Pennsylvania (GO)
2. University of Texas Health Sciences Center, Dallas, Texas
3. Allegheny General Hospital, Pittsburgh, Pennsylvania
4. California Spine Surgery Medical Group, Long Beach, California
5. University of California, San Francisco, California
6. University of British Columbia, Vancouver, British Columbia, Canada
7. Gentinella Hospital, Inglewood, California
8. Hospital for Joint Diseases, New York, New York
9. University of Florida Health Science Center, Gainesville, Florida
10. Professional Center, Akron, Ohio
11. University of California-Los Angeles Medical Center, Los Angeles, California
12. North Oakland Neurosurgical Associates, Bloomfield, Michigan
13. Mayfield Neurological Clinic, Cincinnati, Ohio
14. Nashville Orthopaedic Clinic, Nashville, Tennessee
15. Lakewood Orthopedic Clinic, Lakewood, Colorado
16. Texas Back Institute, Plano, Texas
17. Institute for Low Back Care, Minneapolis, Minnesota